My 1990 Volvo 240 Sedan has approx. 240k miles on it. For a while now it has been consuming fuel at a high rate. The ECU had fault code readout 2-3-2 (faulty fuel injectors) and 1-1-3 (fuel system compensating for rich air/fuel mix). It also puffs out small amounts of black exhaust. A trusted and reliable mechanic told me it was the ECU, so I got one used (from a wrecked 1991 240 w/120k miles) and installed it. After a few miles the CHECK ENGINE light came on again and it puts out the same exact codes. The mechanic seems to think I have the ECU I installed is faulty-which seems ridiculous since it reads out the same codes as the last. Does anyone have any ideas?

Thanks again everyone for all your help.

Had the oxygen sensor replaced with the right one!!!!! (A different mechanic put a Bosch 13913 O2 sensor on-spliced it in!!! And charged $100 for the part which is actually is more like $50!)

The right sensor was much more $ but it works! And no codes whatsoever.

Didn't have a set of jack stands and jack, otherwise I would have done it myself.

Alright guys, first off thanks for all the generous help I am very thankful.

I did some checks at the ECU connector terminals (as outlined in Bentley).

Fuel Inj. checked out read 4.2 ohm at terminals 9 and 18, which seems ok judging from manual that states 4.0 ohms.

ODGuru which terminals should read approx. 16 ohms for ok fuel injectors?

By the way, both the previous and the "new" (actually used) ECUs are white label 951. Right now I have the "new" one plugged in.

Most of the test at the ECU term. I checked were good except for the O2 sensor test. Terminal 24 and ground should produce continuity (when O2 sensor is connected) which it DID NOT.

I also pulled the hose specified at the fuel regulator and YES it smelled a bit like gasoline.

There is a broken gasket, though I am not sure if it is the intake manifold. Either way its NOT good I figure. Its on the engine, approximately right above the oil filter. You can see the gasket broken hanging out a little with a bit a fluid seeping out it seems.

The only thing I am afraid of is what kind of damage this has all caused because it has been running a long, long time like this. When I asked the mechanic a long time ago about CE light he stated "Oh there's lots of 240s with them on." He usually knows his stuff and I figured it was some kind of computer glitch at the time. Until I got repair manuals and checked the codes because it had been running a long time with it on and using up lots of gas.

Terminal 24 and ground should produce continuity (when O2 sensor is connected) which it DID NOT.

There are lots of Bentleys running around with that symptom.

Bentley book error ??
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Art Benstein near Baltimore

An expert is a man that has made all mistakes possible in a narrow field of expertise (Albert Einstein)

Use Bentley and a multimeter to check the various sensor values AT THE ECU connector.

Running rich could be anything from the FPR, the ECU,(rare unless 561 and then only after everything else is ruled out), a bad temp sender or wiring for the ECU Temp sender, to like the code indicated, bad injectors (or their grounds).

If it is bad injectors, they will read either 16 ohms at the ECU terinal which means they are OK electrically but maybe gummed up, to 12 ohms or less which means one or more are bad. If electrically OK and all other sensors verify at spec, time for a fuel spray/flow test.

My 90 was bought with the check engine light on, even after $1400 worth of parts thrown at it by a mechanic who ?knew his stuff? according to the seller. It took me 30 minutes to clean all the electrical grounds to have the light stay off since. And it still has the original 561 ECU at 292+++ miles.

Each problem is unique and as such n3eeds to be treated as such. Put together the symptoms, add some sensor and and other test data, a pinch of other peoples "cure" if something does not seem right, and find the cause.

Duane

hello
what ecu are you currently running in there and what was the one you removed.
numbers that start 561 or 951? white label or pink label?
not the normal mode of failure for the ecu, but not unheard of.
if you find you need a ecu let me know.
i agree with randy and art's suggestions.
thanks
Mike.

How hold is the fuel pressure regulator?

Mounted at the front end of the fuel rail you will see a small vacuum hose coming off of the front of the regulator. Remove it and smell for gasoline.

If you detect a gasoline smell at the vacuum hose it probably indicates the diaphram has ruptured and the regulator needs to be replaced.

Randy

I think the fuel reg. was changed about 2 years ago-during that time the fuel pumps had failed and replaced with aftermarket ones. The main fuel pump (I think it was the main) failed again about 2 months ago (car wouldn't start) and was replaced with a used Volvo pump. All along this CHECK ENGINE light has been on. Mechanic stated "there's lots of 240s running around with CE light on." It wasn't until I bought the 240 Bentley manual that I checked the codes and I took it to the mechanic again to find out what the problem was-which he never did find. In my discussion with others they have stated that it could be the oxygen sensor. Any ideas?

Hi there,

I don't know what will wind up fixing it; OBD codes on a 240 aren't always that helpful. It could be a number of air and fuel related problems, such as the FPR Randy is asking you to check (they have been leaky right out of the box, so newness is not a qualifier), or a chunk missing out of the intake manifold gasket.

Beware of taking the sooty exhaust as a clue, because once the CEL is set, the ECU runs a rich limp-home fuel profile. If you drive too long on this, the oxygen sensor will be clogged with soot, even if it wasn't involved in the original symptom. Always reset the ECU adaptive memory after getting the codes, to give it a chance to relearn any new conditions. To do that, simply remove the 25A blade fuse (out by the battery) for a moment.
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Art Benstein near Baltimore

You can't trust dogs to watch your food.

Yes, pull the vacuum hose off of the regulator and check for heavy gasoline smell.

The fact that it is only two years old does not mean it would not fail. Just one thing to check among many.

Oxygen sensor? I believe you will find a procedure in the FAQ's on using a multimeter to check it.

Randy