2005 Jeep Wrangler (inline 6cyl) with a RIPP Supercharger kit. (automatic transmission)
There is a intermitent stumble starting at around 3800 to 4000 rpm. When it happens it feels like a rev limiter and it wont go away until you let off the throttle. I thought it only would happen under WOT conditions but I was able to make it happen at part throttle by holding the transmission in 1st and 2nd gear. This problem doesnt always happen. I finished up all the tuning on the dyno and out of the 10 pulls I made it didnt do it even once. The only common theme when it happens is at what rpm it happens at. There isnt very much you can log on these vehicles but with the items I can log the only thing that seems to bounce around are the oxygen sensor readings. Im assuming that it might be cutting the injectors but I'm not sure. The boost/vacuum gauge in the vehicle will bounce up and down at that point as well.
I have already replaced the spark plugs and gapped them at .032, I replaced the coil pack and I replaced the bypass valve because the diaphram was defective.
I recently raised both rev limiters and shut off the DFCO thinking that could cause this. It was good for a day and then first thing this morning when I drove it, the problem was still there.
I was able to log the injector pulse with my Snapon and the injector pulse is shut down and back on and etc when the problem is occuring which matches what I saw on the o2 sensors. I cant log torque source. It will do this wether I'm at part throttle or wot just not everytime.
I was not able to log torque source but I was able to log torque desired with dataviewer and that would bounce from around 350 to 0 along with the injectors going from roughly 16ms to 0ms during the surging problem.
I have found that when the torque desired gets to roughly 350+ at 3800-4000 rpm it will cut the injectors. I'm thinking that maybe something is missing that requires adjustment. I raised the air flow tables to see if that had any effect. Right now with the raised air flow numbers Im not getting the problem but it is also only hitting about 325 to 335 on the desired torque. Im not sure if the air flow tables effect this or anything for that mater. This is a cable operated throttle body.
Drove it again today and its doing it again. As soon as I get to that torque desired at that RPM. I'm guessing there is like you said some kind of torque management issue. There must be something in the background I dont have access to.
Is is possible to have something like the FSO enable torque used on the Grand Cherokee's that could be added to this? (Torque management>General>FSO enable torque) Is there some other fuel shut off related to torque that the early wranglers use that could be added so I can disable it, or are there some toque limiters on the transmission side that could be added?
If your other scanner can get the info, HPT should be able to. Open a support request looking for these things... they may be able to add them to the scanner for ya.
Well, we replaced the camshaft and the cam sensor/oil pump drive because the gear on both was just about gone. While the head was off we had that rebuilt. We also noticed that two of the primary cats were partially plugged up so we replaced those too. We also installed a new fuel pump. After all this the car drove great for a week and then the problem came back. I pretty much gave up after this.
Then the customer asked me to replace the TPS because he had heard someone else with a similar problem be from a bad TPS. I had tested this item a number of times and never saw the signal drop out. I changed it anyway. Its been a couple of months now and no problems. So I guess it was a bad TPS. I'm not really sure but I'm glad its gone.
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