93 mustang breaking up during acceleration

JDiFet

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Nov 5, 2019
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Have a 93 lx that I bought a little over a month ago. Had some issues, and it sat for a while. New to fox bodies and still new to this car In general. So some insight from experience can help. Before I describe my current issue, I’m going to give some history on the things that I have done to the car. First I changed the ignition control module, the car was un-drivable before I put that in. Put In new plugs, wires, coil packs, Fuel filter, air filter, oil change, had fixed some vacuum lines, replaced the egr valve and sensor. That’s all the work I have put into the car engine wise. And that was right after I got it. The car runs decent. But it has one slight issue, and it only happens when I’m in gear (most prominent from 3rd-5th gear) the car begins to what I believe is breaking up, almost like a misfire. If I’m in any of those gears and I give it more than half throttle. And it only happens in the rpm range from 2k( when it’s the worse) up to almost 3k (hardly noticeable) what I experience is almost like a very violent shudder. The car will jerk, like it’s trying it’s hardest to break free but it can’t. Im not sure if I’m just lugging the engine, or if it’s an actual problem. Because my other car (5 speed corolla) doesn’t do that. Although I understand they’re two different cars and gearing is different and what not. But I have a very strong feeling in my gut that it’s something else. It’s very annoying because around 2k is cruising speed, and anytime I want to accelerate even if it’s lightly, I have to downshift to do it. Another issue is (not sure if it’s related but I’ll state it anyway) when I’m in Neutral, or when I’m downshifting, I’ll blip the throttle. And the engine basically shutters. Like it’s going to stall. It only does that when I flick the throttle quickly. Any suggestions will be a tremendous help
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
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I'm a V8 guy but I would say check for codes, not sure if it is done similarly than a V8, check fuel pressure with a gauge. If it has a lot of miles I would look into replacing the timing belt.
best I can do.
 
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91TwighlightGT

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That is an odd problem. The first thing I would do is try to pull codes and see if anything pops up. You could have something like a throttle position sensor based on your description.
 
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JDiFet

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Nov 5, 2019
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That is an odd problem. The first thing I would do is try to pull codes and see if anything pops up. You could have something like a throttle position sensor based on your description.
it’s really odd, the problem has me so stumped. I haven’t gotten to know the car very well yet. So idk if it’s one of those things where that’s just what it does. I’ll try to pull codes for the thing tomorrow, it’s pouring down rain where I’m at now. At this point I assume it’s fuel/ maybe air related. Clogged injector(s) maybe? Who knows.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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it’s really odd, the problem has me so stumped. I haven’t gotten to know the car very well yet. So idk if it’s one of those things where that’s just what it does. I’ll try to pull codes for the thing tomorrow, it’s pouring down rain where I’m at now. At this point I assume it’s fuel/ maybe air related. Clogged injector(s) maybe? Who knows.
remember with these cars you cannot assume, a problem like yours will involve some investigation, you likely will find it ignition/timing related.
 

JDiFet

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Nov 5, 2019
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Philadelphia, PA
remember with these cars you cannot assume, a problem like yours will involve some investigation, you likely will find it ignition/timing related.
you’re right, I’m getting ahead of myself. Sometimes I can’t help it though. I haven’t pulled the timing cover off and checked it since I bought the car. So it’ll definitely check it out soon. Along with pulling codes of course
 
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Alex129

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Nov 19, 2018
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The engine definitely shouldn't "lug" at that RPM. Out of curiosity, what kind of spark plugs did you use? I can't remember if these later 2.3's had a wasted-spark ignition, but if it does, they work best with double platinum or iridium plugs. Ol' Copper ain't so good at double duty, so they could conceivably break up in the rpm range. Also, ensure that if you gapped them, that it's the correct gap size. 0.044 should be the stock spec.

With new plugs, wires, ignition module, and coils, there's not a whole lot else that's keeping down your ignition system. Next would be fuel, as junkyardwarrior pointed out, and perhaps timing. Definitely check the belt.
 

Foxslider

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Oct 25, 2019
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Check the timing. Make sure you all plug wires are correct from cap to right plug. Throw a new ignition coil and fuel pump on it. These are guesses for 5.0 though.
 

1993TripleWhiteFox

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Dec 24, 2019
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Check the timing. Make sure you all plug wires are correct from cap to right plug. Throw a new ignition coil and fuel pump on it. These are guesses for 5.0 though.
I had a similar issue on a 2.3 many years ago which was resolved with a new o2 sensor. Usually happened when tipping in to accelerate up a hill and more prominent during cruise conditions on the highway. Might be worth the 30 bucks to throw one in and see what happens.