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Author Topic: Bad cold start with bigger injectors  (Read 1534 times)
Mircocsi
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« on: February 04, 2024, 05:02:58 PM »

Hello, i have a problem during the cold start with my new Injectors (0280 158 123) at 4 bar. The Idle during the cold start is completly normal and good but when i go harder and fast on the Throttle the Lambda goes to 1.30 and the engine has misfires and the Lambda regulation goes to +25%. The same problem when i drive and change the gears. When the engine hits 80 Degree mark the problems are away and the car runs fine and drives normal with STFT -1.5 and LTFT 0.7.
The ECU is a 8E0909518AL 0005 BFB .
KRKTE: 0,04433
TEMIN: 0.5
KLTEMINVA: all 4 values to 0.5

TVUB: 8        10        12          14          16
        3,3       1,62     1,15      0,74        0.54

FKKVS with FKKVS fixer corrected.

I checked the Pressure of the Fuel Pump. All the time at 4 bar.

I hope anyone of you have an idea.

Best regards
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aef
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« Reply #1 on: February 05, 2024, 02:05:47 AM »

http://nefariousmotorsports.com/forum/index.php?topic=1316.msg25876#msg25876

I know that what i linked is not temperature related but you should change this first and log again.
In theorie there is no need to change anything temperature-wise if the type of fuel remains the same.
You only have to change coldstart and afterstart when you go from petro to e85 for example
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Mircocsi
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« Reply #2 on: February 06, 2024, 11:47:05 AM »

http://nefariousmotorsports.com/forum/index.php?topic=1316.msg25876#msg25876

I know that what i linked is not temperature related but you should change this first and log again.
In theorie there is no need to change anything temperature-wise if the type of fuel remains the same.
You only have to change coldstart and afterstart when you go from petro to e85 for example

Hello, im again. First of all, thank you for your answer. After i tested to fix the FRLFSDP map without other changes, the car runs significantly worse than before(Bad idle, Bad partial load). I had to fix KRKTE and FKKVS again and now the car runs very GOOD with a STFT of 0% and LTFT of 0,7%. But there is still the same Problem with the cold start and afterstart. Any other ideas? Can somebody call me what i have to log with the ME7logger for this problem?

Best Regards.
« Last Edit: February 07, 2024, 07:17:11 AM by Mircocsi » Logged
gremlin
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« Reply #3 on: February 06, 2024, 03:10:59 PM »

Keep in mind and pay attention to the follows.
The new injectors have significant differences from original one in the shape of the spray cones and the angles of deflection of the torch relative to the longitudinal axis and the direction of the electrical connector.
Also start point of spray will be different.
These geometrical differences will have the greatest effect while the intake manifold is cold, since gasoline will spray in wrong direction and put on  the manifold walls and evaporate poorly.
Look for Bosch documents about injectors and see what's mean alfa, beta and gamma angles for your E-type 2-spray injectors.
« Last Edit: February 06, 2024, 03:14:16 PM by gremlin » Logged
Mircocsi
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« Reply #4 on: February 06, 2024, 05:33:10 PM »

Keep in mind and pay attention to the follows.
The new injectors have significant differences from original one in the shape of the spray cones and the angles of deflection of the torch relative to the longitudinal axis and the direction of the electrical connector.
Also start point of spray will be different.
These geometrical differences will have the greatest effect while the intake manifold is cold, since gasoline will spray in wrong direction and put on  the manifold walls and evaporate poorly.
Look for Bosch documents about injectors and see what's mean alfa, beta and gamma angles for your E-type 2-spray injectors.

Hello, i checked the angles of the Injectors. The new injectors have an orientation angle of 90° and a Y of 0°. α is 25°. the stock have a orientation angle of 270° and a Y of 10°. α is 15°. Does that make such a huge difference?

Im unsure about the TVUB Values. I found different dead times for this injectors with very huge differences. The TVUB values in my first post are from Nyet but there are other from finjector. which are correct? the Dead times from Finjectors seems a bit unrealistic to me

Finjector dead times:

8          10         12        14         16
1,78     1,136    0,739    0,536      0,418

Best regards.
« Last Edit: February 06, 2024, 05:54:32 PM by Mircocsi » Logged
ratosluaf
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« Reply #5 on: February 07, 2024, 12:15:18 AM »

tbh i just slapped this injectors in and got krkte calculated, tvub from sheet (posted that in ev14 topic) and it did work flawlessly. Minor changes needed.

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aef
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« Reply #6 on: February 07, 2024, 05:24:21 AM »

http://nefariousmotorsports.com/forum/index.php?topic=11289.msg95452#msg95452

try these because yours is 4bar and porsche should be 3.8bar.

Remember that your injectors now are much longer than stock and this will change all of the cones, angles, delta and so on.

maybe use 0280158298 instead
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