off topic a bit 87 full size bronco

[ddb]

got a 1987 full size bronco 5.0. i burnt up the motor in the mud. found a 92 H.O. t-bird motor in the bone yard. drove it, ran great. swapped out the all the 92 H.O. parts with the stock 87 parts (lower intake,plenum, dist.) so on. harness plugged right in. also swapped out the flywheel (teeth) and the harmonic balancer (c-6 3 speed tranny) fired up, backfire, spit, miss. pulled the intake back off ,checked all vacuum lines, wires, ect. sealed back up, checked timing,compression. fired back up, same thing . when i drop it into drive it also dies, unless i feather the gas. if it gets going it runs like crap. backfire, miss, no power ect. so this is messing with me big time. the only thing bad on the 87 motor was a broke ring. i have rebuilt many a motor, and this is turning out to be a bigger pain than rebuilding the broke ass 87 motor. nothing else has changed besides the short block. WTF AM I MISSING !!!!!!! i know it's gonna be simple. BTY changed the fuel press. reg. filter and dbl. checked the pumps and lines,all fine. any thoughts,
thanks

 

[Convict1997]

I know you stated you checked the timing again, but how did you do it? Was the motor running long enough to get a timing light on it or are you talking about bringing #1 to TDC and stabbing the distributor? I had the same problem when I swapped the 5.0 on my mustang. Turns out I was at TDC on the exhaust stroke rather than the compression stroke. I'd start by pulling the distributor and turning the motor over and bring the #1 piston back up to TDC on the next stroke. Stab the distributor there and see what happens.

 

[gijoecam]

I wouldn't think it would run at all if you were 360 degrees off on the timing... Every cylinder would be on its exhaust stroke, and it'd be backfiring out the exhaust like a muther!!

DDB, I'm stumped (not that that's tough to do!!). It's EFI, not a carb, correct? Hmmm.... When it backfired on first-start, did it backfire out the intake or out the exhaust? Were you able to get a timing light on it with it running?
Assuming the timing is on, and it's backfiring out the exhaust, it sounds like it's probably not firing on all cylinders.

Here's another thing to ponder: Is it possible that the HO motor from the T-bird has a *slightly* different firing order? i.e. maybe it's got a different crankshaft than the trucks had? I've seen wierder things...

 

[ddb]

did it about 10 times LOL . even tried it 180 off. used a light, pulled the spout, set the timing, plugged the spout back in. then watched it advance with with the rpm's. but this is wierd you could barely notice any change in the performance with the timing 180 off. ran about the same either way. like crap..after TDC both #1 valves closed at 0*. keep thinking PLZ. i found another 5.0 (ho mustang)with harness and computer. but i know this motor good. i ran it for a good hour in the yard before i torched it out. i truely belive it will do the same thing with any short block. if it were a harley then i would expect it to break down just sitting there. it's gotta be simple. i just must be overlooking or missed it. what else ??
thanks

 

[ddb]

I wouldn't think it would run at all if you were 360 degrees off on the timing... Every cylinder would be on its exhaust stroke, and it'd be backfiring out the exhaust like a muther!!

DDB, I'm stumped (not that that's tough to do!!). It's EFI, not a carb, correct? Hmmm.... When it backfired on first-start, did it backfire out the intake or out the exhaust? Were you able to get a timing light on it with it running?
Assuming the timing is on, and it's backfiring out the exhaust, it sounds like it's probably not firing on all cylinders.

Here's another thing to ponder: Is it possible that the HO motor from the T-bird has a *slightly* different firing order? i.e. maybe it's got a different crankshaft than the trucks had? I've seen wierder things...

yanno i have been looking the same way but the literature i can find on the 5.0's are 1-5-4-2-6-3-7-8, the HO's and 351's are 1-3-7-2-6-5-4-8.it backfires out the intake and it is early truck EFI . to answer the first part. i put a real nice 1989 harness and computer in about a year ago. thats the main reason that the t-birds H.O. intake and computer were not used. as far as i can find and anybody i know after 95 is when ford changed up the 5.0 . i never would even think about that headache

 

[gijoecam]

Hmmm... so you're sure you've got the firing order correct? (I have to ask... double-check it wire-by-wire to be sure... just to humor me... )

A guy I work with that works on engines confirmed that the HOs run the same firing order as the 351s, so that's probably not an issue if it's hooked up correctly....

Is it possible that the cam jumped time one tooth? Can you double-check the timing marks on the gears?.... Oh, wait... you didn't touch them in the swap, did you?

Just thinking out loud here... If it's backfiring out the intake, then it means that the spark is occurring when the piston is on the downstroke and the intake valve is open... But in order for that to happen, the cam would HAVE to be 180 degrees out... Either that, or you've got a valve sticking open... You said you ran a compression test and everything checked out, right? Did you check all 8 cylinders?

Hmmm... here's another thought: What about the distributor itself? When you pop the cap with the #1 cylinder at TDC, is the rotor always pointing at the #1 contact or 180 out? I once saw someone that had a busted timing belt on a 2.3L, but it still turned a little bit... We would set the motor at TDC, arrange the wires on the cap to fit, crank it over, get one pop, and then it was done. Put the motor back at TDC, and the rotor was off... For whatever reason, the rotor would spin, but not in any particular order... Maybe you've got issues with the distributor itself? Grab the rotor and see if it'll turn... Maybe it's not in the proper position when it should be?

