1988 240 wagon Gas Mileage Problem

neenertrucker · Post by **neenertrucker** » 28 Oct 2011, 14:28

hi folks, i've got an 1988 240 wagon with 200k plus miles, odometer quit at 177k in 2005 so true miles are anyones guess. bought it in august, and it seems to be running very rich, only getting 14mpg around town or hiway. it starts right up, but idols rough. it shifts through the gears {automatic} perfectly, and just purrs along on the hiway. also, the tailpipe is black, and smells like raw gas. i've cleaned the mass air censor, and, flame trap to no effect.........any clues? thanks for your time..

Post by **billofdurham** » 29 Oct 2011, 13:10

Welcome to Matthew's Volvo Site.

I have split this from the original topic as the problem was not exactly the same.

With a black tailpipe and fuel smell it is definitely running rich. Attached are some things to check.

240 1988 running rich.pdf: (486.71 KiB) Downloaded 189 times

Bill.

neenertrucker · Post by **neenertrucker** » 29 Oct 2011, 18:00

thanks Bill, lots to check there. I keep seeing coolant temp censor as one of the probable causes, are there two temp censors', one for the guage, and one for the engine management system? Because my guage seems to be working fine,

Post by **billofdurham** » 30 Oct 2011, 14:35

There is only one CTS on the 240. The signal that is critical is that received by the ECU, not the gauge. You can run an easy check on the CTS if you have an ohmmeter or a multimeter.

240 1988 coolant temperature sensor.pdf: (249.77 KiB) Downloaded 136 times

Bill.

neenertrucker · Post by **neenertrucker** » 01 Nov 2011, 18:06

Thank you Bill, I will get out the ohm meter an check it out. also, will check out the grounds, Now, if it should seem that it would be an ECU problem, would a junkyard ECU do the trick, or, should I go with a new one. Having said that, I don't intend to sell this car, so, I'm in it for the long haul........

Post by **billofdurham** » 02 Nov 2011, 13:37

As you intend keeping the car I would advise against an ECU from a junk yard. The ECU may be the reason the car is there. Even going for an exchange unit could have problems as it may have unusual intermittent faults that no one has been able to detect or repair.

You can have your ECU checked and rebuilt by companies who specialize in that type of work. However, let's rule out everything else first.

Bill.

neenertrucker · Post by **neenertrucker** » 02 Nov 2011, 19:35

Will do, thank you Bill.