I have had a problem the last two times I have done a track event (at two different tracks). My truck is loosing power in third gear on the long straits. It DOES NOT miss at all! It just feels like all of a sudden I'm dragging a heavy weight. If I let off the gas from WOT to half throttle it will pick up and run perfect. Then I can slowly ease back to WOT and it will run fine. If I floor it again it will lose power again. At Motorsport Ranch in Feb was the first time it happened. I went to the auto parts and bought a new fuel filter as I was sure it was a fuel starvation problem. After installing the new filter nothing changed. Fast forward to last month at TWS at the SVTOA on track event. Same problem. Coming out of the last turn before the long strait, as I climb the banking the truck falls on it's face......let off the gas and it picks up then roll the throttle back on and I'm up to 140 MPH by the end of the strait. Since I had another track event the next weekend at the same track I installed a new set of NGK BR7's. The old one's had 30,000 miles on them and still looked great. Since I did not have a miss I knew this was a stretch but I did not have much time. Back at the track, nothing had changed. The truck will not pull hard down the front strait if I floor it! I did notice that it runs perfect the first two or three laps before this problem starts. Also near the end of a twenty minute session the truck does the same thing on a short strait before turn seven but not every lap. On the front strait this is happening at around 70-80 mph and on the other strait it is around 90 mph. This problem is always when the truck is in third gear. Never in first or second at any RPM. I can't reproduce this on the street. As much as I try it runs perfect. Back in 99 with my first L I had a problem that everyone else that had a PSP chip had......at around 100 mph at the track the truck would fall on it's face. Sal found that timing was being pulled for some reason and fix it with a re-burn. I have a four way chip. I usually run on my towing setting (405 hp/505 tq) at the track. Since I was having trouble I tried two other positions on the chip but it made no difference. By the way....it makes no difference how much fuel is in the tank. I never run with less than 1/2 tank. My high flow cats are completely blown out and I am getting a code about it but I would not think that would be the culprit. I can't think of anything else. Any ideas? Mods below.

long tubes
ported blower
four lb. lower (makes 15 lbs. of boost)
e-fan
PSP four position chip


Jerry

 

Do you have the OD on when you race?

 

No I do not have the OD on. I do turn it on toward the end of a long strait to keep from blowing the truck up but the problem is never when I'm in OD.


Jerry

 

I'm going to the track for the first time in my L, hopefully this SAT. Do I want the OD on or off??

I've never raced an automatic.

Thanks.

 

You want to run with the OD OFF! You will need to turn it on if you run out of RPMs on the straits. I even pull my truck down into second on the really tight sections of the track. Since this is your first time I would just put it in drive with the OD off and watch your RPM's in the fast sections so you don't hurt your truck.

Jerry

 

This might be out there; but have you checked your transmission fluid? The only reason I say this is because of the "dragging" comment. Also since the first few laps don't give you problems, it could be temp or speed related. Maybe you've got a tranny fluid starvation problem. However, the it takes the long straight for the "air" to hit the TC causing the loss of power feeling. I'm just brainstorming here.

-Edward

 

Your best bet may be to data log it. One possibilty is that the EEC doesnt like something (heat, load etc) and is pulling timing. The fact that it only does this when you drive it hard leads me to believe this. Our EEc's have all sorts of fail safes built in to control the engine and transmission when it sees anything it feels may be harmful. I bet Sal will have the best answer to this.

 

Well it's hard to remote diag something like this. You state that it's ok for the first few laps, then it happens. That may be an indicator of the trans fluid getting too hot. That will make the PCM take steps to cool the fluid, such as cutting power, or making the lockup come on differently. It's hard to say for sure, but my guess is that it's related to trans temp.

 

Thanks for all the help. It could be the trans. I have the F/T trans cooler and it was 25 to 35 degrees in Feb. when this first happened but I guess it's possible. I have a temp gauge on the trans and it runs around 220 degrees during a session. I will make sure I'm not running low on fluid. Maybe I will have to add another cooler...or change the one I have out for a larger one.


Jerry

 

I noticed that I was low about 1qt. after running 6 sessions at TWS. I checked the tranny fluid because the shifting felt a little funny like the TC wasn't locking up as it normally had. There was actually a light smoke(like 1/3 the smoke of a lit cigarette in an ashtray) coming from the dipstick tube for a couple of seconds. I ran over to Wal-Mart and topped it off.

 

Jerry ... Mine does the EXACT same thing !!!

It just runs outta b a l l s about halfway down the stretch !!!

Weird ...

 

How much fuel are you carrying? I had starvation problems on my truck when running race rubber.

 

Edward,

I just checked and mine is full of fluid. What I have happening does not feel like anything the T/C could do. It feels exactly like when my 99 was pulling timing. But I really don't know for sure. If I had a preditor (or something else) hooked up during a run would someone like Sal be able to tell what is going on? I really want to get this fixed.


Cliff, I'm glad to know I'm not the only one with this problem. Misery loves company. It sucks to have a guy point you around because you are eating his lunch in the tight stuff in a pick-up truck only to have to point him back by in the straits.


Jerry

 

Nathan,

I never run below 1/2 a tank. How much fuel (full or 1/2 tank) makes no difference.

Jerry

 

It could also pull timing because of intake air temp or even coolant temp but my guess would be intake temp. The program is scaled to pull timing as the air temp goes up.