Which distributor did you use? The old one or the new one? Could that cause something like this?

Just sort of thinking out loud....

-Joe

 

[ddb]

right

well the firing order is set to the HO 5.0's but i also tried non HO it's all in the ecm,cam (firing order) and EFI . when running the early 5.0's (non HO's) and all trucks up to the 95, 5.0's they only ran the firing order 1-5-4-2-6-3-7-8 . all ho's and 351's are the other. but yes i did change the dist. but i have lotsa ford parts tried 3 seperate TFI body type distributors, and 3 TFi modules . hell after the second time of ripping the intake off i thought maybe i had a bad valve or spring , perhaps i dropped a nut down the intake (which i done before,.but not this time) so i pulled the heads off. ran them down to austin jordens to mill down and inspect. john said way within specs. FINE . while the intake was off i rolled the crank to TDC (while watching the #1 intake push rod start to close and piston coming up), then kept going until it hit zero on balencer both valves now closed. in this position the timing between the crank and cam are dead nuts. rolled it around again to tdc and set the dist. in. unless the cam has a bad spot, or wore bearing ,sprocket or some other worn area that only shows itself while the engine is running. it has to be something off engine, unless of course i'm looking over the easy fix as i have a way of doing. it,s quicker to swap motors than go through this. but i know the same crap will happen. wait maybe i should push this POS off a cliff and buy a chevy.

 

[gijoecam]

ROFLOL!! I't got to be something simple....

Wait, so the firing order is set in the ECM? How's that possible? If it has a distributor, the firing order is set by the order of the wires as it comes around the distributor cap, isn't it? (Maybe I'm displaying my lack of knowledge? I admit, I got into cars after EFI came online, so I know just the basics of carbs and distributors with points)

Here's something you could try: Pull the valve covers off (which should be fairly easy, right?) and manually crank the motor over by hand with a ratchet. You should be able to easily see which valves are opening. Watch to see which cylinder the rotor is pointing to to verify the firing order. The distributor should never be pointing to a cylinder that has a valve open. From there, you should also be able to verify that all the intake valves are closing... Maybe you've got one that's stuck somehow? I know they checked 'em, but/....?? I dunno? I think I'm grasping at straws here...

So it's running the EFI module out of....?? I've even got myself confused now.... :dunno

-Joe

 

[ddb]

all the ho stuff was taken off ofthe t-bird motor. EVERYTHING.. replaced with all the stuff from the 87 truck motor
ok early 5.0's eec''s (EEC"s ALSO refered to by some as ECM"s ALL THE SAME THING THE COMPUTER)and tfi's operate like a on 350 chevy throttle body motor. except on fords each cylinder has it's own injector it still pumps fuel constantly to cylinders 1 4 5 and 8 open together and cylinders 2 3 6 and 7 open together. This creates an equal fuel atomsization inside the intake manifold. the difference h.o's SEFI's fuel and spark are matched to operate one cylinder at a time together. hence sequential electronic fuel injection. does that make sense· Sequential Fire is matched to the firing order of the engine. Sequential fire means one injector fires while that intake valve is open. This creates an equal fuel inside the one intake manifold runner during the intake stroke of that cylinder...that ecm,eec can even be matched to grinds on a cam...the TFI distributers .. ones found on early efi motors they really are better . tfi takes distributor timing from the computer and activates the coil. controls advancement ....eec + the tfi controls when and where the spark and fuel go boom. yup the timing is good. i aint pulling the valve cover again LOL you need to remove the plenum to access the #1 side valve cover. if the egr was hooked up i would need to take that off also. the truck is high i need a step ladder to reach across the motor. and i'm tall. i'm sure it's right.. even if i was wrong 90% of the time i would have been on at least once . i set it in when the intake was off anyway. intake valve yanno maybe the trannys shift regulator .thats run by vacuum from the plenum. gonna recheck all the harness grounds fuel pressure and vacuum lines. go looking for dynamite !!!

 

[ddb]

fixed it
oil pump gear was wore out, was eccentric on the shaft. (wobbled) went in and out of time.

 

[gijoecam]

Aaah, OK, so I was on the right track thinking it was a distributor/timing thing... How'd you figure it out? Just yank the distributor to see what's happening?

 

[ddb]

got sick of dinking with it. i found a 1980 5.0 crate motor. stuck that in, and it fired right up and purred. found the bad pump gear while tearing the damn thing apart ... go figure . thanks for the imput

 

[hunterdan]

Isnt the timing set by the crank as well? Even if you pulled all the HO stuff, if you left the HO crank in there, it would still need the HO firing order. Thats my thinking anyway... Glad to hear you got it running though.

Dan

 

[ddb]

Isnt the timing set by the crank as well? Even if you pulled all the HO stuff, if you left the HO crank in there, it would still need the HO firing order. Thats my thinking anyway... Glad to hear you got it running though.

Dan

thats the only thing i could find bad. but it does make sense though. the oil pump gear drives the distributer. valve timing is set by the cam. but i took the HO cam out. thats why no HO firing order. but it did the same thing with either cam . and both firing orders