High Idle, Throttle Sticking

[Felix_29]

Hi All,

I got my car back from the mechanic today. He said the reason it was overheating was because it had a faulty thermostat. He ordered the new one from DMC and popped it in. He also flushed and replaced the coolant system fluid. Checked for leaks, air etc. And my temperature guage is now sitting where it usually sits. Near the very bottom. :)

I think my throttle cable is sticking because whenever I am cruising along at whatever speed and take my foot off the gas I seem to be able to hold that speed most of the time since tonight. Also when I put the car in Park my RPM's jump to about 1500 or just recently 2000 rpm. What is going on?

Also, do these engines run bloody hot usually. I find my engine bay is quite hot even though my coolant temp is cool as a cucumber now. I notice after a my drive tonight that the overflow line off the stainless tank is hissing a tiny bit.

Felix

[Jonathan]

I think my throttle cable is sticking because whenever I am cruising along at whatever speed and take my foot off the gas I seem to be able to hold that speed most of the time since tonight. Also when I put the car in Park my RPM's jump to about 1500 or just recently 2000 rpm. What is going on?

Felix

When you find out please let me know because my car does exactly what you've described here.

[Fox2506]

Sounds exactly like the mechanic didn't put the throttle back together correctly. After all, in order to replace the thermostat, you do have to remove the entire throttle mechanism. I'll bet he disconnected the throttle rod and he put it back leaving a little slack. It should have tension to help pull the throttle closed. I wouldn't blame him though.

Haha. I wanted to say that your problem was the thermostat, but I never got around to posting on your last topic. I had a heat spike one day driving through some hills. Replaced thermostat, and no more heat spikes.

[WelmoedJ]

Temperature gauges are not very accurate devices.
Therefore as a rule of thumb:
When the car warms up and is at operational temperature, read the gauge.
If the gauge's needle is at the same position each time the car is at operational temperature, that's where the needle should be each time.

In my car the OT is usually some 160° F.
A little over it and the fans kick in (this otterstat can be adjusted to switch on at a set temperature).
This makes it easier to set summer (sooner) and winter (later) opening of the thermostat.

In other cars the needle may be a bit lower or higher.
Rely on the "normal" needle position of your car.

Thermostats can have different opening values to accommodate operation in different climates (hotter climates need the thermostat to open sooner, colder climates later).
You ought to make sure the thermostat in your car is the correct one for the average temperature in your (part of the) country.

If Dave S reads this, he may be able to provide the technical info/background on the different values for thermostats and the specific one for your car.

[Bitsyncmaster]

You want a little slack in the throttle cable. The spool spring and throttle assembly springs are what close the throttle. So put some grease on those springs to reduce friction.

[Jonathan]

So put some grease on those springs to reduce friction.

Cool. That I can handle! I just picked up a can of "cable lube" for the speedo cables, so this might do the trick on the springs. It would be nice if it was simple like this. Like Felix says, it kind of maintains speed when you take your foot off the gas (slight gas, not floored or anything), but also jumps up when you come to a stop and throw it in park. Likely hard on the brakes a bit too since it's more or less equivalent to pressing both pedals at the same time when waiting at a red light.

Felix didn't mention it, but I know when I park it in the garage and it revs up to 1,500 or 2,000 I can usually "snap the gas" and it'll settle right back down to the standard 775 RPM.

[Iznodmad]

Remove the inner cable from the outer cable. Clean inner cable with brake cleaner or similar. Shoot cleaner through outer cable and blow with compressed air if possible (put towels down in floorboard to prevent staining your carpets). Re-install inner cable. The above helped my sticky throttle situation without having to adjust anything else.

[Rich]

Also, do these engines run bloody hot usually. I find my engine bay is quite hot even though my coolant temp is cool as a cucumber now.

Felix

Do these engines run hot? No, not unless there's something wrong with the cooling system or you are running up a mountain pass on a hot day with the A/C blasting - same as most cars. You may feel lots of engine bay heat after shutdown or see "heat waves" through the air rising from the engine area in your rear view mirror on hot days - normal. If your cooling system is full, holding pressure and bled and your temp. gauge shows normal then no worries.

