For months I have been dealing with issues with my car that have me on the brink of selling it.

Though the car has been tuned at STM and puts down around 260ish whp no problems, the car has quite clearly lost bottom end punch . The car is essentially stock with a cat delete pipe, boost controller, 02 housing, and walbro drop in fuel pump, and is tuned for around 25psi. Will rev clean to 7 grand without a hint of misfire, but the throttle response on the bottom is so bad, you can mat the thing from a rolling start in first gear from 1000 rpm, and literally count 1 full second before you even begin to feel a hint of pull.

I understand the concept of turbo lag, but this is a tiny stock 8 turbo, and used to spool sharp, clean, and hard before this started happening. Car will hold boost well once it has spooled, and has been boost leak tested twice at STM and no leaks were found. I just drove a chevy malibu gutless wonder for a week straight and when I got in my Evo it still felt soft. This is a problem.

The car surges on cold starts, even when it is 90 degrees outside. You pull out of the driveway in the morning and you can literally feel the car surging until you get down the street a mile or so, and then it cleans up and goes away ( but the bogging from a stop persists). STM also ran a compression test that they said was fine. Idle is fine, it seems like it is very load dependent. Additionally, the #1 exhaust runner is still registering temperatures that are 100 degrees colder than cylinders 2-4. Car looses about a half quart of oil per 3000 miles, and has lost no coolant.


Things I have tried:

New Plugs
New Coils
New Alternator ( Old one failed)
Different Gaps
02 Sensor
MAF Sensor
PCV operation Check/Works Fine
Cleaned Air Cleaner
Evo 9 BOV ( bought used to replace oem 8 plastic valve)

The timing belt was done at 70k at the dealer, about 40k miles ago. Any chance they botched this job and timing has jumped slightly? I am extremely frustrated, running out of money to throw at this thing, and really at wits end. To add insult to injury I just spent $500 on this thing because the alternator catastrophically failed, and of course the tensioner was toast.

Fuel Pressure Regulator?
Sticking Injector?
MAP Sensor?

Where do I go from here........

 

That's alot of boost your running with so little mods it seems like to me. I'm not sure if that's the cause of your problems.

Also if stm ran a compression test and said it was fine I dont think your timing would be off I could be wrong I'm not super knowlagable in the subject of timing.

 

I agree, the boost does seem a touch high but I didn't really want to second guess what I assume to be one of the best tuners in the community. I also figured that with the boost that high the car should hit pretty damn hard once it spools, and it really doesn't.

The impression I get is the turbo is making boost fine, but the motor is not responding to it.

The numbers I recall from the compression test were between 140--150psi, on a pretty warm motor. I have a suspicion there is something going on with timing or spark advance just because of the way it is behaving.

What sensors besides the MAF and CPS have an influence on spark advance??

 

Not sure on the sensors but do you have a gauge? Are you actually seeing it hit 25psi or is that just what it is suppose to be hitting. May be a silly question but if your not actually hitting the psi its tuned to it might fall on your injectors or fuel pump (I doubt its your 255)

Stock injectors and 25psi is risky imo.

 

It doesn't hold 25, I would say it spikes 25 initially, probly holds 23ish. I have an AEM guage in the cabin. Had plenty of fuel according to the dyno sheet.........but who knows. At last check the car had not a drop of knock on the dyno as well.

 

Well if the dyno sheets still read the same hp rating as before but you still fell loss in power it might just be you getting use to the speed of the car I know that sounds ridiculous but I thought the same thing once with my evo that it had lost all its power I didnt feel the tq anymore then my buddy got in it with me and he said it still felt the same as the first day I took him for a ride in it. Thenmy evo was out of commish for 3 months and when I got back in it I thought I gained 50 hp or something

That might be what it is minus your oil problem and surging.

I cant say its definitely not the timing belt but being 40k miles ago I highly doubt it is.
Sadly I am not mechanically inclined enough to tell you what to try next maybe someone else on the forums will. Best of luck with it though.

 

Not saying this is fully the cause but I have to agree. I catch my self getting used to it aswell until it sits for a few days and I'm back in.

 

I guess I should just get it to the track then............trap speeds won't lie.
On another note, I have an open dump o2 housing and I can hear the wastegate coming partially open long before full boost is achieved. When should I start hearing the gate open psi wise? I am almost sure I am hearing it before 15psi.

 

Does ur dump tube leak exhaust at idle? in other words, if you place ur hand on the dump opening, do you feel any exhaust flow? also, are you using an mbc or ebc?

 

Its a hallman mbc.

When I put my hand over the dump tube at idle I can't really feel exhaust flow per say, but I think I actually feel vacuum.

 

Alright so I spent a good deal of time in the car tonight and I can say pretty much that the car has no shortage of power, my main symptom is just a sluggish spool. And when I say sluggish, I mean compared to when the car was essentially bone stock. It could be something as simple as a half turn of preload on the wga arm.......

 

I would double check that gasket and make sure it's divorced.
That would account for loss of spool. It would be a big boost leak upon turbo trying to build pressure.

 

Check the preload on the wga and make sure its tight. hopefully this fixes ur issue.

 

STM put the gasket on the housing when they custom fabbed it, I doubt they would have botched that up. On a bright note my idle today was absolutely flawless with the new alternator in the car........and it feels like it has come around quite a bit.

 

mine peaks at 26 and holds 23 then around 21-22ish at redline. stock injectors and walbro no problems here. but yes, from the list of mods you provided it looks like you are saying you have the stock exhaust with a cat delete pipe only for flow mods. you might want to look into the full exhaust and a licp maybe a o2 housing. heck put in an open element filter while you're at it. can you post your dyno plot?