I hate to ask but I don't think I am quite finding the answer I am looking for so...

I have an 88 vert with a streetported 90 turbo II engine being ran by an 87 ECU (and associated S4 stuff). I am trying to smooth out my acceleration and my idle but am having a hard time adjusting the TPS. I can adjust the TPS to 1 volt but when I open and close the throttle plates a couple of times to verify the reading, it changes anywhere from .8 to 1.2 volts. I can also press on the arm and actually get the reading to go down to .3 to .5 volts. When I open and close it some more, the readings are back up to .8 to 1.2 volts again. Trying to drive it, the acceleration is relatively smooth but it wants to idle around 1500 rpms unless I put my foot underneath the accelerator pedal and pull up. At this point the idle will go down to 800 to 900 rpms.

Anybody have any ideas on what I am missing or what I need to look at to fix this? Thanks.

Dan

 

A.Throttle cable is too tight. No slack atall in it. B. Maybe just a little misadjustsment of the dashpot? C. Possible crud on the aft side of the throttle plates building up and not allowing the plates to close completly. Have to take the throttle body off to fix that.

I'd go with putting a bit of slack in the cable first. I'm not above spraying some spray lube on the linkage and work it back and forth also. If you put some slack in the cable be sure to reset the tps. Make sure the engine is hot.

Do not use WD40, please. Use a lubricant.

 

Actually, I forgot to mention the dashpot (if you are referring to the one for deceleration by the firewall). The actuator for it never touches the plunger. Not sure if that will make a difference in trying to diagnose the problem or not but I can start by looking at the throttle cable first.

Thanks.

Dan