Just when I thought my idle problems were fixed...300E missing again!!
 

Hello Board,

After replacing my injectors my car ran great. I thought my idle missing problems were gone. Well now the exact same problem has resurfaced. It now hesitates very badly on the first start up and each start up thereafter. When I press the gas, the car bogs down and acts as if it is about to stall. My mechanic said that it might be a large fuel relay that controls the mixture at idle. He also said it might be the EHA located on the side of the fuel distributor. Well I unplugged th EHA and the car did not perform any differently. Could the EHA be defective??

Overheating and stalling!! My car is driving me nuts!!

Bump---HELP!!!

Have you or your mechanic tried getting the test harness and testing the EHA, ICV and O2 sensr the way SteveB has often suggested on this forum and in his article?? Without conclusive test results its just a guessing game for us and you.

Just cleared up a headache of my own. After changing coolant, my 300SE had a miss in the #3 cylinder. Checked it five different ways and finally discovered by accident that the plug was bad. It's a Bosch Super H9DCO with less than 5,000 miles on it. Still can't figure if/what the coolant change had to do with it.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD

Sixto,

I'm not sure if you read my post of my tormenting E320 but I just resolved a stumbling issue, that's been driving me crazy all summer, by changing the spark plugs. I too was running the Bosch Supers and they had about 16k miles on them when the problem started.

I put a cheap set of Champions in it and it's been smooth as silk ever since. I know the Champions have resistors built into them but I'm not sure I'm going to trust another set of the Bosch's after my recent hair pulling, head scratching experience.

Makes me wonder if Bosch put out a bad batch of Supers or if they just don't normally last very long. HMMMMMM

Plugs rarely go bad, and almost never in a good engine.

They do get fouled by oil slipping past worn valve stem seals/guides or piston rings. If you constantly need to replace plugs, try and discover why!

In my case the plugs look like I installed them last week. They all look the same - clean. After further inconclusive testing, I think heard a tick-tick-tick from the area of the one bad plug suggesting a bad insulator or cracked ceramic case or something like that.

I haven't sworn off Bosch Supers, but I have to wait until I have to put in a worthwhile internet order since I can't find a local shop that stocks H9DCOs. 'til then it's cheapo Autolite 104s. But there might not be a 'til then since I'll be selling the 300SE shortly.

Sixto
95S420
91 300SE
87 300SDL
83 300SD