Just bought a '90 240 DL with manual transmission. My wife ran it out of gas and am now having idle problems. It barely idles, usually dies. Runs great at speed, no missing. The shift light arrow in the dash continually flashes. It didn't before. It seems possible that some debris might have been sucked into the fuel pump in the tank? Where to start?

On a related note, the check engine light is on, but it was on before the idle problem. According the Chilton's manual I have, there is a port to read the codes. I found the port, but what kind of socket is needed to insert into the ports so that I can get the trouble codes?

Thanks!

 

follow thes einstructions to read the codes... Engine and OBD Diagnostic Codes

that FAQ is for 7xx/9xx cars, but those are almost identical to your 240 mechanically, with two notable exceptions: 1) fuses and relays are all in different places. 2) 240's don't have a 'radio suppression relay', so you can ignore any troubleshooting referring to that.

basically, there's two sets of codes, ignition (spark) and fuel injection. you plug the little wire into pin 3 or pin 6, turn the ignition on without starting the engine, then press the button for a second and read out a code as a series of blinks. repeat reading codes til you get the same one (or 1-1-1 which means all OK). after reading all the pin 3 codes, ignition off, move to pin 6, ignition on, and do it all over.

 

Got some info off the internet and was able to read the codes for the fuel system diagnostics. The codes are 2-3-2, 2-1-2, 1-1-3, and 1-2-1. I read that only three codes are stored, however, I got four. I tried it twice and got the same four codes.

As the check engine light was already on, when I bought the vehicle and prior to running out of gas, I'm not sure which codees, if any, resulted from running out of gas. My Chilton's manual lists the code description, but doesn't provide much detail as to what components may need to be inspected/replaced based on the codes.

Also, after the running-out-of-gas incident, the time-to-shift indicator light in the dash flashes constantly. This must somehow be related?

I've since replaced the fuel filter, but haven't driven the car again. Man, that's a bit of a PITA to replace!

Any suggestions as to where to start? Thanks!

 

did you read the codes in both positions 2 (fuel injection) and 6 (ignition) ? each module can store 3 faults.

2-3-2 - too lean or rich at idle
2-1-2 - O2 sensor signal missing
1-1-3 - too lean or rich
1-2-1 - faulty signal from AMM (air mass meter)

I think I'd disconnect check and reseat the ECU and AMM connectors, and check the wiring to the O2 sensor (on the exhaust pipe or manifold in front of the catalytic converter), then I'd reset the codes (step 2 here, Engine and OBD Diagnostic Codes )

then see if the codes recurr. those codes would be more likely to cause lousy performance and possibly bad gas mileage, then your other symptoms, which sound to me like in-tank pump or pickup and/or level sensor related.

re: the turn signal, thats totally independent of the engine... maybe the turn signal switch or the wiring from the switch to the relay is messed up somehow. bad grounds can cause electrical gremlins like this, too. there's a couple ground points behind the dash to the chassis where lots of brown or black wires end up.

 

I only completed the diagnostics using socket no. 2 tonight. To disconnect and reset the ECM and AMM connectors, is that just a matter of disconnecting the cables from the battery and letting it sit for some period of time, say, 10 min?

 

no, I am suggesting you unplug, inspect, and replug in the actual ECU and AMM connectors to clean them, and inspect them for corrosion, cracking insulation on the wiring harness, etc. on a 20 year old car, all electrical connectors are suspect....

 

Ok, I'll give that a try. To confirm, a failing in-tank pump, or pre-pump can cause a poor idle condition?

Are there any other symptoms of a failing pre pump?

 

the failing in tank pump would make crummy running and frequent stalling when you have less than 1/4 tank.

 

I unplugged the ECU and AMM connectors. All looked good. Should I reset the codes before I drive it?

The fuel filter I replaced appeared to be relatively new. I suppose it's possible any debris the pump picked up when the car was run out of gas made it through the filter and gunked up the fuel injectors?

 

nothing close to large enough to plug an injector should get through those fuel filters.

 

So since the poor idle condition occured after the car ran out of gas, it must be related to the in-tank fuel pump or main pump. I don't understand the purpose of having an in-tank pre pump and a main fuel pump. Could you explain?

Thanks!

 

the dual pump system was quite common on FI cars in the 80s/90s. the tank pump is low pressure, and lifts the gas out of the tank and delivers it to the main pump, the main pump develops the 45PSI or so required for the fuel injection system.

volvos with the 'regina' ignition system have a single in-tank high pressure pump, also later 940s sometimes had a bosch version of this too, its simpler but harder to service.

