Hello everyone-

I have a question reguarding cold starting. I have an '87 245 with 160k on it. It used to ALWAYS start with a flick of the ignition. Even in the coldest of cold days here in Chicago. After about last Christmas or so, it all of a sudden quit starting right up. I now have to *slightly* push in on the gas when starting, and after a couple of trys, it starts and idles pretty smoothly. I'm thinking it might be a faulty thermal switch for the cold start injector, but am not sure. Also not sure if it could be a faulty fuel pump check valve, but if that were the case, it wouldn't start right up like it does when the engine is warm.

When the engine isn't quite warmed (needle not all the way to half), it kind of sputters if I slow down for an intersection. Doesn't ever die, but hiccups. I don't know if these two problems could be related. They both disappear once the car is warmed up and I've been driving awhile. Here's what I've done that can be ruled out:

-new plugs (yes, the gaps are correct), wires, cap, rotor

-new air filter

-throttle body is operating properly

-kickdown cable has been lubed and set properly

-new heat intake hose

-use 93 octane gasoline

-all vacuum lines to the throttle body are hooked up

Tagging on to Tucker's vaccuum leak idea. Have you checked the plastic bellows that runs between the AMM and the throttle body. If it's the original one it could have developed small cracks, which are open when the car is cold and the plastic is stiff and then close when the plastic warms up.

You might check for proper operation of the idle air system. There is a modulating Air Control Valve that the ECU will open and close to maintain a constant idle speed. This also has the function of adding additional air during a cold start. Possibly the Air Control Valve is frozen or stuck in one position, which is the correct position for warm running. Thus, adding a little additional air by slightly opening the throttle valve when starting works, and also explains the rough idle until fully warmed up.

There are some test procedures for checking the valve in the Bentley book.

Good luck!

Roger

You should also check your coolant temp. sensor. There are two of them. one for the guage(single wire) and another for the LH control unit(2 wires connector for the 2.4). It is well-hide under the intake manifold, near the cylinder#3. The last one should be checked for the correct resistance according to the engine temperature.

If the sensor is not working properly, the LH ECU will run with "pre-determinated" temps for a specific period of time, who is not exactly corresponding to your engine real temp.

It could be a possible cause of your problem.

/// Your symptoms indicate the possibility of two different problems. The difficulty at cold start could be the cold start system. The difficulty at half warm indicates that you have a vac leak. Something is heating up and closing. Is there any rough idle? (sputters) Check by spraying carb cleaner at the possible leak sites. The intake gasket, the injector seals, and so on.