I was out driving a couple of nights ago and came across a Z28 on the highway. We did a quick third through four gear run and everything was fine. Later that night on my way home I get behind a car going 10mph under the speed limit. So when we got to a passing section of the road I went to pass him and I noticed that my car didn't respond like it normally does but I was able to pass the other car and didn't think anything of it. About 15mins later I noticed that when ever I would accelerate the car would sputter, boost would start to build and than fall off. I checked numerous hose clamps and all were fine. Also the engine seems to be making a little more noise than usual. I think I hear a slight clang at times. At this point I don't know what else to do.


ps- I'm not getting any codes.

 

have cams?

 

Well you said you checked some clamps, and that would be the first thing I recommend. Make sure there is no un-metered air getting into your motor (leak after the MAF) and go from there.

 

it just seems like a boost leak... it just might not be 100% off yet... did u check the lower ones... boost controler... everything...

 

hmmm....sounds like you're on that stock Evo 8 BOV. Thats probably the issue. its partially opening up, and throwing things off, causing it to sputter. Mine did it too when i was on the stock BOV. I have since upgraded to a JDM MR 9 BOV.

Mine did it when i was going from VAC into boost. if i let off for a second, then got back on it, everything was fine.

i tihnk its that stock BOV.

just my .02

 

The stock BOV wouldn't cause such a thing unless it randomly fell apart. BOVs don't just open up like that and cause sputtering. He probably just fouled his plugs or pulled off an IC pipe.

The worst thing you can do is say, "I checked numerous hose clamps and they were fine." How do you know they're fine by looking at them? That doesn't tell you anything. You need to do an actual boost leak test to determine if you have a major leak somewhere.

Your first step should be to install a fresh set of NGK BPR7ES gapped to .026.

 

kinda hard to diagnose his problem while he's offline lol

 

Check your plugs, been running race fuel? then switched back to pump?.....?

 

I know, I meant none of them came loose, they were still tight. Tomorrow will be the first opportunity I have to spend some time on the problem.

And for the other guys, I have a JDM MR valve.

No race fuel.

 

seriously sounds like my problem... wartalon is right change the plugs!

 

Changing plugs today.

 

I have the HKS DL2, havent had a misfire or p300 code in awhile. Not that it's need for stock boost applications, but eventually you find yourself turning the knob up.

 

I'm beyond stock boost levels so maybe I'll check that out as well.

 

Update:

No one carries the NGK plugs but they say the Autolite 63 is comparable, should I order the NGK's on line or try out the Autolite. There wasn't really any feed back on here about the Autolite plugs so I guess I'll order the NGK plugs unless someone say other wise.

 

stick with the NGK's