Still have issues at idle

[Inferno333]

Good afternoon gents!

I'm sure you're all tired of seeing my ongoing issues with my 06 TB 5.3L. I assure you that I am too!

Basic history: A DoD lifter broke back in November and I had a kit from PCM installed to eliminate the DoD. I've had continuous issues with a rough idle and a slight misfire below 1000rpm on cylinder #7.

Fast forward to six days ago. I changed the oil and put a bottle of Techron cleaner in the tank. After that was done it began to idle pretty rough again and have a lot of hesitation taking off from a stop. I started troubleshooting by spraying a soapy mixture around the injectors and intake to see if there were any leaks. I kept hearing a hissing noise from the area around injector #3. I verified that all the intake manifold bolts were tight and fiddled with the injectors that are able to turn some on bank #1. Nothing seemed to change anything. I used a bit of throttle body cleaner around the bank #1 injectors and thought I heard the rpms increase a little when sprayed around #7.

I'm ready to have this thing fixed. I cannot have my wife driving a vehicle around that doesn't run correctly since she works overnights. What can I do?

My train of thought is to replace the plugs, wires, injectors, and intake manifold gasket. I'm pretty mechanically inclined so it shouldn't be a problem to do in my driveway. Are there any special tools that I'll need for this?

What say you gents? You've got a lot more experience with this platform than I do. Do any of you live near Omaha, NE? Would a video of the engine running be helpful?

Sidebar: Do I need to get an additional plugin for Torque to see the realtime misfire count per cylinder?

 

[Mooseman]

When you repaired the lifter problem, what was replaced? Looked up the kit and it doesn't talk about the cam. If you kept the DoD cam, that is your trouble for the constant idle problems. I remember reading on another forum that initially, a kit supplier said it was fine to keep the DoD cam but later had to eat crow when they were proven wrong. The cam has to be replaced with a non-DoD cam.

A compression test will eliminate any lifter or valve issues. Intake gaskets have been known to fail on these engines which may be the leak.

Edit: Here's some info I found on the cam:
http://ls1tech.com/forums/generation-iv-internal-engine/1692395-looking-advice-l76-dod-delete.html

Edit2: Here's the vendor in question and it states quite clearly "A non-DOD camshaft is required!"
http://www.texas-speed.com/p-717-dod-afm-delete-kit.aspx

 

[Inferno333]

When you repaired the lifter problem, what was replaced? Looked up the kit and it doesn't talk about the cam. If you kept the DoD cam, that is your trouble for the constant idle problems. I remember reading on another forum that initially, a kit supplier said it was fine to keep the DoD cam but later had to eat crow when they were proven wrong. The cam has to be replaced with a non-DoD cam.

A compression test will eliminate any lifter or valve issues. Intake gaskets have been known to fail on these engines which may be the leak.

Edit: Here's some info I found on the cam:
http://ls1tech.com/forums/generation-iv-internal-engine/1692395-looking-advice-l76-dod-delete.html

Edit2: Here's the vendor in question and it states quite clearly "A non-DOD camshaft is required!"
http://www.texas-speed.com/p-717-dod-afm-delete-kit.aspx

This is the parts list that I got from PCM. It was supposed to include a 2006 Trailblazer SS Stock Cam, but it was out of stock for over a week so I went with a 5.3L non-DoD truck cam.

(2) 5.3L Head Gasket
(2) OEM GM Head Bolt Sets
(1) Timing Chain Damper
(2) Water Pump gaskets
(1) Timing Cover Gasket
(1) Timing Cover Seal
(1) Lifters
(1) LS3/LS7 Valley Cover
(4) LS2 Lifter Trays
(2) Header Gaskets
(1) LS6 Valley Cover PCV Hose
(1) 5.3L non-DoD truck cam

I remember telling my mechanic to do a compression test a while back when he was trying to figure out the slight misfire issue at idle. He said they were all normal and nothing seemed out of the ordinary when he pulled the valve covers.

How difficult is it to remove the intake and all the fuel related stuff to get at the gaskets?

 

[Mooseman]

I haven't done mine yet but watched a video and it doesn't seem too complicated.

Not the same vehicle but the procedure is the same:

 

[C-ya]

Torque can see individual misfire counts (current and history) just by activating the expanded PID set for GM/Opel. If you have done that, you can see if they are active by adding a gauge (I use digital numeric) and then scrolling through the list of PIDs until you get to the Misfire section. You should see all 8 cylinders with both a current count and a history.

