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1996 850 turbo rough idle and stutter

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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rspi
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Re: 1996 850 turbo rough idle and stutter

Post by rspi »

Have you changed the ECT? Checked the wires on it?
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steve850
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Post by steve850 »

Checked and cleaned the ETC when i had the head off, but yes, might be worth a double check
Steve in Montreal

2010 XC70 3.2 N/A
04 XC70 2.5T
96 850 Platinum

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abscate
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Post by abscate »

Have you fixed that vacuum leak? That could be the whole problem. You probably have more than one leak and they will mess up your running.
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steve850
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Post by steve850 »

Fixed the vacuum leak, no change. Strange thing is i was messing around with different hoses checking things and accidentally left that hose disconnected, and the car behaves exactly the same. Hoping to pick up a coil tomorrow and try that. Running out of things to replace !
Steve in Montreal

2010 XC70 3.2 N/A
04 XC70 2.5T
96 850 Platinum

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abscate
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Post by abscate »

That's pointing you to another vacuum leak....somewhere.

Smoke test PCV

Fuel pressure regulator torn?
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steve850
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Post by steve850 »

Put a new (used) coil on today, no change. Checked the ETC and found one lead disconnected, not sure that happened the other day when i was messing around with the vacuum hose on the end of the intake manifold...Anyway, starts and runs better when cold, or after sitting, idles better but only runs for about 10 seconds then dies. After five minutes of starting and stalling it won't start unless i pump the gas...if i push the revs up it cuts in and out. I'm starting to think fuel issues. The filter is new, the pump is about 3 years old. Could be the screen have picked up some crud or the pump won't hold pressure...? Am i correct in thinking that the proper fuel pressure at the rail is around 42 pounds? My guage only goes to 10 so i'll have to get another one to test...
Steve in Montreal

2010 XC70 3.2 N/A
04 XC70 2.5T
96 850 Platinum

steve850
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Post by steve850 »

Re the fuel pressure regulator - best test is what? It should just be leak free, i take it...
Steve in Montreal

2010 XC70 3.2 N/A
04 XC70 2.5T
96 850 Platinum

mecheng
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Post by mecheng »

Poor solder joints on fuel relay?
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steve850
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Post by steve850 »

Found that whoever last changed the pump didn't replace the whole unit, just the pump. The in-tank hose was clamped below the metal hose, and not properly secured, so i expect half the fuel was not getting to the engine. Unfortunately, the metal lines on the outside of the pump were rusted and one of the broke while i was popping the lines off, so in goes a new one. We'll see what that does ... !
Steve in Montreal

2010 XC70 3.2 N/A
04 XC70 2.5T
96 850 Platinum

steve850
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Post by steve850 »

Smoke tested again today to double check, no leaks. Just got the fuel pump, hope to put it in tomorrow. If this doesn't do it...??
Steve in Montreal

2010 XC70 3.2 N/A
04 XC70 2.5T
96 850 Platinum

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