M103 mods to improve economy/fuel efficiency - Page 3 - PeachParts Mercedes-Benz Forum

Ozarkdude · #31 01-19-2013, 02:36 AM

People are taken much more seriously when they treat people with respect, rather than insulting them.

RBYCC, I have the factory 103 engine manual here in front of me. If you would be so kind as to indicate as to which part of that manual shows the system enriches fuel mixture at WOT, via O2 output, I would be more than happy to copy the page and post it here.

But it does not. The system goes into open loop at WOT and the O2 signal is disregarded. Fuel mixture is then a direct product/result of fuel pressure, door opening, and mixture adjustment. IOW, at WOT the system is no longer electronically controlled

CIS = mechanical Continuous Injection System. CIS-E = Electronically controlled, mechanical Continuous Injection System.

Jetronic - Wikipedia, the free encyclopedia

Read down to the the heading "KE Jetronic". This is the system used on the M103. Read the first sentence; Electronically controlled mechanical fuel injection.

Can we stop arguing over nonsense now?

RBYCC · #32 01-19-2013, 09:32 AM

Quote:

Originally Posted by Ozarkdude

People are taken much more seriously when they treat people with respect, rather than insulting them.

Perhaps I grow weary of lack of comprehension and then respond to be calling "pompous" by one who had zero to add to the discussion?

Quote:

RBYCC, I have the factory 103 engine manual here in front of me. If you would be so kind as to indicate as to which part of that manual shows the system enriches fuel mixture at WOT, via O2 output, I would be more than happy to copy the page and post it here.

I never stated "the system enriches fuel mixture at WOT, via O2 output," as these are your words based on your comprehension.

I will repeat for the third time and highlight so you can hopefully grasp that the O2 sensor/closed loop is not in operation under idle and WOT.

"The design of the K-Jet III (my typo, should have been "KE-jet, please forgive me ) is to always maintain stoichmetric via the O2 sensor except at idle and WOT."

"except" is the operative word which you obviously glossed over !!!

And then I wrote:

"Try disconnecting your WOT switch which then will keep the system in closed loop, preventing WOT enrichment and see if you get any pinging..."

Note:

The test sequence FOR "ON-OFF RATIO" is on 07.3.11 I-121/20 "Service Manual Engine 103" MBNA s-2421-103

Quote:

But it does not. The system goes into open loop at WOT and the O2 signal is disregarded. Fuel mixture is then a direct product/result of fuel pressure, door opening, and mixture adjustment. IOW, at WOT the system is no longer electronically controlled

See above....This is what I've tried to tell you on two and now the third posting !!!!!

Quote:

CIS = mechanical Continuous Injection System. CIS-E = Electronically controlled, mechanical Continuous Injection System.

Jetronic - Wikipedia, the free encyclopedia

Read down to the the heading "KE Jetronic". This is the system used on the M103. Read the first sentence; Electronically controlled mechanical fuel injection.

Can we stop arguing over nonsense now?

Exactly what I've been trying to tell you from the start...

You stated:

"I simply asked if the CIS enriched at WOT on its own without O2, and never got the answer. "

To which I responded:

"Believe what you want but there is a major difference between CIS and CIS-E which you have on your M103...."

Now you're telling me exactly what I've been trying to tell you all along !!!!

Hence my comment on lack of comprehension, not an insult but a fact !!!!

Now you found out on your own exactly what I tried to tell you..therefore my frustration in one who asks but fails to comprehend the answer...

Always better to do on your own and not rely on another especially on internet forums...

How about we finally "agree to agree"

JayRash · #33 01-19-2013, 09:58 AM

I was under the impression the ke jet sys did use o2 sensor at idle, thats how CO output is kept under check by the ecu.

RBYCC · #34 01-21-2013, 07:14 AM

Quote:

Originally Posted by JayRash

I was under the impression the ke jet sys did use o2 sensor at idle, thats how CO output is kept under check by the ecu.

Hi Jay

My statement was:

"....is to always maintain stoichmetric via the O2 sensor except at idle and WOT."

At WOT the KE-jet is no longer in closed loop.

At idle it is most times in closed loop, but not solely dependent on O2 sensor to maintain stoichmetric. Other elements provide cranking, cold and after start enrichment with inputs such as coolant temp.

O2 Lambda control is made inoperative by signal from ECU under these conditions:

- During deceleration shut-off.
- Under full load conditions.
- During acceleration enrichment or when starting engine at coolant temperatures below 60F until coolant temperature reaches 105F.

The OP desired to increase fuel economy with stock CIS-E.
My response was tune to factory spec and eliminate vacuum leaks.
Beyond that the major component of enrichment and diminished fuel economy comes under WOT.
You can lean the system out, try to retard timing via the EZL setting, but still not enough to over ride the fuel and ignition maps that were engineered by Merc for maximum economy and performance.

The M103-12V was not designed as an economy car engine.
If you like I can post a copy of the window sticker that was on my 300CE when I took delivery of it new in May of 1988.
EPA rated 18MPG City and 22MPG Highway with an automatic transmission, 3.07 rear gear, USA spec with KE III mech/elec fuel injection.

Mid 20's highway is a good as it gets....

Ed A.
Ed A.