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Posted

Hey everybody, Thursday night I was driving from Phoenix (AZ) to San Bernardino (CA) in the pre-storm wind we had down here. Out on the desert, just west of Quartzite (if any of you know where that is) I was driving at 70mph in a 40mph direct headwind (that's 110mph airspeed) and was driving on a slight incline with the truck in cruise when the trans kicked down out of OD and after about 5 seconds the SES light came on. I haven't had a chance to check the codes yet but I just wanted to throw the situation out to get some thoughts. It's a '03 ECSB with the 4.8L. I also have a Hypertech 87octane tune on it. I'm thinking the motor was just working a little too hard and the timing was too advanced. Or, I had just fueled so it could be the fuel cap thing it talks about in the owner's manual. I'll try to get the codes this weekend to see if there are any there. Thanks for reading.

Posted

DO you have tranny Temp Guage installed ?

The series of events sounds like your tranny fluid overheated, Downshifted to reduce temp. and set off a cde to warn you.

 

Just one of the things that could have happened, scanning for thecodes will really tell you.

Posted

I don't have a temp gauge but I have a 26,000lb gvw B&M supercooler. I plan to check for codes tomorrow. Maybe there'll be a clue there. I did check the tranny fluid and it was full, pink, and smelled normal. Thanks for the reply. I'm anxious to get the codes to know for sure.

Posted

Wouldn't you get a message center indication of a trans overheat rather than a ses light?

 

Please keep us updated on this one. I often have some wierdness on this particular drive relating to the lower altitude. Usually engine knock on some cars, I try to burn premium for trips to lower altitude.

 

Thanks.

 

Ken

Posted

My Hypertech can read codes. I'll try to get it done today if I have a few minutes. I spent the whole morning re-doing the front brakes. The d**n Autozone pads I put on were too tight (casting flaw) and weren't backing off of the rotor. Darn-near ruined my rotors. I had them turned and put on a set of Raybestos QS Ceramics. Cleaned and lubed everything. 100% improvement. That may have contributed to the added strain on the motor in the above situation. I could barely turn the rotors by hand. Now they're free like they should be. I'll try to get that code today. Thanks for the info guys.

Posted

Ok, I finally got around to it. I checked the codes with the Hypertech and it gave me P0101--Mass air flow sensor circuit, range or performance problem. Any clues? Was I just pushing the truck too hard (lugging) through the wind? I cleared the code so I'll see if it returns. Although the the SES light hasn't come on since the one time in the first post so I think it may just be a fluke or something.

Posted
Hypergalactic vortex.

 

Ken

 

 

 

 

Yeah, that's gotta be it. :chevy: Actually, I think the 'ram effect' of the 45+70mph wind going into the high-flow filter at WOT probably leaned the mix out too much and caused the MAF sensor fault. The outside air temp was pretty cold too (40's) so the air was real dense. The injectors probably weren't pumping enough fuel for the conditions. I'm sure the advanced timing of the hypertech tune didn't help any either.

  • 1 month later...
Posted

Ok guys, here's where I'm at. I was pulling my trailer (6x12 tandem enclosed) around town today in the 100 degree heat. I got the same SES light, the same code (P0101), at the same RPM (around 3500) as the above situation. Now, since I have seen absolutely NO performance inprovement from my K&N FIPK or from the Hypertech tune I'm gonna remove them both, get a new MAF sensor and just go stock from here on.

Also, the truck is detonating like a M.F. in the 100 degree heat and idles like crap too when in Drive. I've never had to run anything but 87 octane before. Even the 89 doesn't help this. It has no power and pings/knocks like a SOB. I really hope this helps (going back to stock). If any of you have any suggestions on where to go from here I'm open. I'm thinking I will also take the truck in to have the computer updated and checked.

Posted

Get you MAF sensor replaced before you do anything else. If this is malfunctioning the engine control system has no way of knowing how much air the engine is getting to create a proper mixture. I would be careful to protect your cat converters--the O2 sensors should be able to protect them but this is like driving forward by looking in the rear view mirrors.

Posted

Ok, here's what I did. Removed the Hypertech Program. Disconnected the battery to clear any computer memory. Removed the K&N and replaced with stock airbox/intake. Cleaned MAF sensor.

Still idles really low and almost cuts out especially with the A/C on and in gear. I bought a new MAF sensor but haven't installed it yet. I really think the old one is shot so I'll put it in tomorrow. Hopefully this will solve the problem.

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