Another fuel injector install aftermath question Yippee!!

WeaponX

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Mar 23, 2019
212
Pittston, PA
Thought I’d add some humor to it cause god knows I need it with this headache smh!
Anyway I found I had one bad injector in the lot of new ones I bought so I swapped it out with an old one (for anyone following this saga of mine the throttle body was fine the person watching if it opened and closed has no car knowledge and god knows what she was looking at so my bad in picking a bad helper). So it started fine and ran fine with no codes, I just went out to the store about 2 hours later and first it had trouble starting but did then when I pushed the pedal all the way down it bogged down and almost died but didn’t and did it two other times as well.
My question is I cleaned the hell out of the ports on the side of the block cause they were covered in sludge so could it be it’s just burning off the throttle body cleaner? Could there still be or is there air in the lines from when I changed the injectors and depressurized The fuel system? Could it just be I need to build the pressure back up? Is it because there is one old one with 5 news ones and they aren’t working properly in sync?
Like I said there are no codes, no lights and I apologize for all the questions but this is the very first time I have ever changed fuel injectors in any vehicle and honestly I’m so sorry I did because it just seems to have spawned more headaches but I’m glad I have all you guys in my corner!
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
My question is I cleaned the hell out of the ports on the side of the block cause they were covered in sludge so could it be it’s just burning off the throttle body cleaner?

It's possible but unless it was puddles of it, it shouldn't be that bad and should burn off fairly quickly.

Could there still be or is there air in the lines from when I changed the injectors and depressurized The fuel system? Could it just be I need to build the pressure back up?

No. Any air would bleed out right away. The system depressurizes itself slowly every time you shut it off for hours so it's a normal process. It primes the system each time you start it.

Is it because there is one old one with 5 news ones and they aren’t working properly in sync?

It is a little possible that the one old injector might be flowing more or less than the new ones but I doubt it's the cause of your issues.

Have you checked the fuel pressure?
 
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WeaponX

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Mar 23, 2019
212
Pittston, PA
Nope mainly cause I have no idea how. I’m assuming there is a gauge to do this but until next week I’m tapped out so I wouldn’t be able to check until then.
As far as the amount of cleaner trust me when I tell you I was very liberal and used a lot! It was so think and caked on (the slug that is) that it literally looked liked tar and I can say I easily used two cans while the injectors were still not installed, I’d spray those holes out then a flood of black fluid came out the air ports so using the word puddles to describe the amount I used would be an accurate assessment lol
 

mrrsm

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Somewhere along the line... we (The Collective GMT Nation Mind) should have suggested that before you do anything more to this machine, you should probably post up your what your precise intentions are back here first before actually trying out any unfamiliar procedures. The concern I have right now is that; If I am interpreting your latest clean up actions correctly, after removing the Intake Manifold and observing all of the Oil Sludge that got ingested through the Intake-Throttle Body from the PCV Tube in the Valve Cover, you rightly suspected that it would be a Good Idea to wipe out and clean up all of the Open Intake Ports (those 3 Figure 8 Shaped areas).

However... It becomes problematic if you were Dumping in Copious Amounts of Straight Liquid Solvent-Cleaner down inside of them... Two Cans worth, as you mentioned... because the Intake Valves are just beyond and right below those Ports and at the time you were doing this activity, they were in varying positions of being either Opened, Closed ...or Somewhere In-Between as (6) Pairs of Valves ...meaning (2) Intake Valves Per Cylinder as arrayed along the Upper Driver's Side of the Block.

If that Straight Liquid was literally getting Dumped Down In There... This can present you with a very precarious situation if you managed to fill the volumes of each of the (6) Cylinders with substantial amounts of that Solvent-Fluid. If you then Cranked the Engine Over after re-installing the Intake Manifold, you ran the serious risk of Bending One or more Connecting Rods due to a condition called:

Engine Hydro-Lock

This is an Exemplar from a Hydro-Locked DuraMax Engine where the Fuel Injector Stayed OPEN... and the Rotating Assembly had to Yield to the Physical Forces of Hydraulic Pressure inside the Upper Cylinder:

HYDROLOCKEDDURAMAX.jpg


The Physics involved here are well-known to you and provable within your own experience. This is a Phenomena which your very life depends upon each every time you Step on The Brake Pedal and rely upon the Brake Fluid Pressure to consistently apply a Squeezing Force against your Brake Pads and Stop your Vehicle.

