Won't idle when hot

[Vetruck]

These guys were less expensive but would have taken a few more days. I had mine overnighted from anther company that had it on their shelf and got it right out to me immediately.

Here is the best price I found if you can wait a few days for shipment.
http://www.new-part.com/product/merc...FS9dQgodziMAjw

[bpeter]

Thank you for your quick reply. The symptoms that my C220 exhibits are somewhat similar but not that frequent. It occasionally (once per week) stalls on only very hot days. It has so far only happened when the outside temperature was over 90F. When it is colder (e.g. morning and evenings), it never happens. The engine temperature is in the normal range 85-100C (I replaced the thermostat about 20K miles ago). When it is very hot outside, the engine seem like it does not have all the power it should have. I checked the intake air temperature sensor readings yesterday using the OBDII reader and it showed 137F while the outside air temperature was about 80F. I was idling in the parking lot when checking. I know the air will heat up a little bit before it gets to the IAT sensor (the reading seemed a bit high to me, but the guy at AutoZone thought it is often around 130 b/c of the engine heat).

Let me know your thoughts about this or other items to check. I have not checked the wiring on the TB (it is probably still original).

Some items that I have replaced over time are the fuel pump (original Bosch), fuel filter and fuel relay about 15K miles ago. The new Bosch remanufactured MAF sensor and spark plugs have about 2K miles on it. Checked air filter (looked clean- it was replaced about 10K miles ago).

[Vetruck]

bpeter, when you start the car in the morning (first start after sitting for a while) will the car start right up and die a few times and then finally stay running after the 2nd, 3rd or 4th attempt? That was a symtom I had for 6 months when I bought this car. I thought it lacked possibly a bad coldstart injector of something, but when I changed the TB this completely went away and the cars starts perfec tthe first time every time. It used to act alot like it was very cold blooded and had to sit and warm up for a while before you tried to move it, now I can put it in gear immediately and ilde it out of the garage without it dieing or stumbling like it was cold blooded.

hope that info helps with your diagnostics.

[Vetruck]

I also had about 3 or 4 incidences where I had to run recue my better half when she stopped somewhere and then came back out of a store to restart the car and nothing- like as it the overload protection relay or the fuel pump relay or something was going bad. I would open the truck and jiggle the little green box next to the battery adn then tried it and the car fired right up. strange, but I never replaced any of that and since th TB swap I have not had this issue either.

[bpeter]

It never happens in the morning when it is cold. I only see it happen after the car gets to its operating temperature and only on the days when it is really hot outside. So maybe I have a different issue. I can start a new thread and ask everyone if they have any suggestions.