3100 V6 Help Needed [Archive] - GrandAmGT.com Forum


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07-05-2012, 04:20 PM
Hello, unfortunately my first post on the forum has to do with some issues we've been having.

We have a 1994 Grand Am GT with the 3100 V6 engine. When starting the car in the morning, the engine seems to have a little misfire while backing out of the driveway. It doesn't die but you can tell there is a misfire. Every time the car is started, the Check Gauge light and Oil light come on. They stay on for about a minute and then go out and don't come back on until the next time the car is started. The Service Engine Light is not on. Actually, it hardly ever goes on. Has anyone ever heard of this happening and if so, what can be the cause of those 2 light coming on. I've heard suggestions about the oil pump and sender unit so we are going to start there. Does anyone else have any ideas?

Also, do the Check Gauge and Oil light have codes that can be read or is that just applicable to the Service Engine light?

*EDIT*: Now here's another thing. We do wait for the gauge and oil light to go off before we drive the car and the car still occasionally runs rough while coasting or at stop lights and it even died on the way home from work one day while at a stop light. We were able to start the car and make it home. It only died that one time so far.

Thanks in advance for any help.

07-05-2012, 04:51 PM
Those codes can be read For the misfire
and more than likely you need to look at the sending unit. The spot on the engine where it mounts is probably full of dirt. I have only ever seen this happen once on my old 3100 grand prix The sending unit is on the front of the motor where the oil filter is. Hopefully you don't have an oil pump going out. But I would start there
Has the car had a tune up lately ?

07-05-2012, 05:13 PM
I'll definitely look at the sending unit to start with.

Spark Plugs and Wires were changed in Feb. 09 at 79,000 miles. The car now has 92,000.

Looks like the oil pump and oil pressure switch were replaced in June 06 at 68,000 miles.

Is the oil pressure switch different than the sending unit?

07-05-2012, 05:28 PM
Definitely change the plugs and wires. You can actually run the same iridiums as the LA1 engine (3400) and it'll help burn off fuel a bit better.

What I would do, run some seafoam before changing the plugs and wires, burn off all the carbon deposits in the top end of the engine. I've done this twice to my own car, helped smooth out the idle and gas MPGs went up a bit.

I dunno if the older L81 is the same, but is there an oil pressure switch (plug) in the oil pan? If so, check the wiring, the plug connectors and check for dirt and oil getting in there.