The very same Physics apply in this instance of Cleaning Out the Intake Ports inside of the Engine Head as ALL Liquids are INCOMPRESSIBLE. So when the "Irresistible Force Of Rising Pistons" meets the "Immovable Object of the Trapped Liquid Hydraulic Pressure" ... During the action of resistance between these two events, the Connecting Rods will LOSE that Battle and start to BEND ...each and every time. So If the presence of that Liquid Solvent was unable to escape the Compression created in all (6) Cylinders and "Put The Squeeze" on them... it can result in "Bye Bye Motor...".

However... If you have been fortunate enough to have used used a Solvent Spray with a sufficiently High Level of VOCs (Volatile Organic Compounds) that had enough time and exposure to the Open Air to Evaporate... then you might have dodged a 105mm Howitzer Artillery Round Sized Problem and escaped the Engine Destruction caused by the Mechanical Advantage of a Starter Gear working with 650 Cold Cranking Amps while turning the Flex-Plate Outer Ring Gear and Power Rotating the Engine Fast and Hard enough to Bend Connecting Rods.

Beyond that... is the other problem that if the copious amounts of Solvent somehow DID manage to slip by and ooze out of the OTHER (6) Pairs of Exhaust Valves and into the Exhaust Manifold... that Liquid would have nowhere else to go but wind up draining down inside of the Catalytic Converter. Once inside of the CAT; even if only present for a brief period, it can Flash Burn at Very High Temperatures and cause damage to the Ceramic Honeycomb Rare Earth Impregnated Cores inside.

The "Rough Running" you spoke of could be that the CAT has not had a sufficient amount of time to Burn Off the Solvent Residue and is giving the O2 Sensor(s) fits. If you managed to somehow sidestep all of these issues after your Engine managed to ingest (2) Cans of Liquid Solvent...and run properly...then you are A Very Lucky Man!

By the way... Your Profile indicates this Engine as being a 4.3L V6 Engine.

As per @Mooseman 's Suggestion... For taking a Fuel Pressure Reading on the 2005 and Later Trailblazers and Envoys:

Unless there is a Hidden Fuel Line Schrader Valve inside the Engine Bay I'm not aware of... and while I am NOT happy with this VOP's (Video Original Poster's "Catch as Catch Can" Method for creating the means to Measure the Fuel Pump Pressure ...it obviously WILL WORK.

What he shows here is his use of the Main FUEL- IN Line Quick Dis-Connect and an Adapter Nylon Connector he chopped off of an Old Fuel Pump. Then he used a length of 3/8" Rubber Fuel Line to connect things via S/S Hose Clamps to the"Freon-cum-Fuel" Gauge. He then Keyed the Ignition ON and OFF several times to observe and record these actions with his Digital Camera as the Fuel Pressure gradually rose ...and then suddenly Fell Off due to an apparent Bad Check Ball or some other Fuel Pump Failure.

THIS SHOULD ONLY BE ATTEMPTED BY A COMPETENT MECHANIC USING A PROPER FUEL GAUGE AND HOSE KIT AND HAVING AN "ABC" FIRE EXTINGUISHER AT HAND!


His Follow Up Video Reveals the Actual Problem and Clever Fix for It:

 
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Maverick6587

Member
Dec 16, 2018
730
Sterling Heights, Michigan
@MRRSM Wonderful writeup, thank you!

@WeaponX After reading what MRRSM wrote. I would take all of the spark plugs out, unplug the fuel pump relay (relay #41), put a large cloth/towel over the spark plug ports (to ensure fluids do spray EVERYWHERE), and then crank the engine over for a second or two. This would ensure that all liquids get pushed out of the cylinders.

You can also rent a fuel pressure gauge from a local parts store or Harbor Freight has them for $19.

Also, in your previous thread, you stated that your throttle body was not working. Did you or another person actually see it not moving while one of you depressed the accelerator pedal? I just want to make sure we know what is working and what is not.
 
