Date: 1 Jul 2003 16:51:29 -0700
From: (Lance Morgan)
Subject: Re: 2500 - 3000 RPM Bucking (long)

Esa Tuominen <> wrote in message news:<q0j3gv0bn48ee5t7jdh4qbu9obnh0r3eljnopsamcom>... > >2500 - 3000 RPM bucking problem, at steady state throttle, on level > >ground or even more when going down gentle grade. Always reproducible > >when engine is hot (milder and not as reproducible when engine cold). > >No noticeable flat spot when accelerating, and no bucking when gas > >held steady from 3000 RPM to redline > > I think I had the same problem and it was the was the air mass meter. > The adjusting screw didn't response to adjustment in exahust-gas test > either. I did try a 2d AMM, as I believe these are more short-lived than ECUs but, alas, no improvement... > > >- no ground at AMM #4 (should be one, per Bentley, and indicates LH > >ECU is not internally grounding AMM #4: both LH ECU grounds are good, > >as is continuity between AMM and LH ECU) > > Hmm, I was missing ground #5 in ecu (LH2.2), I added it when I found > proper connector. > > BTW. Have you changed your fuel filter? > > Esa Yes, and air filter, plugs, etc. Fuel pressure is good... Drove it again today w/timing light strettcchheddd inside car - spark steady to all cyls, even while bucking... I have to think this is an atypical ECU failure, w/the primary sign being the no ground at AMM #4, w/the key on... Wish I had an oscilloscope, and knew how to use one! to measure the fuel injector pulse width. LM

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