Starting Issues
 

I recently bought a 1992 300ce sportline in very very good condition. Obviously I did the initial pre-buy check etc and everything looked fine... also the guy had receipts of all repairs since 1993 when he bought it.

Suddenly the car has developed some trouble with regard to starting.
1) when engine is cold (engine temp <40 C) - one crack for like 1~2 second the car just starts up..- idles 800~1000 for some time and the idle drops (i presume this is normal)

but car seems a little resistive as if lacking fuel when you drive out - especially if push the gas a little more - it kind of catches on and is ready to fly!

2) when engine hot (engine temp 85~90 C) the car will start up in one crank - no problem here

3) PROBLEM - now leave the car for 10 mins or so and come back and crack up it takes like 15 sec of cracking and gas pedal pumping/pushing to start - also it starts rough and then evens out at normal idling...and drives fine after that.

I took it to an independent mechanic (C& H auto, Chicago) - where we changed Sparkplugs to Bosch Platinums - no improvement. {receipts say flue filter was changed like 3 yrs back with fuel pumps}


Also a voltage check across oxygen sensor was at 0.7 -0.8 - idly i guess it should be around 0.5 - but playing around with the fuel air mixture is very very sensitive and we could not get it at 0.5.

So next it seems as the oxygen sensor - but I am not sure if I am on the right path.. The independent mechanic comes highly recommended but he is also trying to figure it out. He suggests - distributor and wire replacement (tune-up) and fuel system cleaning.

I know a tune is something I need to get done since the car was owned by an older gentlemen and sat for 3 months -so far have changed oil/oil filter and topped off all fluids. (transmission and radiator flush need to be done).

Anyone has an ideas or know what could be the issue??

Fuel accumulator
 

I find it hard to say this but it sounds like you are in the beginning throws of the accumulator going south.Seems like the last week or so this has stood out as a recurring problem.you can find several post on this subject and some good how to info as well.JNT:silly:

Check the fuel pump relay.

i agree the fuel pump accumulator sounds like the problem because the fuel pumps were replaced[along with the fuel pump check valves].

I agree with the accumulator for the hot start issue.

I think your oxygen sensor may be TU. If you can't get it below .7, then the lambda system or EHA (not sure what a '92 CE has) is going to lean the mixture as much as possible based on a false reading. So get the proper (3 wire?) generic Bosch sensor from Phil for $35 or so, then adjust your on/off ratio as described in many posts.

when u say fuel pump accumulator - is this what u are talking about ??
http://cgi.ebay.com/ebaymotors/Mercedes-fuel-accumulator-300SEL-300E-W201-W124-W126_W0QQitemZ320092563566QQcategoryZ33553QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Also where in the engine bay is it located??

yes but it's not in engine bay,it's above fuel pump[s] by right rear axle.

Hot start issue is symptom of leaking injectors flooding the engine.

Try starting with accel pedal down some to verify.

when i depress the accelerator/gas pedal down during warn start - engine catches up earlier ..
does this prove i have leaky injectors ?

It more proves you're flooded.

It also proves you're not lacking fuel, which would be the problem caused by accumulator, etc.

the accumulator being faulty causes a drop in fuel volume which is why your car feels like it's trying to start before it does and by that time the eha which blew out to about 30-40 milliamps has it too rich,hence the black smoke and rough start.

so u are saying the accumulator is fine! !! right?

David - I don't have black smoke during start- also if it was the fuel accumulator failing - then it should also have problems at cold start also - (engine temp <40 C)?

I know it is not an expensive part and can be repalced- but i just want to understand it better how things work..

So far - I have these suspects 1) OVP 2) Fuel accumulator 3) O2 sensor

pls let me know

stand behind your car when someone else starts it [during the time when hard to start] the black smoke will only last 1 or2 secs.

Starting cold without problems would suggest that.

On our previous 300E, replaced accumulator and pump check valves and made no difference in hot starting problems.

Replacing injectors fixed the problem.

Since I already bought the oxygen sensor, accumulator, might as well get the injector and seals and see where it lands up!!
thanks for the helps so far guys will keep u posted.

Cold start -> OK
Hot Start -> OK

Warm start -> problematic.

I agree with one previous post. This is a typical symptom of slightly leaky fuel injectors.

