So just installed a new Ford 351w crate motor in my 1996 bronco and afte dealing with initial problems Bronco is running. Problem is after Bronco warms up the motor begins to run like crap, loss of power, stumbling, etc but when Bronco is cold engine runs awesome. I am getting a code p1744 which is a stuck open TC solenoid pack in the trans but I do not think code would cause engine to run poorly. I am thinking this has something to do with maybe an o2 sensor, ect sensor, etc not sending correct signal to ecu for proper fuel mixture after switching from closed to open loop idle. Any help would be greatly appreciated.
Thanks.

-Rob

 

Do a shout out to fmc400 or greystreak92. They can probably steer you in the right direction

 

did you move over the crank posistion star that sits behind the main pully? double check that all 3 o2 sensors are hooked up. you may also have a vacum leak some place.

 

All vacuum lines/'emissions lines are being replaced but as of right now all working. Replaced egr, dpfe as well. Will check crank position star, o2 sensors asap.

Question what is the sensor located on the drivers side of timing cover, looks like a larger version of a temp sensor?

Question will p1744 cause bad engine idle?


Thanks.

-Rob

 

the sensor on driver side timing cover is the crank position sensor if i recall. can you post up a pic?

 

Here are several pictures of the sensor in question, located drivers side front timing cover.

 

that looks like the oil pressure sending unit.

 

Ok that is correct, Thanks.

So what else do you suggest I check to fix poor running issues after Bronco warms up?

Thanks.

 

Have you checked for codes? Since you have a 1996, I assume you put in a 96 351 in? If so, you probably know you have OBD II, so if you don't have a code reader, any auto parts store should be able to read codes.

That way if there are codes, you can better diagnose what's happening from there.

Anyways, if there are NO codes and you're getting the issues, the things that would come up off the top of my head are some thing that have been mentioned, like vacuum leaks or potentially there is a timing issue. I had stumbling/hesitation and backfires. The thing is, my truck ran bad hot or cold. I replaced my distributor and my issues went away. I didn't have any codes either.

 

I added a new dist with msd cap rotor, msd coil as well. Could issue be the engine coolant sensor or possibly all 3 o2 sensors?

 

It could possibly be the coolant temp sensor and the o2 sensors. It MAY be possible to check the o2 sensors with a multimeter I don't remember though. O2 sensors are pretty expensive so its best to test them if you can. I replaced all three of mine when I did my exhaust about two years ago, but I think they are about 100 a piece... I don't remember but hopefully they are cheaper.

I think the coolant temp sensor is pretty cheap so it may not be a bad idea to change it.

I believe O2 sensors usually throw codes also, but I have heard they don't always do it.

 

Any ideas what else could be problem?

 

Hmm well being it's a 96, you'll have mass air. Potentially your mass air flow sensor is dirty or malfunctioning. That can throw a code too, but I hear it doesn't always do that. I would try cleaning the mass air flow sensor with the correct cleaner, or testing it with a multimeter. I don't know the exact testing procedure, but I think there are a few writeups out there. Cleaning it is easy though, just make sure you don't touch the wires with anything, they are very delicate.

Besides that, have you changed the TFI module? I have read those can cause some issues based on temperature.

Yours should be mounted on the driver's side fender near the firewall. I've heard that they can function normally when cold, but once they heat up, you can get all kinds of messed up issues. They would normally throw a code too I think, but I've also heard with these they don't always throw them. Apparently, Autozone can tests these. However, if they test it when cold, it may pass, but when it gets warm, then the issues could arise. I would try to have it tested several times to get it warm or something and see if it passes then.

The TFI module is pretty expensive, so I would recommend looking at salvage yards for them. I think there are 3 different kinds, so make sure to get the same color you have. There is either a gray one or a black one. I'm not sure where the third one comes into play, but I've read there are three types.

 

TFI, no, what exactly does the TFI do?

 

The TFI I think stands for Think Film Ignition module. It is part of the ignition system. I don't know the exact wiring, but it has 6 pins that go to various parts of the ignition like the ICM and SPOUT connector. I think O'Reilly's considers it the ignition module. Most auto parts stores didn't know what I was talking about when I asked for the TFI.

If the TFI is wearing out, it will cause ignition problems. Because yours is most likely mounted on the fender, it's not as common for it to go bad, but I have read several accounts of them still failing/malfunctioning. If you have one mounted to your distributor, then I would definitely check it, but based on your symptoms, I'd still check it if it is mounted on your fender. It should be bolted on by some hexhead bolts to a little heatsink. It might be normal bolts, but I think they are hex ones.