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850 turbo: massive stuttering/hesitation

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

850T5Ritalia
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850 turbo: massive stuttering/hesitation

Post by 850T5Ritalia »

Hi all,

I recently bought a '95 t-5R. It's an italian 2.0 liter (B5204T).
So apart from a leaking manifold it drove fine for the last 4 weeks. I parked it after driving 20 miles or so and after coming back an hour later it immediately ran like sh*t. On the 20 mile drive it behaved normal all the way. But as soon as I drove away a couple hours later it was hesitating/stuttering.

It happens at al speeds and throttle positions. It is worst when accelarating (from any speed in any gear). Cold or warm engine temps dont make a difference.

On idle it stutters too, but less severe than driving conditions. When reving the engine in neutral it seems to rev okay.

I unplugged the MAF sensor to see if it made a difference. But no, still runs like crap with it unplugged. (I did not get a Check light strangely enough when driving with the MAF unpugged?)

Car has done 270.000 miles

So my guess is to check all the vacuum hoses and intercooler hoses. I've been replacing some of them including the vacuum three already. On first visual inspection al the hoses seem to be fine though.

I would like some advice on other areas to inspect. Apart from the MAF sensor what other sensors can cause this kind of behaviour? Are the TPS sensors on this engine known for faults?

I also noticed it doesnt build full boost. I never did make full boost of which i suspect the cracked manifold, but it's even less now. not at all the times however.. sometimes when accelarating it picks up for a brief moment.

Note: I did park the car with an almost empty tank. It had 25 miles left according to the BC. I filled it up with 98octane (the recent standard for 95octane contains 10% ethanol since last week over here so i suspected that for a moment but the 98(E5) didnt make a difference) I do however keep in mind that the in-tank Fuel pump could be faulty from age and driving the tank almost empty.

Plugs, rotor and cables were done 10.000 miles ago.

Any suggestions would be very helpfull.

Thanks :)
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erikv11
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Re: 850 turbo: massive stuttering/hesitation

Post by erikv11 »

Are you sure the "check light" bulb is not burned out? Might want to check the codes with OBD 1, does your car have it? Or a code reader of course.

Checking all the Vac and boost lines is good idea.
'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 145k
'98 S70 NA, 220k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 293k
'06 S60 R, 167k
'99 Camry V6 :shock: 130k
gone: '96 NA 850 210k, '98 NA V70 182k
850T5Ritalia
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Re: 850 turbo: massive stuttering/hesitation

Post by 850T5Ritalia »

That’s a good one! I never checked. If it comes on with the ignition key switch it should work right? Will check that first and I try to scan it ASAP.
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Re: 850 turbo: massive stuttering/hesitation

Post by BlackBart »

My guesses (simplest, cheapest things first) :

An intercooler hose popped off or cracked.
A dried out (1995...) vacuum line cracked.
Some crud in the empty tank got sucked into the already dirty fuel filter or screen on the pump.
ex-1984 245T wagon
1994 850T wagon
2004 XC70 wagon BlackBetty
Is it time for a 1964 122 wagon?
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erikv11
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Re: 850 turbo: massive stuttering/hesitation

Post by erikv11 »

Crud in the near-empty tank, that's a new one for this thread. Could be.
'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 145k
'98 S70 NA, 220k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 293k
'06 S60 R, 167k
'99 Camry V6 :shock: 130k
gone: '96 NA 850 210k, '98 NA V70 182k
850T5Ritalia
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Re: 850 turbo: massive stuttering/hesitation

Post by 850T5Ritalia »

Thanks! That’s very possible. I’m gonna take out the pump and replace the filter.
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Re: 850 turbo: massive stuttering/hesitation

Post by RickHaleParker »

The car is 24 years old.
1. If it has OBD,
  • Read all the codes.
    Write them down.
    Clear all the codes.
    See what comes back.
2. An afternoon cleaning electrical connectors and checking looms for damage would be time well spent.
3. Smoke test the intake and exhaust for leaks. Seal up any leaks found.
4. Replace crumbling vacuum lines and hoses as preventive maintenance.
5. If you don't know the car's history, a maintenance schedule reset might be a good idea. Do the timing belt for sure, you always want to know where in the maintenance interval the timing belt is.
1998 C70, B5234T3, 16T, AW50-42, Bosch Motronic 4.4, Special Edition package.
2003 S40, B4204T3, 14T twin scroll AW55-50/51SN, Siemens EMS 2000.
2004 S60R, B8444S TF80 AWD.
2005 XC90 T6 Executive, B6294T, 4T65 AWD, Bosch Motronic 7.0.
850T5Ritalia
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Re: 850 turbo: massive stuttering/hesitation

Post by 850T5Ritalia »

RickHaleParker wrote: Sun Oct 13, 2019 11:50 pm The car is 24 years old.
1. If it has OBD,
  • Read all the codes.
    Write them down.
    Clear all the codes.
    See what comes back.
2. An afternoon cleaning electrical connectors and checking looms for damage would be time well spent.
3. Smoke test the intake and exhaust for leaks. Seal up any leaks found.
4. Replace crumbling vacuum lines and hoses as preventive maintenance.
5. If you don't know the car's history, a maintenance schedule reset might be a good idea. Do the timing belt for sure, you always want to know where in the maintenance interval the timing belt is.
Thanks for the input. I will scan the car asap. I was already planning on a smoke test. Seems like a good wat to check for leaks and also detect minor leaks. Since it's an old car with a lot of miles I feel like replacing all the IC and vacuum hoses anyway.. They feel very soft and look old and dry.
850T5Ritalia
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Re: 850 turbo: massive stuttering/hesitation

Post by 850T5Ritalia »

Ok, so as one of you suggested, I checked if my check engine light is working. I said I didn’t get any light when I unplugged the MAF. I might have found the reason.

I attached 2 photos of all the lights that light up upon ingnition II. I don’t see a check engine light anywhere. Save to assume it burned? I will get it scanned and pull the dash to fix the light.
Attachments
6BB49FC7-2867-40E6-8219-D722109112A8.jpeg
F6DBDE37-1661-4ED2-ABB0-6A7BE7505A8B.jpeg
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erikv11
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Re: 850 turbo: massive stuttering/hesitation

Post by erikv11 »

Yep it's burned out.
'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 145k
'98 S70 NA, 220k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 293k
'06 S60 R, 167k
'99 Camry V6 :shock: 130k
gone: '96 NA 850 210k, '98 NA V70 182k
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