Morning start report: 8am. 54 degrees. 46 degrees overnight low. 2 quick Glows fired up immediately, no fuel pedal, nice and smooth I didn't note the rpms but they they seemed nice and normal. Sat 10 sec. Reverse and backed out. Dropped it into gear, touched the accelerator pedal and it eased away. Foot off the pedals. It shifted quickly to 2nd. then 3rd. revs building 1500+ to over 2000 with the slight downgrade. Pull over at the low spot and shift to Park. Motor raced again. Drop it into D/3 - hard shift - engagement throttles down the revs. But without touching the accelerator the RPMs build on their own and it pulls me up the incline pretty forcefully. (I'd removed the floor mat to prevent that diseasal.) Engine Temp was 60 degrees. Continued driving at 1500+ revs without any pedal. But when Engine Temp rose to 80 degrees then revs dropped to 600 rpm and all was well.

This describes the same symptoms and problem I was trying to describe/solve in the initial post. After cold start rpms are 1500+ and inclined to run up fast if tranny is in Park. Once engine temp warms to 80 degrees the idle drops to 600 rpm. I can live with this, but if there's a cure, I'd like to know. Later today I'll try to run and post the open-ALDA 0-60.

Jay Bob, I skim read the pdf and note that the procedure requires 80 degree engine temp. I don't have much issue with performance over 80 degrees, so I'm not sure that will get to this issue. I have never adjusted the hex bolt on the back of the IP. I noted that the lock nut was tight. and it looks like just one thread showing on the hex bolt. Is that the stock setting range?

This happens with or without the ELR actuator hooked up?

Could it be a worn return spring?

Sixto
83 300SD
98 E320 wagon

Have you tried running your test with the OVP removed?

__________________

1986 300SDL 440,xxx

That is my understanding. Intermittent problem regardless ELR.

Think about ways to diagnose by eliminating possible causes and then testing.

Disconnect the two-pin connector for the idle control (on the back of the IP), test by driving for several days. You may need to manually adjust the idle speed up.

Disconnect the cruise control actuator rod or unplug the electrical connection.

When the engine is doing its high-rpm thing, observe the position of the accelerator cable to make sure it is slack. Also check the remaining accelerator linkages. You may need to remove the washer fluid reservoir and leave it out for the duration of all this. When I purchased my '87 wagon, a previous "mechanic" had messed up all the shift linkages to try to adjust the idle (I think) so I had to spend more than a few hours sorting that out one day. The FSM has the specs.

Once you've eliminated all the possible external causes, what is left is the injection pump. What work has been done to the injection pump? There was one fellow who "fixed" a leak from the bottom plate by installing a rubber sheet between the plate and the injection pump. The rubber sheet inside the pump rubbed on components and caused all kinds of odd behavior, which were immediately resolved when the rubber sheet was removed and the proper seal installed. Has anyone tried to adjust the pump governor?

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

Sixto and 86, this afternoon I pulled off the ELR plug and pulled out the OVP. it fired right up and idled really slowly, didn't blip the Tach (300?) The car was sun warmed and drove nicely. At the same place I pulled over and shifted into park. The revs dropped instead of rising - the car was "warm" (but engine only read 60 degrees, not 80 degrees). I've got to say that it performs nicely without those plugs. And backing out the ALDA was huge. Max, I'll try to disconnect the cruise linkage and unplug it tomorrow AM for a cold start - and try for the trifecta.

Before starting it, I opened the hood to see how to undo the cruise linkage. Not sure how to. The Wiper tank is still removed for easy access. And I can see a long plug under the cruise unit and assume that is the plug to disconnect. I left the cruise untouched. The OVP is out, and the ELR is unplugged. I reached in and glowed 2x then quick ignition failed. I glowed again and it fired up. Revs are low. It smoothed out in 10-20 secs. I fiddled under the hood and realized the cruise unit/connecting rod may be implicated in the cold racing! When I moved the accelerator linkage by hand it was very slow to return. But I could manually return it much faster. And it looked/felt like disconnecting the cruise's control rod was the cure. Any insights on the procedure disconnecting the arm so I can test this?

I send down the business end of a big long screwdriver between the lever and socket then twist to pop off the socket. Getting the socket back on is another story.

