Hi guys,

Its another "help me fix my Evo" thread. Seems like there have been alot of these lately.

Anyways, here are the mods I am working with:

Stock block
Ported FP Red Turbo
Kelford 272 cams w/spring & retainers
EPM 02 Dump
Perrin FMIC & RMR piping
RMR Intake w/Perrin filter
Buschur Turbo-back exhaust
Buschur ported/coated stock exhaust manifold
PTE 1200CC injectors / Buschur dual fuel pumps
Tuned on stock ECU @ 28 - 29psi. 440WHP on a mustang dyno.

Problem:

Over time my car has been running richer and richer, particularly inbetween high rpm shifts, at part throttle under normal driving, and now even at idle. By rich, I mean it falls off my gauges scale below 10.0 AFR. When it does this, the car bucks violently back and forth.... Its almost like a backfire or something. My gas mileage has been cut in half - I'm getting 10mpg under normal driving, no WOT.

I dont think it is the tune, as the car ran fine when I first got it back but deteriorated over time. Could it be bad/blown coils? Boost leak?... I have a hunch it has something to do with the ignition... The problems are more noticable when the car is still warming up in the cold winter.

Any idea's?

Thanks guys
Art

 

A boost leak definitely could do that probably the easiest to test as well.

 

is your bov vented into the atmosphere???

 

I had a local turbo shop test me for a boost leak and they said no leak....

I am using a brand new Forge RS Diverter Valve... not VTA

 

exhaust leak??

 

Would an exhaust leak make the car sound any different? It sounds normal with exhaust...

 

Yeah it sounds like crap when you have an exhaust leak, you would tell.

 

I had a bad 02 gasket before and it sounded like hell. I fixed that... sounds normal now but it runs incredibly rich with seems to buck or backfire under part throttle and inbetween high rpm shifts. What the heck could it be?????

 

what does your compression look like??

 

Call me a fool... how do I check that? Is it a cheap easy check that a local turbo shop can run? Thanks.

 

In the individual gears it pulls like a freight train and sounds great, but if I shift to the next gear at high RPM after WOT it bucks and runs rich as hell... what is it???

 

It could be a o2 sensor that has gone bad.

 

I have a Buschur test pipe, which tricks the o2 sensor into thinking there is a cat... could that be the problem? I do not have a CEL...

 

I meant the front o2 sensor, sorry. Although, your description of the problem might indicate that the problem could be something else or a combination of things.

I been having the same problem with my car but right now I'm building my engine so I cannot tell you what could be the problem until it's done.

 

I'm no pro but I have a feeling its ignition. How common is it to have so much hp/boost that we blow out our stock coils or ignition and the car runs crappy?