Okay, here's the engine.. 87 302 HO EFI.

The engine stutters and jerks and shakes and what-not's, you get the idea.. Kinda feels like the engine wants to just die. Now, here's the part I can't figure out.

It happens at any RPM, at any speed, at any gear (5-speed manual), at any engine load.. be it downhill coasting or.. uphill full throttle. It comes and goes as it pleases.. Usually lasts 5-10 seconds or so... Sometimes more.. It seems to be completely independant of any driving condition.

The spark plugs are fine, not fouled or anything, and they're the typical brownish color. THey're not that old either, and the electrodes aren't rounded off much at all. I thought it might be the cap & rotor, so I replaced them.. While the contacts were looking pretty bad, it wasn't that.. So I thought, okay, maybe it's the sparkplugs.. So I had them replaced too. Wasn't that. I feel kind of bad, because it's not my car, and I have my friend buy these parts that don't really fix the problem.

Here's a little bit more history on the car...

Before I changed the cap, rotor and plug wires.. The spark was irregular. I hooked a timing light up to 4 wires and could very easily see an irregular pattern. Also, the engine is NOT stock. I'm assuming the cam and crank are different, because the firing order has been changed, and I'm not sure how one would go about changing the firing order without changing the crank and cam. But that I'm not real sure on.. I'm trying to have my friend ask the guy she bought it from what exactly was done to the engine.

Anyways.. Beyond the cap, rotor, plugs & wires, what would cause something like this? Coil? I was thinking that, but so far my thoughts haven't helped the situation out any.

All help is appreciated.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

I am assuming you are talking about a mustang since you say it is a 302???

 

Drat.. You picked up on it..

 

You dont need to change the crank to change the firing order... and I cant think of a good reason anyone would wanna go with the older firing order. Are you sure its been changed?

What about the ignition module? And I would check the wires between everything on the ignition and make sure they are not damaged.

 

Yesh, the firing order was definately changed.. well, pretty sure it was.. When I changed the rotor, I looked up the firing order in books and what-not, and it was completely wrong.. Car wouldn't start at all.. Fortunately, they wrote the firing order down on the rotor, so I set it to that. That's the only real clue I have to go on as far as knowing whether or not it's the stock firing order.

 

So its 15426378 then?

Id be looking at that ignition module, those do weird things when they go bad. Even a cheapo chinese one should be good enough to diagnose it. Some places can test the module but I've never trusted component tests too much.

 

Some mustang 5.0s have a problem with a wiring connector by the rear of the engine. It's been a couple years so I forget the exact connector. I think the connector get corroded or smashed.


check this place out:
http://www.corral.net/Forums/

The 5.0s (5.0 H.O.)have the firing order similar to a 351W, 351C, 351M, 400.
1-3-7-2-6-5-4-8

don't forget that ford numbers their cylinders different.

LKG DWN
[front]

5 1
6 2
7 3
8 4


289 and earlier 302 had the other firing order.

also, the firing order for the engine is determined from the camshaft. That is why in some catalogs for ford camshafts it says you can use this cam but you must use this firing order.

James


[This message has been edited by james_fearn (edited July 06, 2001).]