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ControlTech
02-10-2007, 22:25
Hi, all,

I've been wrestling with multiple problems with my 98 6.5 since the spring of last year. The original trouble was no cruise or EGR. Since then, the following has been done:

1. New IP and PMD
2. New PCM
3. New PMD mounted on heat sink (now moved to top of wheel well on it's way out of engine bay...
4. Another new PCM (died, no start)
5. New OPS
6. New ignition switch

(The last two items I just changed, since they seem to be at the root of many problems. There was some carbon on a few of the contacts on the ignition switch. The contacts in the OPS looked OK to me.)

The original cruise and EGR problems were fixed after items 1 & 2. 3 & 4 were done to address a "stalling and no restart" problem that left me on the side of the road twice. I've haven't had a "stall and no restart" since item 4 was done. However, I have had a couple of "stall and restart" episodes. I did the ignition switch particularly to address that, and it hasn't happen since. (Although, it was months between the "stall and restart" episodes, so the jury is still out on that one )

Today's problem is the Service Throttle Soon light. Several times in the last few weeks (prior to and after completing 5 & 6), the truck will "stumble" while driving for a second or two, then recover and run normally. During the "stumble", the STS light comes on, then goes off when everything returns to normal. The SES light does not come on, and my codereader reports no codes in the PCM. I've had it to the dealer as well...they cannot find any thing amiss...no codes, anything. Of course, it won't stumble when they have it, just a law of nature, I guess.

Although the PMD is still in the engine bay, it was not very warm when the STS light/stumble happened today (ambient air temp was around -26 degrees celcuis) Since I moved it off the top of the intake, it's rarely even room temperature after a drive. I guess that will change once winter ends (if it ever does )

I've checked all the grounds I can find, and found nothing that looks bad or particularly corroded. Just in case I've changed the ground straps with heavier ones.

ANY help would be GREATLY appreciated. In a weeks time I'm planning to use this truck to tow a 5th wheel as far as the Gulf of Mexico (long way from home in Canada). Right now I barely trust it to go to work. I would just replace the Accellerator Sensor, but it runs around $590 up here, and I've already replaced about $300 in parts "just to cover the bases".

When the truck is running, it's a fantastic vehicle, purrs like a kitten. Thanks for taking the time to read this novel! :)

Mark Rinker
02-11-2007, 07:59
Have you cleaned the contacts at your throttle? How about ALL chassis grounding points? Next I would get a tube of dielectric grease, pull every fuse in the block, and grease each and every contact.

One 1994 of mine used to stumble and I thought it was FSD, IP, etc. but it was a fuse rattling around in its holder and cutting power to the ECM.