SManager injector voltage offset

cv558 · Post by **cv558** » Thu Mar 10, 2011 7:58 am

Hi,

I am trying to run a B18C5 with turbo, stock fpr, Walbro 255 and Bosch 1100cc saturated injectors (IS115-1100H). Car ran perfectly with RC saturated injectors but we had to go for Bosch.
Cranking the car with the Bosch injectors and just the injector size modified to 1100, causes fluctuating idle and the necessity of adding 40% fuel to have a correct afr at idle. I am fairly convinced this is due to the injector voltage. Therefore I have entered the values from the data sheet supplied with the injectors, i.e. base fuel pressure 2.7bar: 8Volt 2.4 offset, 10 Volt 1.65, 12 Volt 1.2, 14 Volt 1.1, 16 Volt 0.75.

Result was that the car cranked way too rich. Then I was told that the base pressure is higher, therefore it ran too rich.
Can you maybe confirm which is the base fuel pressure for an ITR with Walbro and stock fpr?
Also, is it possible to alter the voltage offset for 14 Volt while engine is in operating mode, or would that damage ECU/injectors?

Any other suggestion would be also kindly welcome. Thanks.

Post by **Hondata** » Thu Mar 10, 2011 8:34 am

We have found that the manufacturer supplied injector dead times can be 0.2 - 0.4 ms off (usually too low). This is because often they measure the dead times electrically rather than using fuel delivery.

Idle is often a difficult place to start, so I'd suggest fast idle / light load (approx 2000 rpm).
1. Change the fueling to give a 0% short term fuel trim.
2. Increase the electrical load by switching on the headlights, brake lights, heater etc. Your aim is to change the battery voltage from 14V to 12V.
3. If the engine goes lean then increase the injector dead times and repeat.

cv558 · Post by **cv558** » Thu Mar 10, 2011 8:58 am

Many thanks for the quick reply.
Just to avoid any misunderstanding, can you please explain a bit what you mean by 1.? You mean monitor the values for short term fuel trim and change the values in the fuel table until I get to 0%?

Shall I start with the stock values and go through the process you described (but decreasing the injector time), or shall I take "their" values as a starting point and increase?

Thanks.

Post by **Hondata** » Thu Mar 10, 2011 12:36 pm

1 = change the fuel table around the idle area to get a short term fuel trim of 0%

I'd suggest using the manufacturer values and adding 0.2 ms (200 us). If you change the injector dead time table, change all the values by the same amount.

cv558 · Post by **cv558** » Thu Mar 10, 2011 12:58 pm

Ok, will try and let you know. Thanks very much again.

lowblow · Post by **lowblow** » Fri Mar 11, 2011 12:21 am

if i'm not wrong, BOSCH don't make any 1100 injector...

Luke · Post by **Luke** » Fri Mar 11, 2011 6:29 am

if you type in thos IS115-1100H into google, you'll find them on fuelinjectorclinic.com.

those seem to be denso injectors... nethertheless, this car won't start.

best regards Lukas

Luke · Post by **Luke** » Mon Mar 14, 2011 1:11 am

fyi:

everything's working fine atm.
the problem was the dead time of the injectors. after running on higher rpm, we could get a fine injector-timing and then get down with the rpm and get a smooth idling.

we will go to the dyno asap and will see how much power we can get.

best regards Lukas

cv558 · Post by **cv558** » Tue Mar 15, 2011 11:41 am

Just wanted to say thanks. Engine runs as expected.

:)