V8what?!

Do they spray when they see boost, a certain rpm, or what?

jimmyv13

Supposed to be around 3800 RPM.

DaleClark

iTrader: (55)

They always kick in at 3800 RPM. From what I understand, the primaries scale back the pulsewidth and the secondaries come on, so they're both running the same pulsewidth.

For example, if you were at 30% pulsewidth just before the transition, when you hit 3800 RPM the primaries go to 15% and the secondaries come on at 15%. That's why you feel a little hiccup there on some cars - that transition is tricky .

Dale

HAILERS

Only a slight disagreement. If you push on the pedal like there was a egg b/t your foot and the pedal, the secondaries will not come on line at 3800. You can pull six grand and they will still be offline. Reason: no demand.Works in conjunction with the input from the boost/pressure sensor. Low load being sensed by the pressure/boost sensor = no secondary injectors online. High demand sensed by the boost/pressure sensor= secondaries online.

I've observed this with a Fluke88 patched into the secondary wires at the ECU. Watched the duty cycle. Also done it with a plain old RadioShack meter watching the voltage drop.

V8what?!

If you're cruising down the interstate in 5th gear doing about 70, you're still below 3800. If you press the accellerator and boost it up to (at least) 5psi before 3800, aren't your chances of watching your motor pop pretty good?

RETed

On average, it's anywhere from 3500 - 4000, with 3800 being the typical number throw around.&nbsp HAILERS is right - it has a lot to do with engine loads, as reving the engine in neutral is not the same as 10psi of boost in 5th gear...


-Ted

HOZZMANRX7

iTrader: (43)

The heavier your foot, the higher percentage of time your secondaries are feeding fuel.

Anyone ever done an analysis of, say for average daily driving (however that might be defined), typical % of time the secondaries are active?

Hailers, this sounds like something you might have done. Yes?

XxSpec7xX

Please Help... I just read your replies...

XxSpec7xX

I have an 89 GTU with a severe problem with the EFI system. No one I have talked to can give me and answer. When I press the pedal above 4000 and hold it for more than a few seconds the car goes into limp mode and I get no pedal response at all... Just enough to putt along @ 0-60 in like a minute... I can flip the key off and on and get the power back. (by reseting the CPU) Could my Boost sensor be out or the secondary injectors? What could cause this. I am a week away from buying a Weber Carb Kit to eliminate this all together.... Please help.........

HAILERS

V8WHAT.....I forget where I mentioned 70mph in fifth, but just for you, going to the salt mine today, I pulled 5000rpm in first without the secondaries opening and hit 4500 in third without the secondaries opening. Both times with gentle accceleration and on a level road. And just to make sure the meter was working I punched it at 5000 and 4500 respectively and the secondaries came online.

I think 3500 is the actual trigger point IF the load exists to turn them on. 35..38 ain't much difference.

I think there is a test in the manual where you disconnect the boost/pressure sensor at idle and listen for the secondary injectors to click, click, but my hearing is so bad I'd never hear them being online.

HozzmanRX7...Nope never done that. If you think about it as you probably have, they are not online very much when you get right down to it. We may get over 3500 in each gear all the time, but how much of that time over 3500 is under enough load to trigger the secondaries.

xofSpecrx7xx Cheez. Got me. Ohm out the tps thru its full range to see if its got a open in it?? Set the tps? Got any codes from the ECU(not CPU, please. CPU is for non-essentials like horn etc)? Just a wag if you don't have anything else to do.....swap primary with secondary injectors. Not a very good wag, but a wag(wild *** guess).

HAILERS

Now that I've woke up, I see where I misread you V8WHAT. Sorry 'bout that. Just off the top of my head I don't think it'll pop. I'm counting on the engine having enough fuel with just the primaries.

Now that I've got a wideband in the car, I guess I can test that theory out. I'll boost over 5 prior to 3500 and look at the afm to see how the fuels coming along.

V8what?!

Please do. It sees like (in theory) that your car would explode every time you boost below 3500. But seeing as how that isn't very much boost at all (and the fact that all of our cars havn't blown up by now) I guess it isn't true. Please post your wideband results!!!

RestoTII

actually, the duty cycle would just go up on the injectors, keeping a pretty good mixture and not running lean. If you do boost too much for the highest duty cycle of the primaries, you might run lean, but not for too long since you'd probably be accelerating with 5psi of boost behind you, and your secondaries would probably come online soon