Starts Great, Dies as soon as Warms up! - PeachParts Mercedes-Benz Forum

Chiappino · #1 02-24-2007, 04:00 PM

Still trying to figure this thing out!!! Just cleaned the Idle control valve, new warm up regulator. So when I start the car when it is completely cold, it fires right up, idles at 1000rpm. As it gets to around 60 Degrees Celsius, the idle drops and it dies. You can give it gas and it will run, but wants to die. Any ideas? Thank you again!!!!!

Chiappino
84 Euro 500Sl

MattBelliveau · #2 02-24-2007, 04:14 PM

Fuel pump relay (if equiped).

Chiappino · #3 02-24-2007, 05:52 PM

Yeah it has a fuel pump relay. Is there any way to test it?

just-n-time · #4 02-25-2007, 10:51 PM

Quote:

Originally Posted by Chiappino

Still trying to figure this thing out!!! Just cleaned the Idle control valve, new warm up regulator. So when I start the car when it is completely cold, it fires right up, idles at 1000rpm. As it gets to around 60 Degrees Celsius, the idle drops and it dies. You can give it gas and it will run, but wants to die. Any ideas? Thank you again!!!!!

Chiappino
84 Euro 500Sl

High Idle 1000 should only be for a few seconds then it should drop to say 800 and as it warms on down till it reaches the 700 mark,in gear 600 to 650you have a vacuum leek. smoke test the engine, you probably will find that the idle air lines are one of the leeks,Have fun let us know how you are getting along with it, others would like to know too.

Chiappino · #5 02-26-2007, 03:08 AM

Very interesting..... I'll do some more looking around. Not sure if I can do the smoke test myself. I'm almost to the point of dropping it off at my local shop and saying "fix it"!!! That may be out of my price range. I'll keep you all updated. Thank You

Chase
84 Euro 500SL

Chiappino · #6 02-27-2007, 02:58 AM

After reading some other posts.... and having issues with my ignition module blowing up. I decided to get a new coil.

SO.....

Started her up as usual, let her warm up, started running a little rough, idleing at around 700rpms.... still a little shakey. I try to give it a little gas, expecting it to die. Doesn't die, returns back to idle. Impressive.
Tried it again. Same reaction.

Time for a test drive.

Took her out on the road, 1 mile down the road. She dies as I'm slowing at a stop sign. I pull it into a parking lot. Try to start it, seems like I'm not getting spark (could have just blown another Ignition module) BUT NOPE!!! I let it sit for 10 minutes, and she started up while giving it a little gas and she fired up and idled around 600. I adjusted the air/fuel mixture more lean thinking I'm fouling the plugs. Seems to work.

I hop in the car, take her on and off the freeway for a couple laps, she dies twice as I'm slowing, but stayed at idle about 10 times. HUGE IMPROVEMENT!!!!

I was able to drive the car, even able to park it in it's usual spot. Which has been hard when it wouldn't run. So that's that for now, I'll keep ya updated.

Also found that one of the spark plug wires is arching after it gave me a jolt after touching the top of the distributor. Time for new wires. That should fix the rough idle.
Thanks all...

Chase
84 Euro 500 SL

Chiappino · #7 02-27-2007, 10:29 PM

Well, got new wires today.... took all the plugs out, they were extremely carboned up. I cleaned them up, cause they are extremely new, threw them back in and put on the new wires. Thought I would see a big diffrence!!! Sure did.....car wouldn't idle again!!!! Started up fine, but no go after moving it.

As I got back home, the exhaust sounded really funny..... looked underneath the car. The catalytic converter was glowing bright red!!! Which I'm guessing is because I have so much excess fuel. Guessing my fuel/air ratio is way off. I think I have to bring it into the shop to fix this one.

Chase
84 Euro 500Sl

ctaylor738 · #8 02-28-2007, 01:18 PM

It seems unlikely that the mixture setting could be that far off, so ...

There is an o-ring on the plunger in the FD that can wear out and cause extremely rich running. Definitely worth checking out.

Then I would look at system pressure. It should be around 5.2 bar. If if is high, you might have a fuel pump that's gone hyperactive on its way out or need a new pressure regulator.

Then check your control pressure when warm. It should be around 3.8 bar. If it is low, then you may have a blockage in the fuel return line, a malfunctioning warm-up compensator, or your FD may have gone south.

just-n-time · #9 03-06-2007, 09:48 PM

Great follow up wish more would do the same.JNT

250 Coupe · #10 03-06-2007, 11:46 PM

Cats will glow from a massively rich condition. I got the ones on my '87 5.0 Mustang to about 1100F one night by washing the engine and not drying the distributor cap out. I never had a problem passing emissions with that car but it had a newer generation cat VS the older ones in your car.

Double check the firing order and plug wires. You stated that it ran poorer then you expected after a wire change. It is also possible that you damaged the O2 sensor with the extreme heat. This assumes that you have the Lambda system added to your CIS. I'm not sure what year that happened and the Euro thing adds a twist. www.w116.org has the CDROM online so you can do some research about pressures and on/off ratios etc…

Also, see my post in the Vintage forum about checking fuel pressures.

Michael

Chiappino · #11 03-13-2007, 08:48 PM

After figuring the whole mess out.....thinking I had the car running ok. I threw on new cats, Oxygen sensors, plugs, wires, coil. The car still idles at around 500 rpms. With a little shake. I still think it's a little miss, but my brother says it's just the motor mounts. Put new plugs in yesterday, first time I'd pulled them since we fixed the fuel distributor piston. (Which I had just cleaned the plugs while the fuel distribuor was being fixed) I noticed something very strange. The first cylinders on either side were burning correctly. They had a nice tan color to them. The other 6 plugs were carboned to all hell. Car ran decently well, but they were bad.

Put new plugs in, started her up, ran great, for the first 20 minutes or so. Then back to 500rpm idle and little shake.

I needed to smog it by the end of the month, figured what better time than now to find out it's gonna fail. Sure enough. Gross Polluter. The CO max is .55, I ended up pushing somewhere over 8.5. NO BUENO!!! Not sure exactly what's going on. I'm guessing the whole fuel distributor is shot, but before I go blowing $500 more. I'd love some advice.

The car runs strong, you can only feel the shake when it's idling.

Thank you all.

Chase
1984 Euro 500Sl

ctaylor738 · #12 03-13-2007, 09:29 PM

There is no way to tell a bad FD from bad injectors. Since the injectors are cheaper, start with them. Pull them out and get them cleaned and tested, replace the ones that are beyond hope, and put them back in with new seals and o-rings (around the sleeves/holders).

Then try to adjust your mixture using the voltage from your new O2 sensor. Connect a voltmeter to the sensor and to ground. Adjust the mixture to get around .5 volts at hot idle. CW is richer, CCW is leaner, voltage will decrease as mixture leans.

I will test and clean your injectors if you send them to me. It will cost you shipping and a can of BG-44. Email if this will help.

Good luck.

just-n-time · #13 03-16-2007, 02:18 PM

One other thing I would like to say, people say they clean the ICV but I wonder,is it dirt that is the cause of it not letting in the proper air,for air fuel mix at idle,or is it electrical readings? I say this because I too cleaned one then bought one (used) the second worked much better but I now am like you to low in idle.JNT