Sixto
83 300SD
98 E320 wagon

So, it looked/felt like disconnecting the cruise's control rod will be the cure. I just don't know which of the actuator rods is the one to disconnect. So I got a helper

Unfortunately, as i was watching the linkage in action - with a helper pressing the gas pedal, the throttle connector rod stripped out of the ball socket - as I was looking at it! The unfortunate part is that I broke the 1" long plastic cup socket end while removing it. I broke the threaded section. I can see the threads are all worn off. Looking around I see there are at least 3 of these threaded rods with cup-ends in the fuel linkages. Calling the local stealer resulted in OS. On the brighter side, if I knew which of the linkages I can disconnect to disarm the cruise control, I should be able to take a plastic ball cup off that arm.

Go to the junk yard and scavenge the metal ball ends off an older 617-engined 123 or 126 linkage. Note some are right hand and some left hand threaded. The plastic ones they started using on the 603 are cr*p.

The cruise actuator is the metal can that says BOSCH on it, it is behind the injection pump on the left side of the engine below and in front of the oil filter. Very hard to see with the intake in the way. The electrical cable snakes back to the firewall where it plugs into a connector near the glow plug relay and joins the main harness running along the fender.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

I've begun suspecting the cruise control unit - when cold - is sluggish/sticky until warmed. There is a resemblance in the cold start driving feel that is pretty similar to how Cruise feels. And yesterday's sun-warmed start at about 60 degrees had some of the same cruise sustain, but it didn't race. And I think I'm seeing the cold Cruise linkage return very slowly. Not sure unplugging will be enough. I haven't found a DIY on the Cruise Control unit or removal.

Jay Bob, I'll confirm the unplug tomorrow. I'm hoping the epoxy cure "rebuilds" the plastic rod end. And Monday I'll try finding a 617 non-plastic end. Sixto, The screwdriver-pop worked with a Big screwdriver. And it's dawning on me how lucky I was, because the actuator rod literally fell out the ball end as I was looking at it - not when I was driving.

So what's the next step in the process of finding the cause of the cold start racing: replace the OVP, replace the ELR plug, reinstall the epoxy and zip-tie "rebuilt" accelerator rod's ball end. Lube all of the 3 actuator rods active pivot points, hand work them. And test drive a cold start. Then disconnect the plug for the cruise control, leaving the cruise rods attached. and test that. Here's hoping the glue is good. (Raise a glass, and insert beer here.)

If you remember, I suspected the cruise control servo/linkage on an earlier post in this thread. I have found it to be a common problem. It is always the FIRST thing I check (by removing the control Rod) whenever an unwanted acceleration condition exists. It is "stupid simple" to do, and most always is the problem. Even though you had a mild case, be glad you found it early enough to avoid an accident caused by a mimicked "runaway " condition at speed. I am almost certain it would have gotten worse if you continued to chase other systems, and ignore the servo/linkage.

__________________

All Diesel Fleet
1985 R107 300SLD TURBODIESEL
2005 E320 CDI (daily)

LOTS of parts for sale!


EGR block kit
http://www.peachparts.com/shopforum/diesel-discussion/355250-sale-egr-delete-block-off-plate-kit.html

1985 CA emissions 617 owners- You Need This!
Sanden style A/C Compressor Mounting Kit for your 616/ 617 For Sale + Install Inst.

Sanden Instalation Guide (post 11):
http://www.peachparts.com/shopforum/diesel-discussion/367883-sanden-retrofit-installation-guide.html

Racing at idle seems to be cured. Reconnected the OVP and ELR. Disconnected both ends the Cruise Control's actuator rod and its plug on the firewall. And rebuilt both of the accelerator's rod's ball sockets with a fine-wire wrap (and will look for a spare). Glowed and it fired up. Now when I take my foot off the accelerator before it's warmed up, the car slows rather than holding the revs. And the ALDA tweek has put new pep in her step. Thanks for all your help, guys.

John do you have the small micro switch on the bowden cable .Check it and see if its contacting ,and clicking as it should. This is only a guess .

The microswitch on the 603's is on the throttle mechanism, it is only there to trip the A/C off at WOT.

There is a throttle position sensor inside the IP itself, but it has more to do with the EDS controlling the EGR valve than anything else. Emissions controls.

With the plug removed from the back of the IP, idle speed is completely mechanical and should be low (~450-500 RPM). Any higher and something is out of adjustment or sticking in the linkage assembly.

Looks like the OP found gummy ball joints and a sticky cruise control. Both very common issues on these engines.

If an accelerator linkage rod end was slipping in and out, I can certainly see that resulting in some odd behavior.

Has anyone every figured out the part numbers for the metal ends for the accelerator linkage rods?

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC