LOUD POP while driving! No starty....Help!?

Pokageek

Active Member
Jun 10, 2005
2,767
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46
MA, USA
Hi folks, more fun with the car.. I was out for a nice Sunday drive with the top down ..going uphill and BANG!..some sort of backfire and engine OFF. I would crank but no start. I had to back down the road in traffic make a left going backwards onto another street into a parking spot with people yelling at me to get the car to a safe spot.

I thought the fuel pump went out cuz I couldn't hear it but after getting it home/quiet, it is definetly engaging. I changed out my screaming demon coil with my original and still no start. I will try the TFI module tomorrow. Does anyone else have ANY idea what happened??:shrug:

o yeah, I was not drivng it hard. Maybe 25MPH with slight acceleration.
 
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Keith, I'd do some quick checks. Be sure your MAF didnt come uncoupled from the plumbing. Be sure the dizzy hold-down bolt isnt loose and that the dizzy cant spin. Run your KOEO codes.

Before swapping parts (sometimes this is worse than not doing it, as it adds variables since we know that new doesn't always = functional), I'd do a couple quick tests.

Check for spark. If you have it, you can assume for now that your TFI, PIP and coil are ok.

As you noted, you need to check fuel pressure. A bad pump still makes noise even though it's flowing almost nothing. That's too bad that you can hear it come on because otherwise you could have been lucky and had the inertia switch pop for some reason.

If you find that you have no spark, try to test injector pulsing.

Then take it from there.



Good luck.
 
Keith, I'd do some quick checks. Be sure your MAF didnt come uncoupled from the plumbing. Be sure the dizzy hold-down bolt isnt loose and that the dizzy cant spin. Run your KOEO codes.

Before swapping parts (sometimes this is worse than not doing it, as it adds variables since we know that new doesn't always = functional), I'd do a couple quick tests.

Check for spark. If you have it, you can assume for now that your TFI, PIP and coil are ok.

As you noted, you need to check fuel pressure. A bad pump still makes noise even though it's flowing almost nothing. That's too bad that you can hear it come on because otherwise you could have been lucky and had the inertia switch pop for some reason.

If you find that you have no spark, try to test injector pulsing.

Then take it from there.



Good luck.

Thanks much Hissin50!

"Be sure your MAF didnt come uncoupled from the plumbing. Be sure the dizzy hold-down bolt isnt loose and that the dizzy cant spin."

I checked this and it is ok.

"Check for spark. If you have it, you can assume for now that your TFI, PIP and coil are ok. "

Since I don't have a second person, is it ok if I clamp a small wire connector to the inside of the wire that goes to the coil and have to touch metal so that I can see a spark in the engine bay from inside the car? or will I blow something out?
 
You dont want to risk creating another issue by frying something else.

I'd use a spark tester or spare spark plug. If the tester or plug cannot be seen from the driver's seat (sometimes you have to sit kinda funny to see through the gaps), run a jumper ground wire from the spark tester body (or plug threads) to the engine. Then put the tester/plug some place you can see it.
 
Ok..I have what looks like a testor wire that came with my ignition. I hooked that to the coil and that to an old spark plug (fouled prolly- will that matter for the test?) and touched it to a screw. NO Spark.. So it might be safe to assume I blew the TFI module?

BTW.. during the engine swap the screamin demon coil blew for some reason. They sent me a replacement. Now if their TFI module blew..aut 2000 miles later. Would that indicate that I have some sort of issue blowing these things out? I mean this has all happened in a matter of roughly 2000 -3000miles.
 
Ok..I have what looks like a testor wire that came with my ignition. I hooked that to the coil and that to an old spark plug (fouled prolly- will that matter for the test?) and touched it to a screw. NO Spark.. So it might be safe to assume I blew the TFI module?

If you have doubts, clean the plug with steel wool or a wire brush and a paper towel. Being fouled should not matter (since the plug is firing at 1 Atm and without turbulence or fuel) but since you're car is already acting up, no need to create doubts. You need to observe a nice blue kernal. If it's orange and the battery is decently charged, the coil is probably bad.

BTW.. during the engine swap the screamin demon coil blew for some reason. They sent me a replacement. Now if their TFI module blew..aut 2000 miles later. Would that indicate that I have some sort of issue blowing these things out? I mean this has all happened in a matter of roughly 2000 -3000miles.

Tough to say. The neat thing about the ignition from the TFI forward (and our EEC in general) is that heat-sink tech is used. Since grounds to circuits are modulated, if a short develops, it is less likely to fry components. However, it can wear components out. Now if your ignition had a dead short in the signal wire (to fire the coil, for instance), the coil would not fire repeatedly (there has to be a on/off cycle).


For now:
If you are missing spark, check injector pulsing (a test light can be used in a real pinch if you don't have a noid light. Noid lights are less than 5 bucks).

If you have neither spark nor injector pulsing, the PIP is actually the first place I'd look. Note that the TFI can fail in such a way to corrupt the PIP signal before it reaches the EEC, but this is rather rare.

If you wiggle the electrical wires around that go to the distributor (specifically to the PIP), this sometimes makes a car run. The wiring grommet at the dizzy is a known issue.


If you only are missing spark but have injector pulsing, the PIP should be fine. You know then that it's the wiring, TFI or coil. A test light across the electrical connector to your coil should flash while cranking. If it does but you have no spark, it's the coil or a broken coil wire. If the test-light doesn't flash, ground the test light and check for KOEO power to the coil's electrical connector. If you have that but the test light didnt flash in the previous test, have the parts store bench test your TFI module (because the ground to the coil comes from your TFI module).
 
I can't really help, but if you need a new dizzy I have a stock replacement from Advance Auto with only a couple hundred miles on it. I just need to swap back to my MSD and make sure it still works first.
 
I tried to get the screamin demon tfi module out of the heat sink but the bolts are fudged up..so is it ok to connect the new tfi module without putting it in heat sink long enough to see if I get spark?
 
I believe the TFI module grounds through the chassis, so I wouldn't advise it. You need a special Ford Ignition tool (a 7/32 deep socket, I believe) to remove the bolts.
 
Look at your MAF elements. If you had a backfire through the intake tract, you could very well have damaged them. You could also have blown out an intake gasket and have one hellacious vacuum leak that's causing a huge lean condition when you try to start.
 
keith, i feel your pain. i was there not long ago, believe me. i know how frustrating it can be pouring all this money into it and then having one problem after the next. every time i complain to my engine builder, he smiles knowingly and says, "dude, that is the essence of hot rodding"

good luck and i wish i was closer so i could come over and help you figure out what the problem is.

was the backfire in the intake or in the exhaust? did the pop come from under the hood or under the car?

and where did you get it tuned?
 
I got it tuned at sgs in PA. The backfire came from below...I think. $100 towing later I was back home.

Thanks Chris. I am really frustrated. Now I know why frogs boil in water turned up very slowly. Humans do too.