Login Register

I'm totally stumped

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

Post Reply
058ovlov
Posts: 7
Joined: 28 December 2011
Year and Model: 1994 850 N/A
Location: AZ

I'm totally stumped

Post by 058ovlov »

The back story is that this 1997 NA has been throwing a CEL for over a year (5th Cyl low/ almost no compression and I've just been living with it) Emissions is coming up though. Anyway my MAF sensor went bad and after I swapped it out I inadvertently hooked the white and black vacuum lines on the aibox in reverse. I reconnected the battery, started it up, and bang, Magically the CEL was gone. Drove it around for three days. No codes no CEL. However, I stated getting the "smokestack from the dipstick tube. (Didn't do it prior) So I just figured it was coincidental and it was just the PCV clogged. So I was about to take it through emissions, and gave it the once over, thats when I noticed, I had the white on top and Black on the bottom. No biggie right? Swapped them correctly and BAM!!!! CEL came on. So now I'm contemplating disconnecting the Battery and swapping them back to the "wrong way" in hopes it will magically clear until I can get it through emissions. Any thoughts? I don't see how the ECU could not have reset since I drove it for 3 days with those lines transverse. And with in 10 seconds of hooking them up correctly the engine quieted a little, the sound changed to it's "normal self" and the CEL came right up. At this point I'm baffled and could really use some input.

User avatar
erikv11
Posts: 11800
Joined: 25 July 2009
Year and Model: 850, V70, S60R, XC70
Location: Iowa
Has thanked: 292 times
Been thanked: 765 times

Post by erikv11 »

What vacuum lines are you talking about? A picture would help a lot.

I am confused by your post. At the beginning it says reversing the lines eliminated the code, as if it fixed the problem. But then at the end it says switching the lines back made it run better. At any rate, I'd be very surprised if vacuum lines were related to compression in #5.

What is the code for the CEL, p0305? Gotta know the code. Did you measure compression, is that why you say it is low? Does #5 fire at all?
'95 854 T-5R, Motronic 4.4, 185k
'98 V70, T5 tune-injectors-turbo, LPT engine, 304k, daily driver
'06 S60 R, 197k
'07 XC70, black, 205k
'07 XC70, willow green, 212k
'99 Camry V6 :shock: 153k
gone: '96 NA 850 210k, '98 NA V70 182k, '98 S70 NA 225k, '96 855 NA 169k

Post Reply
  • Similar Topics
    Replies
    Views
    Last post