Author Topic: siemens deka 80lb/s idle problem  (Read 10377 times)

Offline wpp

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siemens deka 80lb/s idle problem
« on: September 05, 2010, 08:17:07 pm »
Hello,

The engine is a bmw m3 3.2 liter. The engine runs very well with 200cmc injectors with a pw of 2.2ms at idle
I have problems at idle, the pw needs to be ~1ms but the engine afr is very jumpy, it reads from 9 to 35..., id i drive it after ~2000rpm it works ok.
Today i tried siemens deka 60lb/s and they have sa same problem.
The 60lb/s injectors i tried work well on two engines i built, s50b30 and m50b25, they have less capacity and they are runing with stock ecu remaped.

If you have any advice...

Thanks

Offline MWfire

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Re: siemens deka 80lb/s idle problem
« Reply #1 on: September 05, 2010, 08:41:55 pm »
flyback is good connected?

Offline wpp

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Re: siemens deka 80lb/s idle problem
« Reply #2 on: September 05, 2010, 08:50:33 pm »

Offline MWfire

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Re: siemens deka 80lb/s idle problem
« Reply #3 on: September 05, 2010, 08:52:25 pm »
i made cars with siemes 660cc and 900cc and no problems at idle.
660cc need 1.4ms and 900cc 1.7ms(slower open time).

Offline rob@vems.co.uk

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Re: siemens deka 80lb/s idle problem
« Reply #4 on: September 06, 2010, 09:08:18 am »
Are you batch firing or sequential firing?
have you tried changing the order when the injectors fire?

Offline GintsK

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Re: siemens deka 80lb/s idle problem
« Reply #5 on: September 06, 2010, 11:25:35 am »
Double check your flyback and injections per cycle.
Bad idling could be from low flyback voltage. It is better with not connected flyback (60V internal FET diode), but then it is risky to fried some MOSFET at higher rpms.
I note with 620cc Dekas - usual 30V above Ubatt (~43V) is bit too low. If it is street car and idling quality important it is possible to rise flyback voltage by changing FETs and TVS diode...

Gints

Offline wpp

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Re: siemens deka 80lb/s idle problem
« Reply #6 on: September 06, 2010, 02:20:02 pm »
I think i solve the problem, the friend who give me the vems told me that the flyback diode is indside the case, i tried puting a diode on the flyback wire and is working. It idles at 1.2 PW and the idle is stady at ~1200rpm and ~13:1 afr.
How can i check if i already have a diode inside the case?

Thanks

Offline GintsK

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Re: siemens deka 80lb/s idle problem
« Reply #7 on: September 06, 2010, 04:31:58 pm »
By opening unit or by checking voltage spike value.

Offline lost

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Re: siemens deka 80lb/s idle problem
« Reply #8 on: September 06, 2010, 04:41:06 pm »


Diode to the left ( in yellow sleeve) is connected  to the flyback.
Open VEMS and simply check is it there  ;D

Offline lost

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Re: siemens deka 80lb/s idle problem
« Reply #9 on: September 06, 2010, 04:41:59 pm »

Offline MWfire

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Re: siemens deka 80lb/s idle problem
« Reply #10 on: September 06, 2010, 09:10:05 pm »
or with DVM messure voltage drop beetween one injector and flyback. If you don't have flyback, voltage drop will be 1-1.4V