|
Hi, I need help! my 740 has 2 problems I think may be related, first there is a strong vibration at idle (enough that both doors and many trims are making noise with the shake) and has extremely poor mpg (11-12 mpg).
The car is a 1991 740 wagon non-turbo automatic with Regina injection, has only 87k km (54k miles). Things that have been done/tested:
new battery
new alternator
new wires/plugs
tested cap and rotor (swapped with new to test)
cleaned TB (was clean)
cleaned IAC
cleaned air temp sensor (right after the filter) (was clean)
new engine mounts
tested intake/vacuum leaks with propane test(none found and all hoses seems ok)
compression on all cylinders of 180
new fuel filter
new timing belt
used a fuel additive injector cleaner with no results.
both problems seems to have come worse over time, but may not be related. For the vibration, it began 4k km ago and was worse on idle in "D" or "R", but now is bad anytime on idle. Seems to go when I give gas to bring idle at 900, but I still feel a small vibration while accellerating (mostly a "feel" in the floor, nothing like the shake on idle).
Idle is stable at 700-750, so vibration not caused by erratic idle. Some day it goes down to 600 rpm, and shaking is worse. Not always seems to be weather related but seems to do it a couple hour after car wash.
Because of the low mileage of the car, up to now everything I tore open to clean was already clean except iac who had just a little junk.
Car start easily each try, either hot or in extreme cold, and has good power in all conditions.
I put a lot of money on it up to now, I would like to know what's the next suspect, I'm not a mechanic but I can use a wrench and follow instruction and like to understand how things work.
Thanks for the help!
|
