1992 coupe - no ECM or BCM codes?!
Thread Starter
Instructor
Joined: Sep 2004
Posts: 165
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From: Middleburg Florida
1992 coupe - no ECM or BCM codes?!
My 92 has been running rough at steady cruise and low throttle. Typically only happens in the 40-45 mph range but lately in the 65 - 70 range. I went to check ECM codes today but the only thing displayed for both the ECM & EBCM codes was "---". No c12 or history codes whatsoever. The CCM codes were all normal. Any idea what could cause this? I used a jumper between pins A&G on the diagnostic plug. If the ccm isn't able to display ecm & ebcm codes, would this mean a code scanner can't read them either? I appreciate any insight you guys can offer.
Instructor
Joined: Mar 2012
Posts: 116
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From: South Lake Tahoe CA
Have you noticed if the tach is bouncing quite a bit? If so it sounds like an ignition module is going bad. Could also be a bad plug wire...these high voltage systems get testy with wires
Thread Starter
Instructor
Joined: Sep 2004
Posts: 165
Likes: 0
From: Middleburg Florida
Thread Starter
Instructor
Joined: Sep 2004
Posts: 165
Likes: 0
From: Middleburg Florida
Even for segment 4 and segment 9? Darn, I was hoping the ECM would give me some insight into my misfire. Have read a few threads that indicate an EGR valve may be the issue but don't want to throw parts at a problem...
Thread Starter
Instructor
Joined: Sep 2004
Posts: 165
Likes: 0
From: Middleburg Florida
"Surging" is probably a better term. The rpm fluctuates slightly and feels almost like the transmission can't decide what gear to stay in (auto). It will accelerate out of these two mph bands with no hesitation or misfire at all. Doesn't happen at any other speeds. The engine idles fine, hard acceleration is fine, just these two annoying speed zones that I find myself in daily.
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Thread Starter
Instructor
Joined: Sep 2004
Posts: 165
Likes: 0
From: Middleburg Florida
Last night, I dug out my old data cable and laptop with a version of TTL Datamaster I downloaded in 2005. I recorded the 20 minute drive in and due to traffic, couldn't get in the two problem speed zones for long enough to have it consisently occur. I felt it a couple times at around 42 mph, but didn't at around 65 or so like I have previously. I downloaded their latest software version this morning and will record it again for the drive home with the updated version. I hadn't looked at their software in so long that I need to read through the manual again to decipher some of the indications. Anyone intimately familiar with datamaster that wants to weigh in on my runs?