 

Got it running again. It seems to idling much better, although it sounds too low. It looks like there is an idle adjustment. so perhaps that's the solution for the low idle speed.

Check engine light is still on, but I haven't checked the codes again.

Regarding the shift indicator light in the dash (the flashing arrow) which is continually flashing. Is there some sort of speed sensor that activates it, or is it just connected to the distributor/coil in some way like tachometers are typically wired.

Thanks!

 

if the check engine light came on again after resetting the codes, read them again, and those codes should definitely clue you into something wrong.

I've never seen the overdrive indicator light flash. its either ON (because you have overdrive disabled) or its off (because overdrive isn't disabled). I'm guessing flashing is indicating some sort of fault code, but on the AW70 schematics I'm looking at (from a 1992 740/940) there's no possible way for it to flash. its ON or its OFF.

What year/model car do you have ? which transmission?

 

I didn't reset the codes after I read them last time, but will.

It's not an overdrive indicator light, but a shift indicator light for manual transmission equipped cars. BTW, I have a '90 240 DL with 5-speed manual transmission. According to the owner's manual, it's intended to show the driver when to shift to maximize fuel economy. As I'm reading the manual, I now see a section on programming instructions for the shift indicator, so I'll give that a try.

Thanks!

 

I know the up shift light on my 1989 VW Jetta was at least partly vacuum activated.

my wiring diagrams for a 1992 740/940 don't even show an upshift indicator... oh wait, its shown on the instrument panel, its the same uparrow light that an auto uses for overdrive (the 5-speed has a seperate '5' light next to it). mmmm, ok, its not very clear, but it comes off the LH2.4 ECU pin 26 and goes through pins 7 and 5 of the OD relay (probably so its off if the car is already in 5th) and goes to the instrument panel pin '2' which is that upshift light. so if its blinking, its coming out of the ECU. Maybe its just trying to tell you to read the codes! hah!

 

ok, I got my hands on the 240 wiring diagrams. trouble is, they are copy protected.

that shift indicator goes from pin 26 of the LH2.4 fuel injection ECU to pin 34 of the console indicator lights, not even a relay in the middle like there is on the similar year 740. the diagrams show the wire is blue-yellow at the instrument panel side, and violet at the control unit side, no indications of where a connector in the middle might be.

so my guess is, the ECU is running in 'limp mode' due to the other engine faults, you really should reset those and see if they come back.

 

Reset the codes and only a 1-2-1 (mass airflow signal) came back. Perhaps the mass airflow sensor is bad?

My Chilton's manual lists some diagnostic tests to run to determine if the sensor is bad. Any other suggestions?

Thanks!

 

I'd find the EFI ECU and reseat that connector too, maybe shoot some contact cleaner spray on the connector before reseating it (with the car switched off!!!). I believe the ECU is near the right side hinge of the hood on a 240. reset the code and see if it comes back. the AMM/MAF has 5 pins.

pin 1 is ground (brown-black wire).
pin 2, 3, 4 go directly to the ECU pins 6, 7, 8.
pin 5 is power via the main relay (same power goes to the fuel injectors and the idle valve.

best way to verify an AMM is bad is to swap it with another car that has a known good one, any LH2.4 volvo 240,740,940 should work, and read/clear any faults before and after testing in both cars...

 

Car is hard to start when cold, or even when it's been sitting 20 min or so. It takes repeating cranking until it starts and runs.

It drove fine today, but stll had the CEL on with the 1-2-1 (MAF) code. So I disconnected the battery to reset the ECU and codes. After reconnecting the battery, the code was 1-1-1 (all ok) and no CEL. Drove it for a bit and the poor idle condition returned with engine stalling a few times.

With the engine running, I disconnected the MAF, and the idle speed increased and smoothed out considerably. With the MAF reconnected, the idle speed slowed and rose and fell - poor idle quality. CEL came back on. The codes are now 1-2-1 (MAF) an 2-3-2 (too lean or too rich)

Is the first condition indicative of a failing fuel pump, perhaps insufficient fuel pressure?

Is the change in idle quality with the MAF disconnected indicative a failing MAF? Since new ones are so expensive, I'd like to confirm that that's the problem before purchasing one.

I suppose I could check the fuel pressure, but my manual provides little detail. Is there a fitting on the fuel rail? Will a cheapo Harbor Freight fuel pressure test gauge have the right fittings to connect up?

Thanks!