302Monster

Hello, all! I can't seem to find out why my f150 stalls when coming to a stop. The motor has been rebuilt, trans rebuilt and many component t's know to cause stalling have been replaced. I have replace the TPS, VSS, MLPS, IAC, PCM, EGR valve fuel filter and cleaned TB and MAF sensor. Vacuum lines and hoses all look good. All fluids good.


The truck idles great with no shutter.


The truck will shutter when breaking to a stop. It does it randomly. I can sense it about to cut off so I can through the truck into nuetral, come to a comet stop and it won't die -if I put back into drive it will shut right off... I can immediately start truck in park put back in drive and roll on. If I come to a stop, put the truck in park and then back in drive it usually won't stall.


I was told my torque covered was replaced with trans rebuild... but I can't be sure.


Know body seems to have an answer.

Codes only showed VSS which was replaced to no avail. No codes are currently present.


Any help would be greatly appreciated.

*302 4x4 E4OD IHE no cats

Thanks for your time,

John

302Monster

Can trans pressure or fuel pressure cause this behavior??

***I can also put trans into 2nd when coming to a stop to keep from stalling (if I catch it right) and the shift back into drive once I build rpms!?!

fltdriver

Fuel pressure can, never heard of trans doing that though. As for the VSS, since you still have a code for it, ensure that it's working properly. I'm not sure which one you are referring to (one in trans or one on the axle) but if it's the vehicle speed that's on the axle try cleaning the sensor and where it goes into, never experienced that issue but have heard that metal fragments can cause it not to read correctly.

302Monster

My apologies... I am not recieving VSS code anymore... I check rear different fluid and had no metal fragments.

Thanks for your response!!!

fltdriver

Not in the fluid, under the sensor, it interferes with it's ability to locate the speed ring, or something like that.

fltdriver

Also. does your TPS show .9-.97v closed, 5v WOT, smooth increase as opening it up?


The only thing I can think of is when you are on the brake the engine is still trying to turn the transmission, like the flywheel/torque converter isn't clutching correctly. Sorry, I'm not a transmission guy what so ever so my wording may be off but hopefully you get what I'm trying to say.

302Monster

I am not sure about TPS -but I will get that answer Will also check for fragments on VSS... I feel as though your correct about the torque converter not "clutching"/locking up correctly. I reckon I can look at some write-ups to test the converter... I was really hoping I was overlooking something else and praying it wasn't the converter.

Thanks again,
John

Serious

There is most likely a leak in your power brake booster. The internal vacuum seal most likely is damaged/has a hole in it, causing the truck to run rough and stall when the brake is applied at idle at a stop light. Same thing happened to one of my vehicles. Quickest way to check, at idle, press the brake pedal and watch for a definite increase/decrease of RPM, usually of +/- 50 RPM, maybe 100. If it's over that, the brake booster usually needs to be replaced, but just make sure the booster vacuum lines are good first.