Ransford2987

I replaced my OEM injectors with Bosch III's and it takes a few more turns of the engine to start cold now. I'm assuming this is because the bosch's open and close much faster than the stock injectors, but I was also told they were plug and play. I've adjusted the Crank Pulse Width vs. Temp table in Tunerpro and have had a little success, but trial and error is the only way I know to test it and I don't always know if I'm on the lean or rich side of the band and which way to go.

Anyone have a similar situation? What did you do to solve this?

RBob

iTrader: (1)

I thought I posted to this thread yesterday, probably forgot to hit the submit button...

What I would do is to get the engine up to temperature and data log while driving around. See what the BLMs are doing. Much higher then 128 and the injectors don't flow as much, lower then 128 and they flow a bit more then the stock ones.

By how far from 128 they are will give you an idea of how much and in which direction to change the cranking PW.

RBob.

Ransford2987

Thanks RBob, as always your input it much appreciated. I have changed quite a few things including the VE tables since the swap, but I remember at low RPMs having my BLMs drop to the low 120s instead of being at 128 like they were before the swap. I've been going the other way with it (longer PW), but I'll try the other way and see how that does for me.

gta324

cranking is hard to get right, its trial and error but do like Rbob said you could get a hint in what direction you should go.

You could also play with ref.pulse vs crank BPW ( not sure the name is correct)

Ransford2987

That crank mult. vs ref pulses, I don't really know what that is. I have a thought of what half of it is, but the ref pulses? Is that from the pickup coil in the distributor? I have messed with it before, but each time it resulted in a SES light and so I went back to what it was before. Though, that's most likely due to the fact that I didn't really know what I was doing.
My car starts better in relatively cold weather, like 30s and 40s, so I think I'll try to come up with a formula that uses the difference in air densities at different temps with a difference in pulse time. I'll probably use the temp at which it cranks the best as a reference and compute the difference using ratios, at least at first.

Quick question for anyone that knows, is the AFR while starting at stoich, or is it shifted lower somewhat?

RBob

iTrader: (1)

Yes, DRP's or distributor reference pulses. That is each time a spark plug fires.

For global changes to the cranking PW use this parameter:

L83AD: FDB 13108 ; SCALAR FOR MAX PW

This is the starting point for the cranking PW. The cranking PW tables modify it to form the final cranking PW.

Cranking fuel is much richer then stoich fueling is.

RBob.

Ransford2987

Forgive me here, RBob, but I don't know what "L83AD:FDB 13108" means. If you could throw some light on that for me I would be greatly appreciative. I started the car up today at around 40*F and it seemed to start ok, or close enough that I'm comfortable with it (a little less than a second of cranking). It'll be colder tomorrow so I'll see how that works with it.

For my knowledge, does the pw vs. temp take the reading from the CTS or the MAT sensor? (I would assume MAT, seeing as that determines the O2 density of the air...)

Also, my first thought to determine this is linear interpolation for the exact temp and PW. Is this correct or is there some other way to determine this? I.e. if I wanted to find the PW for 37*C, which falls between 32 and 44 I would do

(37-32)/(44-32)

and then use that to find the difference between the 32*C and 44*C table PW.

RBob

iTrader: (1)

It is the base PW for cranking. The conversion is N / 65.536 = PW, so:

13108 / 65.636 = 200 mSec

The other cranking tables reduce it down from there.

It appears that the CTS is normally used. With the ECM switching to the MAT if the CTS is in error (malf 14 or 15). Although it would be best to test this on the ECM bench.

The ECM does 16-point linear interpolation between the table values.

RBob.