looking for ideas on fighting a 2-3-1 code on 94 855T w/204k. there is also a hard start (15 seconds cranking) issue that is intermittent.

here's what i've done in last 60 days: volvo plugs, cap, rotor, fuel filter, fuel pump relay, fuel injection relay, used FPR, and checked vacuum leaks with TB cleaner spray. cleaned up TB and hole down to EGR, which was completely blocked. the fuel pump is 1 yr old walbro insert type. fuel economy is 17-19 in town and 22-28 mpg on highway.

fuel pressure is 37 psi upstream of filter at idle, and 33 psi at fuel rail at idle. revving engine did not increase pressure. engine off, pressure drops quickly to less than 10 psi. same with key in position II, pressure spikes to 38 psi then drops to 8 psi and holds.

any ideas what to try next? i am suspecting the pump may be part of the problem?

update: found a few things. first, the EVAP vacuum line near the fuel filter was broken, so i fixed that. i think it was unrelated to other issues, but was sometimes throwing an EVAP DTC.

second, i removed the fuel pump and found that the supply line was slipping off the pump discharge, above the check valve, hence the immediate drop in pressure and low fuel pressure overall. I was getting 28-30 psi at the rail. Under heavy acceleration, car would lose power, almost like ECU was capping throttle due to lack of fuel (my theory). Fuel econoomy was 15-19 in town and only 21-22 on highway, and long term trim was +25% on my generic scanner, which i guess is lean.

After re-installing the fuel pump, fuel pressure tested at 43 psi (300 kPa) at the test port near the fuel filter. Car starts within a few seconds. Long term trim is at zero (+/-) and mpg back to 20 in town and 25-28 on highway. Power under load is way better.

thanks for help Klaus and others.

The turbos also have vacuum lines to the boost controller (on the air cleaner) and the turbo. The long term trim error message you are getting is because unmetered air is getting into the manifold - somewhere! It is NOT gasoline delivery based.

Your fuel pressure readings are normal, and yes, the pressure will drop a lot after key is turned off. Vacuum will seldom increase without a load on the engine, so the pressure reading at faster than idle will remain the same.

You could have a leaking seal at one of the injectors, or that little vacuum line that is hidden under the #1 intake rail. Don't forget to look at the PTC nipple on the air intake line just before the turbo as it can come loose.

You are looking for a small vacuum leak.

Thanks, I'll keep hunting for a leak. Where is the hidden line? Near PS reservoir or near Presdure regulator? Access on that end is tight. I'll look at ptc but I know it is connected. There is a lot of oil leakage/blowout down there near turbo.

If a injector is leaking, wouldn't intake cleaner spray produce a sputtering or revving? When I tried that technique, I got nothing at all locations.

Matt

Access to that particular vacuum is so tight and well hidden by the #1 intake runner, most people don't find it without taking off the intake manifold. The line is held on by a clamp which requires needle nose pliers to loosen, and then it is best to have loooong pliers with a 90 degree bend.

If you sprayed the injector O rings and there was no change in idle, then they should be OK.

Oil by the turbo could be a worn out O ring and seal at the turbo drain, there are videos for that procedure. Access is from below the car. $20 for the parts and 1 hour of labor.

Also check the vacuum line from the fuel pressure regulator to the vacuum tree under the throttle cover. There should be no gasoline in the line. The FPR is next to the fuel rail.

Well, I may have to take off manifold, I can't feel or see that vacuum line. The F P R lines are fine and no gas on vacuum side. Most other lines I have replaced in last few years.

You have a vacuum gauge in the instrument cluster, the boost gauge. At idle it should be in the white, and when decellerating it should be way down. If the needle doesn't move much, it could be that the vacuum line to the gauge is loose or disconnected.

That line by the #1 runner can only be felt with fingers. Removing the intake manifold should only be done when replacing the oil separator lines. If it has never been done, then it should be replaced as those lines get brittle with age. You will need a new gasket and at least 5 hours of time. FCP and others sell a kit.

My gauge is way to left at idle, maybe 11 o'clock if middle is 12. It does move to right when accelerating. When hard accelerating I can take it half way into the white. Does this tell me anything?

Btw oil separator was done in 2009 with knock sensor replacement.

That sounds reasonable. Check the accordian sections of the intake air hose, just after the filter and just before the throttle body, for cracks/leaks. Make sure the hose clamps are tight by trying to twist the intercooler hoses, if there is any movement the clamp is loose.

Check the base of the vacuum tree by the throttle body, the O ring can get cracked. As well as the air supply hose from the idle control motor.

If this is P0231- Fuel Pump Secondary (Feedback) Circuit Low Voltage.
This link may help http://www.obd-codes.com/p0231