 

[Inferno333]

Torque can see individual misfire counts (current and history) just by activating the expanded PID set for GM/Opel. If you have done that, you can see if they are active by adding a gauge (I use digital numeric) and then scrolling through the list of PIDs until you get to the Misfire section. You should see all 8 cylinders with both a current count and a history.

Thank you! I'll swipe my wife's phone and do this today.

 

[Inferno333]

Is there a big difference in injector quality? It's between the Autoline Reman and the ACDelco OEM. The price difference is $80. We probably won't be keeping the vehicle for an extended period of time. Maybe a couple years.

There's also a few intake manifold gaskets available. ACDelco and Magnum. One of the Magnum brand models has the composite carrier and the other has a steel carrier. The price difference between the ACDelco and Magnum models are $34 and $48.

Does anyone have experience with these other brands?

 

[C-ya]

What kind of warranty does the reman have? I used reman/rebuilt injectors in a couple of friend's Jeep Cherokees back in the mid '90s. They both had the same year and model and both of them had 3 injectors start leaking about the same time. I found them on the early innerweb and fixed both vehicles with no issues. I would imagine a reman'd injector today should have a decent warranty and should be OK to use. See if you can find any reviews of their product.

I would almost rather have a steel carrier for the intake manifold gasket. The issue with the earlier GM V-engines was that gasket. It was made of plastic with the rubber seal. When the plastic broke, the rubber ripped with it and that's when you had a leak. I did my truck (4.3) and a friend's truck (5.7) with whatever Auto Zone had. I can't remember the name, but they were both plastic. They held up until the two vehicles were sold.

 

[Inferno333]

What kind of warranty does the reman have? I used reman/rebuilt injectors in a couple of friend's Jeep Cherokees back in the mid '90s. They both had the same year and model and both of them had 3 injectors start leaking about the same time. I found them on the early innerweb and fixed both vehicles with no issues. I would imagine a reman'd injector today should have a decent warranty and should be OK to use. See if you can find any reviews of their product.

I would almost rather have a steel carrier for the intake manifold gasket. The issue with the earlier GM V-engines was that gasket. It was made of plastic with the rubber seal. When the plastic broke, the rubber ripped with it and that's when you had a leak. I did my truck (4.3) and a friend's truck (5.7) with whatever Auto Zone had. I can't remember the name, but they were both plastic. They held up until the two vehicles were sold.

Looks like the reman and the ACDelco injectors both have a 1 year warranty. I'll start googling the brand and see what I come up with.

I've decided to go with the steel carrier. Just a better design all around.

 

[Inferno333]

While checking for injector reviews I found a rebuild service that has excellent reviews. It actually ends up cheaper that the reman ones even after the core return.

WitchHunter Performance

$22 per injector with all new parts and before/after flow testing provided.

 

[Inferno333]

Rebuilding my injectors is out. Their turnaround time is around seven days and I'm not going to get a rental car for my wife. I'll spend the little extra to get the Autoline remans and be good with it.

I also got the misfiire counter working in Torque. It's exactly like my mechanic said. There's a cylinder #7 misfire at ~1100rpm and down. It goes away above that according to the "Current misfire counter." It runs like shit when idling so I need to get this fixed.

Are there any other suggestions before I buy the injectors, plugs, and intake manifold gaskets?

 

[mrrsm]

Your original post holds the Question...and the Answer when you mentioned the clue that the #7 Cylinder picked up activity when the Fuel Injector Cleaner vapours were nearby. These "Plastic" Intake Manifolds are a Moon-cast Shadow when compared to the alignment plane of the Intake Manifold Gaskets of cast and machined Aluminum Manifolds. This is because their methods of manufacture have a great deal of variation and thus... can be prone to bizarre vacuum leaks that will be a torment.

You can get a more precise pin-point on locating these using a standard Bottle of Propane Gas... turned on at very low velocity and using a screw type nozzle without self-ignition...and then guided closely around the intake flange areas. Excessive vacuum inductions lean out fuel mixtures enough to alter the firing characteristics of of certain cylinders. Also... If the the Spark Plug in #7 reads very lean, pale tan to white and speckling ...then that is just more evidence that too much dirty ambient air is getting into the Fuel-Vapour induction stream.

