Hey I am back, and still have same problem with truck. LOL A little refresher, the rpm drop like a rock between shifts with A/C on and no problem with it off.This is what I have done I swaped turbos with my sons truck and no change, that was a lot of work for nothing :smart Then I got a ECM from a 01 and no change. It also has new cam sensor, and new apps.My thought is VP 44 right? Whats left?

Still no codes? :confused:

Nope no codes. I was wondering if light worked or not but ecm that I barrowed had a code because he blew eng. over rev.I am reading a lot of reflash ecm lately, I wonder if that might work.

Man it a wild goose chase for you... I don't think the ECM is the problem though...

Wow! I can't believe no code. Is there a port to try w/ a hand scanner like on my 98.5?

Man I tell you Dave, I have tried eveything I can think of and everything Michael can think of and it is a real killer.I cant even get people to talk to me about it any more because everything they bring up has already been done. This one is for the books for sure.Hey Michael I have a vp 44 on the way, it should be here by monday I sure hope it works. Or I might have to take a road trip to see ya. LOL

APPS Accelerator Pedal Position Sensor????? It under the black plastic cover on the drivers side of the engine by the intake horn. You'll need some sort of scanner to check the voltage though.

Been there, 160.00 from Timbomb.

Is the motor de-fueling because of the larger injectors you're running???? It could be so you don't lose your tranny. You're getting so much more fuel from those sticks and the PCM senses it and de-fuels between shifts because the AC puts even more load on the motor. Thinking outside the box.

Have you considered a bad A/C compressor? Extreme drag may cause rapid rpm drop? :confused:

Man I tell you Dave, I have tried eveything I can think of and everything Michael can think of and it is a real killer.I cant even get people to talk to me about it any more because everything they bring up has already been done. This one is for the books for sure. Hey Michael I have a vp 44 on the way, it should be here by monday I sure hope it works. Or I might have to take a road trip to see ya. LOL

You might be sorry if you did that... You might actual stay here... LOL

Have you considered a bad A/C compressor? Extreme drag may cause rapid rpm drop? :confused:

Well you could check that by twisting the compressor pulley with the belt off and check the pulley bearing then twist the hub and check the compressor internals for grity or grinding feeling...

I will check on it next. I put new compressure on it about 2 years ago, I hope it not going out.Michael your right on that,the temp here in central Tx today is 106 and that is in the shade.So far we have had 45 straight days at above 100 and 60 days total.The rain fall so far is 1 1/2 inches in 3 months and 3/4 of that fell last week.Cattle ranchers around here see for the next 3 years as slim to nothing. One rancher sold all the cattle and trucks trailers and shut it down. Laid off 3 men that been with him for 15 years, people around the states will be see the efects for years to come. If you go out and buy 500 head tomorrow it will be 3 years before he will sell for profit.

Have you ever gotten to the bottom of your issue?

Wow you dug up a old thread, it would be nice to hear if he found the problem.

Hmmm... I got to get ahold of JL and find out what going on I've gotten a few email about posting issues???

Was going through some things I missed being a late joiner. Had a thought about what his problem could be so thought I'd ask if he had found what it was.

Just curious -- what's your thought on this issue?

Just curious -- what's your thought on this issue?

Just thought it could possibly be a weak alternator. So when the A/C clutch engages the amperage draw is overloading the alternator causing excessive drag on the belt slowing the RPM's.

I once had a vehicfle which just ate fan belts... I had the alternator rebuilt & it still did it... I got rid of it before I figured it out. I sure couldn't find any misalignment... but I wouldered if something on the belt might have excessive drag. (Could still have bad alturator bearings). Bad Waterpump bearings, PS, Serpentine belts use an idler.