Another vacuum related issue, only when cold.

[48hp]

So I've enjoyed reading the thousand posts covering vacuum and vacuum related issues. Unfortunately none of which addressed my issue specifically.

Upon initial cold start up the engine idle is a bit twitchy and the vacuum/economy gauge shows only three quarters to left at idle. Once the engine warms to normal operating temperature the vacuum/economy gauge spikes immediately to full vacuum.

Would this suggest the warm up regulator?

I have replaced every vacuum fitting under the hood this evening, minus those found at the throttle body.

Any suggestions would be appreciated. Thank you.

[cctoronto]

Originally Posted by 48hp

So I've enjoyed reading the thousand posts covering vacuum and vacuum related issues. Unfortunately none of which addressed my issue specifically.

Upon initial cold start up the engine idle is a bit twitchy and the vacuum/economy gauge shows only three quarters to left at idle. Once the engine warms to normal operating temperature the vacuum/economy gauge spikes immediately to full vacuum.

Would this suggest the warm up regulator?

I have replaced every vacuum fitting under the hood this evening, minus those found at the throttle body.

Any suggestions would be appreciated. Thank you.

I have a similar issue, motor smooths right out in about 4-6 seconds. I was also thinking that it might be the WUR after reading a number of posts on this matter recently... I haven't noted what the vacuum gauge is doing... I will check it later today see if it is consistent with your experience...

[fjs560]

By twitchy do you mean rough running till it runs for a minute. i have begun to experience that with the 560 now that it is getting colder here. i have not noticed my vacuum gauge but will see what it shows. Generally the hard starting/roughness in cooler weather could be the cold start injector. I am not terribly familiar with the Benz as it is new to me but my Ferrari has CIS injection and the cold start injector is triggered by a sensor in the coolant.

[48hp]

Thank you for the replies.

I am not experiencing a cold start problem at all, she fires right up and comes alive instantly. It's twitchy as in there is a slight miss until warm.

Look forward to your findings.

[daryn]

Slight miss until warm seems to be a fueling issue like my car has. It runs like crap for a minute when cold like one cylinder is missing then vroom the engine speed raises and the car runs fine.

I don't know if the fueling issue is caused by the vacuum or something else though.

[rondor2]

Same here almost. Mine idles rough but runs great very smooth and powerfull. The economy guage is pegged to left at idle.

[48hp]

As an aside...I took the SL out for a nice drive today for the first time after having replaced all of the vacuum fittings last night. Several notes are worth mentioning for reference.

1. The overall idle is noticeably smoother warm and cold.
2. There was a minor WOT sputter that is now no longer present.
3. The idle was +-700rpm and now it is +-800rpm at running temp.
4. Acceleration is more consist, positive and predictable. Fun.
5. The Getrag is fantastic. (nothing to do with this thread's topic but worth noting again.)

Anymore thoughts on the issue outlined above would appreciated. Thanks!

[rowdie]

Techron works wonders for FI.
There was a thread with pics of removing the WUR and cleaning it. It may have been a post within a thread. That makes it harder to find.

Screw you and the Getrag you rode in on. Is my envy showing? LOL.

[48hp]

Originally Posted by rowdie

Techron works wonders for FI.
There was a thread with pics of removing the WUR and cleaning it. It may have been a post within a thread. That makes it harder to find.

Yeah I buy the Techron by the gallon. I'll try and dig up the WUR clean up thread.

Screw you and the Getrag you rode in on. Is my envy showing? LOL.

[rowdie]

Never mind. It was a fuel dist. disassembly and cleaning.
http://www.benzworld.org/forums/r-c1...ing-valve.html