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850 slowly lost rpms-will start- can rev- but idles and dies

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, 850 R, 850 T5-R, 850 T5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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Year and Model: 850 Turbo Wagon 1994
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850 slowly lost rpms-will start- can rev- but idles and dies

Post by Turbolena »


I could use a hand figuring this out . The car had been running great, smooth driving, smooth shifting, and a nice purr on idle.

I have a 1994 850 turbo wagon. Wife was driving it last night and the car slowly lost rpms until stalled out. It did restart a couple of times but in a very rough idle it then lost rpms and killed each time. We had it towed to a mechanics lot, but I went out last night to retrieve the codes listed below is what I found. Also, at that point I started it up, it turned over no problem and I was able to rev the engine and it did sort of stay engaged, but was pretty rough and then if I let off the gas rpms dropped and it died, with traction control light and some other dashboard stuff blinking . In the recent past it has seemed like the PNP swtich was going bad, as I a few times I would need to move the shifter to get the car to start , but that hasn't happened in months.

Here are the codes. The front knock sensor and the preheat codes have been there for a couple of years, even after I replaced both O2 sensors. Could the knock sensor finally have faulted...I don't remember the rear knock sensor showing up before.

A1 - 1-1-3, 1-1-4,
A2- 5-2-1, 1-4-3, 4-3-3, 2-1-2, 3-2-5
A7 - 1-1-1

and then I swear I was in the right port for A3 - but got codes that don't seem to be on the list

Any help would be appreciated!
1994 850 Turbo Wagon
2006 V70R
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Re: 850 slowly lost rpms-will start- can rev- but idles and dies

Post by misha »

Clear those codes and see which ones comes back.
Here is the list of the codes: ... es_a2.html

"A2" Codes are pointing to both knock sensors,O2 sensor and memory fault which could point to bad ecu(which is unlikely).

The things which manage them are ecu and relays.Check MAIN fuel injection relay on fan shroud (grey one)under the hood and fuel pump relay.ALSO check for blown fuses in fuse box.ECU & TCU fuse should be #1,but check fuse list to be sure.

"A1" codes are transmission codes which are pointing out bad TCU(which is HIGHLY unlikely for both ecus to go bad)& p'n'p switch. ... codes.html

Bad voltage supply or bad ground could be the culprit at this stage.Does the alternator works properly and what condition is the battery and battery cables?
'97 850 2.5 20v / fully equipped / Motronic 4.4 from the factory / upgraded with S,V,C,XC70 instrument cluster / polar white wagon
'91 Citroen XM 2.0 SI /fully equipped/mandarine red metallic
History of Volvos in the family:
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Re: 850 slowly lost rpms-will start- can rev- but idles and dies

Post by kahl »

Unplug the MAF sensor and see if it runs. Codes can cascade when this sensor goes bad.
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Re: 850 slowly lost rpms-will start- can rev- but idles and dies

Post by cn90 »


I have the same experience (random stalling), turned out it was MAF.
New Bosch MAF solved the stalling.

But you need to check the usual stuff...air filter, fuel filter, plugs, cap, rotor etc.
2004 V70 2.5T 100K+
2005 XC90 2.5T 110K+
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