Idling Problem - PeachParts Mercedes-Benz Forum

Bishop · #1 10-18-2010, 03:45 PM

I have a 89 S420 that for it's time it has run excellent. I think my wife's been putting a cheaper gas in it to save money.

Now it has a problem idling. I have run two cans of Seafoam thru the gas tank and the performance is 70% better at idle, as long as there is sea foam mixed in the tank.

A fresh tank of 93 octane from Chevron and the idle is rougher. With Seafoam better, with out poorerand idles about 600-700 rpms.

I want to know if a Oxygen Sensor change could help?

Working, money was no object, Retired now with Obama, moneyless and poorer.

pawoSD · #2 10-18-2010, 03:53 PM

How many miles on the engine? Injectors? Spark plugs? ignition components? Running low grade gas is not good for the engine. Fuel pump age? Temp sensors? Air filter? There's a lot of things that can cause a poor idle on a gasser. Check for vacuum leaks?

Its a 420SEL, there's no S420 in 1989.

Retired with no money is not Obama's fault, its called poor planning or living beyond your means. Blaming others is always easier.

Bishop · #3 10-18-2010, 04:34 PM

Please check your information about the s420 in 89 since I've had it for 20 years.

190,000 miles, new plugs and plug cables and only ran Chevron 93 for 19 years. Ran great until cheap gas intro in system.

I retired in 99 with 900,000 in one ira and 500,000 in another ira. Both with American Express FP, Clinton didn't care, Bush protected the country but failed in economics.
Obama killed what's Bush left to fail. Nafta, and promoting American businesses to invest over seas has killed our economy.

I still have 500,000 in invested cash other and drawing interest only for retirement so don't lecture me on my failures. When you get there, look inside your own before you criticize. Professional investing is the way to go, but with a corrupt federals cashing in, causing crashes, it's hard to win everyday.

Should I have stated my income before I requested help on keeping a 21 year old classic on the road?

Look it up and inside before answering again.

Does anyone else have an answer about a 89 S420 idle problem? I was only asking if a oxygen sensor would make a difference, but if you don't know they were made in 1989 please don't help me.

Bishop · #4 10-18-2010, 05:58 PM

Obama scares the hell out of american businesses, everyone is shutting down, waiting for another ignorant speech or bill from the idiot. The Dow is dead and sits, the nasdaq is afraid tomorrow.
This is the greatest country on the planet and right now and for 10 years the economy has produced nothing.
Reagan filled his promises and the USA prospered, Bush 1 followed his rules in the begining but stupidly fell into a Liberal trap and failed, 8 years of Clinton a another Liberal caused the downfall by not killing Osama when he had him in a sniper's crosshairs, 9/11 and 8 years of Bush 2 draining the country again, and you say Obama, ( The most Liberal politician in 50 years ) didn't cause my money woes.
You need a history lesson, or you, yourself are a Liberal.

If you don't understand I'm sorry for you and your kids will wonder why daddy or grand daddy didn't stop the Liberal politicians when they had the chance back in 2008, and again in 2010, in 2012.

Or did your family go with the comet when it came near the earth a few years ago and took their souls with it.

And Yes, I have an 1989 Mercedes 420SEL but when you look up a part you only need to say 89 420......

gregs210 · #5 10-18-2010, 06:54 PM

Those are the old thimble-style O2 sensors if I'm not mistaken. They do get really lazy as they get older and are pretty cheap, so I'd suggest changing it out.

You may have a lot of carbon built up in the combustion chambers from the cheap gas. Try a higher concentration of additives; some have also run a few ounces of pure acetone (IIRC 3 oz per 10/gal fuel) into a full tank of gas, there is lots of info on the web about it. It's much less expensive than branded additives.

One additional idea: the butterfly valve at the throttle body can get pretty dirty with a lip of carbon and other deposits, so open that up, spray some carb cleaner on a rag and wipe it off. It's a common problem on all makes and models and contributes to rough idle.

Now I'll school you about what car you really have and how to budget.

Seriously, good luck with all of it.

Bishop · #6 10-18-2010, 07:32 PM

Thanks,

I'll try that tomorrow morning, sorry for the rant, Liberals just make my skin crawl.

Thanks again...

whunter · #7 10-18-2010, 09:31 PM

Quote:

Originally Posted by Bishop

I have a 89 S420 that for it's time it has run excellent. I think my wife's been putting a cheaper gas in it to save money.

Now it has a problem idling. I have run two cans of Seafoam through the gas tank and the performance is 70% better at idle, as long as there is sea foam mixed in the tank.

A fresh tank of 93 octane from Chevron and the idle is rougher. With Seafoam better, with out poorer and idles about 600-700 rpms.

I want to know if a Oxygen Sensor change could help?

Working, money was no object, Retired now with Obama, moneyless and poorer.

Model: 420SEL
Chassis: W126.035
Years: 1986-1991
Engine: M116.965 V8

Check all rubber hoses, seals, etc..