Limp Mode? - No CEL (1 Viewer)

Oct 26, 2013
Madison, AL
This past weekend I experienced what I believe was a 'limp mode' instance, but not sure this can occur without CEL.

After driving approximately 90 miles in 95-100 degree temperatures at interstate speeds (75-80 MPH) with AC running front/rear, my truck lost power suddenly on the interstate. At the time, I was in heavy city traffic and only moving approximately 45-50 MPH. The first thing that I noticed during the short event was that the air began to blow non-cooled air and the truck was not responsive to throttle. I was able to pull over after about 5 seconds to the inside emergency lane of a 5 lane interstate after I made it across a bridge where there was no emergency lanes. During this brief episode and loss of speed, I quickly turned on flashers and tried down shifting in case it was some kind of transmission issue. Once I pulled off of the road and was in a safe position, the car was idling very rough and wanted to die. I believe that I turned off the ignition without it dying, but it may have actually stopped prior. This all happened quickly and my main concern was getting off of the road safely with my family in tow. Throughout this whole scenario, there were no gauge cluster lights lit (CEL, VSC, etc.) and all gauges were normal (temp, oil pressure). I was in a pretty safe place to exit my vehicle, so I checked under the hood and under vehicle for any visible issues. Belts, fluids, etc., but these were all OK. I called my Dad as we were on the way to my niece's 16th Birthday Party and he began to prepare to come and meet me. While on the phone, I decided to try and restart the vehicle. The truck started and maybe seemed to run a little rough for a second, but when I put it in gear it seemed to be running ok. At this point, I didn't know if I had a locked up compressor or some other issue, but I wanted to get off of the inside of the interstate if possible. I didn't turn back on my AC for fear that was an issue, but I began to accelerate in the emergency lane and made my way back on the interstate. I initially intended to get off of the interstate and traverse city streets/side streets to my destination, but I was not in the best area of town and based on traffic, I stayed on the interstate past the first exit. Each exit, I evaluated the current state and made a decision to keep going (I was about 10 miles from my destination). I made it all the way and the truck ran ok. After arriving, I restarted and tried running the compressor. The compressor ran fine. My Dad had borrowed my Scan Gauge, so once I arrived, I was able to check for any codes, but there were no active nor pending codes. I continued to drive the vehicle over the weekend on several shorter trips and then made the return trip with no issues. This is my daily driver and it continues to run normally.

Background: 2006 LC (UZJ100) with 147k. No current CEL codes pending. Only one CEL instance since 113k that I am aware of was a PO420 about six months ago which cleared on its own and has not returned.

Upcoming scheduled maintenance: air filter, clean MAF and throttle body

At this point, I have replaced my air filter which was due and plan to clean MAF and throttle body as this has been on my to do list in the next few days.

I plan to check the coils for any visual indication of heat, but I have not done this, yet.

I have also considered replacing fuel filter and possibly fuel pump as preventative maintenance. The fact that there were no codes has me suspecting a fuel delivery issue, but I am not sure why the compressor would have dropped out.

Any hints for things to check or consider is appreciated.



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