Hello, I have been trying to fix my bucking problem (where u tab the gas and the car jumps forward and you let go of the gas and its as though u put the breaks on) for a while now with no gain. I cant cruise in anything less then 4th gear without it acting like im riding a bull. I have got the TPS set pefectly, and even tried another dynamic chamber with no gain. The tps reads exactly 1k ohm at rest and 4.55 at WOT so it cant be the tps. Also it ramps up perfectly fine.

Is there anything else that could be causing this such as throttle cable lose or something wrong? Please throw me some ideas, I'm getting tired of attempting to ride a bull for 8 seconds every time I go under 40 mph haha.

Thanks.

 

did you check the timing?

 

ECU ground? I had this happen to me when I took off my intake to fix my six ports, I forgot about the ECU ground and left it off. The car would buck like crazy going down the road and id get like 5mpg lol.

 

Vacuum leaks...

 

Any and all of the above.

The ECU is grounded with a ring terminal under the dynamic chamber and can't be see without removal of same.

I have seen a car like you describe and by installing a gnd wire to the existing gnd wire on the pressure sensors electrical plug, the bucking bronco went away. It would be the wire on the sensor that is either pure black or brown with a black stripe.

Under NO circumstances ground any of the other wires, like the Black/white wire or brown/red wire or brown/white wire (deadly to the ECU to gnd that one).

Only the gnd wire which will be pure black OR brown/black on earlier series four cars.

You can either solder the extra gnd wire to that wire or as an experiment use a wire tap from Radio Shack/Home Depot for a temp installation. Ground the other end of the wire to the engine bare metal. If it works it works. If not, not a big deal to remove the wire tap.

A LEAN engine will also buck. Lean can be caused by a air leak. A fairly large air leak. Or if you have a SAFC it could be caused to go lean by faulty adjustments to the SAFC.

And to eliminate the TPS as the problem.........just disconnect the tps plug and go for a drive and see if the symptoms are the same or have changed. I highly recommend that.

 

Ok stupid . I can add a ground closer to the ecu on the wire that runs out to be grounded on the engine right?

 

My car used to do this too, and I'm not sure if it was because of the TPS or what it was exactly. It used to do it on my car after I messed with the idle and throttle cable after doing the emissions removal on my car. I'm gonna check out my TPS though and see if it's malfunctioning at all just to make sure it's working correctly. I think it could be caused by a vacuum leak too possibly because I've got many of the vacuum ports plugged now after doing the emissions removal, so I guess we'll see. Gonna check TPF and vacuum today and see what I can find.

 

Clip an ohmmeter on the AFM & work the flap.
See if the ohms values move up in steps as you open the flap.
Mine stepped down some as the vane was almost wide open. I think that's normal.
What you don't want is drop outs or uneven steps in the values.

Before you toss it, try CRC "2-26" spray contact cleaner from Home Depot on the contact brushes inside.