Talon idling high causing it to overheat..

[dsm03]

Alright, so Ive been having some idling problems with the car. Its a '95 Talon AWD Turbo and what its been doing is once it warms up and I continue to drive the oil temp just keeps rising and Its reached up to almost 250F of course its going that high when the rpms keep rising. The car starts up fine but once its been driven awhile it'll get to a high of like 3,500 rpm. Which is just crazy.. Now I have replaced the Thermostat, coolant temp/water sensor and coolant temp switch. Still have the issue. I pulled out the thermostat for a couple of days and it still did it...So then I researched to find out if anyone else had this same problem, I came across one post which sounded a lot like mine and the guy said he turned his BISS all the way in and fixed the problem...I went ahead and did that and yeah it stopped the high reving and the highest it would go would be 1,200 but it would quickly go down after just sitting at a redlight or waiting for a few seconds. But here is the thing I thought ok it isnt so bamd anymore so i decide to throw the thermostat back in because i needed heat at night it still pretty chilly here at night...so i was driving today and problem came back..What do you guys think the problem is??

No boost leaks. Had the car scanned only thing that came up was the exhaust sensor is out and yeah that is why my check engine light is on but no other codes it was throwing.

The car is pretty much stock it has gauges, boost controller set at 14psi on stock T25. and 190 Walbro Fuel pump and re-wire. As far as that its bone stock and the car has been doing this before those mods...Need Help Bad!!!












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[hpexperts]

when was your last oil and filter change? do you have the stock exhaust? check the condition of your water pump, oil cooler radiator, radiator cap and fans, air filter and fuel filter this is where i would start. best way is to check is throught the data logger to see what is going on. some times it can be as simple as the ground from the battery. good luck!!

 

[dsm03]

Fuel Filter was Replaced 2mths ago and All fluids were done as well, And Just Changed oil and all other fluids last week... Those are always done on regular basis...Exhaust is stock then only mods i have are the ones listed

 

[Brutus]

Like the previous poster said, you should have a data logger. Just off the bat I would guess your throttle position sensor or biss is bad. Your car should not run with the biss turned all the way in.

If you had a logger you could see just what your ECU was reading off the TPS.

With the car not in gear and warm it should idle around 750 rpms. If you are idleing higher than that with the biss turned all the way in, then your throttle is stuck open, clean the throttle body and replace the shaft seals, or your TPS is bad.

Does the idle surge or go up and down while sitting once it is warm?

 

[kenamond]

I assume you meant to say coolant temp, not oil temp.

Do you have the coolant topped off?

Does the car overheat when you're driving or just when it's sitting?

Does your rad fan kick on when coolant temps hit 205°F?

How do you know the coolant temp? Do you have a logger or an aftermarket gauge or are you just eye-balling it from the stock gauge?

Have you tested the ISC? The ECU adjusts the idle via the idle speed controller. One test is to turn on the AC and see if the idle drops or if it dips but recovers back to what it was before you turned the AC on. The added load on the motor for the AC compressor and fan bogs the motor down, the ECU notices this, and tells the ISC to open up a valve on the throttle body a bit to bump the idle back up. If the idle drops but doesn't go back up quickly afterward, the ISC might be shot. There's a more detailed test with a multimeter, but you'll have to search to find that. You basically measure resistance between pairs of pins on the ISC plug to see if it's in spec. The Haynes/Chilton manual may outline the procedure, too, if you have one of those.

The exhaust sensor code you mentioned...is that the rear O2 sensor or the front? The front is needed, the rear just checks that the catalytic converter is working (emissions stuff). If the front sensor is bad, you need to replace it. If the CEL is for the rear O2 sensor, and the CEL bothers you, check out the O2 simulator tech article on this forum (there are two; the second just elaborates on an older one, but between the two, you know how to do it)...super cheap radio shack parts.

That's all I can think of.

 

[dsm03]

yeah dont have data logger so i wont be able to do that at the moment, im gonna run and check the AC test right now and see what it does and i think the mechanic said that its the exhaust sensor just right before the CAT. So that must be the one in the front then. Oh and Im pretty sure those shaft seals need to be replaced in my TB, could that be the issue??

 

[kenamond]

yeah dont have data logger so i wont be able to do that at the moment, im gonna run and check the AC test right now and see what it does and i think the mechanic said that its the exhaust sensor just right before the CAT. So that must be the one in the front then. Oh and Im pretty sure those shaft seals need to be replaced in my TB, could that be the issue??

The front O2 sensor is screwed into the O2 housing which is bolted to the hotside of the turbo. The rear O2 sensor is screwed into the exhaust pipe *after* the catalytic converter.

Bad boost leaks can mess up your idle among other things.

 

[Brutus]

Yeah, really you have two different (and probably unrelated) problems that need to be addressed seperatly. You have an overheating problem AND an idle problem.

There likely isnt one solution to both problems.

 

[dsm03]

it overheats because the car is constantly idling at 4,000 rpm read the whole post!!

 

[kenamond]

it overheats because the car is constantly idling at 4,000 rpm read the whole post!!

If that was directed at me, please calm down. I read the whole thread along with a dozen others. If your car is overheating at idle but not during cruise, I'd press you more on the rad fan functioning properly (turning on at 205°F). If it's overheating during cruise at 4k as well, then the fan isn't causing that; the radiator isn't doing its job for some other reason.

You fully understand your symptoms, but unless you answer our questions or explain every single detail that matters in your first post, we don't.

So if you answer my questions, I'll make suggestions and maybe ask more questions. And maybe your answers to my questions will help other people make other suggestions of their own. That's how I roll.

I'm not sure if my car would overheat if I just sat there in neutral and held the rpm at 4k with the rad fan going constantly. The fan might not be able to keep the temps down. Or maybe it would handle it and your fan isn't turning on when it's supposed to. It's very easy for you to check that your fan kicks on after the motor warms up (needle starts pointing up a bit on my car when my coolant temp hits 205° - verified through my logger. Needle is horizontal at operating temp...on my car).