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94 850T check engine light while accelerating

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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henrysin44
Posts: 106
Joined: Sun Apr 12, 2015 4:14 pm
Year and Model: 1994 Volvo 855 Turbo
Location: Guilford, CT USA
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henrysin44

Re: 94 850T check engine light while accelerating

Post by henrysin44 » Thu May 14, 2020 6:29 pm

misha wrote:
Thu May 14, 2020 5:17 pm
henrysin44 wrote:
Thu May 14, 2020 3:55 pm
...That would definitely explain why my headlights would be dim until i started driving.
You had a good luck that your battery was in good shape.
Since you ran a car with low voltage charging system...i would suggest to remove negative battery terminal for a few hours in order to reset car's management system and all bad things it could catch because of low voltage.

After that,perform a re-learning procedure for ecu and check voltage output on battery terminals.
Re-learning procedure:
http://www.volvotips.com/index.php/850- ... rocedures/
I'll give that a try, your probably right especially sense the CEL was on only during load.
http://shealabs.net
Daily driver Black 1994 Volvo 855 2.3L Turbo - manual swapped, turbo swapped, green injectors, custom M4.4 Tune, de-catted, custom two-tone interior, V70R seats & rims
Teal 1994 Volvo 855 2.5L N/A Manual Transmission (the back up daily and parts car) - Runs and Drives but the engine knocks
Silver 1997 Honda CRV 2.0 AWD - its in a very sorry condition, but drives
Silver 2003 Subaru Forester 2.5L N/A AWD - Leaks everything

User avatar
henrysin44
Posts: 106
Joined: Sun Apr 12, 2015 4:14 pm
Year and Model: 1994 Volvo 855 Turbo
Location: Guilford, CT USA
Has thanked: 0
Been thanked: 3 times
Sweden
henrysin44

Re: 94 850T check engine light while accelerating

Post by henrysin44 » Thu May 14, 2020 8:07 pm

misha wrote:
Thu May 14, 2020 5:17 pm
henrysin44 wrote:
Thu May 14, 2020 3:55 pm
...That would definitely explain why my headlights would be dim until i started driving.
You had a good luck that your battery was in good shape.
Since you ran a car with low voltage charging system...i would suggest to remove negative battery terminal for a few hours in order to reset car's management system and all bad things it could catch because of low voltage.

After that,perform a re-learning procedure for ecu and check voltage output on battery terminals.
Re-learning procedure:
http://www.volvotips.com/index.php/850- ... rocedures/
Gave it a try but unfortunately im still getting a CEL under load only....this is weird....car starts faster now though
http://shealabs.net
Daily driver Black 1994 Volvo 855 2.3L Turbo - manual swapped, turbo swapped, green injectors, custom M4.4 Tune, de-catted, custom two-tone interior, V70R seats & rims
Teal 1994 Volvo 855 2.5L N/A Manual Transmission (the back up daily and parts car) - Runs and Drives but the engine knocks
Silver 1997 Honda CRV 2.0 AWD - its in a very sorry condition, but drives
Silver 2003 Subaru Forester 2.5L N/A AWD - Leaks everything

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erikv11
Posts: 9661
Joined: Sat Jul 25, 2009 2:03 pm
Year and Model: 850, S/V70, 06 S60R
Location: Iowa
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Been thanked: 276 times
United States of America
erikv11

Re: 94 850T check engine light while accelerating

Post by erikv11 » Fri May 15, 2020 9:05 am

Number one hypothesis here is knock under load. I'm not sure how to track that down but some ideas are to make sure the engine is not running lean, that the knock sensors are connected and mounted, that you are using proper octane fuel.
'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, 286k
'06 S60 R, 167k
'99 Camry V6 :shock: 125k
gone: '96 NA 850 210k, '98 NA V70 182k

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