high idling problem

[Lance]

Hi All, I have a 91 E-250 SMB, 5.8 E40D, fuel inj. I've had a on and off problem with the engine idling at 2000 rpm. Usually when I shut it off it will return to a normal idle speed of 500-600 rpms. I had a EGR code and had that changed plus a acc pedal signal too low and that changed too, about 5 yrs ago. Didn't help, lived with it for a while but got on it again this summer. Had it scanned again, had 2 EGR codes, 334,332, valve not opening and valve above closed limit. ACC pedal too low, 122. Speed Sensor out of position, 452. Due to having some of those things changed before I didn't trust the codes. Had the Idle Bypass Selonoid replaced, didn't help. Changed the ECM, the brains of the thing, thinking it was bad and giving false codes. Wrong, still has same problem. It needs to be on a trip to find out as it wont do it all the time and I don't drive it unless traveling so it's a long process. Going back in for another scan soon. Has anyone got any experience with something like this.

[daveb]

There was this post not too long ago...don't know if you saw it.
viewtopic.php?f=39&t=9517

[Lance]

thanks for the reply, no I didn't see that link, looks like a good source of info. my problem isn't that often, usually have to drive for a few hours but also can happen right off. last year I sat in line idling at the border in Tecate for 2 1/2 hrs and it purred quietly the whole time. If it's idling high I can turn it off and usually it will reset and idle normally, though not always.