MY 350 Z cold starts better now than when it was completely stock, but hot starts are a Pita. For those who are are familiar with the Haltech program:at 80F pulse prime inj is set @ 122ms and cranking inj. rate is 6.225/ 6.125 ms at 80F. Now I know that specific numbers are unique for every car depending on inj. size and base fuel pres.. I am looking for trends as the engine builds temp. do you increase pulse prime rate or decrease it in the 100F to 230F range. How about for cranking inj. rate? If you increase/decease by how many increments? When my engine finally fires it runs slightly rich for about 30 seconds and settles around 14.7 AFR's. Once it starts the motor never dies while idling, so I think I have my Post-start enrichment tables set correctly. Any guidance is greatly appreciated.

 

Increase the start timing too. Just play around with it, save your original map. Then make extreme changes both ways and see what happens.

 

I found a menu tab for Crank Timing under the Ignition folder. Is that what your refering to?

I started backing off (reducing) both the prime pluse inj. to 45ms from 155ms @212F and crank inj. from 5.4/5.20 ms to 4.0/3.75 ms @200F. The engine fires up afer 4-5 revs. and there is no rich fuel smell coming from the exhaust once the motors starts. This is a big improvement. The engine still cranks on 1/2 -1 rev on a cold start.

 

On a hot engine the prime pulse should be in the single digits. I think difficulty starting is from running rich in your case...

 

I am the opposite, hot starts are great but can't get my cold strts down. Actually it starts right up by dies after about 5 seconds.

I think it's enrichment related.

 

Couple tips:

1. Make sure dead time values are correct. If you have to change these, you need to adjust your entire base fuel map by the amount you change the dead time (in the opposite direction). You can use a combination of Shift/Ctrl/PgUp or PgDn to exactly get your tune back to the right values. Triple check values and data log injection times and injector 1 time before/after at idle to make sure you did it right.

2. Use the coolant temp fuel correction table to add in fuel when the car is cold.

3. Use post-start enrichment to add more fuel at the time point where it cuts off. Unless you're flooding it of course - hard to tell since widebands take a while to warm up.

4. Try to identify if you have a whacky low fuel cell value that you encounter on the throttle flare upon starting that you don't encounter otherwise (higher load than idle but still low rpm).

5. Cranking injector times at 0 and 400 rpms should be about 1/2 and 3/4 of the value of the cells at 1000 rpms at idle load. I actually reference a slightly higher load than true idle (which is -7 psi for me). The default table that was in there had about 3 times the amount of fuel needed. It worked OK, but was a waste of fuel and required a few more cranks to start. Now it starts almost immediately - faster than stock.

Great document here to get started tuning with the Haltech:

http://www.haltech.com/downloads/pla...ort/index.html

(Although it's for a different unit, it is very similar)

There are also user forums at forums.haltech.com.

 

^^rcdash, thank you very much. I just need some time to play with it I guess.

 

Start up and die after 5 seconds... use the post-start enrichment table. In some cases up to 20% or so is necessary for first 1-20 seconds, fading out as time grows (I am generally always to 0% by 60 seconds). Also, as rcdash mentioned, the coolant temp correction is playing in as well.

 

Thanks Hal & especially rcdash. This is exactly the kind of imformation I was looking for.