Would a defective WRD cause this?

[rgafitanu@gmail.com]

I decided to edit this post after I did some more tests. The warm up is OK, however it needs a good 5-10 pushes on the throttle to get to the 1200 rpm for warming up. If I do not give it some gas it needs up to 1 minute to raise to 1200 rpm and continue the warm-up. As expected during this time the idle is a little rough. Within 2 minutes it goes down. Recently the rpm reduction at the end of the warm-up is more abrupt than before.
Could this be caused by a thermostat with a sticky feeler that gets stuck extended even against the IP pin pressure? Repeated actuations on the IP linkages may force the thermostat feeler to retract and allow the warm-up process.

Thank you

[rgafitanu@gmail.com]

I had to bump it to show as new.

[mrfatboy]

Do the split linkage test from a stone cold start.  Do not use any throttle when starting.  Once started,  get out of car quickly and push down on the cross over linkage (giving more air). Does the rpms go up?  Engine run smoother?

I am just wondering if you are running really rich during warm up.  I'm playing around with a similar issue.  I had to remove the oval shims under the WRD to lean out FIP during warm up.  It helped.

I think these cars run rich at warm up but I don't think anybody knows how rich is normal.

[rgafitanu@gmail.com]

I wouldn't mind that it runs rich while warming up. I am after the fact that several good throttle pushes are required for the warming-up process to begin. Otherwise it's about 60 seconds for the warm-up to start and rpm to get to 1200. With the engine cold you expect the thermostat feeler to be fully retracted therefore the warm-up would start immediately. It's $24 on eBay so I should get one and replace it anyway.

[mrfatboy]

Maybe I'm misunderstanding you. The warm up process is based on the coolant temp.  The coolant determines the length of the thermostat bulb pin. The thermostat bulb pin pushes on another pin that goes into the FIP. That pin pushes on a lever that leans the FIP (pushes Rack back) until it hits it final resting spot.

The one important fact is that the FIP lever comes to its stop(full lean) first before the air valve begins closing.

Throttling the engine is just going to heat the coolant faster starting the whole process faster.

Now,  if you take out the oval shims from under the wrd the FIP will be leaner during warm up.  I bet your higher rpms will start sooner. I think this might be the result you are looking for.  It did for me: ).   It doesn't hurt to try before you buy a new thermostat.

[Benz Dr.]

Sounds like the slide valve could be stuck shut so that the engine thinks it's already warmed up. That would account for the very low idle speed when cold.