Guys I am having an issue when pulling up to a stop. I am getting rpm bounce as the truck seems to come back down through the gears. sometimes it goes low and right back to normal and other times it will bounce high. I am not sure if it is a mechanical or tune issue and was wondering if this is a normal type of feeling with this truck and procharged. I bought the truck used about a year and a half ago and I had to rebuild the tranny when I got it. I have not really noticed aNY other issues with the truck but I am stumped on this one. I have cleaned the egr ports and the regulator and replaceD the iac. have checked over the vacuum tube but have not done a smoke check though. any thoughts? also anyone know of f150 tuners in sacramento area. this truck was originally tuned by troyer but we all know that story. wish he was still in business.
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What changed between the time it was not doing it and now?

 

Unfortunately the transmission was busted when I purchased it so it has been doing it since I got it and rebuilt the tranny. when I rebuilt it I also replaced the torque converter from another truck and I am not sure if the guy I bought the truck from had troyer also replace the torque converter or had different mods on the tranny. he had troyer install the supercharger and a few other mods and tuned it. probably unecessary info..

 

Anyone have some thoughts?

any tuners out there to give me some help on this?

thanks

 

try changing the iac valve


since you can't or won't check for codes

 

Thanks for reply. no codes or CEL, which can be a bit more challenging. I removed the throttle body and EGR valve and cleaned them all and also removed and replaced IAC. I did try some data logging using my SCT and cannot pinpoint yet where to focus my efforts.

I will try again today trying to pull some data to see if something stands out.

 

who did the tune?


what "fuel mods"?

 

Tune was done by troyer onsite. fuel mods have the Siemens 42 lb injectors - but that is as much as I know. I would imagine if every thing was done by troyer he would have dropped a higher flow pump.but don't know for sure. It runs well except for this issue. I tried pulling more data but thus far nothing stands out. I want to get it tuned again to add something for towing but don't know who to trust in the area and I don't want to spend the money if this issue is mechanical in nature and not a tune issue.

I have been thinking it's the tc because I think the replacement is probably from a 4.6..

 

Look for a small vacuum leak. A large leak will stall out the engine but a small one will make the RPMs move around.