The 190E 16v intake pipes setup - PeachParts Mercedes-Benz Forum

pentoman · #1 10-10-2011, 05:32 PM

All

Do we still have 16v owners on this forum? Used to, back 10 years ago when I joined! However this post may be relevant to all Jetronic cars, I'm not sure as I haven't looked.

So, the intake pipe setup on the 16v is strange, is it not? Here are the bits that I see:

1 There's the main 4 large long metal intake pipes, fed via the throttle to the intake ports.
2 Then there's the four individual rubber pipes taking air from from the PCV (i.e. the camshaft cover) and also taking it from under the air flow sensor via the idle control valve, and feeding this air onto the injector surrounds and into the engine.

Isn't that weird? There are 2 totally separates routes for the air to get to the intake? And those 2 routes then become connected once the gas pedal is pushed, because they both feed from under the air flow sensor? Is it possible that they could suck air from each other?? Isn't the vacuum and air flow going to go all over the place? Has anyone ever seen any other cars with this sort of setup?

I ask because I am investigating why my 16v feels like it has poor throttle response in the first 1/2 second when you squeeze the gas. This is also a criticism I have read in magazines when the cars were brand new. I wonder if it's related? I want to try blocking off some of the pipes and see the difference it makes. Any thoughts?

Russ

tjts1 · #2 10-10-2011, 06:35 PM

Quote:

Originally Posted by pentoman

I ask because I am investigating why my 16v feels like it has poor throttle response in the first 1/2 second when you squeeze the gas. This is also a criticism I have read in magazines when the cars were brand new. I wonder if it's related? I want to try blocking off some of the pipes and see the difference it makes. Any thoughts?

Russ

Take a close look at your throttle linkage and how its designed to function. All these Kjet cars (16v or not) were designed with a throttle linkage that slowed down throttle plate movement in the first 15 degrees from being closed. You have to push the gas pedal in almost 1/3 of the way down to get the engine to really wake up. The problem is Kjet. The mechanical system simply can't respond fast enough to quick throttle inputs, the engine would stall before getting enough fuel. EFI (especially sequential EFI) can react to TPS movement with acceleration enrichment within less than 1 engine rotation even from idle. It calculates the acceleration enrichment based on throttle angle rate of change. This is only active for a few milliseconds before you MAF or MAP sensors have a chance to catch up and take over. This is why Kjet cars feel lazy compared to modern EFI.

pentoman · #3 10-10-2011, 07:11 PM

Yeah.. Okay.. Maybe.

No comment on the intake setup?

duxthe1 · #4 10-10-2011, 07:26 PM

The 4 rubber pipes are for idle air delivery. Idle air is routed past the injector nozzle tips so that the small volume of idle air pulls the entire fuel charge into the cylinder. AFIK, all of the CIS cars do this in some fashion or another. After opening the throttle, the amount of air flowing through the idle air circuit is negligable.

As far as sluggish performance there could be multiple causes. The first thing that comes to mind is poor injectors. If they are pissing and not spraying at low flows it really hurts performance, most noticeable off the line. Late cam timing from a stretched chain could also be a culprit, as well as tight valve clearances. Of course it's all just speculation without testing whats actually going on.

Keep in mind that this engine was designed to make power in the upper revs, and will never be a torque monster off the line.