My 02 Nightmare

[danger]

A couple of years ago... I fulfilled a desire to own a trailblazer. Having been a GMC Jimmy owner in the past.... it seemed logical. That's were the nightmare began. I found an 02' with just over 200k miles on it. It was running a little rough, but for just under 2k, and after throwing a code reader on it which was telling me a cam positioning sensor was bad... I figured what the heck. I bought the trailblazer. Changed the cam positioning sensor, then came the P300 code. It was still running rough, so I changed the plugs... and took it to have the oil changed. I took it for a test drive... and that is when it happened. BOOM! then nothing... it was dead in the water... which is what led me to this forum. A lot of you gave me some great advice... May03 was awesome. I ended up taking the head off, and found that the #4 piston was half gone... the engine was toast....so then came my search for an engine... I wanted to buy one local because I wanted to be able to hear it run. I finally found one, just over 130k miles for an '03 engine. Ran a little rough, but sounded overall solid.... and for 600.00 bucks how can you go wrong. I bought the engine.... well then my local code enforcement came down on me and told me I can't do engine swaps or engine work in my own driveway. so there it sat under a tarp for 8 months... I piddled with getting the old engine ready to swap out I figured I'd do it over night when the neighbor who called and complained wouldn't be awake to see me do it. in the mean time... the neighbor found something to call on me for.... the trailblazer had no current tag... won't run, won't pass emissions, no tag.... so I decided to say to hell with it and pulled the trigger on the project over the 4th of July weekend. had to work on Saturday.... so that was a no go.... so Sunday morning I jump out there early, pull the old motor out( which is a bear when the engine is locked up)... went and bought new heater hoses, rear main seal and transmission pump seal. Get the new engine ready to go... and got it in the hole...now all I needed to do is get it aligned with the tranny, and get the torque converter bolts in. 4th comes along.... get out there early again.... aligns in minutes.... torque converter bolts right up... and then I start putting everything back on the engine ( alternator, power steering, etc...) then I start wiring it up... and WTF.... none of the plugs match with the '03 sensors... so I have to strip them all off the old engine... then I get to the last one.... the upstream 02 sensor.... it won't budge... I mess with it and mess with it... end up rounding the damn thing off (yes even with the proper tools and PB blaster soaks). So now came back to the forum and read where some guy had the same problem... and someone advised him to use a pipe wrench.... this didn't work so well either at first.... I finally get the thing out, and figure out whom ever put it in had cross threaded it, and forced it in... I put the new O2 sensor in and it is throwing a cam positioning sensor code ( here we go again now.) I have a new one that I took off the old engine... change it out... clear the codes and crank it.... check engine light comes back on... not surprising by how bad it is running... check the code... P303... I change all the plugs with AC Delco's ( the engine had autolites in it), and change the #3 coil pack....clear the codes... crank it up, and it's running smoother, but just didn't seem right... so I check the codes again.... nothing.... take it for a test drive and it runs decent, but the idle is still surging and a little off... then comes the magical flashing check engine light.... I get it the block and a half back to the house. shut it down... then crank it back up... check engine light... check the code... p303.... at this point I am saying WTF... and ready to stuff a gas soaked rag in the fuel filler and strike a match to it.... I've now invested about 4K into this thing.... and I am now at a loss... anyone care to chime in with some advice?

 

[djthumper]

Don't go by one person, it was only reported 12 minutes ago and has been delt with.

This is your first posting since 2014...

 

[SnowBlazer]

thanks to the disrespect I received from another member. I have deleted this post. please remove the tread. I will not post here again....

I was curious to see the solution to this. I never saw anyone's post after you posted so idk what happened.

Just remember, It's the Internet, where the little guys hop on here to be the big guys they wish they could.

 

[jsheahawk]

Seriously. Post your question, man. Don't let some shit rain on your parade. Your question may help others.

 

[jsheahawk]

Are you using 41-103 plugs? Is the throttle body clean?

Can anyone explain how the PCM diagnoses a misfire?

 

[MAY03LT]

I vote to do a compression test on #3.

Also someone should do a compression test on your neighbors face. People need to mind their own business.

 

[danger]

Here's the update and I am even more perplexed then I was before. Tonight I swapped the #2 coil with #3 coil, swapped the #3 plug with #4. ran smoother, but still not right... checked for coded.... nothing... checked for pending codes P0300. let it run for a bit, upped the RPM's and the CEL started flashing... I did this a couple more times.... the CEL stayed on. I checked for codes.... P0303... and it runs like chit... I dunno guys... I'm at a loss...

Are you using 41-103 plugs? Is the throttle body clean?

Can anyone explain how the PCM diagnoses a misfire?

yes and yes... May03 has an awesome video on cleaning the throttle body...

 

[danger]

Don't go by one person, it was only reported 12 minutes ago and has been delt with.

This is your first posting since 2014...

Yes I know it is my first post since 2014... as I explained this has been a long road for me, and have been doing a lot of reading on older posts which have been extremely helpful... however I am at logger heads with this problem.... and my frustration level is high....