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Mooseman

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Dec 4, 2011
25,262
Ottawa, ON
I would check the fuel pressure before going any further. Could be a bad fuel pump or pressure regulator.

I gotta ask, what was the reason for replacing the injectors?
 
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WeaponX

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Mar 23, 2019
212
Pittston, PA
It was another person watching it. When I finally had the smarts to say, u start it I’ll watch the throttle body worked fine.
As far as the cat goes I don’t have one. It plugged up about a month ago so for the intern I cut it out (new exhaust on the way) and just put a piece of pipe in place for the time being.
The rough running is only here and there, every once in awhile when I push the gas all the way to the floor (curious to see if the new injectors made a difference) it would bog right down like it was going to stall but doesn’t and only once when I turned it over did it crack longer than usually before it started.
I’ll take out the plugs and relay now cause I have to step out soon and when I come back later tonight I’ll post what happens and hopefully I dodged that huge tank sized bullet because w me if it isn’t bad luck I have no luck at all. I hope to god it’s just the one odd ball injector that’s causing all of this smh
Thanks everyone!
P.S. I have a 4.2 I must have hit the 3 by mistake, sorry about that
 

WeaponX

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Mar 23, 2019
212
Pittston, PA
I would check the fuel pressure before going any further. Could be a bad fuel pump or pressure regulator.

I gotta ask, what was the reason for replacing the injectors?
Because I had a loud ticking coming from the engine and after reports from a couple mechanics who looked at it they said it’s either a bad or noisy injector.
As of now the noise has greatly gone down but I still have one old injector in so I can’t say if all this fixed what I was going after just yet
 

WeaponX

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Mar 23, 2019
212
Pittston, PA
Also I just thought about this my truck has a TB on it right now from the junk yard not the original. I put it on after the fact I was told on TB #3 it wasn’t opening but before I looked myself. Anyway I plan on putting my old one back on but the junk yard one was also cleaned b4 I installed it so it’s not all Funke’s up.
Just a though that maybe from sitting for so long that it isn’t operating the way it should?
 

WeaponX

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Mar 23, 2019
212
Pittston, PA
Well went for a ride. It started fine the both times I started it but when I hit the gas hard it did bog down again but pulled itself out of it and even did it once when I was in reverse but other than that it is running better than it did before the new injectors and house cleaning I did of all the sludge. I haven’t switched the TB out to my old one but plan on doing so and will post an update it just to me minus the couple of hiccups it’s running to good for something major to be wrong (I say that while my fingers and toes are crossed and holding a rosary lol)?
 

Maverick6587

Member
Dec 16, 2018
730
Sterling Heights, Michigan
O2 sensors are not yet my forte but, would the downstream O2 seeing a "failing/failed/missing" CAT and run the system too rich/lean and be causing his issues?

@WeaponX when did you remove the catalytic converter? Also, how long before or after that did your current issue start?
 

WeaponX

Original poster
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Mar 23, 2019
212
Pittston, PA
It started after the install of the new injectors but I do get a code before them it was running to rich/lean b4 the instal so maybe the combination of the two? It’s just so frustrating because other than the once in awhile it acts up it’s running great smh
 

WeaponX

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Mar 23, 2019
212
Pittston, PA
Now I just drove up a hill and nothing worked fine as supposed to b4 it trailed to stall maybe I’m slowly but surely burning all the fluid out.
aim going out on a limb here but I’m assuming if I had that hydro lock I’d be in trouble and walking by now since I’m assuming it happens fairly early?
 

mrrsm

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I'm going to slide out onto that very same Limb with you just long enough to coax you back towards what has already been figured out for us ALL and Nailed it Down to the 'Tree Trunk' .by @Mooseman... Twice:

Post # 2

"Have you Checked the Fuel Pressure?"


Post # 7

"I would Check the Fuel Pressure before going any further. Could be a Bad Fuel Pump or Pressure Regulator..."

The Bogging sensation you feel COULD be a Problem With the Fuel Delivery.. .Starting with Testing the Fuel Pressure with the Engine Ignition Keyed On/Off several times and then Start the SUV and Monitor the Fuel Pressure through a wider range of RPM. The Diagnostic "Tree" will always lead you back to having to Perform THIS Fuel Pressure Test.

