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· Registered
2 Posts
Discussion Starter · #1 ·
Guys, HELP!

89 740 gl est - b200e eng 142k


really uneven idle - shakes car
revs drop to near stall after cold start until warm, then rough
idle datum eratic between 800-1200 (settled not fluctuating)
sounds really throaty - like deisel
worst in low pressure, damp weather
v occasional pre ignition


crypton diagnostic fine
head gasket

is my car dead or is there a sneaky piece i haven't found?

one strange thing - can't stop eng by blocking air intake!

any ideas before i ditch it?


· Registered
2 Posts
I think the "oh, just one thing" may be the key.
If the engine runs with the air intake blocked it indicates a leak somewhere.
When you block the inlet, can you hear air rushing in somewhere else.
Have you had your hands/arms down amongst the inlet tubes etc. and may have dislodged something.
If it is fuel injected, it could also be the fuel pressure regulator. That is the aluminium 'box' about 100mmx70mmx70mm high.
My one is buggered and the car idles like a dog intil it warms up, then it's OK.
However, the air leak is what I would check first.


· Volvo Guru !
5,911 Posts
One easy way to find a air leak is to get carb cleaner or brake cleaner and spray around the intake manifold.If the idle changes you found your air leak.Pull the vaccum line from the fuel pressure regulator and see if there is gas in the line if there is replace the regulator.Have you cleaned the throttle body yet?
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