IPD sale XeMODeX - Experts in Volvo Electronics
Did you know? 🤔
Logged in users can get email notification of topic replies Log in or register (free).
Amazon Link Buy your stuff using this and it helps MVS!

96 850 Turbo Starts but runs rough then dies. Backfires.

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

New2Volvo96
Posts: 2
Joined: Sat Sep 07, 2019 9:15 pm
Year and Model: 1996 850 Turbo
Location: Oregon
Has thanked: 0
Been thanked: 0
United States of America
New2Volvo96

96 850 Turbo Starts but runs rough then dies. Backfires.

Post by New2Volvo96 » Sat Sep 07, 2019 9:32 pm

Hi all. I am posting this in hopes to help my father in law figure out what his problem is with his 96 Volvo 850 Turbo. I helped him replace the PCV system and he replaced the PNP switch but after it all got put back together it now will start but dies after about 5 seconds or less. If you keep on the throttle it will keep running albeit very rough, but it backfires and there is a strong gas smell. We tried checking the fuel pump relay and bypassed it didn't help and it sounds like the fuel pump is working though we haven't tested the fuel pressure yet. I haven't cleaned the MAF yet but I scanned for codes and found nothing and can't imagine a dirty MAF would cause this many problems. I'm hoping someone might have some insight as to what might be causing these issues. Possibly didn't get something put back together correct. Vacuum lines look good but it's hard to test them when it's running so bad. Any suggestions would be much appreciated. Also I should note that his car has something draining the battery so it only starts up when being jumped. Thanks guys!



User avatar
Clemens
Posts: 982
Joined: Thu Sep 03, 2015 12:34 pm
Year and Model: 96 855 R + 94 855 T5
Location: Austria
Has thanked: 67 times
Been thanked: 35 times
Austria
Clemens

Re: 96 850 Turbo Starts but runs rough then dies. Backfires.

Post by Clemens » Sun Sep 08, 2019 1:07 am

what about the intake manifold gasket? if there is a leak, it will run horrible.
are all the injectors seated and connected properly?


Summer: 1996 855 R
Winter: 1994 855 T5M
Donor: 1995 854 10V

User avatar
abscate
MVS Moderator
Posts: 18175
Joined: Sun Feb 17, 2013 5:54 pm
Year and Model: 99T5 ,99S70,2005V70
Location: NYC, ALBANY NY
Has thanked: 200 times
Been thanked: 647 times
Trinidad & Tobago
abscate

Re: 96 850 Turbo Starts but runs rough then dies. Backfires.

Post by abscate » Sun Sep 08, 2019 3:09 am

It’s really easy to pinch something between the manifold doing the PCV

Replace all the vacuum lines that you have no history on, at 20 years old +, they leak now.


Empty Nester
A Captain in a Sea of Estrogen
1999-V70-T5M56 2005-V70-M56 1999-S70 VW T4 BMW

rguzz
Posts: 369
Joined: Wed Oct 07, 2015 8:41 am
Year and Model: 1996 850 turbo
Location: VA
Has thanked: 0
Been thanked: 5 times
rguzz

Re: 96 850 Turbo Starts but runs rough then dies. Backfires.

Post by rguzz » Sun Sep 08, 2019 2:18 pm

Second the distinct possibility of an air leak at the intake manifold, ie the gasket. It can tear most easily in the upper right corner when replaced, I believe around the upper stud located there, but that is from memory. If it was running fine before taking on this job you will need to retrace your steps, unfortunately. Twice as fast the second time! Get a new gasket regardless. There are numerous step by step guides to help you if need be.



New2Volvo96
Posts: 2
Joined: Sat Sep 07, 2019 9:15 pm
Year and Model: 1996 850 Turbo
Location: Oregon
Has thanked: 0
Been thanked: 0
United States of America
New2Volvo96

Re: 96 850 Turbo Starts but runs rough then dies. Backfires.

Post by New2Volvo96 » Mon Sep 09, 2019 5:17 pm

I was really hoping it wasn't the intake manifold but I had a sneaking suspicion it might not be on correctly or a bad gasket. I'll dive back in there and see what I can find. Thanks all. This forum is super helpful.



User avatar
bmdubya1198
Posts: 3153
Joined: Tue Dec 30, 2014 10:45 am
Year and Model: '98 V70 GLT
Location: Charlotte, NC
Has thanked: 27 times
Been thanked: 89 times
United States of America
bmdubya1198

Re: 96 850 Turbo Starts but runs rough then dies. Backfires.

Post by bmdubya1198 » Mon Sep 09, 2019 9:37 pm

I agree with everyone else, make sure your intake manifold gasket isn't leaking. Also check over all other vacuum lines.

It's unlikely given that this wasn't a problem before this work was done, but the car will struggle to run if the voltage is too low. Definitely do a parasitic draw test once this idle issue is knocked out.


2000 V70R Venetian Red/Charcoal M56 Swapped 190k
2001 S60 2.4T Black/Black 230k
2003 S60 2.4T Silver/Black 107k
2007 XC90 V8 AWD Sport Titanium Grey/Black 158k
1993 944 Base Beige/Beige :mrgreen: 221k
1992 Miata Mariner Blue/Black 146k
Sold-
1998 V70 GLT Black/Beige 193k
1998 S90- Silver/Gray 207k
1995 850 GLT Tropic Green... crushed
1988 744 Turbo M46 Beige Metallic/Beige 188k- Never should have sold it


Need used parts? PM me!

User avatar
erikv11
Posts: 9163
Joined: Sat Jul 25, 2009 2:03 pm
Year and Model: 850, S/V70, 06 S60R
Location: Iowa
Has thanked: 56 times
Been thanked: 193 times
United States of America
erikv11

Re: 96 850 Turbo Starts but runs rough then dies. Backfires.

Post by erikv11 » Mon Sep 09, 2019 10:05 pm

You're in good shape with all the comments IMHO. A peripheral comment -
New2Volvo96 wrote:
Sat Sep 07, 2019 9:32 pm
... can't imagine a dirty MAF would cause this many problems. ...
If the MAF isn't visibly oily or grungy, cleaning it will almost never make any difference, not even a small one. Basically not worth spending for the cleaner. Do an unplug-the-MAF test first.


'95 854 T5-R, Motronic 4.4, 185k
'96 855 NA, 140k
'98 S70 NA, 210k (living out west)
'98 V70, T5 tune-injectors-turbo, LPT engine, 280k
'06 S60 R, 160k
gone: '96 NA 850 210k, '98 NA V70 182k

Post Reply