new & different hesitation!

[farfrumwork]

So, I'm having some super annoying hesitation/misfire on my '93 turbo leg. Here is run down...

With any load (uphill is worse) my car will studder (misfire). This is relatively mild, but limits power to basically nothing (can get no more than 85mph floored in 5th - this is WRONG!)

BUT - if I stay in it long enough it will clear up and pull hard at 5200rpm or so up to redline (like it was pulling timing - probably all of it). It used to feel weak over 5k, now the midrange is toast

When the engine is just started (cold) it will bog/kick/buck/mis/etc... to a huge degree with almost ANY throttle input.

I have replaced the plugs (proper NGK's) gapped at .039". New Diamond coil. checked plug wires (newer NGK's). Reset umpteen times. No codes.

I suspected the TPS (like it thinks it's closed all the time), but measured 2 others in Matt's "teh Ghetto Garage" but both had same readings as mine. Everywhere it is stated that the 2&3 pins (middle) should be 10kohm closed and 5kohm open - these all showed 10k regardless of position. The idle switch works (0/1Mohm). What is right here?!?!?!?


Anyhow, any thoughts (deep or not)? This is driving me nuts.

Thanks!
Chad
btw - '93 turbo leg, 76kmi, 3" catted CES TBE, pulleys, MBC (now at 9-10psi - was 12-13), A/W intercooler.

[Legacy777]

I don't think it's the TPS....

Pin 2 is the ground pin.
Pin 3 is power.

You want to measure pins 2 & 4. Then the resistance will change as you open the throttle.

Irregardless....this is the biggy that you should check.
http://www.main.experiencetherave.com:8 ... sting3.jpg

Here's the others just so you have the info
http://www.main.experiencetherave.com:8 ... sting1.jpg
http://www.main.experiencetherave.com:8 ... sting2.jpg

[farfrumwork]

Thanks,

Well that makes more sense, I'll check pins 2&4. Pins 3&4 showed varied resistance with throttle movement - but I haven't looked at 2&4.

I can't open the links you provided unfortunately - I get a connection time out. This seems to happen with that site for me all the time...(?) Is it (the biggie) the throttle position switch test?


Also how about the knock sensor? I am leaning towards that as it seems to get so much stronger past ~5200rpm (when I think the ECU starts ignoring the KS - which I believe happens with the wrx ecu's as well).

-Chad

[Bheinen74]

do you have any check engine codes?
have you checked the MAF? cause your description sounds 110% like what mine did when the MAF sensor was dirty.

are you running a K&N air filter? the oil from it can make the MAF dirty and mess up the way your car runs.

[farfrumwork]

No codes, and no CEL.

I have a paper element filter. I also pulled the MAF (aluminum housing) and tried to blow it out with some compressed keyboard cleaner stuff.

What is the sure-fire way of cleaning the MAF?

I will gladly pull it and clean it again.

I just don't get why it would pick back up after 5000-5200rpm?? I am running 9-10psi now, so it doesn't drop pressure at high rpms (same 9-10psi all the way to redline) - which means that the MAF voltage should still be rising linearly with rpm - right? And no I have'nt checked MAF voltages...

Thanks
-Chad

[Psychoreo]

one way talked about here to clean the MAF is to spray the hell out of it with break cleaner, or to let it soak in a plastic baggy with break cleaner in it. when i cleaned the one on my cougar, i used a toothbrush and some gun lube/cleaner. seemed to do the trick.

[Legacy777]

Try these:

https://www.main.experiencetherave.com/ ... sting3.jpg

https://www.main.experiencetherave.com/ ... sting1.jpg
https://www.main.experiencetherave.com/ ... sting2.jpg

[farfrumwork]

Thanks.

I'll try to clean the MAF. And I can view the TPS test procedure now.... ahhhh kowledge.

-Chad

[georryan]

Maybe a silly question, but have you checked and gapped your plugs?

-Ryan

[farfrumwork]

Yep, brand new plugs - gapped a bit down from the last ones .038 vs .041 (which were also new)

Anyway - HORRRAAAAYYYYY!!!! my baby is back, and kicking ass again!!

The MAF wires had crap built up on the leading edges (approx the Dia of the wire itself - wow). I brake cleansed those, and everything else in the AL housing - then rinsed with alcohol. Let dry, reset ECU, and Bam! Zero hesitation, not even a hiccup.

Now to turn the boost back up (12-13psi should a blast now).

Thanks to all, and especially Bheinen74 - you nailed it!


-Chad (happy booster)

[Bheinen74]

glad you got it. Still running good?