Hey all,

My sister's having a problem with her 96' 850. The car has about 160k miles, and apart from some serious interior deterioration, is generally in good shape and well maintained by the Volvo dealer and her independent Mechanic.

I've been at school, and a few weeks back she phoned me to complain that her car was not running well. She would start it, it would sputter and die. I was busy with finals, but fed her some things to try, and eventually she replaced the Mass Airflow Sensor.

Well apparently after replacing the MAF the car ran wonderfully, so she drove up to the auto-parts store to return the old MAF for core charge, maybe 1/4 a mile drive. When they came back out to come home the car would not re-start, and the only way they were able to get it to start again was to disconnect the brand new MAF, which they did, and brought the car home, and parked it in the garage.

This is where I come in. I came home from school for Holiday and gave the car a little test run. I started it up, and aside from a few rough moments as the car warmed up (Nothing compared to the struggles my car has sometimes I've got a sensor out too, but that's a different problem with a different Swedish car brand for a different forum for a different day) the car seemed fine. I drove around the block a few times, re-parked in the garage, and wrote the whole thing off as a fluke.

Well my 'test drive' was only about 1/10th of a mile, so I wanted to take the car on a more thorough drive when there were other people at home to rescue me, so a few days later I took the car out and drove for a mile or so around my parent's house. I drove it slow, I drove it hard, it seemed to do just fine. I drove home to grab my dad, to go on a longer trip. I was in the house probably 5 minutes. Came out and the car would not restart. Problem indeed not solved.

We played with the MAF a little. Unplugging it, the car would start up. Plugging it back in, sometimes the car would immediately die, other times it would hum along fine.

Does anybody have a clue what is going on here?



To summarize:
• The car was running rough, dying right after starting.
• The MAF was replaced.
• The car now starts and runs fine from cold but, it appears...
• ...The car will now not start when warmed up.

When the car will not start:
• Unplugging the MAF causes the car to start and run
• Plugging the MAF back in at that point sometimes kills the car completely, at other times it does nothing.


I tried unplugging the MAF and plugging it back in like 20 times, I know the contacts get dirty sometimes. Could it be {gulp} a problem with the wiring between the MAF and the ECU?

 

Sounds like a relay issue to me, I know on 4th Generation Corvettes, which I have some experience with, the MAFS will act up if one of 2 relays goes bad. One relay is a Burnoff Relay, the other is just called a MAFS relay. if one goes out it will make it run funny sometimes, sometiems it just wont run at all.

Might be the same with Volvos?

 

Possible that it could be a MAF wiring issue. I know this sounds crazy, but when was the last time it was tuned up? Also, is the check engine light on? If so, pull the codes and see what they point to

 

If you have a bad coolant temp sensor that will stop it from starting when hot.

 

That is true, a coolant temp sensor will cause a non-start

 

Ok can somebody give me some clues on how to diagnose, or do I just go replacing parts blindly? I'll search around...

I got a code reader and the only code was P0102 but that came from starting the car with no MAF in place.

This time I was just warming the car up, to see if it would throw any other codes or whatever, and it totally died.

 

Does your scanner read real time?
If so check the coolant temp.

Also you might want to check the thermostat and see if it is broke.

 

Sounds like a bad fuel pump relay. Try removing it and cleaning the contacts or just replace it.

 

Most likely a faulty ECT sensor. Some other popular causes are:

- Neglect, of course.
- Retiring fuel pump.
- Retiring fuel pump relay.
- Retiring CPS (Cam Position Sensor).
- Retiring MAF sensor (this one is out for you).
- etc...

See attached. Also, refer to my 1st & 2nd replies at:

https://volvoforums.com/m_48928/tm.htm

Happy New Year,


JPN

[IMG]local://upfiles/6892/4E223BC384EA4B6C844DADAF45BFD4E4.jpg[/IMG]

[IMG]local://upfiles/6892/A15C169DEDE34A62B21FC9B18C430487.jpg[/IMG]

[IMG]local://upfiles/6892/65851D560B6F43538DB53B37A522B222.jpg[/IMG]

[IMG]local://upfiles/6892/34D42835B7944183BE77D4754E46AF2B.jpg[/IMG]

[IMG]local://upfiles/6892/1DBB71347BE5459A8B062C64BAA6A237.jpg[/IMG]

 

Ok I'm going to take a crack at it now. She's got a pretty competent mechanic and she goes in regularly. When we first got the car it had 90k miles and I insisted she get the timing belt done. There was some grumbling over this as we went on a weekend trip and, because of complications at the mechanic, her car wasn't done in time and so we couldn't take the 'new' car on the weekend trip. The mechanic commented that the timing belt was practically in shreds, past borrowed time...after that she became pretty good about maintenance . Anyway I don't know what exactly has been done but she's kept all her service records so I'll have a perusal through them, also replacing the blower motor wish me luck!