CEL light coming on Why??

[ajd257]

Howdy, my brother has an early 99 PSD with a 70 HP chip in it (sorry not sure who makes it) but anyway, if he hogs on the truck pretty hard (EX: towing up a steep incline) for any period of time the CEL comes on, after you let back out of it, the light goes off. Whats causing this? Oh, its an auto if that makes any difference. Thanks alot, Andrew

 

[BJS]

first guess is going to be that you are loosing high pressure oil, you're demanding too much oil for the HPO pump to keep up with but that is typically only seen on trucks w/ modified injectors.

To be certian you're going to need to have it hooked up and scanned if the CEL came on then there will be a code stored in the computer.

 

[jvencius]

first guess is going to be that you are loosing high pressure oil, you're demanding too much oil for the HPO pump to keep up with but that is typically only seen on trucks w/ modified injectors.

To be certian you're going to need to have it hooked up and scanned if the CEL came on then there will be a code stored in the computer.

Either that or he's overboosting (like getting on it hard whilst towing up an incline) and that's setting the CEL.

 

[Mike]

If he has stock injectors he probably isnt running out of HPO unless he has a really bad pump, I would lay my bets of an overboost.

 

[budtoh3zo]

My grandmas does it to even empty it will come on if u hog on her.

 

[BJS]

Do you have guages on the truck? I'm guessing not

I've pulled up to 25psi w/ stock injectors and havent' thrown a code but that took an oveloaded trailer & an unlocked t/c /w a heavy foot I was having to watch EGT's & tranny temp more than boost.

 

[Duke]

I just started getting an ses light the last few times I've driven my 450 and I had mine completely cured for 2-3 years.

I think my MAP sensor zenier diode has a bad connection.

Usually it's from overboost and the MAP sensor tells the PCM to defuel the truck and turn the ses light "on". You need a zenier diode to trick the MAP sensor and keep it from defueling and turning the SES light "on".

 

[lukecline]

wouldnt a boost regulator im map line work to in that situation?


Luke

 

[Duke]

Yes and I even bought one. Mine would still set the light no matter what I set it on. Really frustrating.

 

[budtoh3zo]

is that light also for polution? thats what i thougt i read somewere.

 

[Mike]

The CEL or SES (depending on what year your truck is) will come on for a number of reasons. You need a code reader to find out what it is causing the problem.