Sticky Throttle

[MBDiagMan]

My 88 stick shift car has a sticky throttle. There is no idle speed problem of any sort, but when pressing the throttle it does not actuate smoothly. You keep adding pressure until it comes to a point where the throttle snaps open. Since this is a stick shift car, it makes it less than fun to drive.

I replaced the throttle body recently and it corrected lots of ills. The throttle body itself seems okay. You can actuate it by hand smoothly. The cable seems to be very loose in the housing, but I suppose it could be hanging up somewhere inside.

Has anyone ever worked through such a problem?

 

[toptechx6]

I just noticed a similar thread on the "other" forum, but it was a newer car with ASR, the servo on that system complicates the issue. The only thought that comes to mind for your problem aside from the cable is the pedal mechanism, any chance it could be worn and causing a bind?

 

[boomdriver]

My 88 stick shift car has a sticky throttle. There is no idle speed problem of any sort, but when pressing the throttle it does not actuate smoothly. You keep adding pressure until it comes to a point where the throttle snaps open. Since this is a stick shift car, it makes it less than fun to drive.

I replaced the throttle body recently and it corrected lots of ills. The throttle body itself seems okay. You can actuate it by hand smoothly. The cable seems to be very loose in the housing, but I suppose it could be hanging up somewhere inside.

Has anyone ever worked through such a problem?

These throttle cables have a hard sleeve or liner on the wire rope, inside the cable housing. That can sometimes break and catch on the end of the cable as it tries to slid in.
This liner helps to prevent the wire rope from breaking strands and hanging up causing the throttle to stick open.

 

[MBDiagMan]

Thanks for the responses.

I checked it further last night after being out of town since posting this question. The pedal was free and the cables SEEMED free. The throttle arm seemed sticky. I sprayed it with brake cleaner and let that dry then sprayed it with aerosol white lithium grease thinking it would stay put.

When I left the house this morning it seemed to be cured, but started getting a little sticky before I could drive the 20 miles to work. I think I will try the same thing with a different lubricant, maybe PB Blaster.

 

[G Winter]

Did you put on a new or a used TB ? If you put on a used it might still be the TB . This is just the way mine was acting before I started to have fast idle problems. With worn shaft bore the plates stick under vacuum.

Glenn

 

[Hib Halverson]

I'm gonna guess this problem is either the throttle plates and bores being dirty or "gummed-up" or the throttle shaft bores are worn.

Etiher way, I'd get the TB off, clean it up inside and out then inspect it.

If it was just dirty and the shaft bores are ok, then reinstall it and adjust the throttle cable(s) per the service manual.

 

[ex-x-fire]

Doesn't the 4+3 trannys have a cable going to the throttle arm, like a tv cable on TH700s.

 

[MBDiagMan]

When I replaced the throttle body, I used a freshly refurbished unit from XtremeEFI. Although I would never do business with them again, I believe it is okay. They bore it to 52MM and supposedly put a ball bearing on the arm end of the shaft.

There are two cables going to the TB, one from the accelerator pedal and the other from the cruise control. The kickdown signal on the 4+3 is an electrical signal from the computer that actuates a coil in the transmission. The coil then draws a check ball into position, taking it out of overdrive.

I haven't driven the car enough to gum up the throttle body, but I will pull the bellows tonight and check it. Now that someone mentioned that, it does feel like a gummy throttle body.

Thanks again for all the replies.

 

[Hib Halverson]

If your engine is stock or near stock, take the 52-mm TB off and sell it on eBay. You were better off with your stock TB. There are many cases of stock or near stock engines which have no performance gain and driveability loss when a big-bore TB is installed.

Now, if your L98 is highly modified, to the point that the stock TB is the main restriction, then you need a TB with larger bores.