Ok, guys, this is my first post. I have been using the forum for a couple of months and it has really helped me solve some apparently common bronco problems. (Rear window problems, clunking driveshaft, shuttering torque converter, etc.) But anyway, here's my question. I purchased my '95 Bronco with 120k back in December, and have been trying to get all of the "bugs" out of it. It has a 351w. If I hit the gas with the truck in park it hesitates for a second before reving. It sounds fine if I very gently touch the gas, but anymore than that and the engine falls on it's face before waking up. I don't seem to notice it when I am driving, but I know something is not right. I have already changed the plugs, which appeared to be original Mcraft, and the fuel filter. I have checked the vacuum lines and can find no leaks. It seems to me that I have a lean condition, like it's "starving" for fuel, but I am not sure. Also thought timimg could be off, although I don't see how that could have happened, as the enginge appears to be completely untouched. I will be changing the wires, rotor and cap next week (all believed to be original), and hope this will remedy the problem, but not sure. Also going to check the timing after changing parts. What do you guys think??? Any help would be greatly appreciated.

 

it could be the fuel pump. also check the dpfe valve i had simular problem and it was that..another thing it may be is the egr valve.theres some very knowlegdable people on here and im sure they can help more then i.also check to see if it is putting out any codes.
good luck.

 

Definately pull codes. It will save you a LOT of time chasing things that MIGHT Be the problem. Performing the KOEO (Key On Engine Off) test requires a paperclip, a warm engine and about five mintes of your time. From there the computer will flash out the codes and you can either post them here and we can talk you through it or you can check www.fordfuelinjection.com for some additional answers.

The description sounds like it could be something as simple as a dirty IAC which can be cleaned with throttle body cleaner. But even that is a guess...a slightly educated guess but still a guess.

 

Check the timming and remove and clean out your throttle body. You will be amazed.

 

That's probably the problem right there. Also check the timing (as you said) and clean the throttle body as already suggested. Be sure to use a cleaner made for throttle bodies and not just carburetors, otherwise it will ruin the seals. Depending on how well the truck was maintained, you can either just spray it clean as I did with mine (it was remarkably clean at 100K) or if your truck was not well maintained (as it sounds) then you should disassemble the throttle body and clean it out. Also remove and clean out the IAC, it's very easy and can make a big difference. Finally, fill the tank and run some good fuel injector cleaner in the gas, make sure you get enough for the big tank.

 

Also, it's a good idea to run some Seafoam in the oil for about 500 miles before changing the oil. It will help clean the carbon off of the valves etc. This will help with detonation issues and allow you to advance the timing a bit, gaining a little more performance. You can run the Seafoam in through a vacuum line with the engine running (for very dirty engines) but I've heard a couple of bad stories about that and I think that running it in the oil should suffice. Just make sure to drive the truck with the Seafoam in the oil for at least 500 miles to let it do its work before changing the oil. You can also put it in the gas, as well as run it in the oil all the time to help keep things clean.

I would not recommend an engine flush (like Gunk) because it sounds like your motor may not have been maintained as well as it should and you might cause problems with dislodging sludge and clogging oil passages. My motor has 137K well maintained miles and I'm not sure if I even want to use the flush - I bought the can but so far have not used it.

 

Ok, guys, this is what I did today. I changed wires, cap and rotor. I removed and cleaned out the throttle body and IAC. I also flushed the coolant and and changed both diff's fluid (w/ friction mod for limited slip). After doing all that, the problem still exists. I drove the truck around, and noticed the check engine light had come on. I went back home and checked all the lines/connections to the throttle body, thinking I left something undone, but all looked fine. I pulled the codes, and this is what I got. 10, 111, 332, 542 ---I don't think 10 or 111 mean anything, but my book said 332 is egr restricted flow, and 542 was the fuel pump secondary circuit... I don't see how anything I did could have caused these codes, but the MIL never came on before. What do you guys think??? And by the way, thanks for all the replys.

 

One more thing, if I shut the engine off, then restart it, the light goes away and does not come back if idling (left it running for 30 minutes while I was flushing the coolant). Only comes back if I drive around for a few minutes. I think I will clear the codes tomorrow and drive it until the light comes back. Then I will know for sure which code is causing the MIL... I'm too frustrated to mess with it anymore today...

 

The 10 is the separator code and means nothing. The Code 111 is the "system pass" code which indicates no instant fault codes. Code 332 indicates a clogged or malfunctioning EGR valve. It can be removed and carefully cleaned. They tend to clog up with soot over time. The EGR is mounted to the Passenger side of the upper intake plenum immediately behind the throttle body. This is most likely the root of your hesitation problem. Code 542 indicatesa bad ground to the fuel pump motor through the EEC computer. Make certain you have a strong ground at Ground E which is at the left frotn of the engine bay on the upper radiator crossmember.