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I recently started having problems while trying to boost above 0.5bar. At that point the car has started to stutter and doesn't accelerate nicely anymore. The problem has gotten progressively worse during last ~500-1000 miles.
The car now also seems to idle quite badly sometimes (warm & cold). When it doesn't idle well, it sounds as if only 5/6 cylinders were working so one cylinder may be constantly missing for a few seconds, then it works again, and then not ...
I started to solve the problem by changing spark plugs, which didn't help. Next step was testing if I have boost leaks. I did the test by blocking several pipes as described in this picture: http://www.cs.helsinki.fi/u/ttukiain/korolla/moottorikuvat_kasaamistavarten/leak_test_setup.JPG and pressurizing the entire system up to 1.2bar.
During testing I found out two things:
1) my cam covers pressurized -- compressed air started leaking out from oil filler cap
2) there is a leak somewhere in the underside of IAC valve, maybe its gasget is leaking. The leaking sound becomes easily noticeable at 0.5 bar, but the leak seems very small (while tested by wet hand).
For 1), I suspect that I have leaky valve stem seals. Last summer my car would puff smoke from time to time while idling. After changing oil this spring, I haven't seen any smoke puffs, however.
What else might allow pressure to get into head covers? Do you think it is possible that some of my valve stem seals is in such a bad shape that it is causing all of my problem symptoms?
Anyone else ever had IAC valve gasget leak? It might also be something else near bottom of the IAC valve.
The car is a 1994 6-speed Targa with 105500 miles and:
- new stock turbos, changed ~2000 miles ago (no problems in first 1000 miles after the change)
- hks vpc (on default settings)
- apexi s-afc2 (on default settings)
- hks dli ignition
- GReddy 3-ROW front mount intercooler
- K&N air filter
- Blitz Dual Drive Blow Off Valve
- Lightweight Flywheel
- Blitz Turbo Timer
I already ordered new valve stem seals and IAC-to-intake manifod gasget. Any suggestions what to do/troubleshoot next other than changing both of these?
Thanks! -tomi
The car now also seems to idle quite badly sometimes (warm & cold). When it doesn't idle well, it sounds as if only 5/6 cylinders were working so one cylinder may be constantly missing for a few seconds, then it works again, and then not ...
I started to solve the problem by changing spark plugs, which didn't help. Next step was testing if I have boost leaks. I did the test by blocking several pipes as described in this picture: http://www.cs.helsinki.fi/u/ttukiain/korolla/moottorikuvat_kasaamistavarten/leak_test_setup.JPG and pressurizing the entire system up to 1.2bar.
During testing I found out two things:
1) my cam covers pressurized -- compressed air started leaking out from oil filler cap
2) there is a leak somewhere in the underside of IAC valve, maybe its gasget is leaking. The leaking sound becomes easily noticeable at 0.5 bar, but the leak seems very small (while tested by wet hand).
For 1), I suspect that I have leaky valve stem seals. Last summer my car would puff smoke from time to time while idling. After changing oil this spring, I haven't seen any smoke puffs, however.
What else might allow pressure to get into head covers? Do you think it is possible that some of my valve stem seals is in such a bad shape that it is causing all of my problem symptoms?
Anyone else ever had IAC valve gasget leak? It might also be something else near bottom of the IAC valve.
The car is a 1994 6-speed Targa with 105500 miles and:
- new stock turbos, changed ~2000 miles ago (no problems in first 1000 miles after the change)
- hks vpc (on default settings)
- apexi s-afc2 (on default settings)
- hks dli ignition
- GReddy 3-ROW front mount intercooler
- K&N air filter
- Blitz Dual Drive Blow Off Valve
- Lightweight Flywheel
- Blitz Turbo Timer
I already ordered new valve stem seals and IAC-to-intake manifod gasget. Any suggestions what to do/troubleshoot next other than changing both of these?
Thanks! -tomi