I've recently purchased this 16v that is generally in fantastic condition, but for the above issue. Car starts first crank when cold, and runs very strong on the highway or when pressed. However, at times, when warm, the car will struggle to start (I have to give it a lot of gas to start, and then sometimes still stalls), and is also prone to sometimes stalling say when I push in the clutch to coast to a stop light or to downshift for a corner.

I have read as much as I can find here and on other boards, but as this is my first Mercedes, I'm rather lost. I'm reasonably mechanically inclined, and know my way around a multi-meter - I just need some direction.

Thank you!

Hot/warm engine restarts on cars with CIS injection systems are all about retaining fuel pressure with the engine off.

So much so that those cars have a fuel pressure accumulator.

Checking for fuel pressure bleed off would be MY 1st test.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Ok, thank you.

I will start by testing the accumulator as per this post: 190E 16V Hot Start ("Hot Soak") Problem

A couple of simple questions before I tackle this - are there any recommended service manuals everyone here rely on? I have found the factory service manual at http://web.archive.org/web/20060427105508/mb.braingears.com/201_Chassis.htm

Are there any others that are available for download, or should I buy a printed copy, say the Haynes manual?

Also, I've not yet sorted out how to best jack up and support this car. Obviously I know where the rubber jacking points are, but where should I place the jack stands? Are the sub-frame mounts a suitable location? Should I jack elsewhere and place the stands on the rubber mounts?

Thanks so much.

Jack stands under the control arms are just fine.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Ok, I tested the fuel accumulator today by pinching off and disconnecting the rubber line, and then starting the car. The accumulator pushed out two separate squirts of fuel and then stopped completely while the car was running. My understanding is that this is a good thing.

What next?

Bump for any additional input.

Ok, I have done some further diagnosis, and I have some more specific questions. While pulling things apart, I tested some of the electrical components. I will describe what I did and what I saw, and would appreciate any feedback as to whether I'm on the right track.

I pulled the airbox off to check the position of the air flow sensor plate. I pulled the fuel pump relay and jumper-ed the fuel pump to pressurize the system. Based on the factory service manual, this plate must be centered, and must be precisely aligned with This is where I was un-sure of what I was seeing. To my eye it appeared that the plate was considerably higher than that top edge (using the reference point directly below the support bar, on the driver's side of the vehicle). It also has some free play before it engages the plunger. I assume this is what they mean when they say
It appeared to me that even when contacting the plunger, the plate is too high - but I also assume that I may not really recognize what I am looking at yet. If anyone who has done this regularly could chime in with some layman's tips from experience, I'd appreciate it. Also, the .05mm feeler gauge for centering the plate is considerably smaller than the thinnest gauge I had. In practice, how much does the centering of the plate and the setting of the rest height affect operation?

I also have some thoughts on my hot-start issue. I am now suspecting that I may have a leaky injector, which would cause the system to lose pressure when shut down. This would also, if I understand it correctly, flood the intake port of the leaking injector(s), causing it to be difficult to start. It always starts hot with the gas pedal to the floor - ie, throttle wide open - adding extra air to the system, right?

So, I need to check fuel pressure. Is there an off-the-shelf kit I can buy, or do I need some specialized tools to perform this test?

Thank you!