You are looking for SUDDEN DROP OFFS IN FUEL PRESSURE just after the Ignition Key is Turned OFF. And You are observing How Long the Engine Cranks...Before Starting. If it takes 10-20 Seconds to Start and Run. This will strongly indicate a Problem with the Fuel Pump... Fuel Pressure Regulator....A Bad Fuel Pump Motor...or a combination of ALL Three conditions.

Have your "Helper" following your Explicit Instructions to "Turn The Key ON ...Turn The Key OFF... Step On The Gas... Step Off of The Gas..." while you keep your eyes peeled and looking closely at ALL of the Fuel Pressure Gauge Responses under ALL of these Test Conditions. You simply cannot get past this point until you have definitive proof that the Fuel Pump either IS ...or IS NOT "The Problem".
 
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Mounce

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Mar 29, 2014
13,667
Tuscaloosa, AL
Highly doubt he had any hydro lock conditions as those cleaners flash off rather fast by themselves. Now, junk washed into the cylinders and onto the pistons? Yeah probably. But the cleaner likely evaporated before he got the intake reinstalled.

I'm more questioning the new injectors, already had one bad out of the box, who's to say the other 5 are flowing right?
 
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Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Post # 2

"Have you Checked the Fuel Pressure?"


Post # 7

"I would Check the Fuel Pressure before going any further. Could be a Bad Fuel Pump or Pressure Regulator..."

Agreeing with myself.

Highly doubt he had any hydro lock conditions as those cleaners flash off rather fast by themselves.

Agreed. It wouldn't have even turned over right after the intake install if that was the case.

I'm more questioning the new injectors, already had one bad out of the box, who's to say the other 5 are flowing right?

That is another thing I would suspect. What brand are they? New? Rebuilt? The OEM injectors in these trucks are not a high failure rate part, only having heard of an actual failure once or twice. It would have been the last thing I would suspect. Apart from the ticking, was there any other symptom? Ticking in that area would usually be a lifter. There are tests to determine injector function and any shop worth their salt would have been able to do a test called an Injector Balance Test.
 
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WeaponX

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Mar 23, 2019
212
Pittston, PA
Well I went to a garage by me that I know the owner so they did the fuel pressure test for me and everything showed up perfect like it should (mind u on my way there not one issue), went to auto zone to check the codes (totally slipped my mind while at the garage) the codes are it’s running to rich/lean and I have a massive exhaust leak which I knew since the car is off and the pipe doesn’t match perfect.
As soon as I start to drive home it bogs down then once more pulling into the driveway but it is running far longer than before when it has its first issue.
I’m going to unplug the plugs and the fuel pump and turn it over a few times like what was recommended to me previously and see what happens and put the original TB back on.
 

WeaponX

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Mar 23, 2019
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Pittston, PA
Forgot, no other issues besides the ticking which I fully believe the mechanic who told me knows less than me since although it seems quieter it’s still there
 

WeaponX

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Mar 23, 2019
212
Pittston, PA
Found the issue and boy do I feel like an idiot lol. The one sensor that is in my cold air intake arm I guess I decided that the truck would be better off not hooking it up because it was just laying there as I forgot to connect it and never even saw it was off smh.
Anyway I went for a ride and all seems fine it even for the first time ever that I know of is idling at a flat 1k it was before all this usually at 600 so I’m assuming that’s a good thing and probably because there is no restrictions on the air since everything is clean and has clear flow.
I did however create another issue for myself. When re installing one of the coils the bolt snapped in the block so not only is part of the bolt lodged in the block but the coil is loose which I jimmy rigged for now to hold it in place, the coil that is just have no clue how the hell im going to get the rest of that bolt out of the block smh I can’t just have one project go easy for me it always leads to another one.
Anyway for now the issue of the bogging down seems to be fixed I’ll report if it comes back but I am curious is the truck now that it is Idling at 1k rather than around 600 a good thing? Thanks guys u have no idea how much help you have been and how much i app it!!
 

