My 94 VDP is very hard to start at times. Usually after it's been sitting for several hours. I have cleaned the fuel system from the tank to the injectors. It has a new fuel and air filter. I recently changed the distributor cap, rotor button and plugs. The plug wires checked good on the ohmmeter. I cleaned the intake tubes and throttle body with throttle body cleaner (I did not remove the throttle body). Once the car starts, I get a puff of smoke from the exhaust, but it smells more like a lean burn than like burning oil, and it stumbles a bit, but it runs great and gets good mileage. At normal temp, it fires right up, no smoke or stumbling. Everything I have tested seems to be working right. What should I try next???? Thanks, Gunner
puzzled
May 28, 2006
4 Replies
I had a Mercedes that did exactly that.... turned out to be no voltage to the cold start injector. I Dan
You might want to verify fuel pressure at cold startup. I believe there is a residual pressure check valve to prevent quick leakdown of pressure back thru the pump after the engine is shut down. The pump should also run for a short time when the ignition is first turned on to pressurize the fuel rail. The pump then stops until the engine is cranked and running.
I don't think there is a cold start injector, but there is a temperature sensor which signals the Electronic Control Unit to enrich the mixture for cold starting.
Don Young
Don, You are correct. The 94 doesn't have one, or at least I can't find one on the web. The 93's and before do, apparently. His symptoms seem to be engine temp related, though. Maybe a bad thermo sensor somewhere?
Dan
I just checked the Intake Air Temp Sensor.....basically what your Mercedes had. It checks good. I'm going to bypass the fuel pump relay next and see if the 1/2 second pump run circuit may be bad. Thanks for the input.
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