If you can hear the engine RPMs increase... you will have found one or more places where the Intake Manifold is leaking. Because of the differences in temperature around the Engine Block... finding these can move around a bit from one day to the next because these Intake Manifolds expand and contract in strange ways. Unfortunately... This is not a trivial repair and the vehicle will need the work done when you can have it and not need it for anything for a full day...at least. If you could obtain or get a get a good deal on a Brand New Intake Manifold or one from a later model vehicle... that approach would eliminate the question of any warping in the original one presently installed.

A final Word of Warning... Please get yourself a Brand New, Freshly Charged ABC Fire Extinguisher... and keep it handy when using any open fuel or ultra-volatile injector cleaner vapour around open flames or incandescently hot metal. You don't want to accidentally burn the vehicle and the house down when starting a hunt for vacuum leaks:

And here is a "Paint Can Smoker" that can be used to investigate the problem visually as the smoke get sucked in around the vacuum leaks:

 

[gmcman]

Have you tried swapping coils to see if the misfire follows that coil?

Have you hooked up a vacuum gauge and if so, is the needle rock steady or does it fluctuate?

Have you done a compression test yet?

These things will tell a lot.

 

[Inferno333]

Have you tried swapping coils to see if the misfire follows that coil?

Have you hooked up a vacuum gauge and if so, is the needle rock steady or does it fluctuate?

Have you done a compression test yet?

These things will tell a lot.

Coils - Yep - It didn't follow
I have not. Guess I didn't think of that since EngineLink and Torque never fluctuated much.
I haven't done a compression test. My mechanic did a while back when the issue first popped up. They were all good.

This is not a trivial repair and the vehicle will need the work done when you can have it and not need it for anything for a full day...at least. If you could obtain or get a get a good deal on a Brand New Intake Manifold or one from a later model vehicle... that approach would eliminate the question of any warping in the original one presently installed.

I knew that part. I plan to take an additional day off so I have a longer weekend for this. I'll just have to drive my wife to and from work a night or two.

Looks like a new intake manifold is $136 from RockAuto. Man...It's adding up fast again...

 

[mrrsm]

If you have reasonably exhausted every other less expensive or more logical investigative angle to this problem...and you have to pull the trigger for the New IM...

DON'T UN-BOX IT UNTIL YOU HAVE REMOVED THE ORIGINAL IM AND EXAMINED OR PERFORMED A GOOD AUTOPSY ON WHETHER THE OLD GASKETS WERE EITHER MISALIGNED, ROLLED, TWISTED, ERODED, TORN OR WERE JUST PLAIN BADLY INSTALLED...AND IF THE EDGES OF THE MANIFOLD ARE NOT WARPED, CRACKED OR DAMAGED...YOU MIGHT JUST GET AWAY WITH THE PRICE OF A NEW SET OF IM GASKETS.

Some companies will not accept any returns on open products...

 

[Inferno333]

Thanks for the tip!

I ordered new plugs, IM gaskets, and fuel injector o-rings.

Still heehawing around buying injectors and the IM.

 

[Inferno333]

I called around to a couple places in Omaha for a newer reman IM. Basically the same price as a new one.

Think I should go ahead and order a new IM and injectors just in case? Then once I pull he old one off I can see if a new one is actually needed.

Is there anyway to tell if injectors are good just by looking other than obvious damage?

 

[Mooseman]

If it happens to be a faulty manifold, you could probably go with a used one. I have never heard of a reman IM. It's a piece of plastic, nothing to reman there except clean it. If a yard is charging that much for an intake, I call it theft. It's not even that hard to take off. If there's a pick-a-part nearby, you could go that route and get some practice at the same time before diving in your own truck.

You could get the injectors in case they're needed and return them if they're not depending on what you find. You can replace them afterwards if needed. That way, if the injectors are fine, you're not losing $$$$ for nothing.

 

[mrrsm]

I called around to a couple places in Omaha for a newer reman IM. Basically the same price as a new one. Think I should go ahead and order a new IM and injectors just in case? Then once I pull he old one off I can see if a new one is actually needed.Is there anyway to tell if injectors are good just by looking other than obvious damage?

