Just got larger injectors-quick question

wes kiser · Post by **wes kiser** » Fri Jun 23, 2006 1:32 pm

In the cranking fuel tables, is the number in the table the actual pulsewidth, or is the offset added on top of the table value? The reason I ask is I want to know if I need to scale it directly, or subtract it from the offset and then scale that number. Thanks, got my 85 lb/hr's so I can run e85 later, and fixing to drop them in. In my case, it will make a huge difference, because the offset is already close to the same as my warm cranking pulsewideth.

wes kiser · Post by **wes kiser** » Fri Jun 23, 2006 3:12 pm

Got it running. It looks like they were the actual pulsewidth

It is amazing how well the ms2 handles injectors that large. I had to bump the offset down from 1 to .9 , but it is happily idling with a 14.0: 1 afr (same as before), and the pulsewidth is only 1.4 msec at idle. This is with 85lb/hr injectors (that is close to 900cc for you metric types) on a 2.3 liter engine.

Minami Kotaro · Post by **Minami Kotaro** » Fri Jun 23, 2006 3:23 pm

Holy crap. You must plan on making some big power.

wes kiser · Post by **wes kiser** » Fri Jun 23, 2006 3:44 pm

Not really that big, the 52's that were in there were almost big enough. I am wanting to run flex fuel (or at leat ethanol sometime). I came across an unbelievable deal on these injectors, so just though I might as well go big. The car probably makes about 300 rwhp on the pump gas safe tune, and on race gas or ethanol could probably get close to 400. With ethanol these will be probably at a 80% duty cycle.

S.Bretz · Post by **S.Bretz** » Sat Jun 24, 2006 6:05 pm

I'm pimping 96's on a 1.9 lawl. I can't turn the fuel down enough. It idles at 1500 and won't go higher then 12.8:1. I wish I had flex fuel in the area...the the higher amount of feal you need to inject with flex, I should be sitting pretty with a good a/f .... but the closet FF station is about 4-5 hours from here

wes kiser · Post by **wes kiser** » Sat Jun 24, 2006 7:17 pm

S.Bretz wrote:I'm pimping 96's on a 1.9 lawl. I can't turn the fuel down enough. It idles at 1500 and won't go higher then 12.8:1. I wish I had flex fuel in the area...the the higher amount of feal you need to inject with flex, I should be sitting pretty with a good a/f .... but the closet FF station is about 4-5 hours from here

Have you tried bumping down the injector offset (and obviously the pwm high current time to the same amount)? Then again 96's on a 1.9 are pretty huge. How much power are you making, and what kind of engine is it?

tebriel · Post by **tebriel** » Sun Jun 25, 2006 9:10 am

Sam, i'm running 86#ers and I don't have any idle problems with it, it idles around 13.7-14 once the car is warmed out. Sits at about 900 rpm.
-teb

Highbeam · Post by **Highbeam** » Tue Jul 04, 2006 10:36 am

I could use some help gettin my 880's startin and idling in my vw.
I am a builder not a tuner, so take it easy.
v2.2 flybackboard

bad360rt · Post by **bad360rt** » Sat Jul 08, 2006 5:42 am

wes kiser wrote:Got it running. It looks like they were the actual pulsewidth

It is amazing how well the ms2 handles injectors that large. I had to bump the offset down from 1 to .9 , but it is happily idling with a 14.0: 1 afr (same as before), and the pulsewidth is only 1.4 msec at idle. This is with 85lb/hr injectors (that is close to 900cc for you metric types) on a 2.3 liter engine.

That's good to hear, since I picked up 85lbers for my truck, and I was afraid that it might be tough to tune, since they're bigger than what I currently need. I got the MSII tho, for just that reason. Glad to hear that it can handle it. I'll be installing it next month, then the fun begins

PSIG · Post by **PSIG** » Sat Jul 08, 2006 10:41 am

Don't forget folks that .001 resolution is not mandatory for tuning your idle - just tweak your fuel pressure up or down to the next .1 setting based on the over/undersize of your injectors so it's perfect. Idle is the first thing you tune and the base pressure can be tweaked at this time for a solid idle mix and the remainder of the VE table tuned from there. Hi-Res is nice but not a requirement for fine-tuning with huge injectors.

FWIW,
David