How fast does your tbi vehicle start?

**1project2many** · 07-21-2015

Minimum RPM before startup is at 000A but the definitions I have here don't have it. You can edit it in hex or add the value yourself. The conversion is 65536 * (120/N CYL)

**brian617** · 07-21-2015

Crank BPW vs Temp has a big influence on starts as well. Personally I like the longer cranks, gets the oil pumping.

**Mr. BBQ** · 07-21-2015

I had a 92 Caprice, 305 TBI that even with 190k mi on the clock started faster than any other vehicle I've owned. On a day old 30* outside temp start it wouldn't even crank 1.5 seconds before it fired. On a hot start you could basically bump the starter and it would catch and fire, maybe .5 second cranking time.

Now, my 90 K2500 350 TBI has to crank 3-4 seconds on a cold start, and 1.5 to 2 on a hot or warm start. It seems like it takes ages compared to my old Caprice. BUT, it does start every time I've ever wanted it to so I can't complain that much. Even after rebuilding the TBI and swapping in a new EP381 fuel pump (for other reasons) it takes the same 3-4 seconds to crank. No idea.

**joegreen** · 11-09-2021

I'm resurrecting's my old thread. I'm working with the 7747 ecu. Under the scalar parameter "engine startup rpm" the description says "ENG Start Up DRP Periods. Setting affects idle spark.". What are DRP periods? How does this parameter effect idle spark? I am messing around with settings seeing how they affect the speed of a cold start on my truck. I changed the engine startup rpm value from 499 to 50 to see what it would do and it ran horribly. I assume this is because it effected the spark. I changed to back to 499 and all was fine. I noticed different bins have different values for the engine startup rpm. What does this parameter actually control/tell the computer?

**brian617** · 11-09-2021

Distributor Rotation Pulse I believe. Like cam sensor counts?

**PlayingWithTBI** · 11-09-2021

Originally Posted by brian617

Distributor Rotation Pulse I believe. Like cam sensor counts?

IIRC Distributor Reference Pulses (from the ICM to the ECM). If it helps, my 88 C1500 5.7L cranks ~2 seconds when cold and almost immediately when warm with the 7747 in it. It's still the same with the EBL Flash-II.

I'm curious what you find to change that length of cranking although, I kinda agree as mentioned earlier, I like it delayed some so oil pressure can build up before firing.