it wouldn't be the sensor-even if it was bad. the ecm reverts to a "hard program" if a fault happens (kind of like open loop). Id have to look, but i have a strange suspicion that the egr needs to be "set" to zero when installed. (for example) My old Beretta also had the herky jerkys. All the same things pointed to the egr. So, after testing, and proving it was bad, i replaced it. the new one still did it. Puzzled, i looked at the egr and noticed that it wouldn't close 100%. What i found is the ecm had assumed the egr was closed and used the wiper position it was in as zero-when in reality it was in "slot 2" (imaging the wiper as slots,0 being closed-10 full open. this is just for a mental pic to understand what i mean about the position).
the fix was to manually pull the valve closed then installing- thus putting the wiper at true zero.
The only other time i had herky jerky was with a bad purge valve. That never set a code(even though it should). come to think of it, i should do some testing of mine on the gen 1. (ive got the same issues and egr system is good). hmmm
The egr valve I have on there now has been there about 3 years, no 'herky jerky' until a little while ago, so I don't think it's the set-point. Unless... might it be that the original jerkiness was due to the clogged egr plate, but when they reinstalled the old egr valve after cleaning/replacing the plate, it somehow wasn't fully closed?
Ok, so I'm going to try the following: 1) replace the secondary O2 sensor with the $32 one from Ebay, and if that doesn't help, 2) replace the compression coils with ones that work and see if that fixes it. After that, who knows. I contacted Eric and he'll be helping me. I'll keep you posted!
Tracking down the "herky-jerky" is probably one of the most annoying problems.
As you can see on this forum, it often involves running through the possible problem parts
EGR plate (cleaning)
It makes mechanics just as much as it irritates owners.
No herky-jerky so far, but the trouble light is on again; went once for a P0420 code, and back on 4 days later. Is it a false code from the secondary O2 sensor, a sign that my cat actually is broken, or the primary sensor causing trouble now that it's plugged in? Or something else entirely?
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