idle control motor failure 240

My idle control motor on my 83 b21ft doesn't seem to be doing much of anything, i can unplug it and the tps and the thing runs about the same (generally OK, just a slow idle when cold). All the wires are new and I cleaned it out (was oily).

My question is, when in the normal failure mode, will this non working idle motor be a possible cause of my lousy (about 17 mpg with a new cat converter) fuel ecomomy or produce rich running?

I don't feel liek replacing this $100 part right now, but will do it if it is causing damage, especially to my new converter. Any wisdom is most helpful.

Reply to
John Roden
Loading thread data ...

The idle motor only controls the amount of air bypassing the closed throttle. Thus the only thing it affects is idle speed, it won't have any effect on mileage, or your new cat. The failure mode depends on the position of the valve inside the motor. If the valve is closed, then you'll have symptoms such as you mention. It could fail open, in which case you'll have OK idle when cold, but a high idle when warmed up. Often they are gunked up, preventing them from working correctly, but sometimes the motor is just burned out, so cleaning won't help. Make sure that your throttle switch is adjusted so it clicks when transitioning to and from the idle stop.

When I suddenly had poor mileage on my '83 240 Turbo, I first tried the normal tune up stuff, which didn't help at all. Then I determined that the oxygen sensor wasn't working - an new one fixed the mileage back up to where it had been. This is what will hurt the mileage and the cat.

Reply to
Mike F

Oops, I just bought a new one today. I think I understand now that the idle system and the fuel injection are two distinct systems. Am I asking too much to expect this 245 turbo to get 20 miles to US gallon? (I did do the tune up stuff and 02 sensor already). Maybe I have a leaking injector or somesuch. I could be driving a big caddy or a 1 ton truck if I wanted to get 15 mpg...

Reply to
John Roden

I normally got about 425 km per 50+ litres on my 245 Turbo (manual trans). This works out to 19-20 mpg (US gallon). With a dead oxygen sensor the distance was only 300 km (14 US mpg). With my 1998 V70 T5, (auto trans) the same type of driving usually nets me 10 litres per 100 km, about 23-24 US mpg.

Reply to
Mike F

My dad has a 245T with an automatic, he said it gets about 25 mpg on the highway, not sure about around town. I have a 242T and get similar mileage with a manual, but I probably drive it a bit harder.

Reply to
James Sweet

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.