Engine cutting out momentarily

[1987cp]

Starting to scratch my head on this one ... each of the last three times I've had the wagon out, the engine has cut out momentarily while accelerating on exactly one occasion. Today it sounded like it made a huge spark underhood when it happened. After the cut-out incidents, it goes right back to running and driving totally normally. Since my guess is that something mechanical that would make the engine cut out shouldn't allow it to immediately start operating normally again, I'm pointing the finger at the ignition for now.

Potentially questionable elements of the ignition system: Ford Motorsport wires, purchased used; parts-store HEI module, possibly overheating; homebuilt wiring, possibly shorting out; currently unknown condition of spark plugs (haven't checked 'em yet, should probably do that this afternoon if I get a chance with the kid and the MIL's dog both hanging out here). I'm also thinking I should dial back the initial timing to the 10-12 range (from about 16) until I get this sorted out .....

I suppose there might also be the possibility of a fuel delivery problem, but my experience with that so far (at least, due to improper calibration of the car's EDL-1406) is usually a reproducible stumble under certain operating conditions (load/throttle), and when it's made popping noises it's never been as loud and sharp as what I heard today.

Any thoughts?

[Wray-Wray]

only thought iz datz way outta my league u lost me like half way threw that one lol

[mrltd]

only thought iz datz way outta my league u lost me like half way threw that one lol

That made less sense than the original post...



It's either ignition or the carb isn't quite right. MIght be a bad wire or plug, or the carb is dumping a tad too much fuel on accel.

[Lincolnmania]

is the gm hei module sitting on a good sized heat sink?
i had superlincolns tfi on a block of aluminum and the tfi module overheated and shit the bed......solution was to get a tfi mount from a mn12 thunderbird

[1987cp]

It's on a Slot 1 style CPU heat sink, but I do need to remount it. More to the point, I need to get smaller screws and mount up the Mallory OE-replacement module I just got from Summit.

What's the MN12 use for a TFI heat sink?

[ÆJackacks]

a beater of mine had the same symptoms while accelerating, i kept it topped up for a week and it stopped. like it has air bubbles or dirt going up the line or something, i really had no idea. try keeping it above half tank of gas for 3 fills

[1987cp]

Sounds weird. Can't hurt to try it, though!

Got the new Mallory module installed with nice new #8 self-tapping screws (old screws were #6 or so - didn't fit quite right). Just gotta find the heatsink grease and toss this thing in the car.

[packman]

I would point the finger(s) at the ignition too. I saw this happen once when a kid in a roots blown Monte Carlo tried to race me. The ignition cut out sometime after he shifted into second and blew the hood scoop off of the car. Also sounded like somebody fired a heavy rifle when that thing blew.


Packman

[gadget73]

I had problems like this with the boat, bad connections between the pickup in the distributor and the ignition module turned out to be the problem. I'd check all the wiring and connectors, probably something is getting intermittant.

[1987cp]

I hear ya there. The wiring is all new and heavy gauge (10 AWG power/coil and 12 AWG to the inductor, with appropriate terminals and plenty of heat-shrink0, but it's still homemade and partly exposed to the elements and hence slightly suspect. One thing I did notice when tossing in the new module last night, the extra lead I added to the "-" side of the coil for providing a tach signal could possibly have been flopping around in close vicinity to the hood or fender. I would imagine that temporarily grounding that lead should make the ignition sort of not work correctly for a brief period of time and possibly even cause the sparking sound I heard ..... probably a good motivation to hurry up and connect the tach again already, no? :p

[mrltd]

Hmm, maybe?

[1987cp]

Well, that loose end (literally) is buttoned up, and I did have a mostly-uneventful drive to Steak'N'Shake this evening. Car's running slightly smoother and quieter, too. I did get one pop-and-stumble incident on tip-in from a stop, which suggests I should either go ahead and dial back the timing (which I haven't done yet for some reason) or change back to a heavier stepup spring .... my vote's currently for backing the initial timing back to the 12-14 deg. range, since the car is otherwise driving very well at the moment. Having all my gauges working again is a nice plus.

Thanks for helping get my brain in gear, guys!

[gadget73]

I had problems like that with my VW, the zip tie I had holding the tach wire in place broke and it was laying on the rear axle. It rubbed through the wire and every now and then it would ground out, causing a funky stumble. It did that for 3 months before I happened to be doing something else and noticed the tach wire laying on the axle. Oops.

[1987cp]

Interesting - so it's not just me. :p Oddly, when I went to dial back the timing, I found that it was actually showing right about 0 degrees. That can't be good for efficient running! I dialed it back up to 12 degrees and took it around the block. It still has a weird flat spot slightly off the line, so I'll play with that later. Thanks again!

[Mangjura]

Well mike it might be from you taking those on ramps a little too fast...........