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View Full Version : Stumbling KA....sucks


thx247
02-20-2004, 01:34 AM
I moved a USDM 93 DOHC KA into a Canadian 91 hatch. Swapped the AC and PS mounts and the speed sensor out. Car started right up, drove it around. Drove it to work and during work...maybe 90 miles or so. Later that night though the car started to stumble on the freeway. A cough here or there. We pulled off and got gas since I was low enough that maybe that was the cause of the stumble.

A little later on that night the motor began to act out alot. Several times I almost stalled it on the freeway, and it was barely running at some points. I pulled off the freeway and it died at the stop light. I started it up again and drove it 100feet further out of the intersection and it died again. It wouldn't start after that for 5 minutes or so. Then it started and I drove it home...barely. It was barely running.

Thus far I have done the following:

(Only done at idle so far)
Checked to see if cylinder was not operating properly by pulling injector power, or spark plug. According to the FSM my cylinders are firing and being fueled properly.

Replaced the MAF with a spare.

Replaced spark plug wires and coil wire (more spares)

Checked connections, battery voltage while off and while on. All check out alright.

Ran the car under load without the O2 sensor and I still have the problem. I ran the car without the purge and vac line on the Charcol canister, plugged and unplugged (desperation)

All I can tell so far is that the stumble is only when the motor is under load. It usually appears when I am on a normal street with traffic. Whenever I drive on a quiet street the motor works just fine ;)

Getting on or off the throttle does not seem to affect the stumble. Getting on throttle either clears it up, or the car just accelerates while stumbling. Getting off the gas does not appear to cause the problem nor cure it.

My EGR is working properly as far as I know. My throttle is not open, I did not miss a vacuum line that I know of since I just installed the motor. I inspected most of the lines and did not notice anything amiss.

The donor motor just passed smog with flying colors a day before I pulled it. The recipient chassis also passed smog recently, and its original motor was working well enough that I tracked it for 150 miles without any issues.

I don't have a fuel pressure guage....and I have not replaced the spark plugs (Which were working JUST fine less than a day ago in the original car, and for a brief while in the new car)

I have not pulled the plugs yet. And I didn't mess with the fuel pump or filter.

Thats about everything I can think of so far...


Any ideas?

adey
02-20-2004, 03:28 AM
Check your EGR for sticking - if you have an FSM it's described there; basically you hold your finger on it while pulling the throttle... or something like that. Also try replacing your PCV and cleaning out your AIV. Try a new rotor and distributor too... clean your MAFS with brake cleaner or automotive electrical contact cleaner, clean your air filter, then try starting the car up again.
Good luck!

thx247
02-21-2004, 12:41 PM
I was playing with it again this morning. I swapped out the ignitor coil...no change. Then I checked the voltage on the fuel pump...checks out fine.

Then I started to think what else could be going on here...got flustered and I said "well screw it I'll change out the plugs" since thats just one less thing that could be broken.

While I was doing that I noticed a loose ground right above the O2 sensor. Sonvabitch.

I finished with the spark plugs and tightened the ground. Car seems to work fine again. I highly doubt it was the plugs....I'm going to take the new plugs out and put the olds ones back in just to be sure the ground was the cause.