: My Cimarron is sick... Please help.

10-18-06, 04:52 PM
I am new here, but could use some help. I have a 1984 Cimarron. It is truly a nice car for being an '84 . The problem lies under the hood. When I start the car, the RPM s climb to 2000 rpms on a good day and up to 3000 on a bad day. And it stays there. You have to have a heavy foot to put it in gear or you may end up hitting anything in front of you or behind.

Now once it is in gear it will drop to 1500 rpm (while the brake is on) leave your foot off the brake and you'll be doin' 40mph in no time.

I have been all over the car looking for causes, and cannot find any vaccuum leaks, and everything else is plugged in.

Any ideas ????

10-19-06, 07:30 PM
Could be an obstructed throttle plate not closing all the way.

In terms of electronic causes, we have:
Idle Air Control motor
Throttle Position Sensor

To a lesser possibility:
MAP sensor

And any of these could be compounded by a bad IAT sensor (Intake Air Temperature) sending a signal that it's colder than it is. You should change that one anyway because they are about $15 and the old GM sensors tend to drift toward an excessively cold reading in their old age.

If this doesn't help, you might want to post this on a J-body forum. There are a lot more Cavaliers and Sunbirds from your era than Cimarrons left, though it doesn't sound like a model-specific problem.

10-20-06, 09:07 AM
Thanks for your reply. I removed the Throttle body assembly and I am in the process of rebuilding it. I had to order gaskets so I have a delay in progress. But will update this post if it changed anything.

I noticed under the assembly on it itself there are what appears to be hairline cracks (several) do you think it would cause a air leak ? And affect proformance ? They are not huge just there.

10-20-06, 02:04 PM
:eek: Cracks?!?!

Never seen that. Make sure they are in fact cracks, not just scratches. If they ARE in fact cracks, they could cause excess air to get in, causing the engine to run away as it has been. That would be very odd though.

What exactly is it do you think is cracked (or hopefully just scratched), and what is it made of? It sounds like you are talking about the intake manifold. I think your car has a metal manifold, so that would be very strange. I don't know a lot about your engine (assuming 2.0 SOHC with Electronic Throttle Body Injection), but this doesn't seem to be an engine specific problem, rather one that could happen to any engine.

10-20-06, 02:04 PM
Okay... Little update.

I got my gasket put it all back together and......no change. So that eliminates the throttle sticking thing.

Now I was playing around and when I plug the PCV valve with my finger it idles down to 600-750 rpm BEAUTIFUL !!! But it doesn't fix anything.

Besides plugging the hole (which I am not going to do) Does this help with any guesses ??

Also the TPS is an adjustable one, and I loosened the screws and moved it both ways, and it did nothing. Now shouldn't this change something ??? Does it mean that it is defective ?

10-20-06, 02:11 PM
Sorry should have explained better. And I should have taken pictures before I put it back together.

The intake is not cracked or damaged. The Throttle body assembly once you remove it and flip it over, now you are looking at what is the bottom of the assembly. The surface (not mating) has hairline cracks. I guess the best way to explain it would be looking at a OLD dried out gasket how they get the crazing effect when they are dried out . I do not think they go through any wall and even if it did they would be all internal.

It does look/seem to me as the car is running that it is dumping excessive fuel . Also i should mention that this car runs super does not miss a beat and absolutely no smoke at all.

10-20-06, 02:13 PM
Oh yeah,

They tell me that the car does not have the IAT sensor when I call for one. Is there anything else it would be called ????

10-20-06, 02:14 PM
They do say there is an Air Cleaner Temperature Sensor

10-21-06, 04:23 AM
Same thing. It's a thermistor whose value changes based on temperature of the air. Have you replaced your PCV? Those valves CAN jam you know... I'm betting you have, because you mentioned it, though I'm just making sure.

An easy test for the PCV is to take it out and shake it. If it rattles, at least you know it CAN work. It may still have dirt in it keeping it from working properly though. If it does not rattle, it's shot.

If the PCV is doing that when connected, that also opens up the possibility that you are getting a decent volume of stray air into the crankcase or simply the top of the head. Check your valve cover for anything that looks like it should be attached but isn't. Make sure there aren't any totally open breathers. If your PCV is bad, any of these things could make it pull in extra air.

08-03-07, 06:55 PM
Zorb750 is correct, I had the same problem on my 1983 Cimarron. I replaced the Idle Air Controll Motor, I also replaced the thermostat. The problem was over. My RPM is way down and when warm sets at 8 on the gauge.