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UsualSuspect · 07-10-2014, 09:01 PM

This past week while climbing some steep hills, I will sometimes get a check engine light just as the RPM's climb to 2500, then when it shifts up to the next gear the light goes out. The engine temp was 201, the tranny was the same, 201, so it was not overheating. It did not go into limp mode either. It only happens when I have the TOAD attached to it, and even then it is hit and miss. Any ideas, or just something it does every once in a while because it can.

KIX · 07-10-2014, 09:07 PM

I think the C7 max rpms is 2500.......maybe your check engine light is telling you that.

UsualSuspect · 07-10-2014, 09:15 PM

I would have thought since I did not manually downshift it, it would know when to upshift. I climbed the Grapevine heading north, did not do it. The first time was climbing the grade on Highway 168, I think it is 8 or 10%. It did it again heading South on 5, the first big climb on the Grapevine with the lane restriction, did it twice there, but did not do it on any of the other climbs.

gatorcq · 07-11-2014, 07:34 PM

Max RPM is 2650 for a CAT.
Did you check the coolant level ?
Temp is 226 for a CAT where it will give a warning before derating.

1ciderdog · 07-11-2014, 07:53 PM

By chance do you have an MP-8 installed? I have one on mine and found I had to turn it down or I had check engine light along with bells or chimes when it shifted as we crossed the peak of the hill. Scary things for a moment.

UsualSuspect · 07-11-2014, 11:05 PM

Quote:

Originally Posted by gatorcq

Max RPM is 2650 for a CAT.
Did you check the coolant level ?
Temp is 226 for a CAT where it will give a warning before derating.

Coolant level is good, the engine temp was 201. The highest I have ever seen it was 205.

UsualSuspect · 07-11-2014, 11:07 PM

Quote:

Originally Posted by 1ciderdog

By chance do you have an MP-8 installed? I have one on mine and found I had to turn it down or I had check engine light along with bells or chimes when it shifted as we crossed the peak of the hill. Scary things for a moment.

No MP-8, bone stock. I am probably going to end up running it into a Cat Dealer and have them see if they can figure it out. Something is probably getting ready to go out, hopefully we can find it before it derates or dies.

lacdubonnet · 07-12-2014, 10:09 AM

i have a 2005 with a c7 with same problem .finally after one year found a shop that knew what they were doing.my problem wasthe turbo was over boosting which turned on my engine lite,the boost should not exceed 25 psi mine was only a few lbs over,replaced valve sensor on engine .10 minute job,make sure you air filter and fuel filters are good first,process of elimination before replacing expensive parts
good luck

UsualSuspect · 07-13-2014, 10:24 AM

Quote:

Originally Posted by lacdubonnet

i have a 2005 with a c7 with same problem .finally after one year found a shop that knew what they were doing.my problem wasthe turbo was over boosting which turned on my engine lite,the boost should not exceed 25 psi mine was only a few lbs over,replaced valve sensor on engine .10 minute job,make sure you air filter and fuel filters are good first,process of elimination before replacing expensive parts
good luck

Thanks. I may change it out and see what happens. I have to drive 70 miles to a competent shop.