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It's come time to ask the internet for help with my woes and how to get back to 29mpg highway instead of the accursed 12 I'm currently getting.
The specs and story:
1991 Volvo 240, 164k miles on the odometer; owned since 2012 and 121k; mostly a grocery-getter but did 100+ miles a day for a few months in 2017 before any problems (other than the temperature sensor interpreter thing between the thermostat and the gauge that makes the temperature occasionally appear to go haywire when the car's actually fine). It had the thermostat replaced in 2013 before I knew about the gauge issue. It's still got one of the front turn signals shattered, and is an ugly car at best. Last spring after having it sit all winter, I had to get the battery replaced due to it burning up a wire somewhere down by the alternator, and drove it until I switched to my truck for summer. This past winter I noticed that maybe it smelled a bit like gasoline when I was driving it. This fall, I got the polarity on the jumper cables reversed due to them not being marked on the battery, figured that out eventually, jumped it, and ended up getting a new battery because the one that I got last year would not hold a charge. This is where things get weird....
When I first started driving it again, I noticed it hesitating a couple times when I was in gear, but that has since stopped happening so I'm attributing it to old fuel. The awful thing is that it's getting 12-13mpg highway, even though it seems to drive as it always has, if perhaps with a bit less power due to running very rich. Every time I drive, I can smell the unburnt gasoline in the exhaust, but thankfully not from other areas of the car. It's throwing the following codes on port 2:
2 - 3 - 2 "Fuel trim (lambda control) too lean or too rich at idle", indicates "If too rich: high fuel pressure, leaking injector"
2 - 3 - 1 "Fuel trim (lambda control) too lean or too rich at part load", indicates "If too lean: air leaks, low fuel pressure, bad sensor"
1 - 1 - 3 "Fuel trim (lambda control) too lean or rich", indicates "Mixture incorrect; O2S wiring fault"
2 - 2 - 1 "Fuel trim (lambda control) too lean at part load", indicates "Lean; air leak; low fuel pressure; bad AMM"
and
1 - 4 - 4 on port 6, which is "No load signal from fuel injection system", indicates "Bad fuel injection relay; faulty wiring from LH to EZK; bad LH module"
Could I have fried my fuel injector relay by jumpstarting the car incorrectly?!? Or should I just try replacing the AMM, fuel pressure regulator, and O2 sensor, and then go from there? Or try replacing the fuel injection relay first? So many things it could be...
FYI, I've already replaced the air filter, did the wires and spark plugs (the old ones were heavily fouled with soot), as well as the little vacuum hose that goes between the throttle body and the fuel pressure regulator. When I replaced the old tubing, there seemed to be some oil/gas in there, but I looked at the end of the new tubing today and there was no gasoline in it, only some fumes - which indicates that the fuel pressure regulator might not be bad after all. I'm kind of at a loss at this point, and with so many conflicting signals I just want to know which part is the most likely culprit before I spend tons of money and time on things that MIGHT help, but end up making little to no difference. I also want to avoid taking it to a mechanic if at all possible, because I'm a chick and every experience I've had so far in my life with having someone else fix my vehicles has ended up with me being swindled in retrospect - so damnit I'm just going to do everything I can by myself. What can I do to track this problem down further, other than just start replacing things until I get decent mileage again???
I haven't looked at the distributor cap or rotor yet, but it's something I might take a look at if none of the other replacements fix it. I'll be doing the AMM and FPR today if I can get around to them.
Start by checking the wiring to the O2 and the AMM. Verify the wiring is good with no breaks and the connections are good and clean. These two sensors provide feedback to the ECU so it can adjust the amount of fuel mix to deliver. If the wiring is good, then consider replacing the O2 and AMM. Throwing both an AMM and O2 using the parts cannon gets expensive very quick so its best to check cheaper things first. I used to get used AMMs at the junkyard for about $35 - cheap enough for me to take a chance on them in case they were bad. But I haven't seen a 240 or 940 in the junkyard around me for about 5 years now. If you need a replacement, make sure you get a Bosch. They are more expensive but I haven't heard anything good about other brands out there.