When they leak a little, hot start is not affected because there is not enough fuel to leak out. Cold start is also not affected because there is enough time for the leaked fuel to evaporate.

Warm start is affected because there is leaked fuel (flood). Enough fuel has leaked and not enough time for it to evaporate. You can further confirm by doing a double start. Start it (it may not start). Stop and wait for a few seconds. Start it again (it should start now). The first (failed) start will burn off the leaked fuel and the second start will be successful.

Before you try to replace the injectors, try to clean using an approved fuel injector cleaner. Contrary to what have said by many, MB does approve two injector cleaners in their 2006 approved service products for all engines. On page 15, one is an MB product that you can buy from the dealer. Another is Chevron Techron.

You can get a 20 oz bottle and put in the tank and filled it up. Do a mixed driving and preferably over a few days. Let the car sit after driving (Let it leak so the cleaner can clean the injectors to simulate the leaky situation). Or you can go to Advance Auto Parts and get two 12 oz bottle (buy one get one free before the end of this month).

You should notice some improvement after one application (a few successful warm starts). You may need a second application. Change the oil after the applications.

This should cure deposit related leaks. If it is an internal (parts related), then this cleaning will not fix.

i am having the same type problem with my 1985 500 SEC USA version. I can be driving with my foot on the gas and the car will lose power and go dead. then it is hard to start but if i let it sit for about a minute it will re-start with ease what do i need to do to fix it

1985 500 SEC USA version engine stalls
 

i am having the same type problem with my 1985 500 SEC USA version. I can be driving with my foot on the gas and the car will lose power and go dead. then it is hard to start but if i let it sit for about a minute it will re-start with ease what do i need to do to fix it

This is helping me zero in on my situation, although I am guilty of what stevebl scolds us not to do, namely throwing parts at a problem.

My car, 1991 300CE at 143m, bought it at 111m. It has always had a slightly sluggish start. I occasionally get a quick cold start so that must be the cold start valve working? But for most cold starts, it doesn't catch for a couple of seconds, but it will catch. If I let go too soon and it does not start, and then I restart, it catches immediately. A hot start is fine also. But anything less than a hot start, it stumbles. The car otherwise drives and idles perfectly. I decided to change the fuel filter and since I was going to be rooting around there, I decided to change the accumulator. I only have history back to about 87m and no record of these changes. It's been a few days, and absolutely nothing has changed.

I have used Techron every so often since I bought the car. Some new injectors are on the way, so I'll give them a shot.

Thoughts?

Thanks,

glenmore
1991 300CE
2000 C280
1990 LS400

give a try replacing the injectors and see what happens

Thanks loubapache -- will do as suggested and keep you posted!!

I am having similiar issues with my 1991 300 sl . Morning starts are normal, after sitting for ten minutes to 1 hour the engine stumbles to life, after sitting outside in the hot sun ( 75-80 degrees ) this is my worst condition , :confused: it will sometimes require several attempts to get started,starts after short shut downs such as refueling are normal. Can flooding from leaking injectors be a problem after 8 or 9 hours if the vehicle is sitting in the hot sun??I was thinking about pulling spark plugs to see if they are fuel soaked to verify flooding ... any thoughts? Thanks dan

Also was thinking about coolant temp sensor being faulty...normal start after sitting over night (cool temps) difficult starts after warmed to normal operating temps and allowed to sit but not cool to stone cold . Any ideas? Thanks, Dan

OVP Relay
 

Did you ever consider the OVP relay?????

NOTORIOUS for crap like that-

Overage Voltage Protection relay

Is there a reliable way to test the OVP relay???

Does a 1991 300sl have an OVP if so where is it located? Dan

Stargazer, well how did you do?what where the results of your changes and did you do one at a time so we would gain the info needed for others?JNT

How cold ?
 

I was under the impression that the cold start injector,only operates when it is very cold out,That it dose not work just any time you start the car! Temp must be low enough for it to get the signal to inject!JNT:rolleyes:

On to the injectors! On removing the air filter, I had a eureka moment, when I saw that one of the injectors had an obvious leak. Luckily it was one of the easy ones to get to. The pairs of injectors on either end have great access but the two in the middle look difficult. I changed the leaky one and one other and am waiting some more in the mail. The injectors themselves look fine, the delicate tips look just like the new ones. The fit of the new Oring and new insulator in the head is tight. I had to tap them in with a 15mm socket. The old ones came right out. The old seals were very brittle and mashed. It was nice to freshen up the seals but after a couple of starts, I don't think this is the cause of my stumbling start.

glenmore
1991 300CE
2000 C280
1990 LS400

Here is a tip from a veteran MB shop owner. He advises that as our engines get some miles and age on them they tend to leak air. Thus when starting you should give a little throttle, press accelerator pedal down, then start the car.

