My 1986 300E has a cold start problem like many I've read about in this forum. First start in the morning (or after it sits a few hours) is difficult. I can start it only by holding my foot down on the accelerator pedal while cranking. It catches pretty quickly, then I have to carefully keep the RPMs at 1000-1500 for about 15 seconds and it will then hold a low idle while it warms up. The idle speed when warm is about 700, 600 in Drive. Power seems okay.

At this point, I'm ready to buy and replace the EHA. Every thing else I find seems to be okay:
* the dual engine temperature sensor (rear of engine) has the correct resisatnce on both legs and the wiring is fine to both computers.
* the OVP relay and fuse are fine (replaced a year ago)
* voltage is getting to the cold start valve
* idle control actuator resistance is 8 ohms (seems reasonable) and it is getting voltage to it.
* repaced the plugs, wires, cap and rotor a few months ago.
* All of the vacuum and air hoses seem intact and I am getting pretty good vacuum.

Anything else I should try before I get an EHA on eBay? (And is a used one a reasonable risk?)

Thanks.
Brent Smith
1986 300E 273k miles

Maybe the idle control valve is gunked up. Does it slide open and closed nicely?

I thought the EHA was more likely to play up when warm.

__________________
1990 300TE

"24 hours in the day. 24 beers in a case. Coincidence? I don't think so."

Good idea. I'll pull it in the morning and clean it and see how it operates.

Thanks.
Brent

Look at ps2cho's website www.w124-zone.com for the idle air hose replacement DIY. Could be your problem!

I removed the idle control valve to clean it and found the following:
* the hose from the air intake to the valve had a 2" split
* after cleaning the idle valve, I noticed that the de-energized valve only opened about 1/8". When applying power, it might close or not. When de-energized again, it might open to 1/8" or it might stay shut. A little prodding with a screwdrive ands it would open, but just a bit.

I replaced the hose and put the idle valve back in (no spare). Now, it will not idle at all by itself even after warming up a bit. If you take your foot off, the engine will stop.

Does the idle control valve open further than an 1/8"? It also seems to stick. I will plan on getting a replacement if I can find one. Any comments out there with idle control valve experience?

Thanks.
Brent

It should open all the way but only close most of the way and do both smoothly. Did you clean it with carby cleaner? If you are getting it to click by applying power then maybe there's some gunk still in there. If you can get to a wrecker yard then try and pull a used one for now.

I think a newie is about $250 from various sites inc peachparts.

__________________
1990 300TE

"24 hours in the day. 24 beers in a case. Coincidence? I don't think so."

Thanks benzme. That is what I expected. This one is probably shot. I cleaned it with carb cleaner, but the "shutter" has a hard bind and will only open a very little bit and sticks closed. There is probably an internal return spring that is broken. I'll have to get another one, maybe used.

Brent
1986 300E

I got a good spare in front of me but you're a bit far away

Have you tried running with it disconnected?

Don

__________________
1990 300TE

"24 hours in the day. 24 beers in a case. Coincidence? I don't think so."

yeah...mine opens and closes no problem as well. Need a new one.

Thanks, guys. Even disconnected, the problem is that it sticks at closed or at just about 1/8" open. It is probably stuck closed since the car will not stay running. Previously, it was probably stuck at the 1/8" open and would run after warming up a bit. I'm just going to get another one. There are used ones on eBay for $40-70. The new ones are $200+. I may try a used one--since I'm a cheapskate.

Brent

I had similar problem with low idle start when cold. Replaced the idle control valve with used one and starting and Idle sequence back to normal,YYYAAAYYYEEE!!!

I replaced the idle control valve with a used one from eBay ($50 including shipping). I also replaced the hoses connected to the valve. They were hardened and cracked. The car now starts from cold in one try and holds the idle just fine from cold to warm-up in Park, Drive with or without the A/C.