Throttle/Cold start issues... ??

[SharkTech]

Hey guys, hope everyone is well.
LEO, can't wait to see the final product, I check that thread everyday just aching for updated pics, etc. Looking good!!!

(call it a 1979 US, it is far from original, once being a race car, but started as a 79 US)
Anyway, here is my problem. Started about a month ago. My Land Rover is in pieces as I am restoring the complete steering system, pump, box, lines, etc. So, have been driving the 928 back and forth to work, good times. Noticed a bit ago that the throttle was catchy, or stiff, had to give it a good press to initiate the travel, once going seemed fine but would (catch) once in a while. And, definitely felt a little sticky or stiff.

SO, the problems have gotten worse, big time, over the past day or 2. The throttle is very sticky and does not feel smooth through travel, like it is stressed. Now, it is sticking, yummy, especially when you get on it, likes to pin itself there at 4500 rpms, till you (kick) it back down. Scary stuff, no doubt.

So, that is one issue. Also notice that the cold start valve is sticking, does not wanna come back down after 2 minute warm up, etc, has to be (kicked) down as well, half the time. Also, wants to run high at 16-1700 rpms randomly, in traffic, sitting at lights, etc. I have to let the downshift come down to about 1000rpms then clutch in for the idle to sit properly at still, even then sometimes starts to rise back up to cold start, weird.

So, I was dealing with the idle issues until I figured it out, but this sticky throttle thing is just plain suicide, safe to say I took the Wifey's Honda Odyssey to work today. That thing is actually awesome, if you are aloud to use that term for a mini-van.

Alrighty oh great ones, thall shall listen to your greatness and wisdom, send me in the right direction and I shall go.

Throttle cable ready/needs replacement?
Do not know MUCH about cold start valve on CIS, physical unit to replace/maintenance that can be done???

Open ears, and thx a ton, in advance...
Cheers

[Opelotus]

As far as the throttle cable goes, if nothing obvious turns up in a visual inspection, it wouldn't hurt to oil/grease the various components to see if it helps at all (check the actuating lever behind the pedal perhaps?). You could also disconnect the cable from the throttle body and move the cable manually to see if it is sticking, also check to see if the throttle body itself moves freely.

[DPW928]

A sticking throttle or cruise control cable could be causing both of your problems. Check the throttle cable as Opelotus stated. If the throttle cable has free movement and about 1/8" of slack in the idle position, check the cruise control cable to make sure it isn't causing the throttle lever to bind. If no slack in the throttle cable, the adjustment is on the firewall where the cable exits the cabin.

[SharkTech]

This is all great info, thx much, keep it coming...

I will spend time tonight on the beast once I am home, hope for tons of feedback between now and then, for troubleshooting this evening.

[MPDano]

My throttle was doing that and started getting worse like yours. My issue was a fraying accelerator cable that you could see when you pulled on it from the engine side. I think it was so frayed, only a couple strands were holding it together. Replaced it and all is good. I think I posted a pic here or on my forum somewhere.

Like the others have said, physically check that cable. Disconnect the Cruise Control Cable to help you in troubleshooting.

No idea on the Cold Start as mine has always worked, but like any injector, you could probably take it out and try and clean it up some. I use good ol Carb Cleaner on my old CIS Injectors until I ended up buying new MB's.

Report back after your physical inspection.

[MPDano]

Here you go. Found my old thread and it has some pics too:

http://forums.pelicanparts.com/porsche-928-technical-forum/528488-engine-racing-times.html

[SharkTech]

Thx guys, appreciate the info.
After a full visual inspection nothing seems to jump out at me. But, as my step son was in the car pressing the gas down and up, I was on the engine end, lubing the throttle end at the intake. Looked fine, but making a few strange clicking noises, like something is hung up or off track. After lubing, etc it seemed to go away, sounded good, looked like it had full travel, etc. So, I got in and started it up. Ran fine, cold start valve still sticking a bit but kicked it off, idled fine. A few blips of the gas and WHAM!!! Stuck again at 5500rpm's, yikes??? (and that in MY car is scary, radical motor/exhaust for sure)

So, back at it. Now notice my pedal is almost all the way down, only about a 1/4 to an 1/8 of travel, like you have the gas pedal 3/4 down, but everything inspects okay. But, now it seems that at the intake end that mechanism that hold the throttle cable is off, like a spring is not doing its thing, etc. Nothing looks frayed, out of whack, etc on the intake end, firewall on both sides, pedal connection, etc. hmmmm....

Continuing to investigate.

[emmanuelli]

Hi SharkTech:

Did you ever figure out the problem with the cold start system? I am experiencing something similar on my 86 5Spd. It started out of no where just the other day. The throttle is not getting stuck when pressed, the engine just revs up on its own up to about 2000rpm.

[MPDano]

If you have Cruise Control, you can remove the cable that also runs next to the throttle arm. Mine was defective and for some reason caused a Prius runaway affect.

Have you also replaced all your vacuum hoses?