Limp Mode

WHT05 · Jul 8, 2013

I need some input. I was towing a camper this past weekend it weighs about 6000 pounds. 2 times on the way to where i was headed, i was going up a hill and put the pedal down to keep momentum and when it down shifted it through it into limp mode. but then if i would turn the truck off and turn it right back on it would be fine. it only did it twice so i was just wondering if anyone would know what would cause this.

Gary · Jul 14, 2013

Somewhere north of 240* EOT they derate, I'm not sure where the coolant will start to derate. Your going to have to look at those temps and see what is going on.

Mdub707 · Jul 15, 2013

I've done it a time or two towing my camper with tunes I shouldn't have been towing with. Too much heat causes it. Are you towing tuned? Do you monitor any of your temps? The gauges on the dash are all but useless, need real gauges to see what EOT and ECT are.

HOOV3R · Jul 15, 2013

Overboost will also derate.

WHT05 · Jul 16, 2013

It is not tunned. The truck is stock except for 4" exhaust. All of the gauges on the dash were where they were supposed to be. You are not the first person ive talked to that have said those gauges are worthless.

HOOV3R · Jul 16, 2013

Pull codes with a good scanner. There should be a soft code listed.

WHT05 · Jul 16, 2013

Will there still be a code listed?

Mdub707 · Jul 18, 2013

Most likely yes there will be a soft code. A soft code is just one that doesn't trip the CEL. Try reading it with a good code reader. Likely the one from advanced auto (or the likes) wont pick it up.

I can't believe you managed to do this with a stock truck. The ONLY times I've ever done it was when I was towing with a really hot tune on, and I also did it one time holding boost at a light to race someone. I held it up too long apparently. It took off just fine but when I coasted to the next stop, it had no power at all. Reset itself after driving for a mile or two. I lost the speedo and everything that time.

suprdzlduty · Jul 18, 2013

Bad Map sensor will cause this.

Bustedknuckles · Jul 18, 2013

Just had a truck in doing the same thing, plugged oil cooler was the culprit.

WHT05 · Jul 19, 2013

Thanks for all the help. If it is a plugged oil cooler will there be any other symptoms?

Mahdeys · Jul 19, 2013

yes, coolant and eot will vary widely. Anything over 10-15 degrees is too much. We need codes though, anything can put a 6.0 in limp mode.

Mdub707 · Jul 19, 2013

Yes, that would be a good idea to monitor the EOT and ECT. Some of the newer flashes actually set the wrench light on when the temps spread too far apart. If it's bad enough that it's sending your truck into limp mode, that needs to be addressed ASAP. It typically leads to blowing EGR coolers and headgaskets.

Do you have a way to check those temps? You need to monitor those and let us know what you find. An oil cooler rebuild is only $275 or so, and a coolant flush and coolant filter should be on the list of things to do, if you find that it's plugging.

WHT05 · Jul 19, 2013

I dont have any way to monitor those. I did have a FICM put in back in march and had the truck flashed. Would that make a difference? Its just wierd cause it only did it twice on the trip and it hasnt done anything since. granted i have not towed anything since then.

Radio · Jul 19, 2013

Mine was doing this last time I towed a good load. Wrench light came on and it would derate till I cycled the key. A cheep scan tool won't pull it. I used the MOTIS at our shop and found over boost faults. Gummed up VGT can cause this as well as bad EBP sensor or MAP sensor.

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