A bad engine temperature sensor can also cause rich running conditions as can exhaust leaks upstream of the O2 sensor. However, the codes don't lean that way.
- replaced FPR, as I did smell more gas in that vacuum line I replaced after driving it a bit
- checked distributor contacts, they look fine, remarkably good for a car pushing 30
- replaced O2 sensor, original was carbonized to the point that even solvent would not remove the deposits
- bought new AMM, realized it was 6 pin instead of 4, returned it, new one on order
- changed the oil because why not, it bleeds Hershey's syrup no matter how many miles I go between oil changes
I'm only getting two codes now, 1 - 1 - 3 and 2 - 3 - 2 so it may very well be a bad injector. At this point I'm confident and fed up enough that I'm ready to just start yanking plugs out and replacing all the s#!+ that can be replaced, simply because everything is old and I want my fuel economy/reliability back.
When you pulled the spark plugs was there a difference between any of them. Meaning was one blacker then the other. that would indicate a possible bad injector. While the plugs were out did you do a compression test or a leak down test.
When you pulled the spark plugs was there a difference between any of them. Meaning was one blacker then the other. that would indicate a possible bad injector. While the plugs were out did you do a compression test or a leak down test.
Not that I remember. They were all a bit over-gapped, rounded from age and use, and black as night with soot deposits. The new ones just went in last weekend though, so if I pull them out one by one on a cold engine, should I be able to immediately tell if any of them are wet with fuel/more burnt than the rest?
Not that I remember. They were all a bit over-gapped, rounded from age and use, and black as night with soot deposits. The new ones just went in last weekend though, so if I pull them out one by one on a cold engine, should I be able to immediately tell if any of them are wet with fuel/more burnt than the rest?
They should not be black. Normal plugs run light brown or light gray in color. You would be looking for A leaking injector and if they all get black then you have a sensor telling the ECU to enrich en the mixture. Start the car and warm it up then drive it at highway speeds and then pull the plugs and see what you have.
They should not be black. Normal plugs run light brown or light gray in color. You would be looking for A leaking injector and if they all get black then you have a sensor telling the ECU to enrich en the mixture. Start the car and warm it up then drive it at highway speeds and then pull the plugs and see what you have.
I'm talking about the old spark plugs... presumably original, or at least installed 7+ years ago prior to me buying the car. They were all equally soot-coated and scorched-looking.
I know it's running rich still, and I'll probably pull at least two of the new plugs next time I get a chance and see if they're both getting sooty or if I'm dealing with uneven richness.
The only things I haven't replaced yet that the codes indicate could be the problem are the amm and injectors. More updates to come.
They get you the correct parts for your car. I usually try to pick up AMMs from the junkyard as they are quite expensive new. The Bosch ones are what you need. I have never heard anything good about the aftermarket brands.
I don't believe Bosch is making new ones anymore, they are all "remanufacturered'. many are sold as remanufactured Bosch but are in fact remanufacturered by someone else. Its a tough call, but the middle or top price ones sold by IPD are probably good.
Update: Finally got a new AMM, replaced the old one.
The accursed thing now runs even worse.
It still throws the same codes, and it's started doing this horrible, waltzing-type of rough idle when I first start it up.
chugchugcha chugchugcha chugchugcha chugchugcha... until it warms up.
Then it just gets s**t mileage.
I've wiped the codes and disconnected the battery multiple times, start it up and it runs okay-ish for about half an hour or until I start it a second time. Then if it's cold I get the rough idle, or if it's warm I just get the check engine light and it starts drinking like a sailor on shore leave. One weird thing I noticed when replacing the AMM is that there seems to be oil in my intake right past the AMM, although the old one wasn't fouled or anything. Is my car just doomed?
if its throwing AMM codes, then something is seriously wrong. maybe the wiring is broken somewhere, or maybe the ECU is bad, or maybe all your AMMs have been bad, really hard to say. a good test of the AMM would to be to find a 240/740/940 1990+ LH2.4 car, and swap the AMMs, if the good car messes up, then you know that AMM is bad.
1991 240 Running Rich, Making Me Poor
