940 turbo, 1993, sluggish and fuel rich (gray smoke)

Post by **billofdurham** » 04 Oct 2009, 12:45

Yes, it could be the cat. If it is restricted you will have all the symptoms you are experiencing. Get the fuel pressure checked first as that is a cheaper fix.

Bill.

MSMMMDD · Post by **MSMMMDD** » 05 Oct 2009, 18:16

Thanks, I will check the fuel pressure first.

I also meant to ask when I was doing the vacuum check the turbo bypass valve did not hold pressure, is it suppose to hold vacuum? It sure looks like it should.

The fuel pressure regulator did hold pressure, I have to check the fuel system pressure next.

Post by **billofdurham** » 06 Oct 2009, 11:32

The bypass valve should hold vacuum. There was a technical service bulletin in March '94 covering this problem.

940 TSB 114 turbo bypass valve..pdf: (88.83 KiB) Downloaded 353 times

Bill.

MSMMMDD · Post by **MSMMMDD** » 06 Oct 2009, 14:53

Bill, I am amazed. How do you find all this information?

Post by **billofdurham** » 06 Oct 2009, 15:38

Lots of books plus old Volvo publications from a friendly ex-Volvo tech.

Bill.

MSMMMDD · Post by **MSMMMDD** » 11 Oct 2009, 13:07

Have checked the fuel pressure, plugged the vacuum leak in the turbo bypass valve, replace the O2 sensor. The catalitic converter is not plugged. Went ahead and replace the sparkplug wire / plugs / distributor and rotor (needed a tuneup anyway). All 4 of the injectors are clicking like they should.

Runs fine through first gear, but in second it starts to bogg down and surge. Can't get to third. Still think it is running rich.

No codes are showing now despite driving it 10-15 minutes. Anyone got any other suggestions?

One other thing. Checked all compression for the cylinders. In order 140,145,150,160 psi. All are close together. But I don't know what is "low"

Post by **billofdurham** » 11 Oct 2009, 15:30

Starting at the end, my favourite way, compression should be at least 128psi so you are looking good.

Other things to check:
Throttle switch and connector. This is the cause of many problems on the B230F engine.
Engine Coolant Temperature (ECT) sensor. This is the sensor for the ECU, not the gauge, and is hidden under the inlet manifold branch going to cylinder #3.
Intake air temperature sensor in the air intake hose near the air filter.
Engine speed (impulse) sensor on top of the flywheel behind the engine. This often suffers from bad insulation.
A long shot - the idle speed air control valve which is on the left side of the engine below the intake manifold.

Bill.

MSMMMDD · Post by **MSMMMDD** » 12 Oct 2009, 05:11

Thanks Bill, i will keep looking.

MSMMMDD · Post by **MSMMMDD** » 25 Oct 2009, 19:47

Found it.

The problem was simpler than I expected. Decided to replace all vacuum hoses..just because. My daughters boyfriend walks up and asks me if there was suppose to be a hole in the air hose?????

So, the rubber connection for the intake hose from the turbocharger has a 1 inch hole. Running rich when trying to accelerate. Lots of air coming out when the turbo is kicked on. No indication of an issue at the MAF because that is before the hole. A little duct tape confirmed the solution, now I just have to find the right part.

Sometimes, when I work on cars I am my own worst enemy. I had checked the hoses from the air filter. Did not realize there was a rubber boot connecting the 2 hard pipes.

Post by **billofdurham** » 26 Oct 2009, 16:38

Glad you found it. Thank you for the update.

Doesn't it make you sick when your daughter's boyfriend notices things?

Bill.

940 turbo, 1993, sluggish and fuel rich (gray smoke)

Re: 940 turbo, 1993, sluggish and fuel rich (gray smoke)