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Discussion Starter · #1 ·
i have 93 GT, who has a shaking issue, and runs a little funny,
i have searched and posted on other forums with no luck....

the car shakes, at the motor, at any RPM, and shakes rougher at about 1200 rpms, she usually runs good but has this awkward shaking problem i cant seem to identify

i have changed the harmonic balancer, with no results,
and most recently the car started to 'putt' under acceleration, not ping from timing, but could not accelerate, at a dead stop while waiting for the light, the shaking got more intense, then after about 15 minutes of driving back to my place, while panicing, it started to run normal again, which leads me to think the ECU, wiring or a sensor is possibly messed up,

with this all said the problem seems to only get bad when the car runs hot,
which it does do occasionally,

Mods include,
underdrivin pulleys, stage 1 cam, headers dumped, 70 mm throttle body, cold air intake, and ACS superchip

i am tempted to remove the ACS superchip, as i feel the issue is the computer timing,

any help would be great, thanks
 

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cylinder not firing? any recent mods lead to this condition?
 

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Before going into anything else, did you check to make sure all spark plug wires were connected?
 

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Discussion Starter · #4 ·
Before going into anything else, did you check to make sure all spark plug wires were connected?
all the plugs/wires are connected, although it could be a cylindar misfire, i didnt think or that, i also though it could be a MAS, or PCV valve,,...

any thoughts??
 

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you need to pull the codes(KOER, KOEO) to eliminate any bad sensor equipment. did it just up and decide to start doing this? detonation will create heat....
 

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wire harness ground attached to back of driver side head? 10 pin connectors tight? computer grounded properly?
 

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Discussion Starter · #7 ·
im definetly thinkin some kind of wiring, electrical issue,,

although i dont know where to begin looking

there are no engine codes, as in the light is not on,
forgot to mention the car has a pulsating idle,
almost like it lopes but not because of a cam,
 

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CEL light doesnt have to be on for codes. check them. like stated also check the 10pin connectors between the intake/firewall and your grounds. they sometimes get corroded and dont make good connnections.

if it were me, id be hunting for 1 or more non firing cylinders. was the car running fine and it just began doing this from nowhere? i dont think its the chip or the eec.
 

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Discussion Starter · #9 ·
CEL light doesnt have to be on for codes. check them. like stated also check the 10pin connectors between the intake/firewall and your grounds. they sometimes get corroded and dont make good connnections.

if it were me, id be hunting for 1 or more non firing cylinders. was the car running fine and it just began doing this from nowhere? i dont think its the chip or the eec.
i have checked the arcing on the distributor, so there are no misfires at least at the distributor, im not sure where these 10 pin connectors are, but could they cause the car to run this bad?

and i need to check the ground on the back of the head as well, great advise thanks guys, i have been so frustrated with the 5.0 i almost wanna sell it lol:livid:
 

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While the car is running pull one plug wire off at a time. It should run worse when you remove a plug wire. If it doesn't, you've found a cylinder not firing more likely than not.

Have you pulled plugs and checked them? Start simple and work to harder from there. Look at all the obvious things.
 

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Discussion Starter · #12 ·
While the car is running pull one plug wire off at a time. It should run worse when you remove a plug wire. If it doesn't, you've found a cylinder not firing more likely than not.

Have you pulled plugs and checked them? Start simple and work to harder from there. Look at all the obvious things.
i did pull the plugs to find all with normal wear, except cylindar 8 which was caked with oil,, idk whats with that bc i put a compression test across and it hit 150,


back to the problem, would the 10 pin connector behind the intake cause the car to run this bad?

thanks again every one
 

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Discussion Starter · #13 ·
about the 10 pin connectors, they are the 2 circular shaped plugs behind the intake?
if so i checked the 2, and they are good and clean,

and about the ground behind the driver side head, if that is the braided wire ground, it is in good contact
 

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So your going to ignore the oil fouled plug? Did you pull the plug wire on 8 to see if the miss got worse or better while it was running?

Good luck with it
 

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Also are you sure the balancer is on all the way? Not saying anything about you, just thinking of the simple first.
 

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Discussion Starter · #16 ·
Also are you sure the balancer is on all the way? Not saying anything about you, just thinking of the simple first.
i havent checked the arcing from wire to plug, just distributor cap to wire,
although i believe the valve seats are needing replaced, which i plan on doin soon, im going to just go with a set of ported polished gt40-p heads and do away with the oem heads anyways,

the balancer was replaced during troubleshooting and after it was replaced the car still ran the same,
 

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What's the fuel pressure? Pump issues?
 

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The KOEO and KOER and cylinder balance tests will at least tell you if the computer thinks something is wrong. They take 10 mins to do, and are free. I'd start there, then post results here.
 

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i havent checked the arcing from wire to plug, just distributor cap to wire,
although i believe the valve seats are needing replaced, which i plan on doin soon, im going to just go with a set of ported polished gt40-p heads and do away with the oem heads anyways,

the balancer was replaced during troubleshooting and after it was replaced the car still ran the same,
I'm not talking about the arcing. They could still spark to the plug but the plug may not fire etc.... I'm asking you to unplug each wire individually while the car is running to see if the mis-fire gets worse or stays the same. If it stays the same you found the hole with a problem.
 
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