302 rebuild problem - Ford Forums

clhay · 03-30-2004, 06:17

Either I've misunderstood something or my rebuilder is missing something here.

Just had the 302 in my 87' Bronco rebuilt with a new set of GT40p heads, Comp cam(31-255-5), Ford Motorsport 1 5/8 headers(fiberwrapped), Ford 9mm wires, Autolite plugs(764), disconnected the smog pump (though still in the bracket) and a K&N airfilter. I haven't change the cap and rotor cause they have been in the trucck for less than 2500 miles. But maybe I should!

When cranked, the engine starts but stalls out. This happens 3-4 times before it finally "catches" and idles. Idle surges a bit then levels off.

TRUCK DOESN'T SEEM TO HAVE ANY MORE POWER THAN BEFORE THE REBUILD!!!!!

My mechanic seems to think the erratic idling is related to the "missing" emissions stuff. Any thoughts????????? I am wondering if the EGR is affecting the power deficit.

The mechanic is "tweeking" the timing some (he originally set it to 10 degrees) but it isn't running any better with this degree adjustment.

Am I (and my mechanic) missing something major here?? I am also wondering about the IAC.

Just thought about this...................better pull codes.

What should I do with the lines for the emissions stiff since the GT40P does not accept the lines(no inlets)?? Plug, pinch, or can they be removed???

Sorry that this is so long but I am truly frustrated.

'92BigBronco · 03-30-2004, 09:43

First off, give the engine time to break in a bit. Bearings don't wear in but rings do need to seat and the engine will be a bit "tight" for the first 100 miles or so. Take it easy on it for awhile and it will surprise you.

Second, this is obviously an EFI application right? The changes you've made will require a custom chip to operate properly because it's a speed density system. Because it is a speed density system, the computer cannot compensate for the changes without a little help. Do a net search for a custom chip and you'll find what you need to get her running right. All it requires is a few hundred bucks and a list of all the modifications done to the engine.....they'll take care of the rest. Most places will update the chip at no charge if you decide to make any more changes such as a blower, different cam, etc. down the road.

For now, don't drive it. Most likely you're running lean and you'll end up with a hole in a piston if you're not careful. Detonation due to a lean condition is not what you want in your new engine.

Brian

clhay · 03-30-2004, 10:46

Brian,

thanks for the reply. I was under the impression from several other Bronco owners that have done this swap that this modification has been and can be done without chips or mass air conversion. In fact, if you take a look at www.fullsizebronco.com, at least 3 guys have done this same change. Their truck ranges from 84-88. My mechanic is out today and hasn't had time to "tinker" around with my 87 efi Bronco.

Another note, many of the other replies I have gotten range from 1) Vacuum line issues to fuel pressure to possibly a clogged cat.

I would appreciate any further suggestions you might have. In addition, if it comes down to having to get a chip, can you give me a number for reputable chip outfit?

'92BigBronco · 03-30-2004, 15:50

I believe '86 was the first year of Ford's EFI 302's which are all equipped with the speed density. I'm not sure how "mild" your cam is when compared to stock, but changing to an intake, head, and cam combination that is just slightly more wild that stock will require you to either convert to mass air or get a custom chip burned. The computer simply can't adjust for the extra air entering the engine.

Depending on your cam, you may also need to swap out your injectors in favor of the larger 20# Ford Motorsports injectors to supply the amount of fuel you'll need.