Hi All,

I am helping out a friend with the above vehicle,I am new to Volvo.

Initial problem(s), hard starts, rough idle when cold, runs rich to the point where it is spitting raw gas out of tail pipe, when warm it idles too hi but still rich,

I was able to fix most of those symtoms by closing an air intake(bypass)before the throttle body to the manifold, this electrically controlled valve sits on a hose that connects the air intake (b4 throttle body) to the intake plenum, I found this valve to be in the open mode all the time, and causes engine to race,
this valve has the 12v common lead and 2 others that I assume will be grounded by pcm as needed, so far I only cut the 2 wires after forcing the solenoid in the closed position, the engine now starts normally and idles around 1100rpm,(5 speed) but still running a bit rich,the plugs still fouling a little, I have the timing set around 7 degrees.

Since I am working without a manual, I would appreciate any input you can provide, thanks in advance.

Sincerely
Sam

Thanks to all who replied, your input helped to finally resolve this problem, although not completely yet, the rich mixture was caused by a faulty Fuel pressure regulator, I was measuring 100 PSI at the fuel rail, nothing coming out on the return line, ordered the part, then the regulator decided to blow a diaphram and started to leak thru the vacuum port into the throttle body, not much damage, installed the new one today after complete fuel clean up, spark plugs cleaned as well, now I am measuring 30 PSI at 1000 rpm idle,oops forgot to measure the 02 voltage, I was reading over 1 volt before, supposed to be .2-.7, however plugs looked clean after 25mile trip, will keep an eye on it, I forced the Idle valve shut it still won't go below 1000, if I connect the leads for the valve it opens fully and the idle climbs to 2500-3000, this is definetly being caused by the ECM, verified the leads all the way to the ECM, no grounds, I think one of the output drivers is not working, or it could be the ECM reacting to an input signal,is it possible ECM not getting the rpm signal? I left it disconnected, since it is a 5 speed, 1000 rpm is not really that bad.

I would appreciate any input anyone might have on this ECM issue, meanwhile I will continue surfing the FAQ. thanks again.

Sam

check fuel pressure regulator for leak back into throttle body.

Thx J, I plan to install a pressure test point on the rail, what PSI should I get, I don't like the sound of the underside fuel pump, it sounds like there's air in the lines, yet both pumps were replaced as well as the relay by a shop before he came to me.

sam

quick check for fpr is to remove vac hose while running and see if fpr diaphram is leaking gas. You will see/smell it.If it's original just replace it.Also make sure vac hos has clean ends that are snug.
By the way to properly set the air bypass valve you need to ground the test point(located with co2 adjust on front rt fender well near battery.)

Thanks muchly for the speedy reply, there's a wealth of info where you directed to, I already learned what and how that valve works. thanks again Aleekat.


sam

Go to the top of this page, click on arrow next to "features". Scroll down to 700/900faqs. Lots of rich running issues covered under "performance". The valve you disabled, Idle control valve. Also covered how to test it and clean it.