Hesitation/Stumbling problem with B6 SOHC

[Flyer]

I can feel the car stumbling under the following conditions:
- Engine has been fully warmed up
- RPM is between 1,200 and 3,300
- Any gear is engaged
- Gas pedal is depressed

In the past few months, I have replaced the following on the car:
- Fuel filter
- Fuel pump
- Timing belt
- Spark plugs
- Thermostat
- Coolant
- Oil and filter
- Muffler
- Cataylic converter

The only possbilities I can think of right now are either a blockage or clog in the fuel line somewhere, or the more dreaded cylinder crack. I somehow doubt the cylinder crack, as I hear zero knocking from the engine. Anyone have any ideas?

To expand a bit: No codes have been present at all, before and after the ECU reset, which was performed two weeks ago.

The problem began when there was a nice hole the size of my fist in the muffler about 1.5 months back. In addition, the car had been running with the wrong distributor (it had the one for the DOHC engine). However, that problem was fixed quickly.

I did a few more driving tests, and the car jerks stronger (insert obvious sexual joke here) when in third of fourth gear from roughly 800 RPM to 1,500 RPM. The car currently idles around 1,500 RPM, occassionally dropping to 800-1000 RPM.

Coolant temperature sensor appeared to be fully functional when the thermostat was replaced, re: this topic I made

In other news, I hate that spot in front of the door that acts as a crap collecter >_>

[guido101]

did u change ur air filter? also check for vaccum leaks, and try some fuel injection cleaner.

[Bumpysbro]

check ur coolant temp sensor, and how long has it been since the o2 sensor was replaced? and also try checking for codes

[Flyer]

To expand a bit: No codes have been present at all, before and after the ECU reset, which was performed two weeks ago.

The problem began when there was a nice hole the size of my fist in the muffler about 1.5 months back. In addition, the car had been running with the wrong distributor (it had the one for the DOHC engine). However, that problem was fixed quickly.

I did a few more driving tests, and the car jerks stronger (insert obvious sexual joke here) when in third of fourth gear from roughly 800 RPM to 1,500 RPM. The car currently idles around 1,500 RPM, occassionally dropping to 800-1000 RPM.

Coolant temperature sensor appeared to be fully functional when the thermostat was replaced, re: this topic I made

[Limegreen mx-3]

have u check ur vaf/maf what ever the metal box is called that is part of ur intake system..

[Bumpysbro]

do you have a vacuum gauge to check how much your making? usually around 16inches at idle throttle closed is good. because if theres a leak its letting unmetered air in screwing up the mixture. have your checked your rubber intake hose for cracks? if all else fails you could go to a dealer if you have one close by and they could put a scan tool on it and see what the input/output for the engine is.

[Flyer]

Air filter has been replaced and the tubing has been checked out. Lines are all clean with no cracking.

[2fazed]

hopefully this isn't your problem. but before I knew my tranny was gone, it was making my RS overheat, and cause it to jump on idle when the coolant was low. It did that for months. I didn't know what was going on, till the clutch went toast. decided to replace both at the same time, and pretty much fixed the idles and overheating.

[Flyer]

hopefully this isn't your problem. but before I knew my tranny was gone, it was making my RS overheat, and cause it to jump on idle when the coolant was low. It did that for months. I didn't know what was going on, till the clutch went toast. decided to replace both at the same time, and pretty much fixed the idles and overheating.

You know, that would give me an excuse to do the BP swap, but I lack both the space and the proper tools to perform such an endevour...

[OldMan]

Did you change the strainer in the fuel tank?
It is located on the bottom of the fuel pump. If you did change it did you replace it with the longer rectangular strainer? Most fuel pump kits seem to come with a shorter almost square strainer. This would cause your car to momentarily lose fuel when tank is not full and you are turning. Just a possibility.

OldMan

[SuperK]

I vote o2 sensor.


The single wire o2's don't throw codes when they go bad.
The o2's work until about 3500RPM, then it's shut off (for maximum POWAH!)

they're really cheap for the sohc, go ahead and replace it. Or disconnect it and see if the car runs differently.

My car used to hesitate like that, and as soon as it hit 3200-3500rpm, it'd be like something just "kicked in" and make it drive. Meh.

[nos92mx3]

have you checked the cam timing?