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Old 08-21-2005, 05:53 PM   #1 (permalink)
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TWEAKING YOUR K JETRONIC

Anyone interested?I'll tell you how[}:)][;)]
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Old 08-21-2005, 05:54 PM   #2 (permalink)
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RE: TWEAKING YOUR K JETRONIC

Quote:
nutz4benz - 8/21/2005 7:53 PM

Anyone interested?I'll tell you how[}:)][;)]
What is the best and quickest way to depressurize the system in order to replace an injector or two? My 280E seems to need #s 1 and 2.
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Old 08-21-2005, 05:59 PM   #3 (permalink)
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RE: TWEAKING YOUR K JETRONIC

Quote:
flyboyike - 8/21/2005 4:54 PM

Quote:
nutz4benz - 8/21/2005 7:53 PM

Anyone interested?I'll tell you how[}:)][;)]
What is the best and quickest way to depressurize the system in order to replace an injector or two? My 280E seems to need #s 1 and 2.
Remove the fuel pump relay ,start and let it run until it dies.Then attempt to restart to remove residual pressure[:)]Also recommend using flare wrenches[;)]
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Old 08-21-2005, 06:05 PM   #4 (permalink)
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RE: TWEAKING YOUR K JETRONIC

Quote:
nutz4benz - 8/21/2005 7:59 PM

Quote:
flyboyike - 8/21/2005 4:54 PM

Quote:
nutz4benz - 8/21/2005 7:53 PM

Anyone interested?I'll tell you how[}:)][;)]
What is the best and quickest way to depressurize the system in order to replace an injector or two? My 280E seems to need #s 1 and 2.
Remove the fuel pump relay ,start and let it run until it dies.Then attempt to restart to remove residual pressure[:)]Also recommend using flare wrenches[;)]
Thanks, that's what I thought, same procedure as an EFI vehicle, basically.
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Old 08-21-2005, 07:01 PM   #5 (permalink)
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RE: TWEAKING YOUR K JETRONIC

K Jetronic systems are able to provide all the fuel needed for modifications for street vehicles.The goal is to increase the amount of air entering the engine to increase power.The problem is that the flap(plate) is a serious restriction to airflow.To modify the airflow sensor is extremely difficult,but the plate itself is what makes the rest of K Jetronic components
operate.But all is not lost seeing that K Jetronic is not just limited to Mercedes applications.Using an airflow sensor off of another K Jetronic equipped vehicle with a larger bore(plate) will dramatically increase airflow into the engine.

When the increased airflow is achieved,you will need to increase the amount of fuel also.As we all know,this is done by turning the 3mm allen screw in the airflow sensor(remember small increments make big changes).This enriches the mixture throughout the entire airflow band.

If this creates flat spots and hesitation,add a load sensing system pressure regulator(one from D Jetronic works with a little modification).Aftermarket or one from a D Jetronic will allow you to adjust for proper system pressure.A vacumm line comes off of the regulator and connect to the intake manifold.[:D]

Those with worn transmission and engine mounts will want to repair before doing this modification[}:)][}:)]
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Old 08-21-2005, 07:09 PM   #6 (permalink)
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RE: TWEAKING YOUR K JETRONIC

Forgot to add;expect a 17-23 HP increase from this mod if not more[:D]plus more torque.
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Old 08-21-2005, 07:19 PM   #7 (permalink)
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RE: TWEAKING YOUR K JETRONIC

Instructions for regulator
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Old 08-22-2005, 07:58 PM   #8 (permalink)
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RE: TWEAKING YOUR K JETRONIC

Will the airflow sensor of the 280E fit the 230E?
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Old 08-23-2005, 12:05 AM   #9 (permalink)
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RE: TWEAKING YOUR K JETRONIC

Quote:
zoom2 - 8/22/2005 6:58 PM

Will the airflow sensor of the 280E fit the 230E?
If the fuel distributor off of the 230E will fit on
the 280E airflow sensor,then yes[:D]Only use the control plunger that comes with "ANY" airflow sensor
because these are machined to exact tolerances for the
airflow sensor they are originally mounted to.Using a
plunger from another airflow sensor 9 times out of
10 results in binding and fuel leakage into the airflow sensor itself(recipe for disaster)[xx(]
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Old 09-27-2005, 04:27 PM   #10 (permalink)
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RE: TWEAKING YOUR K JETRONIC

mrnutz4benz

The old K jetronic has been jetting along in my 1978 280e with no real problems for the past 27 years. Recently I became aware that my gas mileage wasn't what it used to be, and I started wondering, is it possible to tweak a Jetronic? Or does this Bosch fuel injection system last forever and ever?

For the recent tune up, I ask the mechanic to check the fuel pressure, and he noted - the operation of the fuel pressure regulator was intermitant / defective. Do these regualtors wear out? If so, is it an easy part to replace? It doesn't cost much for the part. The name fuel regulator implies it's importance shouldn't be ignored.

As far as I know, there has never been much maintenance work done on my Bosch K Jetronic fuel injection system. Do these Jetronic's last forever, or is reasonble to suspect that after 27 years some replacement parts are timely?

After the tune-up, the 110 engine purrs like a kitten although I haven't checked the gas mileage. If it's not too much trouble I was thinking about installing a new fuel pressure regulator. We replaced the fuel pump and main fuel filter a couple of years ago.

I live in Denver at a mile 5,280 feet above sea level, so the air is thinner and presures are reduced at this high altitude, by a factor of 83% (?)and the timing specs change about 11 degrees. Not a computer chip to be found anywhere in a 1978 280e -220,000 miles.

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