Lots of work done and results are limited

Hi Scottie!

Hope all is well...

I have another issue that is baffling.

I had the fuel and air filter replaced and had the fuel injection system cleaned up.  The Fox was tested for fuel pressure, rechecked the Timing cause a new belt was installed.

After all that the Fox still didn't run like it should as described below. Oh and the coil was replaced or swapped out of a known good running Fox.

I suggested they replace the CTS and they didn't have time so I bought one an replaced it and the Fox ran like it should...or at least I thought it did. It certainly ran better than when it left their shop.


When I get to a certain RPM typically at the upper end of any given gear or if I were to floor it.. the Fox will begin to die/run roughly as if its running out of gas??! One way I've found to get it out of this cycle is I'll slow down and put it into first gear causing the engine to rev a little and it starts to run normally or smooth again. Otherwise it could stall out or just continue to run rough.

Another scenario would be if I get up to about 75 MPH it will cut out acting just like I describe above.

The CTS I'm using is made by Wells Technology and sold by Auto Zone.

Model SU425

2.2-2.8 K Ohms @ 20° c

0.280-0.350 K Ohms @ 80° c


Would a Bosal or Delphi CTS etc possibly improve the performance? Or what else could it be??? The Fox acts like it's got a "governor" built into it.

ANY Help or suggestions would be deeply appreciated. 

Very Truly Yours,


Comments (2)
No. 1-2

Thank You! Scottie... Here is a tip from a friend @VW Vortex. Which I am going to try first i'm pretty sure.Feel free to chime in please! Have a blessed day ahead. raphael "The plunger in your fuel distributor is sticking. Pulling the plunger out and cleaning and lubricating it is an involved process. While a good maintenance step, this also involves undoing and repeating some fairly precise adjustments to the fuel system.

What tends to work as an alternative, is running Marvel Mystery Oil in your fuel. Slosh 4-6 ounces into the gas tank at every fill up and your car should run better. If I forget to put the Marvel Mystery Oil in with a fill up, it becomes obvious pretty quickly, and my car starts to behave a little like you are describing. Maybe put even more to start.

The CIS system was not designed to run with ethanol fuels. Ethanol fuel has a shelf life of 30 days. It breaks down and gums up the system (while also slowly eating the rubber hoses). MMO is a great lubricant, as well as a great cleaner. Won't solve all your problems over night, but I bet it will improve things over time."

Scotty Kilmer
Scotty Kilmer


weak fuel pumps do that or clogged filters not allowing enough volume of fuel, and a clogged up cat or exhaust system also