91 190e won't start
 

I have a 91 190E with idling and starting issues.The idle was erratic and the engine was hard to start, so I was checking the idle air control valve. When I would tap on the valve the idle would even out.I purchased a ne Iac valve and replaced the old one.Now the car will not even start.Does anyone know what could be going on.The car has 150,000 thousand miles and has had a recent tune up.:mad: :confused:

Are you sure that neither of the idle air hoses going to the valve became disconnected when you replaced the valve, mainly the one going under the intake manifold? If this hose comes off, it will not start.

Scott P.

Iac
 

I did have the hose fall off and I reconnected it.I had to actually remove the oil filter to get to it.The valve has an arrow on it.Should this be pointing up.I'm almost positive that this is the same way the old one came off.It still will try to start but just can't manage it.

I am not 100% sure from memory, but I believe that the arrow goes in the direction of the air travel through the valve.

Scott P.

Got it running at lunch time.Arrow points up.It was idling kinda high so I tapped on the new Iac and it smoothed right out.It still takes alot of cranking to get it started.Any ideas?

When I cleaned ours (removing it) I found all the hoses hardened, forming a poor seal at connections, and some cracked. I ordered and replaced all these hoses, as well as the rubber lower half of the airflow meter plenum and the wedge gasket holding the valve. Prices through Phil were pretty cheap. Had no problems.

Steve

What could be causing the hard start issue.It takes at least two tries to get it started.Could it be a fuel injection issue.Just how does the fuel injection system work on a 91 Mercedes?:confused:

Check for "CIS injection" posts. Continuous Fuel Injection. The fuel pressure regulator holds a constant pressure to the fuel distributor, where mechanical and computer assisted hydraulic controls regulate the required injector flow for the airflow metered at the Airflow Meter - the flap below the air cleaner. If any airflow BYPASSES the airflow meter vane - due to air leaks - the fuel/air ratio will be incorrectly metered, and the resulting combustion mixture will not likely be in the range for ignition to occur, particularly with a cold engine trying to start.

The mixture for perfect and complete combustion is called the stochiometric point, and the actual mixture is compared to that in a ratio called 'lambda', measured by the oxygen sensor in the exhaust path once the engine is warm. Then, the mixture can be corrected at the fuel distributor for smooth running and low emissions.

In a nutshell.

Steve