WeaponX

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Mar 23, 2019
212
Pittston, PA
And yes the original throttle body is back on and I cycled it threw a few times without the plugs and relay for the fuel pump
 

mrrsm

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Not to put too fine of a point on it... but unfortunately, whenever we forget to ask up front about any "After-Market Equipment" being installed on 'Troubled Trailblazers', it usually happens that we find out about them ..."After-Wards" when they come back to bite us. I'm Guilty of forgetting to ask about this possibility more often than most. Your situation here is an Object Lesson in Reminding me to Remember to Ask that Question about AM Equipment more often and at the outset of these investigations. :>(

Hopefully... You won't experienc any more Bogged Down Engine Power Problems disguised by having Non-OEM Equipment going 'sideways'.
 

WeaponX

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Mar 23, 2019
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Pittston, PA
Well it seems I was wrong again as it’s bogging down once again. I’m lost at this point since everything seems to check out the only thing it could be now is a bad batch or mid matched injectors. I’m out of ideas
 

Mooseman

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Dec 4, 2011
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Ottawa, ON

mrrsm

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Well... with the prior "Liquid Solvent" issue... It seems like a good time to perform a Compression Test; which will be remarkably straightforward with this GM 4.2L Atlas Inline Six Cylinder Engine. Here are the Orders of Operation:

(1) Obtain an Inexpensive Compression Tester Kit from Harbor Freight.
(2) Obtain an OTC "Trigger Activated Remote Starter Cable" from Amazon or AutoZone.
(3) Follow the Instructions on Hooking Up the Two "Trigger-Starter Button" Wire Connections.
(4) Pull out the Fuel Pump Relay. LEAVE THE IGNITION KEY OUT OF THE IGNITION.
(5) Carefully Unplug the Ignition Harness Connectors and Unbolt-Remove all of the Coil On Plugs.
(6) Use some "Canned Air" to Blow Out any Debris or Dirt from within the Spark Plug Wells.
(7) CAREFULLY... Unscrew each Spark Plug and KEEP THEM ORGANIZED 1->6.
(8 "Read" each Plug Electrode...Look for a "Nice, Fried-Chicken Brown" Tan-Tope Color.
(9) Gently Thread in the Compression Test Hose into Cylinder #1 (Work from Front to Back).
(10) Connect the Compression Hose to the Compression Gauge. Set the Parking Brake.
(11) Depress the "Trigger Button" to Turn the Engine Over & get Readings on the Gauge.
(12) Perform this Test DRY for ALL Cylinders 1st... Then squirt in a JUST a Few Drops of Motor Oil.
(14) Repeat (9-11) as a WET Compression Test on ALL (6) Cylinders...Front to Back.
(15) record the Readings for EACH DRY-WET COMPRESSION TEST FOR EACH CYLINDER.
(16) CAREFULLY.... Re-Thread in ALL Spark Plugs and TORQUE them to SPEC...
(17) Re-Install the COPs (Coil On Plugs) DO NOT OVER-TIGHTEN THE SMALL COP BOLTS!
(18) Re-Connect up the COP Harness Connections correctly.
(19) Re-Install the Fuel Pump Relay.
(20) Start the Engine at IDLE... Do NOT Race The Engine... there will be some Exhaust Smoke.
(21) Shoot a Brief Video of How the Engine Runs at Idle and Pan the Camera all Over the Area.

Harbor Freight Compression Tester Kit Link:


HFCOMPRESSIONTESTERKIT.jpg

Amazon "OTC Starter Button Trigger Switch and Cables" Unit:


OTCSTARTERBUTTONTRIGGER_.jpg

Then... Organize your Compression Test Results...and POST the List back here... And Keep your Fingers XXXXed.
 
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m.mcmillen

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Apr 29, 2016
554
Wisconsin
but I am curious is the truck now that it is Idling at 1k rather than around 600 a good thing

What does it idle at after it warms up? Higher idle when it is cold is ok but when it warms up it should be around 600-700 RPM if I recall correctly. If it stays at 1,000 RPM all the time either something is going on with your throttle body or you have a vacuum leak.

It would also be helpful if you posted the actual code number instead of the description of the code.
 

