Ford 360 Backfiring

[neohic]

My uncle has a 1974 Ford F100 with a 360 FE in it. I recently did a fuel injection swap on it using a similar kit I used on my CJ. It came from Performance Fuel Injection out of Michigan. It’s basically Howell components and an HEI distributor. Basic easy setup. 

 

It’s mostly done but I’ve got a backfire I’m trying to figure out. Runs great!... annoying backfire through the tailpipe though. 

 

 

Thoughts?

 

[Eagle]

Check the firing sequence. You changed the distributor. I did an engine swap once and crossed two spark plug wires. Dumb, but I did it, and it made the difference.

[Pete M]

interesting.  does the FI system produce any codes? 

[neohic]

8 hours ago, Eagle said:

Check the firing sequence. You changed the distributor. I did an engine swap once and crossed two spark plug wires. Dumb, but I did it, and it made the difference.

 

I can again but I must’ve gone over it at least a dozen times. What tells me the firing order is good is how well it idles and accelerates. For the most part, it runs great! If you rev it, it’ll stop for a bit. Then the pops will sneak up again. 

[neohic]

27 minutes ago, Pete M said:

interesting.  does the FI system produce any codes? 

 

It does. Kevin at Performance Injection burns his chips based on old GM stuff. You can still put a paper clip in the ALDL port for codes. All I’ve gotten is “random misfire”. 

[Pete M]

is that like the weatherman telling you that it's currently raining on you? 

[jdog]

Which way are you counting the cylinders for your firing order, Ford is different than gm and Chrysler.

[Pete M]

could it be a wire randomly arcing? 

[neohic]

2 hours ago, jdog said:

Which way are you counting the cylinders for your firing order, Ford is different than gm and Chrysler.

 

This is what I was going off of. 

[Pete M]

watch it in the dark and maybe you can find a stray arc.  be sure that your eyes have adjusted or you might miss it.  could even be a bad spark plug.

[jdog]

whats the base timing set at? could it be a leaking injector, would explain why it runs great when in the throttle but when sitting at idle for a while the fuel build up? does this thing have a air fuel ratio or any kind of data?

[neohic]

1 hour ago, jdog said:

whats the base timing set at? could it be a leaking injector, would explain why it runs great when in the throttle but when sitting at idle for a while the fuel build up? does this thing have a air fuel ratio or any kind of data?

 

It’s pretty basic as far as fuel injection goes... which I love. Base timing is 8* btdc and then the computer takes over. No additional info from the computer. 

[jdog]

so from what i'm seeing its a gm based system, wonder if a scan tool would tell you any data? the timing sounds correct. I'm still leaning towards a leaking injector might not be a bad leak, can you look in the throttle body and see what the spray patterns like when its at idle? Does this motor have adjustable rockers? I'm not knowledgeable about these older fords, but i know Ford did use them at one time. 

[neohic]

So I finally got back to this today. Firing order is good. All sensors check out. No vacuum leaks.

 

What I found late this afternoon was a funny looking spray pattern through the right injector. I unplug it and the backfire instantly goes away. I plug it in and it comes back. It idles just fine on one injector but if you rev it then it’ll give a code 44... oxygen sensor senses lean condition. What it won’t do it run on just the right injector. I think the left is good... the right has issues. 

 

Pictures to keep people interested. 

 

[Pete M]

thunk you might be able to get away with a good soaking/cleaning of that injector?

[neohic]

I’m going to start with calling Kevin at Performance Injection being I already had issues with another throttle body he sent me. 

[neohic]

The saga continues... yes, after two years. This truck has never run perfectly but I was hoping it was carburetor issues. It just sings since the fuel injection went on all the way until it gets to operating temperature. Sensors have gotten moved around, calls have been made, and yet the issues remain. While this should’ve been a weekend project, I’m way too far in to just chalk it up to some kind of old truck quirk. 
 

 

Today the heads came off. These FE engine are goofy in that the intake manifold makes up the top half of the heads and the pushrods go through the upper intake half. Not anymore work to pull apart the top half of the engine... just an annoyance. 
 

 

The internals were squeaky clean under the valve covers.

 

 

With the heads off the cylinder walls were found to still have cross hatching. At some point the intake was off as evident with the mass amount of red silicon and some old Felpro gaskets. I skipped completely pulling the intake for now as I wanted to keep everything consolidated as much as I can. So what did I find?

 

 

 Gross! The top picture is the right side and the bottom shows the left. It’s obvious which combustion chambers had fouled spark plugs. There wasn’t any obvious signs of head gasket issues so I’m going to circle back to carburetor issues. I think what’s happening is the old toilet mechanism on the intake was dumping fuel at an unsteady rate and as a result the valves started sticking over time. A couple of them are just burnt.

 

With everything apart the plan is a full rebuild for the heads. I’ll clean up the top of the block and put it all back together. Hopefully that’ll be sooner than over the course of the next two years.