[DeLorean03]

Felix didn't mention it, but I know when I park it in the garage and it revs up to 1,500 or 2,000 I can usually "snap the gas" and it'll settle right back down to the standard 775 RPM.

I remember I had the exact same identical issue. Nothing seemed to help: I have a mega-tight spring on my throttle spool, I white-lithium greased the throttle spool and cable, I checked the idle speed motor, the idle speed ecu, checked all the wiring connections to the idle ecu, fiddled around with the "hammer and microswitch" right under the air filter box, tightened all 3 brass screws near the throttle plates, visually verified my throttle plates were closed - NOTHING worked...

Until...I replaced my entire throttle cable with a new one from John. Was really not too bad of a job. Cable is about $85 and is under "Engine" on John's website:

http://specialtauto.com/delorean-parts/images/throttle-cable-new.jpg

Ever since then, I never have had to "kick" my throttle down by use of the accelerator pedal.

[David T]

Lubricate the throttle cable as per the recall. Make sure the outer throttle cable is properly inserted into the end fitting. If it is not it will hold the throttle open by not allowing the throttle arm to get to idle. Also make sure at idle the throttle arm is setting the idle micro. With the motor off you should hear it click when you move the throttle spool and let it go. You may have to disassemble the throttle spool to clean and lubricate it so it moves easily and smoothly.
David Teitelbaum

[Ryan S.]

I am having a same issue. First time I took the throttle linkage off to replace my thermostat, everything went fine. No issues with idle/RPM. I had to take it apart again last week to access my water pump hoses and now throttle doesn't go back down. I am guessing that I may have move/pushed throttle linkage parts around too much while I was accessing water pump area???? I may have handled it rougher than before. I hope I didn't damage or stretched anything.
Anyways, I sprayed some lubricants and even added the spool spring back in but no luck. It always springs back to the original position but not quite enough (by a hair). I have to push the spool and RPM backs down to normal idle speed. I may just take it apart again and try to reassemble carefully.
Thank you

[Bitsyncmaster]

Another issue I found on my car was the clip on the passenger side valve cover had worn through the outer black plastic cover. Then water starts to rust it there. It's easy to look at after you remove that clip.

[dn010]

Felix didn't mention it, but I know when I park it in the garage and it revs up to 1,500 or 2,000 I can usually "snap the gas" and it'll settle right back down to the standard 775 RPM.

When I had this issue with my original engine, I ran a spring from the throttle spool where the linkage connects, to the rear closing panel. It didn't look extremely nice but, problem solved. The spring would pull on the spool to keep it closed, kind of like old cars with carb springs to return the linkage.

[Rich]

I am having a same issue. First time I took the throttle linkage off to replace my thermostat, everything went fine. No issues with idle/RPM. I had to take it apart again last week to access my water pump hoses and now throttle doesn't go back down. I am guessing that I may have move/pushed throttle linkage parts around too much while I was accessing water pump area???? I may have handled it rougher than before. I hope I didn't damage or stretched anything.
Anyways, I sprayed some lubricants and even added the spool spring back in but no luck. It always springs back to the original position but not quite enough (by a hair). I have to push the spool and RPM backs down to normal idle speed. I may just take it apart again and try to reassemble carefully.

There are a couple of things to try additional to notes already posted here. The first bit may help isolate which part of your throttle system is the problem. Sometimes it is due to a combination of little things.

A. Separate the throttle ball-arm link from below the cable quadrant and run the engine in neutral using that arm to test it. If it still won't quite idle then the problem is downstream, otherwise it's in the pedal/cable/quadrant end of thing. The ball link pops off easily like the door strut link does, using a tiny keeper pin.

B. On the throttle side of things see if your throttle spring looks clean. A good long spray of brake cleaner thru the plastic nozzle/extension can get a lot of built-up gunk off of the return spring down by the throttle body, reducing the friction between the coils.

C. On the cable side you need to verify that there is slack in the cable at the throttle-closed condition (with the link connected up again).

D. And be sure that the cable quadrant return spring (coiled around the outside of the quadrant spool) is on the tighter of the two detent slots on the body.