Nistune Forums

I have this issue sometimes on colds startups (11°C, car stayed parked for 2 days), usually below 10°C.
My enrichment tables are very low according to my 750-850cc injectors.
18 18 15 13 11 9 7 5 3 2 1 1 0 0 0 0

After_start enrich:
100 90 80 70 60 50 40 25 15 10 6 4 4 4 4 4
(anything lower causes problem after the initial crank pulses ... rpm rise up and die immediately)

Is it a lack of enrichment ?
It looks it's too rich as TP and injection keep increasing and RPM keeps dropping (at cross point), but it may be a consequence.

(AS_ENRICH / inj offset is yellow boxes)

1st startup, engine dies:

2nd startup, engine up (10 seconds later):

What brand of injectors? If they are anything drilled out (Deutchworks) then all bets are off. The fact you don't have a specific CC (flow rate) for those injectors is also interesting

My injectors are Chinese 740cc injectors. Stop sarcasms , they are pretty decent value.
My previous DW 740cc were 370cc redrilled that static flow only 600cc !! DW is making money ...
My Chinese injectors really flow 740 or 750 or 800, 12 spray tiny holes (laser) I don't really care once the tune is done correctly. Drilled injectors are not all bad neither. My point is the price DW sells them, poor support to get replacement when one injector fails (they are used ones !!!!) and they are 600cc, not 740cc as advertised ....
With 600cc, the inj. pulse was in 15-16ms range @15psi, now it's 12-13ms range @15psi, so probably in the 750cc range ...

You can notice my fuel map is pretty flat, so the injector response (flow vs. ms) is pretty linear and predictable.
They are all matched, otherwise I would notice it @ idle, 1.90ms is a pretty low injector value @idle and my idle and AFRs are very stable and fully under control (fuel trims). Latency is 1000us to remove any constraint regarding this.

The only problem is warm cranking, and sometimes cold ranking @10°C if I reduce too much the initial crank pulse (...).
Warm cranking is definitively an issue because you play in the 2-3ms ballpark with no progressive behavior and I suspect an injector not behaving correctly when all are fully open for initial crank pulse. I managed to enhance it by tweaking the crank pulse in different steps (new crank algorithm):
First pulse(s) 6ms (E85 blend) when starter didn't raise RPM up to 200rpm yet
Second pulse and following in the 2-3ms area, typically with this shape against RPM:

I want to avoid this injection bump on startup too:

I changed again my injectors and solved all my issues of hot cranking.

My previous were chinese yellow 12 holes, pretty good on all the range, except cranking when playing with 2-3ms. I suspect the 12 holes drip more than they spray when the crank pulse is short.
I just tested them on my bench (should have tested them few months ago before installing them ....). 2 of them have inconsistent spray patterns. They flow from 750 to 840cc (static). Dynamic flow was more on par.

Whatever, I found other chinese injectors, I tested them. They are surprisingly flow matched. They are all in the 660-675cc static flow. They all behave the same. Spray pattern is 2 wide tilted cones, fine.

Good crank shape.

These 675cc injectors require a latency as low as 600us to keep the idle in the 192-range (aka 0) for the fuel map, and a smooth transition from TP=8 (fuel correction factor=5) to TP=112 (fuel correction factor=44).
All of this for a given Injector conversion factor: 200 in my case (i.e. 200/255) with E85: 30% unleaded, 70% alcohol currently.
Max. TP=106 @15.5psi.

If people wants to test these chinese injectors, PM me.

The previous 12 holes 750-840cc injectors.

RomChip200 wrote: ↑Thu Apr 21, 2022 8:29 am I changed again my injectors and solved all my issues of hot cranking.

My previous were chinese yellow 12 holes, pretty good on all the range, except cranking when playing with 2-3ms. I suspect the 12 holes drip more than they spray when the crank pulse is short.
I just tested them on my bench (should have tested them few months ago before installing them ....). 2 of them have inconsistent spray patterns. They flow from 750 to 840cc (static). Dynamic flow was more on par.

Whatever, I found other chinese injectors, I tested them. They are surprisingly flow matched. They are all in the 660-675cc static flow. They all behave the same. Spray pattern is 2 wide tilted cones, fine.

1650489154999.jpg

1650489154976.jpg

1650489154958.jpg

These are really working fine.
1.50ms pulse range @ idle.
TP=95 @14.8psi AFR=11.17/11.71 with factor=40 E85=66% 12.95ms max.

Good stuff. So effectively from this one the Chinese ones are a better gamble than DW ones.

From what you have shown, the crank time in ms proves an issue with finer control unfortunately. Crank volt table I've added won't help here, since the result is still 'integer' so cannot do fractional pulsetime without some further patching (which you have done for your Z32), which is difficult with so many different ECU base code to work from