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Thread: Speedometer jumps/bounces and car trembles/shakes Reply to Thread
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Topic Review (Newest First)
12-04-2012 01:31 AM
Problem solved

I think u might be having a problem with ur Mass Air Flow sensor aka MAF sensor my 94 tbird had the same problem but the only diff was that the rpm and the Speedo would jump I bought 2 cats new wires spark plugs and coil pack and all to find out that the maf was the problem wich was worth on 8 buckaroos at AutoZone vs 400 for the cats and stuff
05-14-2007 10:08 PM
Originally Posted by fastfocus00 View Post
i had the same problem. its prolly your speed sensor malfunctioning. my car did the same thing. have someone replace it and it should take care of it. your speedo and tach and trip run off the speed sensor which is part of the tranny so when your speedo jumps around it makes the car feel like its shaking and what not.

x2... I bet its the Trans speed sensor
05-14-2007 09:30 PM
kndlz28 Mine did about the exact same thing. Here's my old thread.

And FWIW, it was the engine grounds. Good luck!
05-14-2007 08:30 PM
fastfocus00 i had the same problem. its prolly your speed sensor malfunctioning. my car did the same thing. have someone replace it and it should take care of it. your speedo and tach and trip run off the speed sensor which is part of the tranny so when your speedo jumps around it makes the car feel like its shaking and what not.
05-14-2007 03:15 PM
StupidZX3 I replaced the plugs and wires also, about a day after that, the car threw a CEL on and started to shake even worse.. Turns out the coil was cracked... Replaced it, and the car runs perfect now, no more jerking of the speedometer or bucking of the car.
05-02-2007 11:29 PM
Jeremyy I have replaced the spark plug and wires, which has lifetime warranty.

Bosch Platinum 2 spark plugs and Duralast wires. Saved $200 than let mechanic do it.

Now the shaking problem of the car seems gone. We had P0304 error code which means #4 cylinder misfire. It did not go back to normal once we replaced it. But after we fasten/enforced both end of the wires, the problem seems gone so far. I suspect it is contact problem, and replacement of spark plug and wire might not be needed.

The speedometer still jumps, but not as often or bad. I suspect that misfire worsen the speedometer problem, although they seem unrelated.
05-02-2007 06:54 PM
whynotthinkwhynot That doesn't explain the speedo issue, but it's highly possible that the two problems are not related.

If you purchase "Lifetime warranty" wires, keep the box, or when you need to change the wires again, don't destroy the new wire's box, and put the old wires in the new box to return to get your money back. That is the only way to get plug wires for free for life.

JRPASMO mentioned a common problem with the Focus, and that's the wires leading to the coil, on some vehicles these wires are too short and one ends up being pulled out of the connector. This connector should be looked at with scrutiny. If you find yours to be suspect, then you can get a replacement part from the Ford dealer to fix it.

There is also the voltage regulator plug that goes in the back of the alternator. Several people have had problems with this plug also.

I must say that I prefer the old Ford OBD1 wiring connectors that you could pull on all day long without pulling a wire out.
05-02-2007 05:28 PM
jrpasmo Check connection to the coil pack...there are 3 wires....sometimes the like to brake and.......
05-02-2007 03:16 PM
Jeremyy The mechanics said they think it's the problem with spark plugs and spark plug wires.
They said they "spot on ignition wire with electricity coming through". And the engine is misfireing erratically.

I and my friend will buy some spark plugs and wires to replace ourselves, as they said it cost almost $300 for them to replace it.

Any thought?
But I will post if this solve the problem.
05-02-2007 11:34 AM
whynotthinkwhynot If you disconnect the VSS, which yes it can be disconnected, then you'll not have a speedometer at all. The two are related, but the other way around... deja vu... did I write this before?

You can replace the VSS, but it's likely to be expensive, and not be the problem. Try taking the car to Autozone or some other auto parts store and asking them to scan your car for codes. The best time to go is a time when there are not many people there, but they will do this for free. Write down the codes, and bring it in to check it against the list of engine trouble codes we have here. That will also help some in diagnosis.

If you take the car into a mechanic, ask him to thoroughly check wiring that's near the exhaust. LilDisco (I think) had a problem with weird things happening that was the result of wiring that was burnt by the exhaust which was not easily obvious because the part that was burnt was facing in the other direction. I'm fairly sure he had to get under the car to find it.
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