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Old 03-02-2021, 01:14 PM   #1
Brami63
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Exclamation K jetronic turbo issue ?¿

Hi
My current setup
A 1998 b230fk bottem end
A 1984 398 head with d camshaft
A c13 turbo with around 0.4 bar boost
A original k jetronic from an 1978 b21e
And a original fuel pump from an 1978 b21e
In a 244 gl from 1978
And all new filters and injectors

It runs great except the power stops at 3500rpm what i think comes from a fuel shortage because of the stock k-jet + fuel pump so i orderd a high capacity fuel pump what still needs to be installed but i'm not sure this fixes the problem.
I also tried a six port k-jet of a bmw 520i because I heard that the six ports have more capacity. Well i didn't check any numbers and the power now stopped at 2000rpm 😄 so that wasn't very smart

So actually the question is: does any of you guys now what the numbers need to be on the k-jet that is suitable for a 2.3 turbo, in case the high capacity fuel pump doesn't solve it. All other tips are welcome as well!!


Best regards
Bram
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Old 03-02-2021, 01:31 PM   #2
dl242gt
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When using kjetronic. You need boost enrichment. From your description you don't have any boost enrichment happening. On the US model B21FT enrichment is provided by the lambda controller which is signaled by a boost switch on the firewall. This changes the fuel pressure in the fuel distributor for more fuel. One the Euro B21ET the boost enrichment is provided by the control pressure regulator. This has an extra section on the bottom of the unit that when pressurized by the boost pressure drops the control pressure for more fuel.

So, you'll need to come up with a control pressure regulator from a B21ET which is not a common part but maybe you can find one. Or you can adapt one from another turbo kjet car like an Audi 5000 turbo. Porsche 930 turbo also uses that method.
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Old 03-02-2021, 01:40 PM   #3
dl242gt
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B21ET control pressure regulator part number is 1276946.
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Old 03-02-2021, 02:51 PM   #4
Brami63
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Quote:
Originally Posted by dl242gt View Post
When using kjetronic. You need boost enrichment. From your description you don't have any boost enrichment happening. On the US model B21FT enrichment is provided by the lambda controller which is signaled by a boost switch on the firewall. This changes the fuel pressure in the fuel distributor for more fuel. One the Euro B21ET the boost enrichment is provided by the control pressure regulator. This has an extra section on the bottom of the unit that when pressurized by the boost pressure drops the control pressure for more fuel.

So, you'll need to come up with a control pressure regulator from a B21ET which is not a common part but maybe you can find one. Or you can adapt one from another turbo kjet car like an Audi 5000 turbo. Porsche 930 turbo also uses that method.
Thank you this was very very helpfull!!
I think my parts guy has one so that not the problem
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Old 03-02-2021, 04:28 PM   #5
Leon_pp
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you need a turbo WUR (warm-up regulator)
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Old 03-03-2021, 07:32 AM   #6
Brami63
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So i installed the turbo WUR but there isn't that big of a difference. It now stops at 4000rpm. Maybe i didn't connect the air pressure hose at the right plug. I connected it to the small one at the bottom. Any suggestions?
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Old 03-03-2021, 11:46 AM   #7
dbarton
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It didn't appear clear that you installed the B21ET CPR. If you're unsure, it will have Bosch PN 0 438 140 082.
There's a pic of this one here:
https://k-jet.biz/product/0438140082...150-surcharge/

Here's a Bosch cross reference. Unfortunately the 082 CPR is not listed as being used on any other car, but there are a lot of possibilities listed there if you can find more on them.
https://pim.yakarouler.net/get-docum...0000COB300.PDF
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Last edited by dbarton; 03-05-2021 at 08:39 AM..
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Old 03-03-2021, 01:44 PM   #8
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K-Jet is known to deliver about 45 hp per cylinder. B21E is four cylinder model, so most you can get is something like 180 hp when everything is correct. 240 Turbo K-Jet is built from six cylinder model, having bigger diameter on air flap. And hits the wall at 230 hp.

How did you connected injectors with that BMW fuel distributor?

I quess you need fuel distributor from 240 Turbo or from Saab Turbo.

Open the waste gate and try how high you can rev.
Get wide band lambda
Get couple 6 bar pressure gauges and measure control pressure and system pressure.
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Old 03-03-2021, 03:14 PM   #9
dl242gt
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Have you upgraded the intank pump? It helps to provide more fuel for a turbo engine. I second the suggestion to find out what your system pressure is and the control pressure. From what I recall the hose should go from the intake manifold to the lower port on the control pressure regulator. So, I think you got it correct if that is where you connected the hose.
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Old 03-05-2021, 08:04 AM   #10
Brami63
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Quote:
Originally Posted by dl242gt View Post
Have you upgraded the intank pump? It helps to provide more fuel for a turbo engine. I second the suggestion to find out what your system pressure is and the control pressure. From what I recall the hose should go from the intake manifold to the lower port on the control pressure regulator. So, I think you got it correct if that is where you connected the hose.
Well i think i connected the turbo wur correct. And i checked the numbers so it is the right one. My car lift isn't available at the moment so the high flow in tank fuel pump isn't installed yet. I will let you know what is the result of that improvement.
ps. I don't have the equipment to measure the fuel pressure.
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Old 03-05-2021, 09:02 AM   #11
OttoB
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If you are playing with k-jet you NEED equipment to measure fuel pressure (s). Must have.

Go to the store selling hydraulic stuff. I use double (long) banjo bolts to connect gauges.
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Old 03-26-2021, 10:05 AM   #12
Brami63
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So I installed the new fuel pump what seems to work fine i can smell and hear it runs a lot richer but can't feel te difference, i went to the hydraulic stuff store and bought a hose with a t split where the meter is connected. I made the wur adjustable. I connected the line withe the meter between the wur and k-jet. Now my reading are 2.1 when cold and not running but when i start it it goes immediately to 4.9 bars and stays. Now i tried to well "adjust" the wur bij moving the pin a bit up and a bit down but the meter stays on 4.9 bars while running. I read on an other forum that there an adjustment screw behind the copper cap on the bottom of the wur, i tried to give this a view turns but again nothing happend (I'm guessing this controlles the opening of the boost pressure or something) do you guys have any suggestions?
Best regards
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Old 03-26-2021, 01:10 PM   #13
dl242gt
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Well now you know you are not getting the proper control pressure. The WUR is clogged or the internal adjustment is off. When you make them adjustable. You can only adjust the pressure in one direction. Then you'll have to take it apart to get to the adjustment to lower the control pressure.
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Old 03-26-2021, 01:49 PM   #14
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If the return pressure is high that means too much fuel is being returned to the tank. 4.9 bar is full pump pressure so I don't think the WUR is clogged. Most likely you didn't reassemble the regulator properly. Make sure the pin is properly installed on the diaphragm.

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