How bad are boost leaks for the car?

[~97TalonTSi~]

I did a search and couldn't really find my answer. Anyway, I just did a intake leak test and found a lot of leaks in various places.

Would this explain crazy A/F reading at idle and part throttle? For example, the guage will sometimes hang out in lean for a while and then sometimes it will sit on the rich side. The car responds to it too. I can tell by the exhaust notes and if I'm at a light and the guage is hanging out on the rich side the car will sorta take off by itself (auto) and if it is lean than it hesitates. This makes it impossible to tune the AFC, no matter the setting, that's what it'll do.

How much will a leak affect the cars performance and more importantly can the motor be damaged? I'm not relying on the A/F for tuning, just wondering why its being different. My timing and EGT's are all the same.

I don't have a FPR and I know I need one, but I've had the 255 in the car for about 3 months before it started this...would the new turbo be the difference?

Or lastly, could it be a bad O2 sensor?

Thanks

 

[RedTurboEclipse]

i dont know if it could be bad for the motor, but i know there will be a lack of performance, depending on how bad/amount of leaks you got.

 

[Turbo Guru]

The serious boost leak that plauged our 98 GSX before we bought it led to the eventual and untimely demise of the factory T-25. By over working to achieve factory boost levels while leaking boost it ate it's bearings. It continued to kill the bearing even after the leak was fixed, finally the bearings disintegrated and it died.

In the course of finding the leak the car never ran right. Due to the turbo probably pushing extremely high boost to compensate for the leak, intake air temps were through the roof, A/F ratio was never consistent or correct. It was possesed continually with either knock (from intake air temps) or stutter (from being rich [the MAS was reporting way more air then was actually reaching the engine.])

It is imposible to tune with boost leaks. My advice is to just fix the leaks wherever they are.

Joe

 

[~97TalonTSi~]

I haven't been driving the car cause I was getting so frustrated with trying to tune it. It made sense that the turbo was working harder than it had to...I'm glad I parked it until those are fixed.

Thanks

 

[Violater101]

So your saying because your car was rich, it caused the car to stutter? And when you say stutter, can you be more descriptive??? as in a hesitation feeling, but the car still maintains a constant speed? I'm trying to diagnose this misfire or hesitation i'm getting. I'm changing the plugs tomorrow and hopefully that will fix it.

Thanks,

 

[Turbo Guru]

Originally posted by Violater101
So your saying because your car was rich, it caused the car to stutter? And when you say stutter, can you be more descriptive??? as in a hesitation feeling, but the car still maintains a constant speed? I'm trying to diagnose this misfire or hesitation i'm getting. I'm changing the plugs tomorrow and hopefully that will fix it.

Thanks,

It wasn't a stutter like a misfire, it was more like a bogging/ rapid surging at high rpms. I don't feel that it is the same problem you are experiencing, because ours was due to a MAJOR boost leak. When Mitsubishi tried to diagnose the problem with the car they couldn't find the problem. We did a boost leak test per VFAQ and found the clamp that holds the factory UICP onto the intercooler was missing. Once the leak was fixed it ran much better. However the damage was already done to the turbo and it died within a week or so.

We recieved our AGP T-28 from UPS today and should have the car running this week (time permitting.)

Joe

 

[Violater101]

Thx, my problem is more annoying than anything, the car runs fine if I just punch it, no stutter/misfire/hesitation or anything. Its been raining so much here lately and I don't have a garage, so I havn't been able to check the gap on my plugs. If its clears out tomorrow, I plan on changing my injectors ...going to denso 720's,change the plugs, and then tune it. Gotta make sure my LTFT and STFT's are close to 0% before I can do any tuning though. Going to be quite interesting since the temp at night is alot cooler now ..what gave me around 17lbs of boost last friday night gave me 22 last night.

 

[~97TalonTSi~]

Thats about as bad as my leaks are. The one clamp just wasn't sealing at all...plus there was a hole in one of my welds . I really hope this fixes my idle and part throttle surging.

 

[BatmanGSX]

It's really bad for the turbo. Especially the enemic T25, which will fail easily if spun too fast. The 14B and 16G do a little better but when they fail from being overspun it's pretty dramatic. Turbine wheels exploding and such.

 

[Turbo Guru]

Originally posted by BatmanGSX
It's really bad for the turbo. Especially the enemic T25, which will fail easily if spun too fast. The 14B and 16G do a little better but when they fail from being overspun it's pretty dramatic. Turbine wheels exploding and such.

Tell me about it! I have been cleaning up the mess under the hood of this car for a week now, It sucks when the turbo pukes 50% of it's oil into the intake tract and I have to pull it all out and clean it with gas.

 

[~97TalonTSi~]

Ok, for you guys who helped me before. I fixed all my leaks and triple checked it up to 20 psi with an air compressor. But the car is still doing what it was in the original post. It also feels like it's missing, but only when I first step on the throttle. I'll try to explain this...I'm stopped at a light, everythings fine, go to take off normally and the car studders real bad and sounds like is misfiring, has no power what so ever for a few seconds and then it kinda "wakes up" and takes off totally fine. It will cruise on the freeway at 3-3500 perfect but trying to cruise in traffic it just doesn't want too. Its almost like the ecu just can't make up its mind on what to do.

So my 1st question...could the fact that I do not have a FPR be the cause (hence, it's not missing, it's loading up with fuel?) The reason for this question is I did not have these problems with the 255 + T-25 and no FPR.

Could it be the coil pack? Or bad O2 sensor?

What are the symptoms of a bad O2?

Thanks