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B230FB exhaust puff and varying idle

Brotkasten

Brotkasten

Jonas
Joined
Aug 21, 2017
Location
Wolfsburg, Germany
Malzeit,

my 940 with 220k miles on it is acting up. The idle is sometimes dropping to 400-500rpm. It even oscilated betwen normal and low rpm in 2 a second interval one day. Sometimes it starts bad when warm.

Also, when engine braking or reving there is a puff-sound in the exhaust (im worried it could harm the CAT)

There were false air problems. I fixed those . I also tried a known working amm, changed the cps, tps, iac, cleaned out the throttle body, cleaned the grounds and checked the ignition.

I'm now going to adjust the valves. Does anybody have a different idea / something I should do while adjusting?

Thanks guys!
 
My different idea would be to stop just adjusting a bunch of crap and find out what the problem is.

What is your fuel economy like?
 
Without question it's a good thing. But if you start changing random things when there's a problem you can easily mask the cause of the problem without knowing it.

I might suggest checking for vac leaks with a smoke tester that you can easily make...
 
Replacing high quality OEM parts with aftermarket junk is also a faux paux. It's also a rookie move. Been there done that. Threads that start with, "I replaced A, B, C, X...." tells me that very little diag was done and the parts cannon has been loaded and fired. That being said, as a professional tech I still, unusually, throw a part at a problem if it may save me time on an educated guess.


At the shop, the first thing I would is spend 5 minutes with the smoke machine to check for air leaks. I don't believe claims that there are "no air leaks". Brake cleaner hose down, at home, and listen for changes in idle.

And as a human, I still make mistakes and misdiagnose problems sometimes. Good luck and post back.

Does your speedometer work?
 
Last edited:
ZVOLV said:
Replacing high quality OEM parts with aftermarket junk is also a faux paux.
Click to expand...

Well, the TPS was faulty (I tested it), the IAC was changed by the previous owner, changed the CPS from aftermarket to Volvo original (the car was not starting sometimes - fixes that) and the AMM was suggested to me by another Volvo owner (mine is fine tho.)

ZVOLV said:
Does your speedometer work?
Click to expand...

Yes, I resoldered it.

Otto Mattik said:
Why focus on the valves ?
Click to expand...

360.000km and I cant tell if they were adjusted in the past :'D

intothelabyrinth said:
I bet the backfiring when coasting down is an exhaust leak.
Click to expand...

You are right! A clamp was loose. Problem is gone now :lol: I wouldn't even call it backfire. Just some weird puffing sounds :lol:
 
intothelabyrinth said:
I bet the backfiring when coasting down is an exhaust leak.
Click to expand...

^^^^^^^^^^^^this^^^^^^^^^^^





And parts changing is not diagnosis.....
Just the introduction of a possibly new set of problems due to the functionality of the "new" part and the damage inflicted while changing said part.

Ah, I see it's fixed...
 
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