560SEL high Idle - PeachParts Mercedes-Benz Forum

garymand · #1 01-04-2007, 02:25 AM

Thanks for all the threads on similar problems. I finally found the source and solved the problem. EHA was off by about 1/8 turn, I think CCW, the little 2mm screw has no friction. I wasn't prepared for that and I'm usde to making sure an allen is seated so I moved it maybe 1/8 turn to start.

First: I learned how to test everything that effects idle and timing. Everthing tested good. The only way I could get the idle from 950 and timing from 20 to 25 was to lean the idle and take the vacuum off.

I finally took a close watch on the EHA current and it was +3 at 2500. I took two 1/4 CW and idle stayed high and the balance worse. So I went back 1/2 and another 1/4 and got lower idle and timing but balance between idle and 2500 was alittlle off. Another 1/4 ccw and idle/timing went lower now easily to 600 and 10, but 2500 current was -6. Back one 1/4 and 2500 current was -3, but I could get close to balance with an idle about 800 and timing about 20. So one more and I over shot a little. So 1/8 back and amazingly with just a little mix adjusting the balance was was overlapping and current was tight around 0 both 2500 and 700.

Timing is 5 with no vac and 15 with.

Sure glad I didn't go in swapping. Would have been faster if I had parts to swap... And thanks I've learned a lot.

david s poole · #2 01-04-2007, 05:09 PM

if you have to lean the fuel to get idle to come down then you must have a vacuum leak or two.when the throttle is closed the idle valve should be the only place that admits air into the intake.the idle speed computer if working correctly will keep speed down to 650-700.if you add more fuel and speed goes up then unmetered air[vac leak] is getting in.also at idle timing should be 12 deg btdc not 15.

garymand · #3 01-15-2007, 03:47 PM

Thanks David, I spraid carb cleaner at each injector got no change, around air horne assem and still no change. Is there a best way?

I rechecked to day with cold engine and found the EHA at 20ma dropping down to 3ma as engine warmed. Took awhile in the 40 degree weather. Finally got fluctuation 3.2 to 5ma. pin 3 voltage came in at 4.2 - 6V at idle and 6 - 6.5V with plug off ICV (1500) and 0 - 1.8ma EHA.

And Idle was back up at high 900 and 25 advance, 5degrees with no vac. Like back to where I was. Made no changes.

david s poole · #4 01-15-2007, 04:35 PM

you need to have someone run a smoke test on your intake manifold and you will see all the leaks.the rubber air balance tubes that join the injector cups together are famous for having small cracks on the underside where you can't see them.

just-n-time · #5 01-15-2007, 05:26 PM

HI I just ran the test again on mine and found nothing out side so I will have to move inside with some soapy water and a spray bottle.But to answer your question about smoke testing, I and my Dad kept bee's He passed last year,
and the bee stuff has come in handy.just find some one who has a bee keepers smoker I took mine and added a cooper line so I could get a smaller
stream of smoke find a leek and it will suck the smoke in much safer than spraying flammables all over the warmed Eng.Plus the harsh chemicals do harm the rubber seals and if they are already week,well you know.
j-n-t

garymand · #6 01-15-2007, 08:03 PM

Thanks, I do have aneigbor with one hive box. I'll ask him. It's getting close to 200k and I'm just starting to see and feel the aging starting. All the rubber is starting to harden. Wouldn't be surprised at a few cracks starting.

just-n-time · #7 01-16-2007, 07:11 PM

How did you make out with the local Bee keeper?