Steve

Another trick is to turn the key On and wait for 10 sec before turning to the starter position....this assures full fuel system pressure before crank..........

Totally frustrating, isn't it?

Hey just-n.... i haven't had a chance to do it yet .... I just ordered some injector seals -- and will have it this week - then planning to do it this weekend ..also it is 40 - so am waiting for warmer weather also...

I also bought a fuel filter , fuel accumulator and OVP etc -- just to be sure!!

Update. Well I changed out five of the 6 injectors, and the stumbling start is basically the same. Although the car had been running plenty smooth, it runs even smoother now. The last injector is the one right by the cold start valve so I'll change it with the cold start valve. There are also some air hoses there and I just know they'll break if disturbed. I also tried a new fuel pump relay, which powers the cold start valve but again no change to the start. So that leaves me with the cold start valve as the last item to change. I'll throw in the towel after that.

glenmore
1991 300CE
2000 C280
1990 LS400

I will be doing the same thing tomorrow. Any tips on do's and don'ts would be appreciated. Am also prepared to change the rubber underneath the cold start valve, which also connects to the ICV. That will be the real challenge but have read some tips to deal with it.

Am hoping all these work will be worthwhile. What I am trying to corrrect is the false start to my 89 300e which I suspect to have leaky fuel injectors.

5 of the 6 injectors have pretty good access. I did most with a regular allen wrench but a short stubby would have been handy or best would be a ball allen. You can probably reuse the insulators but might as well change them and you'll need both new insulator O rings and new injector seals. Flare wrenches are handy. I also just changed the fuel filter. The insulators with new O rings are a tight fit. I tapped them in with a 15mm socket. Oil liberally around the new O ring with fresh oil. Take care when pulling out the old insulator. There will be a lot of dirt and grit there stopped by the O ring. Liberally oil the shaft of the new injector before you press it into the new seal. What I did was to hold the new insulator, insert the new seal into the insulator, oil up the new injector and press it in. Make sure the injector is correctly seated into the seal and then pull it and the injector back out of the insulator. Put the new O ring on the insulator and press into the block and then plug in your new injector w/seal.

I bought a new cold start valve gasket. It is just a piece of stiff paper.

The new injectors did not fix my stumble start but the car does run even smoother and throttle response seems to be crisper.

If you have and tips concerning the cold start valve, let me know. That is my next step.

Thanks,

glenmore
1991 300CE
2000 C280
1990 LS400

I'm pretty sure the your problem is related to either the fuel distributor or the black Bosch EHA valve mounted on it or BOTH.

Try to disconnect the EHA the start the car after 10 minutes to see whether it starts or not. If it started that doesn't mean that the EHA is bad but it could be the fuel distributor.

A couple of years ago, right after a head gasket replacement, I had an intermittent hard start. I took it back to the shop and he read some codes and suggested I drive it a bit more to confirm symptoms. He probably knew at that point what the problem was but didn't have the heart to tell me right after just doing a head gasket and water pump on the car. By accident I discovered that the EHA was not plugged in. I plugged it back in and the car was back to normal.

Could you over the diagnostic again?

Thanks,

glenmore
1991 300CE
2000 C280
1990 LS400

Very good write-up:
http://www.peachparts.com/shopforum/tech-help/159346-124-chassis-idle-air-hose-tricks.html

Another post suggested bleeding fuel through the distributor by taking the metal pipes one by one.

Anybody tried this with success?

posistion sensor
 

most likely the problem:book:

Cleaning
 

have them sent to a pro for cleaning much cheaper:pirate:

Why Not Fix It
 

Once the Idle air lines get hard they leek so replace them,Its cheep and solves a great deal of troubles when you go one step farther and replace the entire rubber pieces of the intake and vacuum ports.Very cheep insurance!:laugh2:

Wow.
 

:dizzy2: Thats a lot of parts!:dizzy2: