Topic: possible engine issue

[boardkat]

background: '09 GXP 5MT coupe w/ GMPP tune/sensors/CAI
mileage: 2600
symptoms: engine hesitation @ WOT/full boost in 3rd/4th and leaking oil from the block

while trying to diagnose a really bad 3rd/4th gear WOT/full boost hesitation today, i was checking all of the engine harness connections, with particular attention given to the ones in and around the high pressure fuel pump.  most likely it's a GMPP MAP/TMAP harness crimping issues (previous owner had the dealership do the install), but i figured it wouldn't hurt to snoop around before i brought it to the dealer.  to my *great* surprise, after i popped the engine cover off, this is what i found:



that's the front of the engine (oil leaking from the passenger side).  any idea what could be up?  the car only had 1300 miles on it when i bought it a few weeks ago (and now has an additional 1300 of highway driving and grocery getting).  after the issues i had on my previous car, i can't believe it's all seemingly happening again.  in addition to this, the subwoofer is blown, the rear defrost only works some of the time, and it already succumbed to the infamous air bubble (that took many months in my previous car to rear it's ugly head).  i can't win

[tazz]

There is a TSB on the rear defrost IIRC.

[boardkat]

There is a TSB on the rear defrost IIRC.

i thought that was only for the 'vert (this is a coupe)
anyway, i'll see what they say.  more concerned about the engine at this point, frankly!

[tazz]

I know just throwing that out for you that you can check into it.

[spider]

The oil leak is from a bad valve cover gasket, not the head, fortunately. Curious to hear what the hesitation is caused by.

[boardkat]

The oil leak is from a bad valve cover gasket, not the head, fortunately. Curious to hear what the hesitation is caused by.

agreed.  i took a closer look and saw a rubber gasket in there.  feeling less concerned.  but the hesitation, yeah, i figure it's the crimped harness.  or a bad flash.  time will tell.

[G8TR]

There were a few bad flashes out there to begin with if the tech wasn't familiar with doing the work. People usually found that the flash wasn't loaded correctly, so there was no real change.

[boardkat]

There were a few bad flashes out there to begin with if the tech wasn't familiar with doing the work. People usually found that the flash wasn't loaded correctly, so there was no real change.

yep, exactly how this car feels right now.  i'm gonna have them use MDI to reflash instead of tech II.  also going to try to convince them to remove the butt connectors and solder 'em.  stay tuned (no pun intended)

[G8TR]

Good luck, hope it works out.

[boardkat]

dealer couldn't pinpoint the leak, added dye.  suits me fine, waiting on a replacement subwoofer and the cooling system check valves to come in anyway, so hopefully it'll be obvious when i bring it back in.

[boardkat]

bumping this back up.  the dye hasn't revealed the location of the leak, but that's the least of my concerns.  they've now confirmed my hesitation issue @ WOT - no codes are being thrown, but when they datalogged, all cylinders are randomly misfiring.  they're getting on the phone with techline today, since they've followed all the FSM guidelines and are at a loss.  very satisfied that i found a dealer that isn't afraid to reach out for help.  we'll see what happens.

[DeepBlueGXP]

Thanks for the update, I hope they can get it fixed for you.  Sounds like a bad ground somewhere.

[boardkat]

Thanks for the update, I hope they can get it fixed for you.  Sounds like a bad ground somewhere.

when i spoke to the tech, i *knew* i'd forgotten to mention something (and didn't check myself).  but i had a friend use the same dealer and they found a bad ground on the block, so i'm confident that they examined that (or will eventually).  thanks for reminding me to ask though!

[boardkat]

also forgot to mention that they moved coils and plugs around, and that didn't change the misfiring, so there's another culprit down.  and i personally checked all the fuel-related connections (packs, pumps, sensors) from the engine harness to make sure they were seated, no issues there.

[boardkat]

latest update: they have no idea, and neither does techline.  it's primarily a misfire in cylinder 2, but all have exhibited misfiring at some point.  not enough to set a code though.  they went through a whole boatload of diagnostics, datalogging, reflashes, etc to no avail.  i'm picking it up today with instructions to run it for a week or two, and see if it resolves itself, lol.  but i now have a case number opened with GM, so it's kind of out of the dealership's control, and i respect that - gotta play to get paid for warranty work.  interested to see what happens when it likely doesn't resolve itself in the next week of driving and i drop it back off.  stay tuned!

[spider]

Time to get out the soldering gun & shrink tubing. Keep us updated.

[boardkat]

Time to get out the soldering gun & shrink tubing. Keep us updated.

GMPP kit is off, so is the CAI.  i soldered the stock MAP/TMAP sensors back on already, dropped in the ECU with stock tune, put the stock airbox and filter on, and cleaned the MAF for good measure.  it's no longer a GMPP/sensor issue, and a TAC case now exists.  wouldn't be surprised to see a GM tech out in the PNW shortly to help diagnose.

[2.0 tspeed]

Might have a engine starting to blow

[boardkat]

Might have a engine starting to blow

it had less than 1200 miles on it when i first picked it up a month and a half ago (3000 now), and was exhibiting the same behavior, so i'll really be surprised if this ends up being a mechanical issue.  i have a strong feeling it's fuel-related, and/or electrical.  we'll see.

[Gentleman Jack]

Looks as though the KP forum " gremlin " has found you.  That damned thing moves around this forum like a virus....

[boardkat]

ha!  i've always had that monkey on my back.  my previous 'vert had all sorts of brake issues, never completely resolved (in spirited situations, they were fine on the street) even though i bleed fluid a bazillion times, tried multiple pad/material/rotor swaps, brake master cylinder, brake booster.. not to mention a whole assortment of other issues (that were actually fixable and taken care of at least).  fool me once.... and all that

[joshmass]

You sound like you know what you're doing but I thought I would throw this out there....Have you checked the plugs? The previous owner may have done something stupid like switching to E3 in hopes of improved performance/mileage. Knowing how sensitive these engines are to alternate plugs, it could be the issue with the misfiring.

[boardkat]

You sound like you know what you're doing but I thought I would throw this out there....Have you checked the plugs? The previous owner may have done something stupid like switching to E3 in hopes of improved performance/mileage. Knowing how sensitive these engines are to alternate plugs, it could be the issue with the misfiring.

the dealership told me they swapped coils/plugs around to see if it changed which cylinder was consistently misfiring (#2) - it didn't.  i don't have a tech II (yet) unfortunately, so i have to take their word.  that said, i did pull plugs before i brought the car in, to see what was in there and to eyeball their condition - and they were all 41-108.  couldn't find my gap tool though.

[Graywolf]

Its hard to understand your problem. If your problem is hesitation I would inspect the blow off valve,three little screws and its off. Watch out because its spring loaded so you don't drop it. pull out the rubber gasket and check it for tears or holes.  If that is ok, have they checked the # 2 coil. If  it is skipping fires then that could be the problem or the wiring to it. Have them do a simple compression test and also pop off the valve cover and inspect the rollers and lifters[followers]. These can break and there is a bulletin on this problem from GM. Also inspect the chain and sprochets on the attenuator when you pop the valve cover. I do not like you having oil in the engine bay. Yes it does look like a valve cover leak but at that low mileage Good luck keep us posted

[boardkat]

the hesitation is most definitely due to the misfire, tech II clearly showed that.  we both have our suspicions about the culprit, and are inclined to think it's a fuel issue caused by something electrical.  unfortunately, now that it's a TAC case, the dealership's hands are tied, and are only doing what they're told from here on out.  it'll end up being a field engineer that diagnoses and fixes the problem in person methinks.  i just hope it doesn't drag on for months!