I have a 1985 euro 500SEC that has been retrofitted with the cat and EHA valve. and I have spent a lot of time researching this forum to tune my car correctly to closed loop along with the perverbial intermitant high idle that seem to have started within the last 9 months. Great forum.

The current emission test is an idle and 2500 RPM back to idle. Fortunately the high idle problem did not occur at the 2 test runs. Results were high on HC and CO at idle.

HC PPM Max is 220 and CO % 1.0 max my reading were:
1rs idle 254 4.93
2500 91 .98
2nd idle 236 4.51

I thiought my timing might be off so I reset fromTDC to 10 BTDC and got vertually the same results. So I am thinking about tackling the closed loop tuning again brushing up on the posting again. I tend to think I am running a little rich.

I bought a volt ohm meter with Hz to see if I can make the adjustments.

I pugged the meter into the back of the EHA after the car was warmed up.(no #3 pin on Euro) When I first looked at the reading they were stable at about 46% (or 36%).
I thought this was great, but after about minute the readings started to bounce around 39-69 or there abouts and would not stablize. Restarting dulicated the results. I figured my meter is telling me there is a lot of adjustment going on and look for average. If I lean the car out while running I can adjust the range and figure an average will do. Interesting by making mixture richer with the 3 mm wrench, I can go to 99% and can feel the EHA not vibrating so my % must be for off.

Like to know if I am on track with this in hitting closed loop?

To add to the excitement the car decides to go into high idle 1500 RPM when I restarted it after 15-30 minutes. After about 5 minutes it dropped back to normal 700 RPM. Since I had the meter there checked the frequence across the ICV and it was like 1% (or 99%) at high idle. Basical the same a pulling the plug off. I have cleaned the ICV a couple of times trying to find out source of intermitant high idle ICV or ICU. When it dropped in RPM reading was more like 60%. I do no know if this is part of the problem emissions problem, but I think the idle control unit must be the source of the high idle because the value seems to work OK. Any help here would be apprecaite.

Thanks,

Kurt