Well... You're NOT going to be believe this... but many years ago... when I found myself in the same situation that you are with wanting to know how to make Multech I and II EFIS either serviceable again or ready for the Trash Bin... I decided to invent a Fully Functional, Off the Vehicle Fuel Injection Cleaning Machine and ...in Memory of Dr. Victor Frankenstein... I Christened this Device:

"The FrankInjector Machine"

Here are all Four Generations of the Device... Memorialised in Digital Images and Videos:
http://s557.photobucket.com/user/60dgrzbelow0/library/HOMEMADEEFICLEANER?sort=3&page=1

PS... And no... I no longer use the machine any more... But I do have fond memories of Designing, Building and Using the Monstrous Thing... Your Best Option is to send yours off to an ASNU Company like the ones on eBay... Or just buy a set of their Rebuilds... and you will save a lot of Time, Money and Aggravation!

 

[Inferno333]

I found a used intake manifold for $75 at a parts yard. I'll check it out on Tuesday. I ordered a brand new set of ACDelco injectors from a store on ebay for $200 shipped

The first set of parts should be here Tuesday so I'll be tearing into it then. I'm hoping plugs and the gaskets do the trick.

 

[Inferno333]

I got it all pulled apart now. The IM gaskets had some weird areas and the head mounting surface along with the the IM seemed pretty dirty.

Is there a way to clean off the injectors? There's build-up on that plastic cap on the spray side. Maybe a toothbrush and carb cleaner?

I'm replacing both sides of the o-rings on the injectors to see if it helps. Still have new ones coming though.

The used IM comes in tomorrow morning, but I don't think the stock one is bad.

Do I need to lubricate the mounting surfaces prior to putting the IM back on?

 

[mrrsm]

Good and Observant "Autopsy"... If you think your observation will help others down the road...memorialise in Digital Images and Post them here for future reference and as confirmation of what you discovered. While the original Intake manifold is off the engine... Take a really bright Flash Light and REALLY look over everything in the open Intake Port areas. While it would be my preference to spray a soft white cloth with Berryman's B-12 and then carefully hand wipe out each port... My fear in your situation is that you might accidentally spray the fluid down inside the various cylinders, dislodging "Gritty Sand and Black Mung" that will drop inside and do a Royal Ruination by abrading the cylinders...and do more harm than good.

Nonetheless...if you are able to do this VERY CAREFULLY... and not invade the areas around the Valve Stems and seats...lest the Berryman's eat at the PTFE (Poly-Tetra-Flouro-Ethelyene) Valve Guide Seals... then by all means... do so. During your Upper Head Surface Cleaning... avoid using any Compressed Air ...even "Canned Air" because the adjacent Oily Dirt can easily be shot past any open valves and wind up down inside many of the Cylinders. The idea is for you "feel" the areas around each port where the Oval Plastic Gaskets seat for any obvious dents, scrapes or surface defects to avoid repeating the problem over time.

Go back up to @Mooseman 's Video and study the generic information about how to prep and install your Intake Manifold. Don't be afraid to Jot Down the Steps and get an idea in your mind how to clean and prepare all surfaces to "accept the kiss" between the gasket interfaces and the angles and contours of each head. There are a fair number of ways to tighten and torque down an Intake Manifold...some are better than others... nothing too exotic and NEVER with any adhesives or soft sealants like BLACK RTV...unless your Manual calls for them. The cleaner and the drier the metal surfaces are ...the better. Just take Your Time...

As the IM drops into place... keep your eyes peeled 360 degrees circumferentially around the entire Intake Manifold to ensure that no fasteners, blowing leaves, dirt, loose small tools or debris manage to fall inside at the last moments before you button up the top of the engine. If the Manual calls for "Staged Tightening" of each fastener...don't rush the process...give this Plastic Monstrosity every opportunity to remain flush and square as you persuade the damned thing to "Behave". Its best to take Digital B4 & After Images...in case you think something is not quite right... and if all goes well... BECAUSE WE ALL WANT TO SEE AND LEARN FROM YOUR PRESENT WORK.

The Condition of the EFI Caps can be improved by wiping the Black Plastic Shrouds with Berryman's B-12 and then dried. The Four S/S Spinnerets nested within each one may have some brown residue of baked on fuel that can be cleaned off with a Cotton Q-Tip thoroughly soaked (Berryman's B-12) but mind that any cotton threads do not get left inside. The problem with the Toothbrush & Berryman's is that occasionally, some of the Nylon Bristles can get enthusiastically stuffed into the Spinneret holes... and break off inside of the EFIs.