WeaponX

Original poster
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Mar 23, 2019
212
Pittston, PA
It’s running at 1k constantly so I have something new to look for although I might know where to go, the hose on the manifold itself that goes from bottom to top was as hard as a rock and I had to move it to get to the one bolt on the manifold so there is a great chance it’s bad, I meant to replace it but didn’t because I had no hose at the time of the re install.
ill see what I can get done today and re post. The injectors are referbs which should have meant they were tested b4 sold but I guess not but they are sending me a new set, can’t wait to take that all apart again I’m so excited lol
 

WeaponX

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Mar 23, 2019
212
Pittston, PA
What does it idle at after it warms up? Higher idle when it is cold is ok but when it warms up it should be around 600-700 RPM if I recall correctly. If it stays at 1,000 RPM all the time either something is going on with your throttle body or you have a vacuum leak.

It would also be helpful if you posted the actual code number instead of the description of the code.
This did start to happen when I put the original TB back on it was fine when I had the one on out of the junk yard
 

gmcman

Member
Dec 12, 2011
4,656
Looking at your injector threads, I'm trying to get an understanding of the sequence of events leading up to the injector change.

I saw where the mechanic heard the ticking...and was the engine running good or bad at that time?

Do you have the Torque App? Can you get us a list of the codes?

As far as fuel pressure, what was the pressure with the engine off, and the pressure with the engine running? Also how long did it hold pressure with the engine turned off?

I know you said they checked this, but something isn't adding up and we need to know those values.
 

WeaponX

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Mar 23, 2019
212
Pittston, PA
I will get the codes but I’m not going to lie I know how to fix a lot but a lot of what I’m doing to the TB I’m learning as I go.
This is everything sits as of now,
The truck still idles at 1k and before the new injectors it was about 6-700 so I’m assuming it’s because of the new injectors with a lot better flow idk? But ALL the new injectors are in now, throttle body, intake manifold and the ports on the block are spotless clean!
It’s running great actually the only issue I’m having now is at times (mostly when hot) I’m having trouble starting it but it does start it just feels like it doesn’t want to which I had an issue similar to this with a GTI I owned and it was the starter going bad so I’m thinking that’s the issue here.
There has been no bogging down, no lose of power (other than how horrible my exhaust is which is getting fixed in 2 weeks).
The other issue that might be causing the trouble starting is I had to take off two coils to get to the bottom bolts of the throttle body well one of the long bolts for the coil snapped in the block and I have yet to tap it and pull it out so the one coil pack is not bolted in I had to jimmy rig a set up to keep it on so I’m also thinking that because that coil isn’t bolted down that maybe the contact isn’t what it should be or because of not being bolted in it’s not grounded?
So as of now to break it down quicker
-having trouble starting (mostly when hot)
-idle is at 1k and maybe that’s ok?
-snapped bolt for one coil pack in the block so it’s not bolted properly.
Guys like I said I’m really teaching myself a lot on this truck so if I don’t describe something right or don’t know what your trying to say please be patient with me. I went to school for mobile electronics so I have some back ground but a lot of this stuff is brand new to me so even this I’m 43 a lot of my IQ on this stuff is 10 lol. So again I really appreciate all the help I really do and I know you guys are but please be patient with me because there is a lot I’m still ignorant to
 

mrrsm

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Empirical Learning on the GM 4.2L LL8 Engine can become a “Harsh Mistress”. Without knowing to what extent you had to go to make the Temporary Repair work… These two Threads cover the BEST way to UNFUBAR the situation for around $50.00 and this method WILL return the condition of the Stripped Thread Lines for the COP Fasteners back to OEM Factory New:

https://gmtnation.com/forums/threads/how-to-repair-stripped-out-coil-on-plug-fasteners.20017/

https://gmtnation.com/forums/threads/ignition-coils.20015/
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Do you have a link to where you got the injectors? Seems to me that your troubles started when you changed them. Other than the ticking, was there any other engine issues?

1000 RPM at idle is NOT normal. Should be around 650. You need some diagnostic tools to read live data from the PCM. A Bluetooth OBD2 adapter and the Torque app for Android will allow you to get data for different parameters like the O2 sensor and fuel trims. Otherwise, we're just shooting in the dark.

And you need to get your fuel pressure checked or check it yourself. You can rent for free from most parts stores a fuel pressure testing kit or HF has them for ~$20. It's a good tool to have.

