1988 bronco 2 auto trans 2.9 engine 4x4
when driving and I come to a stop, and when you start off it wants to hesitate hold back. you can keep the foot pedal in the same position and it will clear up in about 3 sec, or you can floor it and it will go with no hesitation. I have replaced the distributor cap, rotor, plug wire, eec relay, tfi module, fuel pump and screen in the gas tank, fuel filter, idel air control valve, oxygen sensor, pcv valve, exhaust system, and also had the trans rebuilt. I had a tune up done before this all started to happen. I took it to a repair shop they put it on the computer and all the sensors are working but the tech can't find the problem. so I checked all the sensor conections to make sure everything was tight, I stared to unplug some conections to see if the engine would run, when I unpluged the intake air temp sensor and drove down the road it drives fine no hesitation it's been about two weeks with the sensor off and it drives fine. I checked the sensor with the ohm meter and it is working fine but when you plug it back in the engine hesitate. what can be the problem I NEED HELP could the sensor be bad?

 

I would check the TPS sensor for erratic operation. Chances are it may be in that circuit.

 

Thanks I will try it. but I unpluged the tfi sensor and drove around and it did the samething (hesitation) and everytime I took my foot off the pedal the engine died.

 

TFI=Thick film integrated, that is the ignition module, not the TPS.

Disconnecting it is not the right way to test it. You have to use a scantool or a DVOM to test sensors.


You could also have a problem with the MAF sensor or MAP sensor if so equipped.

 

what is a break-out box? chilton auto library says to install this between the pcm connector and the wiring harness.

 

I think they are referring to a scanner or code reader.

Follow my "The Basics" to www.batauto.com

The code retrieval procedure is there courtesy of Knuckles and
0patience.

 

I've run into a strange on 1 time in the many years of turning wrenches, on the same type ford. It turned out to be the distributor itself. Seems high milage causes the shaft to become magnitized, and send false reading/impulses to the module..It'll act almost like the timing is off, and the engine has to "catch up" to itself. Once your up about 15-20 miles per hour, everything smooths out.. In this case (the truck I was working on, not yours.) the repair was a new distributor..This truck I was working on set no codes..How about yours? Any codes?

As for a break out box, it's a box and cable assembly that is connected between the car/truck's ECM and connector. There are 60 holes in the box, in which you would then place multi-meter leads to make checks. If, for example, the repair manual says check resistance between pin 6 and pin 25 you'd place your meter leads in holes 6 and 25, measure the resistance. This allows for live readings on all ECM circuits.. Neat little box; expensive to buy, and most times a pain to hook up...