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850 T-5R stalling issus

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

GhostNZ
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Year and Model: 1995 850 T-5R
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850 T-5R stalling issus

Post by GhostNZ » Mon Oct 28, 2019 4:15 am

I have been having stalling issues with my T-5R for months, engine runs fine then just cuts out after a random amount of time. :?
Sometimes when it stops it will start again but run rough for a few min until it dies completely (seems to be hunting for idle), it has spark when cranking and the fuel rail is pressurised.

I have replaced the camshaft position sensor, water temp sensor, IAC, coil, spark plugs, fuel filter, fuel relay, battery..
I checked over the vac lines I could get access to and could not find any leaks.
It had an aftermarket alarm/immobilizer that I have removed and that appeared to have fixed it however it just stalled out on me again today...

Usually leaving it for 15min "fixes" the issue however today it didn't, I then pulled the ECU out for 30 sec, reinstalled and the car started straight away??
It didn't seem overly warm and it felt secure (although the lever doesn't travel as far as the trans ecu does?)

Can anyone think of anything I may have overlooked, could the ECU or ECU connector be faulty in some way?



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abscate
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abscate

Re: 850 T-5R stalling issus

Post by abscate » Mon Oct 28, 2019 4:54 am

Welcome

Distributor cap, rotor, and spark plug wires all critical.

You need to confirm correct pressure at the fuel rail to eliminate fuel delivery issues. The weak part of this system is the fuel pump relay. Did you use a Volvo replacement?


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RickHaleParker
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Re: 850 T-5R stalling issus

Post by RickHaleParker » Mon Oct 28, 2019 5:44 am

GhostNZ wrote:
Mon Oct 28, 2019 4:15 am
Can anyone think of anything I may have overlooked, could the ECU or ECU connector be faulty in some way?
ECU connector, sure could be. The ECU connector had 24 years to build up oxidation. Clean the connector with MAF cleaner. Just resetting a ECU, as you already have done, often does the trick, but clean it away.


Platform: P80 1998 C70, B5234T3, AW50-42, Bosch Motronic 4.4, Special Edition package, Plant: Uddevalla Sweden.

Platform: X40 (Nedcar) 2003 S40, B4204T3, AW55-50/51SN, Siemens EMS 2000. Plant: Born Netherlands.

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850oldschool
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Re: 850 T-5R stalling issus

Post by 850oldschool » Mon Oct 28, 2019 11:29 am

It sounds like you are having a similar issue to the one I'm having with my 96 NA. Mine also starts up and runs fine until it gets thoroughly warmed up after a little "rest", but it's been getting worse.

Have you pulled the codes yet? Does it stall less in cool weather? I was playing with my new (to me) scanner last night and I noticed it can read out the ECU temperature. Mine was 42°C (107°F), which seemed kind of high when the ambient was about 40°F.

Also, is it safe to use something like Deoxit on the ECU connector? I've looked at the CRC and WD-40 electrical cleaners and they both just contain fast drying solvents, which will remove oil contamination, but none of the ingredients look like they would remove oxidation like Deoxit does. What I don't know is if Deoxit is compatible over the long term with the particular plastics, etc. in the ECU. If the ECU is just a standard circuit board with a standard conformal coating the answer is probably yes, but it would be reassuring to hear from somebody who has actually used Deoxit on a Volvo ECU connector.



GhostNZ
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Re: 850 T-5R stalling issus

Post by GhostNZ » Mon Oct 28, 2019 11:27 pm

OEM fuel pump relay used.
Rotor and distributor cap look fine, as do the leads.

I'll double check the ECU connector later in the week, didn't appear to have any corrosion but probably worth cleaning anyway.



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