This video will help with how to use it. Just ignore what he does with the pressure regulator since you don't have one (it's built into the fuel pump in the tank)


We would need to know what your pressure is when you prime it, if it holds that pressure for a few minutes, when idling and at 2-3000 RPM. It should be between 50-57 PSI.
*** Please be careful when attaching the pressure gauge's hose to the valve on the fuel rail. It's in an awkward position and any strain on that valve WILL crack the rail. Ask me how I know.
 

WeaponX

Original poster
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Mar 23, 2019
212
Pittston, PA
Actually I thought back, whenever I would fill my tank and when I say fill I mean all the way up the next cause I try to pack it in right before this repair it had a hell of a time starting the first time after I filled up now it’s doing the same thing just intermittently and still after I fill up.
It’s running great not one issue at all with bogging down loss of power nothing the only issues I’m having is at start up. Could my pump be on it’s way out or could the filter be muked up?
All 6 new injectors are now in and no codes have appeared other than exhaust related due to my cat being removed.
 

WeaponX

Original poster
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Mar 23, 2019
212
Pittston, PA
Actually I thought back, whenever I would fill my tank and when I say fill I mean all the way up the next cause I try to pack it in right before this repair it had a hell of a time starting the first time after I filled up now it’s doing the same thing just intermittently and still after I fill up.
It’s running great not one issue at all with bogging down loss of power nothing the only issues I’m having is at start up. Could my pump be on it’s way out or could the filter be muked up?
All 6 new injectors are now in and no codes have appeared other than exhaust related due to my cat being removed.
I meant neck not next sorry
 

gmcman

Member
Dec 12, 2011
4,656
And you need to get your fuel pressure checked or check it yourself.

I agree 100%.

We need more info...could be a bad fuel pump, or old plugs/coils. The plugs and coils wouldn't cause a high idle, but a hard start when cold. I don't feel that's the issue though, points more to a fuel issue. @2001ZR2 just went through a very similiar scenario and it was his fuel pump.
 

WeaponX

Original poster
Member
Mar 23, 2019
212
Pittston, PA
I agree 100%.

We need more info...could be a bad fuel pump, or old plugs/coils. The plugs and coils wouldn't cause a high idle, but a hard start when cold. I don't feel that's the issue though, points more to a fuel issue. @2001ZR2 just went through a very similiar scenario and it was his fuel pump.
My plugs and coils were just replaced and have maybe 3k miles on them. I’m thinking maybe the issue was there before (like when I said I had issues starting it the first time after a fill up) and then when I ran the pressure out to replace the injectors I furthered the issue the fuel pump was already starting to have.
It seems it has more of an issue starting hot then when it’s cold
 

gmcman

Member
Dec 12, 2011
4,656
Well, a fuel pressure test is definitely needed. Another area that could be a culprit is the oil pressure sending switch. I don't know if the PCM needs a signal from the switch to allow the motor to start, so I'm only guessing.

I know some late 80's GM vehicles exhibited a hard start when hot and would crank for about 2-3 seconds before the motor would fire.

So if that's the case, I wonder if the oil pressure switch would delay the signal to keep the engine from firing right away when the oil is hot. Again, I don't even know if our PCM's use that info while cranking.
 

WeaponX

Original poster
Member
Mar 23, 2019
212
Pittston, PA
Well, a fuel pressure test is definitely needed. Another area that could be a culprit is the oil pressure sending switch. I don't know if the PCM needs a signal from the switch to allow the motor to start, so I'm only guessing.

I know some late 80's GM vehicles exhibited a hard start when hot and would crank for about 2-3 seconds before the motor would fire.

So if that's the case, I wonder if the oil pressure switch would delay the signal to keep the engine from firing right away when the oil is hot. Again, I don't even know if our PCM's use that info while cranking.
I just changed that as well about a month ago cause it was leaking really bad even right threw the plug.
 

WeaponX

Original poster
Member
Mar 23, 2019
212
Pittston, PA
Just a thought what about changing the fuel filter, I’m sure it’s a good idea anyway since I’m willing to bet it has never been changed and since I ran pressure out of the system a couple times for this project maybe junk got lodged. Also what about the sensor on top of the air intake manifold? I had to move it to do this work maybe the moving around caused it to break. Both parts are cheap so either way I don’t think it will hurt
 

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