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5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

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Old 04-09-2012, 09:54 PM   #1
cepowers18
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Default Car jolts/jerks

Hi all,

I have a rebuilt 1994 Mustang GT (306) with TFS heads, cam, and intake, and it jolts or jerks a lot when cruising and it makes is a noticeable clanking noise. It seems to happen in any gear when the RPMs are 2K or below and I'm simply cruising down the road giving it a little bit of gas. When I'm giving it a good bit of gas everything is fine - it only seems to happen when decelerating or when I'm only giving it a small amount of gas. The RPMs don't fluctuate when it happens. It also jolts/jerks quite a bit from 55-65 mph in 5th.

My first thought after reading some other threads were that it was running lean, so I've replaced the spark plugs, fuel filter, and O2 sensors but that hasn't helped things. I thought that it could also be in the tune but I haven't tried pulling out the chip to see how it runs without it.

Any suggestions? Is it possible that this could have something to do with motor mounts?
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Old 04-09-2012, 10:12 PM   #2
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Hard one for anyone here to diagnose without hearing and feeling that. My first guess would be a deadspot in the TPS, coming back alive creating the jolting. Overheating fuel pump might do the same.

Clanking might be something as serious as the flexplate to converter or flywheel to pressure plate bolts coming out. Don't ignore it. The jolting is creating the clank, which means something is loose.
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Old 04-11-2012, 04:05 PM   #3
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I thought it might be the clutch as well. That may be a good place to start. I suppose it might be worth pulling the chip, too.

The TPS and fuel pump are both new parts from the engine swap, so in theory they shouldn't be malfunctioning but I'm sure anything is possible.
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Old 04-12-2012, 10:11 AM   #4
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I pulled the chip and it still seems to jerk/jolt a little at the same RPM ranges and speeds, but not as much as with the chip in. After I pulled the chip and started up the car, the idle surged a bit more but once it smoothed out I think it ran better than with the chip. The lope and the shaking from the cam isn't as violent as it is with the chip either

Any other suggestions for the jerkiness? Now it almost seems like a sputter or something.
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Old 04-14-2012, 04:25 PM   #5
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Update:

The chip is no longer in and I've driven it several times to see if it would smooth out. Turns out that it still jerks and jolts without the chip in, but not as violently. I've also cleaned the MAF, air intake sensor, IAC, TB, checked the TPS voltage, and re-gapped the spark plugs to .054. TPS voltage is .94 and at WOT it's 4.6, so I believe that is fine.

Does anyone else have any suggestions? Would taking a video and posting it help at all?
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Old 04-17-2012, 12:38 PM   #6
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Bump. Any other ideas, anyone?
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Old 04-17-2012, 12:39 PM   #7
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You need an oscilloscope to check the TPS, not a multimeter.
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Old 04-17-2012, 09:12 PM   #8
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mine jolted and stuff and i replaced the TPS and it stopped, its not that expensive just 35 bucks
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Old 04-19-2012, 06:15 PM   #9
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Ok, I've done a ton of searching and I can't find an answer to this anywhere. Apparently there are two TPS sensors for 94-95 5.0 Mustangs - part #'s F2SF-9B989-CA and F1SF-9B989-AA. Does anyone know the difference between the two?? My car has the F2SF part # on it, but I can't find a replacement part anywhere! Auto Zone, Advance, Napa, O'Reilly's, Rock Auto, nowhere. People have the F1SF-AA part, but I don't know if that will work with my car.

Anyone know the difference between these two?
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Old 04-19-2012, 07:08 PM   #10
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As I remember, the difference was how the connector socket is positioned on the sensor. You will have to look at the sensor to get the number.
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Old 04-19-2012, 07:08 PM
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1500, 2010, 2011, 2k, 5th, 89, changing, filter, fuel, gt, jerking, jerks, mustang, rpm, wot

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