Good afternoon everyone. I have been reading this forum for a while and have gotten very many repair questions answered by simply reading old threads. The time has come for me to ask for some technical advice.

My 1996 850 GLT (171,000 miles) will not stay running at idle. Before the motor reaches 2500 rpm's it runs very rough. If i am able to get the motors rpm's above 2500 it runs perfectly fine. After i let off the accelerator and the car goes back down to idle it shuts off.

What i have done so far:

Thought the cat maight be clogged?.... removed it and started the car with no improvement.

Fuel filter clogged?....replaced it with no improvement.

Old plugs, wires and distributor components?....... replaced within the past year and all in good working order. no cracks or moisture present

Timing may have jumped a tooth? ...... Timing is spot on and belt kit was replaced 25,000 miles ago.



This ECU is not giving me any codes to help diagnose the problem. I have done everything i can gather to do from my haynes manual.


Does anyone have an idea of what else to try? or a had a similar problem?




Any help would be sincerely appreciated since i honestly do not have the $$ to visit a technician.

Thanks,
Christopher Hannigan

 

Did you check IAC valve and throttle body? They may be clogged.

 

Kind of sounds like bad Mass Flow sensor. Unplug the mass flow and if it will idle then the maf is bad.

 

At the advice of stojakovic i removed the IAC valve and gave them a good cleaning. It seems to have helped out alot but the car still jumps in idle from 700-1200rpm in almost a rythmic patern.



Thanks for the advice Tech.... unplugging the MAF made the vehicle run worse/not at all. So i assume it is not a MAF related problem.


I appreciate the help guys. If anyone has any advice on how to clear up the sporatic idle please let me know.


Thanks-Chris

 

Is there a code for the throttle position sensor?

 

"At the advice of stojakovic i removed the IAC valve and gave them a good cleaning. It seems to have helped out alot but the car still jumps in idle from 700-1200rpm in almost a rythmic patern."

I did the exact samething and it reve up and down for about an hr or so, I think it need to recalibrate with the computer......but cleaning was not enough for mine,,,,,275.00 later and its a new one.

 

There are no codes at all.

One additional thing that i did notice is that the motor is running extremely rich. Major gasoline fumes coming from the exhaust.

Due to the way that the motor is hard to start (randomly), misfiring at low rpm's and running very rich i am thinking that the cam or crank position sensor may be the problem.
Does anyone have a link for how to test both of these sensors?

Thanks-Chris

 

It could still be a mass flow sensor.

 

Since I was getting no where scratching my head thinking about it I decided to start my diagnosis over.

Well I am glad I did because the first thing i did was test the fuel pressure and it was high. 51-K.O.E.O. and 88-running. When I shut the car off it doesn't hold the pressure at 88 it slowly drops down into the 50's. Any suggestions?

 

If it is to high then the fuel pressure regulator is bad.