car starts but won't idle

[Ben850]

The front O2 sensor seemed to be the culprit in my '96. I did change out the MAF as well with a salvage part, but genuine Bosch. Most important with both of those pieces.
The car had those symptoms when I had bought it. That is why it was so cheap.

The history of my '96.
https://www.matthewsvolvosite.com/forums ... 35&t=56550

[gmh]

Have you messed with the intake hose (between MAF and bottom of the turbo) or any of the rubber turbo hoses lately? Your symptom (start and quick stall) could be due to a massive air leak if one of these has popped off.

[socalover]

i haven't touched anything under the other than to check the oil and coolant but I'll look at all the hoses tomorrow morning. I was hoping it was the ignition switch finally going out which is an easy fix.

[abscate]

Aftermarket MAFS are really hit or miss on these cars. There is lots of junk out there. Look at the sensor for the Bosch label and logo...unfortunately there are even counterfeit parts rampant in Bosch lines.

The reason the Bosch part is more expensive is because it works.

[S40V70DAD]

I just fixed a similar issue: Hope this helps.
Can't believe it myself, but it was a FUSE! I can duplicate the problem by swapping the "bad" 10A fuse back into the Fuel Pump slot.

To be clear here was the cars' issues:
Symptom: Starts but does not idle; runs fine with foot operating the throttle, but stalls immediately if you remove foot.
Originally it ran for a week after purchasing car, then the problem appeared intermittently, 2-3 times in one week – wouldn’t idle upon start-up but then ran fine after it was run/warm for several minutes. THEN, a few days later, it became a HARD FAILURE, constant all the time will die without operating the throttle. FYI; OTHER odd note, the FAN coming on even when cold.

ACTIONs TAKEN:
1) Removed and cleaned ICV (idle control valve)
2) Bought and installed brand new ICV
3) Ordered an OBDii reader to get codes (but from other posts here I don’t see this leading to resolve)
4) bought STARTER FLUID to go hunting for vacuum leaks. Nothing obvious found (person in car kept a steady idle as I sprayed starter fluid over vacuum hoses and all around).

FINAL SOLUTION:
Read that a Fuel Pressure Regulator solved on guys similar if not exact issue according to his description. So not wanting to spend $140 to find out, I wanted to use a Fuel Pressure Gauge to simply measure the pressure - but in one day could not find one to borrow. So I did a lazy man and depressed the Schroeder valve on the test port and fuel spewed out. Not sure if the pressure was adequate but also because the car ran fine operating the foot throttle also seems to indicate to me that the fuel is being delivered just fine. So then I thought to at least check the FUSE - it looked weird somehow in the loop arch, couldn't tell if it was blown, ohm'd out using a DVM and it rang the continuity beeper. Also the leads were discolored, but all my fuses are discolored. side note: Previously I had a Cruise Control issue not working that seemed to be fixed by cleaning the tarnished leads on the FUSE. So I cleaned the leads on the 10A Fuel Pump fuse and re-inserted it. - No change. I did the same to a few other fuses (10A Engine Sensors ? , 15A VACUUM PUMP), and each time went to start the car. - No change. Then I swapped out the 10A Fuel Pump Fuse with another 10A fuse, and the CAR STARTED AND IDLED with no foot operation of the throttle pedal. I was able to swap the "bad" fuse back and the car would not start, swapped it again with the other 10A fuse and the car would start.

[abscate]

Wwwwhhhhaaaatttt?

Glad you solved it, and thanks for double testing.....but that makes very little sense.

Back away slowly from this car, burn some incense, and go to church of your choice on Sunday to make sure the demons are exorcized