Quote:
Originally Posted by Matt B
Codes are in the shop manual (which I highly recommend) in the Central Control Module (CCM) diagnosis section (and in the article linked earlier). However I'm speaking about a 91, maybe it's different in your 94 case. In my case it was a faulty secondary vacuum selenoid and stuck check valve leading to an inoperable pump which in turn leads to a lack of vacuum at persisting WOT condition in high gear acceleration (4th+). Then the engine control sets a rev limit, too.
As said you can easily verify the correct vacuum operation by monitoring the pump (or pull the vacuum line off the pump and hook up a manually operated pump to see how well vacuum is held)
When your car is that low mile (like mine is, only 18.5k mls of which the last 1000 took 10 years) it's recommendable to first fully service everything and then carefully wake her up. I found a lot of issues, oil & vacuum leaks, defect sensors, selenoids, Stone Age fluids etc.
If the secondary system was never used it's very likely that the secondary intake section is packed with deposits and needs to be carefully cleaned by driving with secondaries active for an extended period. I just pulled my plenum to fix that defective selenoid and took the chance to inspect primary and secondary intake valves with an endoscopic camera. There is A LOT of deposits though they actually were used. Primaries instead a super clean.
Again, given that I just made the same experiences like you, I really recommend to work though the car first and then put load on her.
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I have read through the article prior, that's where the info about the ECM codes not being visible comes from. And I couldn't find code 61, strange.
A local club member had some simple advice for me that wasn't too far off of one of your recommendations. He said to put in some injector cleaner and go drive it for an hour at freeway speeds and then put another bottle and do it again.
Soon I am going to try to change out the serpentine belt. Hopefully won't be too difficult if I can figure out the tensioner.