 

[Mounce]

Compression test is indeed in order as mentioned. That would be my next step, you've swapped everything more than enough times, it's definitely that cylinder, not the parts.

If compression checks out then start looking at wiring to the coil and injector to make sure you're getting fire and fuel.

Did you use your original wiring harness?

Original injectors and fuel rail?

 

[Mooseman]

Check my thread on misfires I had recently had:
Stumped on misfire

Please don't laugh at the end result. It does however have all the steps to check for a misfire. One test you might not be able to do is the injector balance test. Maybe some dirt got into the fuel line and is buggering up the injector.

Since yours is misfiring on #3, you can't do my mistake . You do have a whole parts engine with spare parts you can use.

Final thought, did you check the intake bolts? Might be a leak there. During the engine swap, did you take the intake off? Maybe a gasket went out of place. It has happened.

 

[djthumper]

Please remember there are only a few staff members so when you report a post it may take us some time to take care of it. Most of our members try to be helpful and if they notice there has been no response at it is outside of their expertise they will at least acknowledge you.

 

[danger]

Compression test is indeed in order as mentioned. That would be my next step, you've swapped everything more than enough times, it's definitely that cylinder, not the parts.

If compression checks out then start looking at wiring to the coil and injector to make sure you're getting fire and fuel.

Did you use your original wiring harness?

Original injectors and fuel rail?

OK, let me try to answer all the questions at once.
Compression tests on each cylinder was @ 90 psi or slightly higher.
Yes I used the original wiring harness. coils have been tested all delphi and all ok... fuel... well judging by the fact that just sitting there idling it appears to use a ton of fuel... there might be some issue there....
injectors were the ones that was in the engine when I heard it run... rail is the same... this was a complete swap engine.... other than changing all the sensors ( the trailblazer is an 02 and the engine is out of an 03...) and changing out a couple of bad coils. I also almost forgot... it had autolites in it for plugs and I put the correct ac delco plugs in it..... everything was left in place when the engine was dropped in.

could I be looking at a bad TPS? and if so... why would it throw a P0303?

 

[Mounce]

So you've verified spark on #3? Since compression was good, if you've got spark, sounds like a fuel issue. Such as your original harness possibly isn't properly firing the injector.

 

[danger]

So you've verified spark on #3? Since compression was good, if you've got spark, sounds like a fuel issue. Such as your original harness possibly isn't properly firing the injector.

It wasn't an issue before the engine was swapped... but who knows... I can run a voltage tester on the plug... what kind of voltage should it be putting out?

 

[Mounce]

No reason to voltage test the coil or plug, you've swapped them and it stayed on #3 ruling both of them out.

Take the coil out, stick a plug in it, and ground the plug (hold the end/threads to the metal) somewhere to a solid metal surface such as the block or head.

Side note, I originally thought the misfire on the new engine was the same cylinder with the bad piston. I just reread a bit and see #4 was the bad piston, not #3. I was leaning so hard towards wiring because I thought it was the same cylinder. Apologize for the misdirection.

 

[Mooseman]

Maybe try to swap out the spark plug with another cylinder. That's one thing I tried in case it was a bad plug.

Just a reminder to clear the codes after each part swap or change to ensure to get fresh readings and codes.

 

[danger]

OK guys, I checked the plug and coil pack again... both work... I did notice upon cold start up I smell exhaust fumes strongly.... and I took a screen shot of a diagnostic... not sure if it would help... cleared the code and it is showing a pending P0300...

 

[djthumper]

Hopefully the P0300 turns into one of the cylinders so you know which one to really deal with.

 

[danger]

Hopefully the P0300 turns into one of the cylinders so you know which one to really deal with.

it keeps turning into a P0303.... when it turns into a P0303 it runs like crap.... but I clear the code and it runs better.... but still not right...

 

[djthumper]

Move the coil pack to number one and see if it follows the pack.

 

[danger]

OK Guys, I think I have figured it out... I decided to start from scratch tonight. When I initially installed the engine. I checked compression... I have since bypassed that step in my diagnostic of this P0303 problem. Tonight I started with a compression test, and #3 is only putting out 33 psi... that combined with the heavy smell of exhaust when cold leads me to believe I have a bad exhaust valve or valve seat. I have done some research and apparently the i6 is know for this issue... which is disappointing... I'm not sure I have the will to tear down this engine to do a head job... aside from a leak down test... does anyone have any suggestions? and no I can't return it...

 

[Mooseman]

Only way to know for sure is to do a leakdown test.

To say that an engine is known to have a particular issue is misleading. Of course, on the net, you will only hear about failures but for each of those, there are thousands out there that have/had long lives. I got the one in 10 000 that had a timing chain tensioner issue. In anything mechanical, there are bound to be some that fail. There have been a few that had failed valves here but they are very few and far between.

Sorry if I sound harsh. Even though I have seen the inside of my engine way too many times, I still think it's a damn good motor.