Shaking problem on start up 1989 300E

[300ESUPER]

I have posted this problem before and I have gotten some really great advice. My 1989 300E has a problem shaking when I start it up. The rpms do not hold. I have to press the gas pedal to keep the car on high idel so the car does not shake and sometimes the car stalls. I have to start the car 2 - 3 times to get the car to stay on (this happens sometimes). After driving for a couple of minutes the car is great. When I get to where I am going I will turn the car off. I will get back to the car after 20 min and the car starts up great. When the car is sitting for a couple of hours the problem comes back. I should mention that there are some times that the car starts up great, this is usually when it is a bit warmer outside but not all the time.

This is a list of parts which I have changed in the last couple of months:

Distributor rotor
Distributor cap
Voltage protection relay
Water temp. sensor
Battery
Neutral saftey switch
Fuel filter
Both Fuel pumps

Please help!!!

Fab

[TeeJay]

Have you checked your sparkplugs? One may be fouling up.

[MattBelliveau]

And Sparkplug wires?

[300ESUPER]

The sparkplug wires are 4 years old and the spark plugs are 1 years old. How do I test the wires?

Thanks

[300ESUPER]

Would a fuel pump relay cause this problem?

[Mike Murrell]

In my experience, a faulty fuel pump relay either prevents the car from starting or causes the engine to die while underway.

I doubt your shaking issue could be attributed to an FPR.

My 2 cents.

[BENZ-LGB]

Originally Posted by 300ESUPER

I have posted this problem before and I have gotten some really great advice. My 1989 300E has a problem shaking when I start it up. The rpms do not hold. I have to press the gas pedal to keep the car on high idel so the car does not shake and sometimes the car stalls. I have to start the car 2 - 3 times to get the car to stay on (this happens sometimes). After driving for a couple of minutes the car is great. When I get to where I am going I will turn the car off. I will get back to the car after 20 min and the car starts up great. When the car is sitting for a couple of hours the problem comes back. I should mention that there are some times that the car starts up great, this is usually when it is a bit warmer outside but not all the time.

This is a list of parts which I have changed in the last couple of months:

Distributor rotor
Distributor cap
Voltage protection relay
Water temp. sensor
Battery
Neutral saftey switch
Fuel filter
Both Fuel pumps

Please help!!!

Fab

fab, I previously owned a 1991 420SEL. When it develpoed a rough idle upon start up, the dealer suggested throwing parts at it, to the tune of $2k. I rfused and instead took the car to an indie.

The indie perofrmed a leak down test and found that one of the vavles was sticking open when cold. He inserted soe sort of metal shimmie and the valve was working better. the best thing, no rough morning/cold idle.

I am not exactly sure of the explanation above. all I know is:

1. He did a leakdown test

2. He inserted some sort of shimmie on one of he valve springs

3. The rough idle went away forever

4. It cost less than $200.00 (as opposed to $2k)

Have your indie try it.

[Beach_Benz]

1990 300SE
Engine 103.981
Chassis 126.024

I too have been experiencing the same rough cold (meaning engine has not been started in 8 hours or more) start up as mentioned above. I just bring the rpms up manually to about 1000 after starting and hold the idle there for 15 seconds, and then I let off the pedal and the engine idles beautifully. I know this isn't a fix, but it does work for me.

[haasman]

If all the above problems are related to hydraulic lifters, Larry Bible on this site had a great suggestion that I have used with good success: Run a diesel oil in your engine for a few oil changes. Use a 15w-40 type. The diesel oil has better cleaning and oil impurity suspension qualities. It helps in cleaning older engines and their valve train.

Haasman

[300ESUPER]

Thanks for the suggestion but I thought it was a bad thing to use deisel oil in an non-deisel vehicle.

Fab

[halman2228]

..does the 300 have one? If not, what does it use as a compensator for cold engines?

Symptoms are pointing (me anyway) in that direction or possibly a temp sensor failing (a LOT cheaper fix)...

Search the forum - it's a common enough problem that its posted with the correct solution I'm sure...

Kevin

P.S. - search "cold start" and you'll most likely find the thread with your solution

[300ESUPER]

I have already changed the water temp sensor and I also changed the ETC sensor.

Is there another temp sensor that I should look for?

Thanks

Fab

[haasman]

Fab

Thanks for the suggestion but I thought it was a bad thing to use deisel oil in an non-deisel vehicle.

Not at all. It is generally excessive for ongoing oil but to clean out the engine innards it is a great idea.

Haasman

[simmo300e]

Originally Posted by haasman

If all the above problems are related to hydraulic lifters, Larry Bible on this site had a great suggestion that I have used with good success: Run a diesel oil in your engine for a few oil changes. Use a 15w-40 type. The diesel oil has better cleaning and oil impurity suspension qualities. It helps in cleaning older engines and their valve train.

Haasman

That's an interesting suggestion. I wasn't aware there was a special oil for diesel engines, probably because I've never owned one. However, just for reassurance, if I was to do this, will it mix OK with normal oil or should it be flushed before changing?

(Might seem a silly question but the last time I caught a diesel discussion mid-thread I did ponder, just for a minute, the practicalities of putting a bottle of high-detergent ATF into my petrol tank to clean out my injectors )

[haasman]

It think putting ATF in a gas car is a quick way to kill the cat.

The oils are compatible. It is that the diesel specific oil suspends dirt particles better and also has, as I understand it, better detergents.

I am about to change the injectors on the 93 190e. I am wondering if your car, being a 1989 300E, might not also be a candidate? Every so often before an oil change, I will run a double-dose of Techron Fuel Injector cleaner in less than a full tank. I will drive the car fairly hard (once warmed up) and it does seem to help. But if your injectors are leaking and stubling at startup is a sign, no cleaner will cure the problem.

Haasman