These Multech II EFIs occasionally show Connector Blade corrosion where the light Galvanized metal surfaces vibrate enough to wear through the protective metal coating inside the Metrapack compartment. If you see any rust on these... clean them well; lest they cause arcing and sparking if jumbled around by engine vibration. Don't apply any oil sprays inside. The triple rubber insulating ribs generally seal out everything well enough to work... even if submerged under water. Look over each EFI connector for any loose or abraded wires. They are very Tough Hombres as wire harnesses go... But on occasion I have found damage on top where small rodents decided to gnosh on them and make for some sketchy idling problems until the got replaced.

 

[Inferno333]

I really wish I would've thought about taking pictures. I'm always too eager to get it back together and check my work.

The metal plate IM gaskets are the way to go! They stay perfectly in place and feel so much like a quality item.

The only thing I need to check back on in the video is where the 4 wire connector goes near the back of the IM.

 

[Inferno333]

Alright! It's back together. That plug at the back is likely the DOD plug that I don't use anymore.

Good news: It runs a little better.
Bad news: Still has a slight misfire on #7.

Tomorrow's project is changing the plugs. I'm hoping that's the cure. If not then I have injectors coming in on Friday.

 

[Inferno333]

Plugs are done now. I didn't realize that my mechanic put Bosch plugs in it last year when all the major repairs were done. I'll post up a picture of what they looked like. They were all pretty decent though.

It runs a little smoother now, but still has some roughness to the idle and a misfire every once in a while when it's idling. It doesn't have the hesitation at a stop anymore now. I'll try to get a video of it running posted too.

The new injectors come in tomorrow, but I'm going to hold off a little bit on installing them to see if they're needed. I'm betting it won't make a big difference. I changed both o-rings on the injectors yesterday and cleaned up the injectors.

 

[Inferno333]

So the truck is back to running mediocre at idle. It had over 26k misfires on #7 from the history in Torque. A couple other cylinders had some misfires too.

I already returned the new injectors, but I'm starting to think those are the issue.

I did the paper at the exhaust thing and found that the paper does suck back to the exhaust. Probably not a good sign...

I'm going to recheck the torque on the IM, but we will probably just live with the rough idle until the truck can be sold. There's no way I'm paying more money to have the heads pulled and get a valve job done if that's the issue.

I wonder if anyone here wants an 06 TB with the 5.3L, tow package, and a dod delete kit.

I forgot to add that I sent out an oil sample to Blackstone Labs from my oil change a month ago.

The report said that everything was within the normal range. They did say there was excess sodium in the oil, but didn't find any coolant.

 

[Mooseman]

Only way to tell for sure if it's a valve is with a leakdown test but you can start with a compression test.

I just wonder, if it's possible, that a new lifter is failing or only fails to work at idle?

 

[gmcman]

I would run a can of BG 44K through it. If you have carbon built up under the valve then this would really loosen it up if not remove it. Easier to drop $25 as a solid hopeful before you tear into it.

Another idea is to remove the valve cover and observe all the exhaust valves and see if #7 has any excess play in the rocker arm when the valve is seated....compare #7 to the rest.

The paper test possibly leads to an exhaust valve not fully seating.

 

[Inferno333]

Do you just run the BG44K through the fuel?

I'll give it a shot. Valve covers are easy. I'll give that a go too. Maybe they weren't torqued all the way or something.

 

[gmcman]

Do you just run the BG44K through the fuel?

Yes.

Generally avail through most dealers, I add the can as I'm filling up to thoroughly mix, be sure to run the tank to near empty afterwards, don't fill up halfway after you have added the treatment.

Don't start the engine with the valve covers off as you may get excessive oil running onto the exhaust...just bump the key but with the fuel pump relay removed.

You can get a remote start tool, not sure if all GM ignitions keep cranking for a few seconds after you release the key....many do, just fyi.

 

[Inferno333]

Thank you for the tips! I'll do the BG44K this weekend.

Is the only place to get it the dealership?

 

[C-ya]

You can order it from Amazon or elsewhere on the net, but you may be able to find a local retailer with it. I'm guessing you can buy the product without have them "do their thing". http://www.bgfindashop.com/locator/index.php

 

[Inferno333]

Thanks. I found an Advance Auto about five minutes away that supposedly has it.

 

[Inferno333]

BK44K added. I told the wife to get on the gas while going to work. Lets hope it does the trick.

 

[gmcman]

You don't need to drive it too hard, the chemicals will work on the deposits.

Hopefully this at least helps or cures the exhaust being drawn back into the tailpipe.

At the very least it's good for the motor, keeps the combustion chambers, mainly the valves clean