Speedo and Limp Mode ???
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Speedo and Limp Mode ???
So my last three trips towing my fifth wheel I've gotten the wrench light. I suspect it's an over boost. I monitor the boost with a scan-gauge and the last two times I got the light at around 29 psi. Pull over, shut down engine and all is good. I brought it to a local diesel mechanic who couldn't replicate the problem and found no codes. He asked me to hook up the trailer so he could test. He's an old school guy and to get the engine to temp he hammers down on the brake while in gear and revs the engine for about 30 seconds. During this process the engine goes into limp mode, no wrench light, and speedo doesn't work. He thinks that may be part of my problem. I'm not so sure as this has never happened under normal driving conditions. I suspect the engine revving at whatever Rpm's with out the vehicle moving and in gear trips something in the computer and triggers the limp mode and is completely unrelated to my turbo issue. And he can replicate the speedo issue without any problems. Thoughts?
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Joined: Mar 2006
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From: IL
I don't know much about diesels but here's a thread I was reading about overboost, maybe it will help a little.
Overboost/check engine light question? - Ford Powerstroke Diesel Forum
Overboost/check engine light question? - Ford Powerstroke Diesel Forum
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Joined: Mar 2007
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Thanks. My biggest question is how he is triggering the speedo to stop working by hammering the brake while in gear and revving the motor.
I don't know much about diesels but here's a thread I was reading about overboost, maybe it will help a little.
Overboost/check engine light question? - Ford Powerstroke Diesel Forum
Overboost/check engine light question? - Ford Powerstroke Diesel Forum
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