Odd backfire sound from EFI motor ....Updated to HELP!!!

[rtreads]

The good news is my York compressor install is almost done. But when I was putting it all back together, I let it run to warm up and top off the radiator. While letting it do this, from no where it developed a back fire. It is not perfectly consistent. I was not messing with any of the mechanics of the motor at all... just the belts and accessories.

Any ideas what could cause this? This is the only issue holding it back from being up and running. If you want to come by and take a look, it would be really appreciated.

Thanks,

[Shawns Fords]

I am curious to what this is. I dont know when I could take a look at it. I am slammed between work and school now.

I can give you some things to check, like vacuum hoses and timing. I cant think of anything else right now but know there is some other things to check with EFI.

[rtreads]

I have checked time and it is at 10*. The weird part is that I didn't mess with any of the mechanics. I didn't touch the dizzy, plug wires, ect. I had it running fine and then this back fire developed as it was idling.

[rtreads]

I have been thru this thing over and over. It has stumped me as to why its doing this...

[rtreads]

Would the battery beind dead for 2-3 weeks change this situation any? I left the laptop plugged in and it drained the battery. The computer would have not see the appropriate voltage for about 2+ weeks.

Is it in some learn mode and I should just let it run it out? It has the standard A9P mustang computer.

[Booger]

Not sure how refined they were back then but I know the newer computers do go through a learning process to adjust all the fuel trims and such. You might be onto something. Is it more of a stumble or stutter or is it actually popping through the exhaust or TB?

[Mitche11]

The battery being completely dead will kill the EEC's stored data and it may have forgotten all of your Bronco-specific engine perameters. It may be tuned using the factory defaults of a 5.8L with stock intake, at sea level, with a bunch of emission control which I doubt you're running. I'd drive it a little and see if it clears up as it learns.

[rtreads]

Not sure how refined they were back then but I know the newer computers do go through a learning process to adjust all the fuel trims and such. You might be onto something. Is it more of a stumble or stutter or is it actually popping through the exhaust or TB?

I think it is a backfire coming from the intake. You can smell the exhaust from the TB.

[rtreads]

The battery being completely dead will kill the EEC's stored data and it may have forgotten all of your Bronco-specific engine perameters. It may be tuned using the factory defaults of a 5.8L with stock intake, at sea level, with a bunch of emission control which I doubt you're running. I'd drive it a little and see if it clears up as it learns.

...they never came with a 5.8 stock. There aren't any bronco specfic perameters... just what the running history has been for 3 years.

It doesn't sound healty to run. I am worried about damaging something.

[hockeydad4-22]

Sounds like an issue for our own dr. phil, he of viperwolf fame!

[rtreads]

So I just started it again. I figured screw it I was tired of loosing sleep over it. I fired it up and there was a back fire. I let it run for a couple seconds then revved it a little. Sure as $hit the back fire went away!!?!!!?

Now a tap/tick sound are noticeable. While it was running, i sourced it to a valve cover. I put my hand on the cover and you can feel something hitting the underside! I would bet its a rocker.

So the question is.... Are they oil filled lifters and it just needs to run? Or am I way off and there is internal damage some how? Are the rockers loose? I don't know much about how to work on valves, rockers, and lifters.

I hope someone can shed some light as to what is happening.

[ZOSO]

Yes lifters need to pump up with oil. Do a leakdown test and compression test. If you can pull the valve cover and inspect the springs/rockers/pushrods.

[ZOSO]

now that you mention it when was the last time it was started? sounds like a stuck valve/lifter.

[rtreads]

I pulled the valve cover and this is what I found. 2 rocker arms twisted out of place, a proven pushrod, and a bent pushrod.

It looks like the small dome end came off the exhaust pushrod, letting the rocker float and twist around. I have no ides what bent the intake pushrod?

What do I do now? I was thinking I need to order 2 new pushrods, and a rod guide since is worn a little. I have no idea how to work on valve train. The current parts are from comp cams, so that's where I was going to order replacement. Unless otherwise suggested? Have any tips on this repair and how to? Any help would be appreciated GREATLY!

[rtreads]

I think that is a great idea.... anyone have a loaner scope, or know where rents them? Napa and advance do not have them for rent.

[rtreads]

Its a little far... I'm in Highlands Ranch. I really appreciate the offer. Maybe I can grab it from you tomorrow or this week sometime?

[rtreads]

Is there anyone that knows about valve train, that want to help me put this back together before the breakfast? I would love to be able to drive it again!

..., food, $, you name it!

I am ordering 2 new pushrods and a guide from Comp Cams today!

[hockeydad4-22]

Is there anyone that knows about valve train, that want to help me put this back together before the breakfast? I would love to be able to drive it again!

..., food, $, you name it!

I am ordering 2 new pushrods and a guide from Comp Cams today!

I would love to be there to learn - I know little to nothing about it myself and Rtreds is pretty close to my house so if you do not mind an amature watching and learning - I would really enjoy it.

[Viperwolf1]

I think the weld could have broke on the one pushrod and the flopping rocker could have caused the other pushrod to get bent. Definitely put a scope in it if you can though. How many miles since valves were touched?

[rtreads]

I cant say exactly. I bought it with this motor.

[Shawns Fords]

I have had about 4 different Ford engines do this to me, including the 400 in my 81. It didnt bend, but it fell off. My FE it had 3 bent pushrods, and I just put new on there and ran it, it wall all ok afterwords. I hope a piston didnt hit your valve, thats not an interference engine (if I remember right) but it is still possible, usually they can pop off after the engine has set for a long time, or if it is over revved the rocker floats and that allows the pushrod to fall off.

[Shawns Fords]

I would love to be there to learn - I know little to nothing about it myself and Rtreds is pretty close to my house so if you do not mind an amature watching and learning - I would really enjoy beating on it with my block of wood and hammer.

you crazy man!

[Viperwolf1]

I cant say exactly. I bought it with this motor.

Well then it has enough miles to show nothing was very wrong with the way it was built. Chances are it was just a part failure.

[rtreads]

Ya that is what I am thinking too. If all goes well tonight, I will be at the breakfast on Saturday.

[rtreads]

So my help tonight for installing the new rods bailed... Can anyone direct me to a source of how to do this? I would like to get it running for the breakfast.

Thanks!

[Viperwolf1]

Pull the old ones out. Loosen the nuts. Put the rocker on the valve tip and pushrod. A little dab of grease on the contact points is good. Tighten the nut until the pushrod can no longer move up and down. It may be able to spin but no up/down. Tighten nut another 1/2 turn. That should put the piston inside the lifter in the center of it's range of motion. Make sure to inspect everything for cracks or damage first.

Also put that cylinder at TDC on compression stroke first. You can use the cylinder before it in the firing order to determine stroke then add 90 degrees turn to the crankshaft.

[rtreads]

Thanks for the directions everyone. I spent some time reading up on this too. It seams really simple. I didn't get to it tonight, but I will for sure tomorrow. I will let you know how it goes. I hope by this time tomorrow I have taken it for a test drive and it all checks out.

Thanks again everyone!!

[rtreads]

Thanks to everyone that offered advice. I successfully swapped out the bad rods and guide. It's back up and running!!

Thank you!!!

[Shawns Fords]

Glad you got it handled, wish I could helped, but im slammed between school and working. Them pushrods can be frustrating for sure.