1996 850R stutters dies when warm

jacsil · Post by **jacsil** » 31 Dec 2013, 02:16

the 850R has about 125k miles on it. recent work includes new heater core, replace the pvc system.
Recently the radiator fan not coming on when in stop and go traffic. It turned out the power wire to the fan had shorted.( my guess is the fusible link blew although i could never find where it was or how to replace it. As a temp fix we ran a power line from the seat warmer fuse to the fan and it works. While the car did get above normal temp wise it never overheated.

Since then the car had been running well for a few months until a little over a month ago when it started hesitating when warm usually in stop and go traffic. it continued to get worse starting to die at red lights when coming to a stop. it would also hesitate/stutter while driving on the freeway. It does die out on the freeway at times. sometimes it just starts to loose some revs and giving it gas doesn't do anything then it will catch itself and pick up and go. other times it the revs drop to around 2k and then stay there for a moment then dropped completely to zero and the car dies. until it dies the power steering , brakes are functioning.

my son is the one who usually drives the car. I fix it. anyway he took it to a non Volvo shop to check the codes and the code for the crankshaft position sensor came up. They replaced the sensor they didn't use a Bosch sensor they used a vdo brand which i believe is owned by Siemens. I picked up the car dove off and it was still warm drove it for a bout 4 miles and bingo hesitation and then dying when coming to a stop. i brought it back and we went for a long drive in a hilly area and he good duplicate the problem. went back to his shop and he put it on the scanner. he said the fuel trims looked decent and he couldnt get the problem to duplicate itself.

Since then I hooked a fuel pressure guage up on a long hose and taped it to the windshield. from the best i can tell the fuel pressure does not drop off when the car is hesitating or stalling . although i think it might be a little week. it is usually around 39 but when applying throttle it will go up to about 49.

i have replaced the fuel pump relay, the fuel filter, air filter, took the throttle body off and cleaned it, cleaned the idle control valve, i also bought a used maf to see if that was the problem.

it did stop doing it for a day and a half and then bingo started up again.

i have purchased a code reader that provides live data. I clear the codes and do a hard reset on the ecu and the code that keeps popping up is the crankshaft position sensor (which was replaced)

Also it seems as if the more the car is driven during one day the worse it gets. especially multiple trips.

Yesterday i drove it about 30 miles in one direction on the freeway and it only hesitated but never died. when. i parked the car for about 15 minutes then got back in and got on the freeway in the 30 mile return trip it died off about 5 times. i did have the scanner on at the time. and the stft would go up and down between mostly -5 to plus 3 or 8 sometimes the spread was wider. the ltft were around -12 to -15 the tps at idle is 8.6 the fuel system fluctuates between CL , CL fault, OL and OL drive it may have hit CL drive.

Today did another longer trip about 25 miles each way. On the first leg of the trip it hesitated a bit on the freeway once warm then when i got off the freeway it started dying after about a mile of stop and go. I parked for about a half hour and it ran horible on the way back completly dying several times. the ltft at one point got to -25. when this happened it threw a running lean code as well as the crank code.

I then put the used maf in that i bought erased codes let it sit for about an hour then got back on the freeway. this time when it was starting to die on the freeway i tried giving it gas to keep it going and it backfired a couple of times and threw a code for misfire cylinder 5.

i dont know if shorts can cause problems but one of the rear speakers cuts in and out. also the rear spoiler isnt on and so the wires to it are cut. both have been like this for over a year.

Oh a few months ago the car was getting harder to start and I would have to jump it in the morning. a new starter cured this. I do think there is a drain with the car off. after letting it sit for a few days the battery went dead.

ECT it seems to be functioning properly per the scanner. when warm and on the freeway it stayed a steady 192 once off the freeway it goes up over 192 and in stop and go it even got up to 119 for a moment

im very frustrated is the stalling calling the crank sensor to throw a code or is the crank sensor causing the stalling, it is new. could there be a short in the wiring. i dont even know where to begin to look.

STARTS RIGHT back up. when it dies it starts right back up and keeps going. although today on my third trip if it died it would start up right away but then when i went to take off it would die again, this lasted for maybe 10 minutes then it started running better,

Thank you for help

Today

Post by **phils94850** » 31 Dec 2013, 06:39

That's classic fuel pump issues, acts up when hot...Your fuel pump id say is your problem, the numbers you posted are low ... when under boost it should increase fuel pressure 1lb for each 1lb of boost. This will cause the hesitation and problems your having.

Post by **kcodyjr** » 31 Dec 2013, 07:10

+1 possible fuel pump issue, BUT, it could also be the MAF. They also act up more when hot.

Disconnect the MAF and drive it like that. It'll run kinda crappy, like an old carbureted engine out of adjustment, but if it's a MAF problem that'll stop the stalling. If so, get a new one, Bosch branded. Do not get a used, rebuilt, or aftermarket mass airflow sensor unless you really enjoy having these kinds of problems.

Post by **kcodyjr** » 31 Dec 2013, 08:06

You know, that used MAF you put in might or might not be good. I'm leaning toward not good, but, it's worth resetting the adaptives and trying again. Disconnect the negative battery cable and touch it to the positive cable for 10 seconds. Then reassemble and drive.

jacsil · Post by **jacsil** » 31 Dec 2013, 08:47

phils94850 wrote:That's classic fuel pump issues, acts up when hot...Your fuel pump id say is your problem, the numbers you posted are low ... when under boost it should increase fuel pressure 1lb for each 1lb of boost. This will cause the hesitation and problems your having.

The Stalling doesnt always happen when under boost it also happens when just cruising on the highway without much gas peddle being used as well as when coming to a stop.

jacsil · Post by **jacsil** » 31 Dec 2013, 08:49

kcodyjr wrote:You know, that used MAF you put in might or might not be good. I'm leaning toward not good, but, it's worth resetting the adaptives and trying again. Disconnect the negative battery cable and touch it to the positive cable for 10 seconds. Then reassemble and drive.

i did this already and no changes I will clear the codes one more time and try running with the maf unplugged and see what happens. the thought did cross my mind that the used maf I bought is also bad.

Post by **rspi** » 31 Dec 2013, 09:32

Man, that is a tough one. Hard NOT to throw parts at it.

I think I would replace the ECT to see if that helps. I know it's not tossing a code but if it's bad, it will mess up your fuel mix.

jacsil · Post by **jacsil** » 31 Dec 2013, 10:06

i have an ect i can put in (its a not a bosch) i got it from napa auto parts. wouldn't the ect readings be off with the obd live data readings?

The used maf i put in was from a 96 850 turbo. I only took the bosch sensor itself not the whole assembly. at this pointy I'm not even sure if its the right one. the screws that held mine in were 6 point torx these were 5 point.

Post by **kcodyjr** » 31 Dec 2013, 11:12

Nobody *EVER* pulls sensor elements like that. The replaceable unit is the entire plastic cylinder.

Go back to your previous MAF until you get one that isn't hacked.

jacsil · Post by **jacsil** » 31 Dec 2013, 12:44

kcodyjr wrote:Nobody *EVER* pulls sensor elements like that. The replaceable unit is the entire plastic cylinder.

Go back to your previous MAF until you get one that isn't hacked.

yes i should have taken the whole thing. I also found out that the 2.4 turbo model had a change over mid year as far as the maf goes. which i think is the one this had. while the 2.3 was the same for the whole year. which is what i had.

Im going to put my old maf in and try driving with it disconected to see if it makes any difference.