Caleb_91RS

Hey guys,

Car is a 91 with a 3.1, auto. 98K miles.

The problem begins when I start the car after the temperature reaches 220 (fan comes on at this point). After I shut the car off and go back to start it the RPM's will surge and if I try to put it in gear it'll either die, or if I try to drive anywhere I'll get the most god-awful misfire I've heard. If I get to around 45 MPH the misfire will go away and the car will drive like normal.

In the past year I've replaced the spark plugs, wires, thermostat, fuel filter and ignition coil. I also replaced the vacuum lines that look like a "T" coming off the back of the upper intake since they were leaking. I also know that the cap and rotor will need replaced.

I was planning on replacing everything needed for a tune-up but I wasn't sure if there was anything else I should check or replace.

Thanks!

Base91

iTrader: (1)

You should check the injectors and fuel pressure regulator too. If they are original they likely need to be replaced/rebuilt.

Street Lethal

iTrader: (16)

Replace your ignition module...

Caleb_91RS

Thank you guys for your replies, have a bit of an update.

Yesterday I bought a new ICM, cap, rotor, wires, and plugs. While changing the spark plugs I noticed the number 1 and 2 plugs were covered in oil. After everything was installed I started the car and let it sit and it idled fine and everything seemed normal until I went for a drive.

The car starts fine and idles normal at around 1K. When I start driving the RPM's will bounce anywhere from 500-1K and sometimes drop below 500 and then die (This also happens when braking, but goes away once stopped). Also, the car will hesitate and sputter. (I also noticed a couple backfires into the intake on one occasion). These problems go away once I hit about 45 MPH.

I'm not sure what the problem could be. Vacuum leak? Something not installed correctly? Does anyone have suggestions on what to do next? Thanks

OrangeBird

iTrader: (1)

Your very next move should be a compression check of all cylinders . You could find 6 cylinders with acceptable compression , and the oil in cylinders 1 & 2 could be from valve stem seals . You could find cylinders 1 & 2 with lower compression than the other 4 which could indicate deeper problems . But till you do the compression check , it's just guessing . Were this mine to diagnose the oil covered plugs would be the first thing I'd track down as two misfiring cylinders really could be the cause of everything you've described wrong with the way it runs .

Street Lethal

iTrader: (16)

Don't get confused between fouled plugs and oil filled plugs. If your backfiring, then your running lean, thus not burning fuel, and the plugs foul and have a flat black cake like look and will smell like fuel. Oil will literally have oil on them. Replace those fouled plugs, no amount of cleaning will bring them back anyway, and plugs are cheap enough. Now, make sure your base timing didn't move when fiddling with the distributor, make sure your timing is correct with the EST disconnected using a timing gun. If it is, disconnect the battery and let the ECM reset, as your computer may be in default mode from making changes with the battery still connected, you may have triggered something. So disconnect it for a few minutes and allow it to reset. If the idle still seems unstable in Park/Neutral during regular idle, hook up a vacuum gauge to the intake manifold and get a reading from it. This reading will tell you if there is a problem with combustion, so don't get too ahead of yourself.

Caleb_91RS

Well after searching around more threads I thought that maybe my TPS was bad, so I bought a replacement at Autozone. Installed the new TPS and it seemed to run a little better, but not much.

Later on I drove the car, I let it sit in the driveway and warm up and once the temp reached 220 the RPM's started to surge and eventually the car died. Once I tried starting it back up it misfired until it died...again haha. I thought this problem would be solved with the new ICM?

Would it be worth buying a new EGR? I've read that this could also be apart of the problem.

What will the compression test tell me in regards to what could be wrong?

thatoneguy5x

before you go around replacing every single sensor under the hood try to do a bit of diagnosing. what code does it throw when it dies? does the car smell like it's leaking fuel? do you ever get a steady idle? it will be a whole lot cheaper than just throwing random parts on the car. a digital multi-meter can be your best friend in a third gen.

I had a surging problem with my 92 3.1 when it would reach operating temp, especially when cruising at low speeds and coming to a stop. it ended up being my IAC. you can pull yours off for a good cleaning and lubing. just make sure you disconnect it before you pull it off. and if you pull it off connected don't turn the key because it will send the pin flying.

best of luck.