kannigand

Hi all im new here al the way from SA and we trust me we are starved in SA for stuff. Anyhows heres my dilemma, I have a 1987 w124 230e and have been bored so have gone about turbocharging it. The engine hasn;t had much work done to it, slightly bigger pistons and the heads been gasflowed. the Turbo is running a moderate 0.4 boost. It runs well under 120km but once I go past that mark it starts to detonate. Ithought it could have been fuel and added in a 5th injector on the boost pipe that comes on at 0.1 bar boost but that still doesn't help I feel my problem is with the KE jetronic it may be starving at higher speeds. Also wondering if the added boost with affect my vacuum advance on the distributor ? any help info greatly appreciate it. increasing fuel pressure ??

RBYCC

What type of control are you using to turn on the 5th injector?
Have you ever read your air fuel ratio at different RPM values?
Under boost you should be around 12.5: 1 AFR ( .85 lambda )

The KE Jetronic will only do so much.
You either have to change the pulse under boost via the EHA or use additional injectors.

Curious as you say that your additional injector is in the boost pipe.
Is it before your air valve assembly?

I run two additional injectors mounted between the air valve and the throttle body.
Control is by a Split Second additional injector controller with a built in MAP sensor,
The control is 3D mappable via laptop computer software entry.

I maintain 12.5:1 AFR under boost and no detonation even in +35C ambient temp.

kannigand

hey Thanks for the info please excuse my stupidity sometimes cause we may reference things by different names here and well just starting out with this turbo story so stil llearning a bit picking up info from the few installers that know here in S.a( most of them wudn't want to do my car so i did most of it myself) I havent gone the full fuel management route yet( financial problems) hence I have got a Hob switch on the intake that switches on a microfueller control unit that works of the coil to power te 5th injector and where you can adjust your Fueling on. mine is the older w124 engines so it stil has the half electronic and half mechanical fuel injection system. My fifth injector is mounted where my boost pipe attaches to where the airfilter used to sit on directly over the airvalve. should i move it ? How can i change the pulse of the EHA. Pre fuel management system days the HOBB switch microfueller route was the only way to go I checked it up in one of them Bosch K-jetronic books i had for performance tuning so it should work(hopefully) My last alternative when I get some money is to put it a fuel rail and fuel management system and do it that way but that be a long time coming so I just trying to get it running best as i can at moment. How much timing advance you running ? What horsepower are you making at what boost?

RBYCC

I'm running a modified Turbotechnics twin turbo kit on a M103-12V I6 with the same Bosch KE-Jetronic CIS-E semi electronic injection.
Timing is stock with the R16 resistor removed ( supplied on USA cars ) which gives me a slight advance.

Not many installers in the USA want to turbo or supercharge a CIS-E system because they are not familiar with it and prefer to change over to a new fully electronic injection system.

I was fortunate and used one of the few installers left who has boosted CIS-E for many years.
Learned a great deal on a daily basis and discovered that there is an inexpensive method ( About USD $ 400.00 ) using a stand alone controller that just fires the additional injectors.

I would change the location of your fifth injector.
You are upstream of the air valve and the throttle body.
The fuel atomization is dropping out as it hits the air valve and just dripping into the throttle body.
I would install it downstream of the throttle body in the intake manifold before it branches out.
This might resolve many of your problems.

I use a Split Second AIC1-A2L stand alone additional injector controller to control the two additional injectors on my six cylinder M103-12V.
It's a self contained unit with integral MAP sensor so no external Hobbs switch is required.
Simple install need +/- 12V, speed signal from tach. vacuum from intake, and wiring to injector.
It's 3D mappable and programmed from a laptop.

http://www.splitsec.com

I run a fixed .48 boost with an air to air intercooler and have no detonation regardless of ambient temperature.
The Split Second controller maintains about 12.5:1 / .85 lambda air fuel ratio.

I'm not big on dyno numbers as I use them to compare base line versus modifications.
Using a load dyno we showed around 206RWP versus a baseline of 135RWP.
I look at actually performance, and using a G-Tech 3 axis accelerometer it runs 0-60 in the low five second range.

tanktube67

wellcome to MBW

Fuel filter

RBYCC

His engine is turbo charged and it's detonating under boost.
Engine runs well under 120kmh/72mph which indicates adequate fuel delivery.
Adequate fuel delivery doesn't equate to amount of fuel passed through injectors in their cycle.
He needs to enrich the AFR to compensate for boost at higher engine rpm.

kannigand

Hey thanks, the Splitsec unit seems to be a good way to control the injector. I will have to look this weekend to see if I can move the injector as well a little lower down. to see if that helps. Any info with regards to the Bosch K-jetronic itself, Cause I have some reservations that that mite not be working 100% as it should. SOme times when the engine gets a bit hot the idle increases then drops later. Need to find some good information on my specific model and all the wiring connections.

Speaking of which is your K-jetronice set a bit richer or is is still on the standard setting?

RBYCC

My K-Jetronic is set to factory spec.
It functions as stock and nothing in the factory control knows that the engine has twin turbos!

The beauty of using the additional injectors with a stand alone control for boost enrichment is that the engine at idle if set to factory spec will pass any exhaust emission test.

Boost doesn't begin until 1500+ rpm...

kannigand

Cool- Sadly I cant get hold of a split sec timer here in SOuth Africa I tried emailing Split sec but no response from them( do they still exist) Any information you have on setting up the factory k-jetronic cause I think that is gone all out of whack by now. wiring diagram sensors etc?