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96 Trans Sport transmission/electronic problem

All,

My '96 Pontiac Trans Sport (3.8 V6) has a bizarre problem. It's a dual gas/LPG car, but the problem occurs both on gas and on LPG. Problem is: when I'm on the freeway, the car tends to shift down to 3rd gear on the auto transmission and will not shift up to 4 or OD anymore. This occurs mostly when I release the throttle or when I near-idle for a while (e.g. in heavy traffic). Stopping and re-starting the car allows back to OD, but usually only until the next time I have to take off the cruise control. I believe it is a problem in the transmission control electronics, but am uncertain. No one knows this type of car around here (I brought it to France when I moved there) so service doesn't seem a likely option. Anyone seen this problem before?

Also, the car's oil pressure meter seems to stay just in or above the red, even though the oil level is fine and the oil was changed. Is this normal?

Furthermore, the car runs lousy on LPG below 2000rpm, but this may be a problem that's just due to the low octane value of french LPG.

Thanks, Robert

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a
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I have worked on some LPG cars all GM. They run a module for the LPG that picks up the tps and o2 only. The module fools the computer for the rest of the readings. I would disconnect the LPG module if it is wired to make that possible. Usually it is. Also, I would check any grounds from the module for a bad connection. It is tied to the tps directly and switching over to gas does not make its connections disappear. I have seen many upshift problems when the LPG system is starving. Like when the LPG regulator is bad or a bad diaphram in the LPG converter. Also check your vacuum connection to the LPG regulator.

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Reply to
R

First thing to check, before you try anything else, is to make sure the engine to body ground connection is PERFECT. Mine was intermittent and it nearly drove me nuts. Oil pressure all over the map, tranny shifting funny,and half a dozen other odd symptoms that popinted in a dozen different directions.

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nospam.clare.nce

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