Who has arbitrarily adjusted the length of the throttle control rods?
 

I've been working on my 85TD and noticed that the throttle rods are way (some 1/2" or more) out of specs per the FSM section 30-300 for the 123.193 which I believe is the US version of the TD.


This car is sluggish off the line but the only things I've done that might affect running is adjusted the valves and changed fuel filters. Would you go through the FSM procedure and set the rods to specs?


I'm thinking of recording the initial lengths before making any changes so I can go back if necessary. Might this process be beneficial, a waste of time or detrimental?

I've not done it but would the way you have planned. The small things add up and make a difference. Check and clean the banjo bolt on the back of the intake.

Always wanted to check the boost pressure too but never did. It would be a rather safe bet that the pressure is lower than spec as the cars age.

Good luck!!!

+1 on that banjo and the line connected to it.

As for linkage, can you reach full throttle when using the pedal?

I've adjusted mine several times (turns out the biggest problem was that one of them was installed backwards by a previous owner), and found that the "factory specs" are assuming a best-case scenario, so it will still take some trial and error on a system that has worn parts. It's definitely worth doing, making sure the pedal clicks the switch under it (if you have one), and that the linkage hits all the stops.

I had some issues early on with throttle response and I checked the linkage with the FSM. Large set of metric calipers and patience, the response definitely improved.

I forgot. I did clean the banjo on the back of the head but haven't tested boost - but that's easy and a good idea. There are boost adjustment threads on here depending on which of 2 stock turbos are installed.

Same experience when I first got the Car. It was scary slow on the low end but once it got going it ran normal. I dreaded having to stop.

Apparently the former owner changed the lengths of the linkages. Use the correct manual and restore them to the factor specs.

Another thing that can cause it is if the part between the Pedal Linkage on the fire Wall and the Throttle linkage falls apart. It usually pulls out or the rubber cracks and breaks.

Start with factory settings,than adj.to what is needed. Note:each time a good performance
mod is done,less throttle is needed on take off,transmission will shift earlier a different
adj. may be necessary.
On the 84-85 300sd there is a bolt on ball that is adj.,more throw/less throw,also effects
trans shifting,injection pump position.
Get a couple extras when at the yards,drill hole and elongate to what ever linkage you may want to change. Can make a great diff. in performance and feel of vehicle.

There is a rubber thing about cube shaped which isolates the metal parts. With age it always falls apart and out. This leaves the throttle linkage flaccid an unable to reach WOT. Hooking it back together with almost anything will be an improvement. I believe I have used short pieces of rubber hose in the past with reasonable success.

A example of diff.throttle adj., Had a 240d,ran good,needed to push way down on pedal
to get going good,made car feel really slow. Shortened the throw on the lever to injection
pump,by adding the adjustable ball,now pedal inside only needed to push a small amount
but the lever to pump moved much further,even though the vehicle had no more power,
it did seem too,the car now was much more pleasing to drive.

I think Id start with an optical tachometer, and set the idle RPM, then adjust all the linkages from there.

Just my gut - havent done it. I do think that it takes more pedal on my 300CD than my 240D. The CD is powerful, "fast", and accelerates well. Its just a perceived push distance...

That reminds me. Tach doesn't work on this car. I haven't looked into it but isn't the pickup on the balancer?

The tach not working on mine was first the fuse on the relay behind the passenger side panel on the hinge side of the door jamb. Then the second time I pulled the big connector nearby and water poured out. That time I bypassed the EGR box and it's worked ever since.

The 85 is different. The 85 has a pickup on the flywheel, which sends a signal into a comupter in the passenger footwell.

The diagnostic plug and balancer pickup is still there, and will work but the tachometer is different itself so you would need to swap out an old one...

Thanks, I'll look at the 85Sd parts car. Hopefully the TD and SD are the same.