Irradical idle once reaching operating temperature

[Family XJ]

1998 Spyder GS

Last Thursday we jumped in the car and started to back up and it acted like the front wheel was trying to run over a ball. So we pulled forward I got out and didn't see anything. So the wife backed up and it did this again. I figured the Alternator was going out since it had been squeeling for a while. I pulled the positive wire off while running and car about died and put it back on and it was fine then pulled it and the car died. So a quick trip to the parts store across the street and a new Alternator was put on. Squelling was gone. Started the car again and it started running real bad a gain.

Saturday morning I got a scanner and it said bad CPS. So off I went and got a CPS, timing belt and balancer belt and new motor mount. If your going in go in once and replace it at the same time. So I came home. Replaced it all and the car started and ran great. Actually better than it has since we have owned it. Drove around for a little bit then came home. No more codes either.

Got up Sunday and headed for the beach. Drove about 10 minutes. Ran in the store came out drove thourhg the BK drive through and then headed down the road. Drove it for about 30 minutes and then it hit again. Car cut out driving down the 4 lane. Pulled over and let it set a few minutes. Car started right back up. Drove for 7 seconds and it runs irradically and then dies. Called for a tow truck. We kept starting it and driving 7-8 seconds and then coasting as far as we could until the Wrecker showed up. Brought the car home and plugged the scanner in. It said Cam Sensor. Replaced cam sensor and it was running good until operating temperature. Same symptoms as before.

Only now no codes. Runs fine until hot then irradical idle and eventually dies. Shut off keys and restart and then 7 seconds it runs bad and dies. Saw someone with same issues and EGR fixed theirs. So I got a new EGR. Same issues. Went to my buddies and got his good coil packs and MAF and still same issues. So We are stumped. To keep this straight we have replaced

New
CPS
Timing belt, balancer belt,
Cam Sensor
EGR,
Coil packs,
MAF

I don't see any vaccuum leaks and if there was it should run bad contantly not after getting hot. So we are stumped. Anyone got any ideas? I can get a computer to test it all. Not sure what else to check since she runs great until its hot.

 

[YZFR1]

You could also try blocking off your FIAV and testing out your ISC, those are pretty common culprits for running rough, plus you could get like 1-2 hp from blocking the fiav

 

[jtmcinder]

Irradical? As in: conservative?

 

[Family XJ]

What is FIAV and ISC?

We have emissions here in NC so I can't be messing with anything that effects that.

Could a Clogged CAT cause this once hot?

 

[1983gsp]

Each time you replace the cps it runs good for a little while then dies. Sounds like something is killing the cps or you are getting faulty cps's.

 

[Family XJ]

I only replaced the CPS once when it initially pulled a code for it. Since then it has ran until hot then it acts crazy. I will try to get my video uploaded tonite. Its just a crazy thing

 

[niddydsm]

i would check the fuel pump/ fuel filter....

 

[H@xtGSX]

Irradical? As in: conservative?

I was thinking it was a conjugated form of irradiation... The motor must be radioactive.

Is the oxygen sensor reading right? Are there fuel pressure problems? Is your throttle body still connected to the water lines? Is the IACV voltage correct (it has to be able to move both ways, or things like what you describe happen...)?

 

[Family XJ]

Tonite we checked fuel and it seems to be fine. Even continues running once car dies. Couldn't check pressure since I don't have the fitting for the fitting for the rail. Going to get it tomorrow. We did unhook the IACV and it ran fine for a while then started running bad again. Going to have a guy bring his by tomorrow and see if his acts the same way wen unplugged.

We are definitely getting frustrated with it. I know its something simple though

 

[H@xtGSX]

The IACV is a frustrating turd. The easiest way to check it is with a voltmeter. Mine went bad and made me want to beat my car to death with a Nerf bat dipped in water and then frozen... Not sure why it required such a specific weapon, but that is what I wanted to use at the time.

 

[Family XJ]

I am going to get one off my buddies car and see if it helps. I will keep you all posted.

 

[Family XJ]

Any other ideas anyone? Getting frustrated as all get out

 

[Mitsubishiown]

My car is doing something similar but mine hasn't died yet but it would have if I didn't shut it off myself The car drives like shit too I can push down on the pedal and it just sits there and stays at the same speed it was going for about 5-6 seconds then all of a sudden out of no where it goes up to like 4000rpms like it should have the second I pressed it.

 

[Family XJ]

ok We swapped computer, IAC sensor, checked the cat to ensure its not clogged and the other sensor on top of the intake manifold next to the TPS. still nothing helping. I am about at wits end with this car. Really don't want to take it to the dealer but may have to.

Any other ideas?

Also sprayed ether arou nd all the vacuum lines and changes fuel filter and checked fuel pump.

 

[Mitsubishiown]

You check the ISC you said? If so where is it I need to check mine and don't know where it is or how to test it :/

 

[Family XJ]

IAC sensor right below the intake on the throttle body

I asked what the ISC was and where it is located. I don't know what it is.

 

[Mitsubishiown]

How do you check it with a vultimeter? And is so what do you look for? There is a very good video on how to check the ISC but I still need a damn part number!

DSM ISC motor testing & Replacement - YouTube

 

[Family XJ]

Looks like a good video but it looks like that is for a 2.0 turbo motor

 

[Family XJ]

Well we still haven't fixed it yet. It cuts completely off when it reaches operating temp. So I can only assume its heat related. We are pulling no codes on a good scanner and voltage is normal while running. It just reaches operating temp and studders and dies. Let it sit for a few and it will restart and die as soon as it reaches operatin temp.

Would a water pump not waorking cause it to shut off? . its not over heating at allI am going to tap the heater core line and run it until warm and then try running the cold water to see if it will stay running. Its a shot, since I don't know where else to go.

 

[Viper588]

Well we still haven't fixed it yet. It cuts completely off when it reaches operating temp. So I can only assume its heat related. We are pulling no codes on a good scanner and voltage is normal while running. It just reaches operating temp and studders and dies. Let it sit for a few and it will restart and die as soon as it reaches operatin temp.

Would a water pump not waorking cause it to shut off? . its not over heating at allI am going to tap the heater core line and run it until warm and then try running the cold water to see if it will stay running. Its a shot, since I don't know where else to go.

Im having a very similar problem with the same car. While i don't have any solutions, my problem goes away if i unplug the MAF which obviously doesn't solve the problem but it has let me use the car when i have no other choice. Good luck in solving the problem! Please post when you find the problem as i will definitely be watching this thread to fix my car as well.

 

[Family XJ]

We will. I have a donor car of sensors so it helps for testing

 

[yoyo13131]

Re-adjust your FIAV and see if it's still doing it. If your FIAV's adjustment is off it will be letting to much air into your throttle body when your coolant is hot.

I remove my throttle body and all electronics and test the wax ball spring inside My sink. If no water gets though when the water is Very hot you know it's adjusted properly. And when it's cold water should beable to leak though it. Basically this is your choke.

Oh.... You have the dumb 420a motor huh? I don't know if they have the same throttle body setup as the 2.0's

 

[spyderdrifter]

What is FIAV and ISC?

Since I didn't see anyone answer this for you, FIAV is Fast Idle Air Valve and ISC os Idle Speed Control motor. If you have already obtained that info then disregard

Oh.... You have the dumb 420a motor huh? I don't know if they have the same throttle body setup as the 2.0's

He's got a 4g64 since he has the non-turbo spyder. So the intake manifold/TB should be the same as us turbo'd models.

 

[Viper588]

any change?

 

[foxracing2216]

try stuck throttle? my car did it after engine warmed up for a while and couldnt figure out what it was..