Random, violent hesitations
 

I have a 1992. While accelerating in any gear, any rpm, I'll sometimes get a really bad hesitation as if the engine is locking up or I'm slamming on the brakes. I just changed the plugs and all the coil packs look fine. I just sea foamed, replaced the air and fuel filters, replaced the maf, and it still hesitates. It used to have an automatic transmission but I did a 5-speed swap (2004 Impreza), still hesitates so I've ruled out the tranny.

Anybody have some ideas? There is a cel on but it's for some egr stuff. My car also loses horsepower at higher rpms, falls flat on its face.. that's probably egr-related but I'm more worried about the hesitations than power right now.

If you are feeling froggy, try changing out the 02 sensors. We had a car do that at the pumpkin carve meet. Changed em out and violah! It is the same issue we had with Dan's 94 pearly too.

Tom

How does the O2 sensor do this? So if you were to remove the O2 sensor, would you experience this violent hesitation?

I replaced one of them with a new one, waiting for napa to be restocked.

I thought if you remove the O2s it just runs in closed loop? Or was it open? One of the two.

not sure either. it sure was strange to me. This is a real problem for people experiencing it, it def is not easy to diagnose either

Tom

apparently, wacked out O2 sensors on the EG33 can cause extremely rich mixtures to the point of raw gas puddling in the exhaust pipes (I think OT was the first person to come across this little joy:rolleyes:).
If replacing both O2 sensors doesn't clear up the problem, I'd look at the FPR and the ECU.
-Bill

or extreme lean conditions. This would cause erratic timing to be pull and thus the hesitation esp at highway cruising

Tom

What about MAF? Remember our convo the other night Tom. We troubleshot my issue down to the faulty Z32 MAF.

He said he replaced the MAF in the Original Post.

I replaced the MAF in his car with no results... This is something completely different.... What the hell are you doing posting here, we haven't heard from you for a year:p:lol:

Tom

If it's any consolation to anyone, my car also has this problem.

It did when it was driveable anyway. :rolleyes:

I'm getting crap gas mileage (~230 miles a tank) so I'd guess it's going rich..

yep, that too;):D
-Bill

cam position sensor!
 

That sounds exactly like the problem I had. At first, I thought it was MAF too. My problem turned out to be the cam position sensor (attached to the driver's side valve cover area across from the battery).

My symptoms (while accelerating)
- fell flat on its face at higher RPM's - this happened for about a year before the next two symptoms which occured within a two week period. No CEL of any kind.
- violent hesitation - the motor would totally lose power for second and then gain it back - almost like a bad fusible link that shorting against the frame. I'm pretty sure this led to one of my motor mounts tearing in two.
- bad miss (ultimately blew out the main converter) - this got progressively bad on my way home from work one day that by the end of my commute, the car wouldn't rev past 1800 RPM in any gear (with the gas pedal floored). Finally got a CEL, and it indicaated the cam position sensor. Don't wait until it gets this bad - change it now. You can get them new from Oreilley's for $150 or so or get one used.

My fix - $40 and one used cam position sensor from Budfreak (before his demise) later and the problem went away. Took me ten minutes to change it out. I removed the battery to make it a bit easier.

Hope this helps.