For the past year my car (
For the past year my car (1985 308QV USA car) has had a cold start and a hot start issue. I have already replaced the check valve in the fuel pump and the accumulator. I do not drive the car much, but this is becoming a pain for me. Below is some more info regarding these problems.
When I start my car the idle is suppose to be about 2,500 rpm until the engine is warm. However, when I start my car cold the idle is at 1,000 rpm's for about 30-60 seconds. After that time the idle goes down to 500 rpm's for about 10 minutes. After 10 minutes when the car is warm, the idle returns to 1,000 rpm.
During the past two weeks I though my Aux Air Valve was bad. I tested the AAV and it checked out OK. Today while in the shop, we noticed that the cold start air valve that is connected inline with the AAV is missing on my car. It appears that someone removed the cold start air valve and bypassed the high idle system. This appears to be the reason why my cold idle RPM is so low.
Does anyone know where this part is suppose to be located in the engine compartment and where the electrical connection is? I show my car at FCA events and I need to keep everything 100% stock. If anyone can take detailed pictures of a USA 308QV engine, I would be very interested in looking at the pictures. I would like to see exactly how this part is piped in and where it is located. Please feel free to email them to me at [email protected]
Also, I do not have a cat on my car (it was hollowed out by the previous owner).
When my car is at operating temperature, I have a difficult time starting the car. This does not appear to be a heat soak problem (when the car sits for several minutes) because if I shut the car off for a few seconds (or stall at a red light), I have a very hard time starting the car. As I previously stated, I have already replaced the check valve in the fuel pump and the accumulator. Murphy's law was working today and I could not recreate the hot start issue (this is a first!!!) while in the shop. As a result, we could not take any fuel pressure readings.
We were able to read the CO levels, and the car was running rich. The CO level was about 3.5, and we lowered it to 1.3. I wanted it to be at 1.2 or lower, but the engine idle did not sound right at any setting below 1.25-1.30. Would a CO setting of 3.5 cause any of my problems? Is the current setting of 1.3 OK?
My mechanic believes that the emergency fuel shutoff switch on the fuel distributor may be defective and causing my hot start problem. His theory is that these switches go bad (this is apparently a common problem on Mercedes), and when they fail, they do not active the fuel pump. So if my switch is bad, the hot start problem may be related to the switch which is not activating the fuel pump when I go to start the car. I am told that the switch cannot be replaced and that a brand new fuel distributor is required (several thousand dollars). We are planning on jumping the emergency shutoff switch and seeing if this corrects the hot start problem. What are your thoughts on this idea? Any other ideas as to what is causing my hot start problem? We have run out of ideas.