Anyone NOT have a slight hiccup when pump2 comes on?
 

I have been messing with this since day one with my LT8. I have a slight hiccup when pump2 comes online. I have moved this around from 2000 to 3000, it happens where ever I move it to, I tried moving the amount down to +22 and up to +35 with no noticeable change. If anyone doesn't have this hiccup, please look over my settings and let me know what I change to rid myself of this annoying nuisance. Thanks.

My settings are:

Pump1:
AMT: +4
PULSE:+2
TRIG:+14
STOP:00Hg
ADV:+5

Pump2:
START:2000
AMT:+30
TIME:+10
TRIG:+20
STOP:00Hg
ADV:+5

If there is anything you need other than what I have listed, let me know.

I would assume yours is just dumping waaay too much fuel. To give you an idea, I'm running an AMT of +5 on pump2.

-David Guy

damn.... never went that low. What injectors are you running? I am running 550 pri's and 680 sec's. That's kinda what I figured, but I do not have a wideband to see what's going on. My EGT is not helping at all..as you may know

I was running 4x720cc never had a problem at all.

What were your settings, do you remember?

I run 760 primary and 850 secondary.

I'll drop the AMT down quite a bit and give that a try. Thanks for the replies...

Get a wideband!!! :P

Thanks numbnuts...j/k


Well, I moved pump2 AMT clear down to -8% with no change, still hiccupped. I tried changing the TRIG and TIME, with nothing doing. What else could it be?

never had a problem. I run 550cc and 1680cc combo

What are your TRIG and TIME settings?

I went to 3D mode today and got it tuned pretty good through 6 PSI. Thanks Pirahna ;)

The hesitation is STILL there. I can see the AFR's jump lean when the hiccup occurs, I went up to +30 on the AMT and it still goes lean for just a split second. I'm going to go higher maybe up to +40 or +50 and hope to get rid of it.

pump2 problems
 

I think it could be your TRIG (ie. pump2 trigger) value is too high. Try bringing it down from 20 to 15 or 10 then the pump2 will come in much quicker. BTW do you have the Microtech manual, there's some good info in there.

Adrian

Why do you think it's the trigger? Its purpose is to activate the pump2 via a percentage of manifold pressure difference. I get the hiccup regardless of manifold pressure, if I ease up to the pump2 start or if I floor it, I still get the hiccup. Maybe I don't understand the trig feature.....

I am dead set on a fuel or timing issue, but it happens wherever I put the pump2 start.

Yes, I have the manual and have read it MANY times, unfortunately, it doesn't go into great depth explaining each feature.

hiccups
 

To progress any further with your tuning you really need a wideband meter (I use the Tech Edge WB, it cost me approx $500aud). If the hiccup's being caused by a fuel issue it should show up on the WB (ie. as being either too lean eg. 15+ AFR or too rich eg. <10 AFR). If its some ignition issue then datalog the hiccup, and have a look to see if there are any spikes or inconsistencies in the ignition timing.

I'll look at my datalogs and see if there are any obvious inconsistencies in comparing them to yours.

Adrian

I have a WB on there and I have verified a lean spot, the AFR jumps from low 12's to high 13's at the hiccup. No matter where I put the AMT, from +1 up to +99, it still hiccups with no noticeable changes.

I will check the datalog tomorrow. Thank you for your help...:)

hiccup
 

I reckon its the +5deg. ignition advance on pump2 that's causing your 'hiccup' problem. My pump1 and pump2 settings have 0 advance, and they work just fine.

Adrian

I have had my ADV changed to zero on pump 1 and 2 for a while, no change.

Adrian

Had the exact same problem.Changed 2000 to 8000 or max of your system to eliminate pump2. Play with pump1 settings since it is active all the time then.
Make sure your primary and secondary injectors is not swopped around.


Skillie

That sounds like it doesn't really fix the problem, just a way around it. I don't believe my pri/sec injectors are backwards but I guess I can check.

jimmy, what size injectors are you running?

bring your P2 start up to 3000 and your P1 pulse to 7 or 8 and see what happens to your lean spot.

Ray

I've got 550 primaries and 680 secondaries. I'll give those settings a try and report my results, thanks.

now that i've had time to go back and read what i've written i don't think that is going to work.

i would move the P2Start to 3000.

P1Amt seems fine if you aren't having any problems
P1Pulse is ok if you aren't having problems there
P1Trig looks to be ok
P1Stop can come down to 5Hg see how it acts there, shouldn't give you any problems

as for P2 lets start at P2Time

just for shits and giggles try and set P2Time to +20
just changing P2Time to +20 should significantly richen the mixture because you'll have a minimum of 20 timed pulses firing while P2 is active

ignore what i said before, i don't know what i was thinking i must have misunderstood what the problem was.

i think what may have been happening is that with P2Time set to +10 it may have fired its 10 pulses and turned off before the motor got enough fuel.

since you changed your P2 Amt values already do me a favor and do some comparison datalogs while changing the P2Amt. i'd like to see if there is a change in inj. mS values.


Ray