I just installed an Apexi FMIC and power intake, radiator, and fuel pump, and I wanted to do some wideband testing before the autocross this weekend. Plugged up all the stuff and went out to make some runs. Made one 3rd gear run, which had mid 11 ratios. Then tried to make a 4th gear run, but had to bail out due to traffic. Made one more pull in 4th to redline. Again A/F's ranged from 11.3 to 11.7. Max boost was 0.77 bar and the max duty cycle was 84%. That all should be fine from my understanding.

After the last 4th gear run, the car started vibrating. You can feel it in the clutch pedal, the gas, and the shifter. I started thinking the worse, but the car doesn't smoke, the vacuum is still what it's always been (right around 400 mmHg at idle), and it starts and runs fine. It may be down on power or at least hesitate on giving it gas, but I'm not sure if I'm imagining that. Still boosts fine.

I pulled the plugs and the two leading ones are black, the two trailing ones brown. My hopes are that the leading's are just fouled, so we scraped them off but it didn't seem to make any difference. I have some new ones I'll be putting in at lunch.

I think that's all the facts. So can you guys suggest anything for me to check if it turns out not to be the plugs? State autocross championships are tomorrow and I was supposed to leave for them at 5:30 today, so time's short!

Thanks a billion

 

Also, the vibration changes with RPM.

 

do a search on MAP sensor. Sounds like it popped off.

 

Yeah, forgot to add, checked MAP and it's still on. As well as all other hoses that I could see. Thanks for the tip, though.

 

Well, crap. I just swapped out the leading plugs, and it didn't make any difference at all. It's looking bleak that things will be fixed by 5, but I'd still appreciate any ideas at all.....

 

Nevermind. Went to make a few full boost runs to see if I could get away with running it this weekend, and all the power's gone and it won't idle anymore. Sounds like classic apex seal failure. At least it was nice enough to break close enough to home to get it in the garage!

 

Did you get a compression test done, yet?

Sounds like it still could be a popped vacuum line?

Any change on how much vacuum you showing at idle?

 

Haven't done the compression check yet. Should be getting to that sometime this week. I double-checked all the vacuum lines before I went out for its last run. It basically progressively got worse rather than breaking all at once. Sounded like a diesel engine running at the end.

Vacuum dropped about 100mmHg from 400 to about 300, the best I could tell. Again, it wouldn't idle, so it was hard to tell....