Buick 3800 problem

[PB86MCSS]

I have a new issue on my 90' Buick LeSabre, started this past week but tonight it got worse. When driving along, in gear, sometimes just cruising along sometimes when braking, the RPM's will surge up 400-500ish, the SES and Temp dummy light will flash and go away, within a millisecond then the car resumes as normal. It only stalled on me one time at a stoplight and started right up again no problem. It seemed to do this when the car was colder at first once per drive or so but tonight it occured a handful of times on each way of a few mile trip. I checked the codes, code 43 is present (ESC Module) but has been an intermittent code since I bought the car in 05' and never had these symptoms. The temp is fine according to the stock gauge and scantool, voltage normal too...scantool reads 13.2-13.4 at idle. Not sure what might be causing this, any ideas? My guesses are alternator, wires shorting out somewhere (hope not), ECM or module/coil. The module/coil was "updated" to the Delco II style a few months ago, I did fry one module right away after not putting grease between the plate and module but it has been problem free since then (this was early September). I do have spare modules and a coil set to swap on, spare ECM although it had a bad quad driver (car was still driveable though) to help troubleshoot. Tomorrow I'll check for any obvious wiring damage.

[theavenger333]

could also be the coolant sensor.... did it with mine

[PB86MCSS]

Did yours have the same symptoms? Didn't do it so far today, the only thing I saw that might be a cause was the battery cables were touching slightly...adjusted some stuff and no issue but I won't hold my breath that this solved it quite yet.

[theavenger333]

some of them... but not all of the same symptoms. just know they are common to shit out, cheap part to replace.... dunno, with the swapping of the coil packs, and the trouble you had with all that mess it's unknown.

[PB86MCSS]

Well, the problem I had was due to not using any grease between the module and bracket, so it overheated. So I saw the error of my way on that one. Car drove fine last night and today too....so maybe the battery cable or spark plug wires touching were the issue. Still not convinced but perhaps.