Guys,
I started to tear my car apart to try to fix my backfire and stumble. Took the turbo off and look what I found. Is these cracks a big deal or not. I think it is junk please let me know your opionion on this. There are a total of three cracks when the turbo was rebuild last year it had one small one.
Yea there pretty common, mine has them, But I'm thinking like you are, its considered junk to me. So I will go to a larger size turbo eventually. But meanwhile it'll be alright to run for now
Would this make my car backfire above 8 lbs of boost with the 3 cracks or am i looking for something else.
Mine is cracked also, but it boosts to 10 - 11 psi fine.
Any suggestions on what would cause the backfire and stuttering then.
Mine does not backfire at all. This sounds like and additional problem. If no one knows exactley what the problem is, you might have to do the process of elimination on each individual items that have part of this particular problem. Good luck Red90.
Quotebackfire above 8 lbs of boost
Could be the spark plugs, wires, ignition coils.
What spark plugs are you running and at what gap?
Also, what brand/how many miles on spark plug wires, coil packs, and ignition module?
Also, and chip or injector mods?
I'm pretty sure all T-25s are cracked on the turbine side, but personally I haven't seen two and not that big for sure. The ones on my turbos were considerably smaller. I have plenty of other problems but those never caused any. yet.
Quote from: GutlessSupreme on February 17, 2008, 07:29:04 PM
I'm pretty sure all T-25s are cracked on the turbine side
Last time I had my turbo off, it wasn't cracked. :laugh:
X2....both times I had mine off, I had zero cracks.
Did you clean off by the wastegate? The carbon and oil could have hid your cracks. If you shot blast it they will appear in most cases unless you have a new turbine housing on your turbo. Both of mine had cracks. I doubt that is your problem all it would do is bleed of a like .3 psi at most. Not going to cause drive ability issues.
Ken
ok lets see if I can get all the answers here. Plugs are AC Delco, Gapped at .028, AC Delco wires, injectors are yellow tops(new), new FPR,used ignition module and coils off my 98 monte 3.1, bosch O2 sensor everything is less then a year old and has about 1,000 miles on them And I mean everything I have replaced all sensors. Spent over 4,000 so far on this car My chip is a kenny chip as well.
My bets on the coil. Get a new one or a newer one with less miles on it from the yard. My GP was doing this hesitation thing on tip in throttle on the highway. I replaced a bunch of sensors and all it turned out to be was the Module or coils. I had a spare and swapped them in and it was fine.
Ken
I'm going to bet either coil or ICM. My ICM and two coils were bad and they were making my car run like total ass. After I got them replaced, and after 9 months of replacing everything else, she ran great again. You said they were off your Monte, which would have a 3100, not a 3.1. Is there maybe a difference in the part? And no the 3100 and 3.1 are NOT the same.
I check the part numbers and they were the same and sorry it is a 3100 my bad. Well i will just bite the bullet and get new coils and ICM. Hope that fixes it. If not I am going to replace the cam in the spring. Thinking maybe a bad lobe. Since this is a issue with these motors anyway 136,000 miles so it couldnt hurt.
There are a couple of people here who have had bad lobes, myself included. But you'll notice it way before 8 PSI. It'll sound weird and feel like you lost a cylinder even below boost.
Remove the rear valve cover and have someone crank the motor (you can pull the fuel pump fuse if you'd like, but it won't be too messy or anything, regardless). Watch the last two rocker arms from the driver's side, lobes 9 and 10. Those are the ones that go on these motors. If one of the rocker's isn't moving, you've got a problem.
Besides that, I would definitely try another ICM/set of coil packs. You can find them cheap on ebay sometimes off of newer 3400 or 3800s, I don't think they're any different.
That, and get a Delco O2 sensor in there. Bosch is junk for our cars.
If you are concerned about a bad lobe do a compression check to rule it out. If it's worn it's usually on cylinder #5, lobe 10 or 11.
Its more than likely something simple. From what I understood about these cam failures, if it didn't happen before 50k miles it was unlikely to happen at all. Check the plugs, or just replace them with R42LTS AC Delco plugs, they are real cheap.
Good luck man.
Already have r42lts plugs in and they are new will do compression check this weekend
After checking the ignition, I would move on to the fuel pressure, might be running out of fuel and knock pulling timming out. My turbo coupe did this from low fuel pressure at high boost.
Quote from: R Dubya on February 18, 2008, 06:25:53 PM
if it didn't happen before 50k miles it was unlikely to happen at all.
Mine went at 154k.
Did you have a lobe 10 failure? I can't recall :icon_redface:
That comes from me talking about these engines with the techs at the dealer I was working at.. it's a general statement from one of them. Obviously it's not 100% but when cams fail at 30k miles, it's a lot different than 150k. It would be nice if it didn't happen at all! :laugh:
If you had a bad lobe the car would backfire, stall out intermittently, and it would also be pushing boost back through the intake (at least it was on mine).
I swapped in a ICM and coils from my girlfriends old 3100 97 buick skylark gran sport. They work fine, might not be the same pn but output and connections are probably the same. Much like all GM fuel pumps the P/N change does not necessarily dictate a function change. Try the coil and icm before you do anything else.
Ken
When you had the plenum off changing the fuel injectors, did you make sure that all the vacume lines didnt break and were installed correctly? Also, did you make sure to plug the PCV valve hose back in.
yes I replaced all the vacaum lines when I had the intake off. I am going to replace the ICM and coils hopefully next weekend. God I hope it fixes it.
if you are near an Autozone or Advance or many other places, they are capable of testing the ICM with the coils off and see if it fails.
It is possible for one circuit to fail and prevent the firing of one coil, I've had it happen. Before you drop the $100 bucks have them test it.