Braineack

iTrader: (62)

Flood clear mode this can be set in "More Cranking Stuff" Sometimes you might want to temporarily stop the injectors from injecting fuel during cranking to clear a flooded engine. This is achieved by holding down the gas pedal during cranking. The MegaSquirt needs to know at what point of gas pedal deflection it should turn off the injectors and a good starting point would be just before floored.
To get this value, go to Tools, Calibrate TPS, and push the gas pedal almost all the way to the floor - about where you think the fuel should be cut off and hit Get Current. Remember this value and hit CANCEL on the Calibrate TPS dialog. Insert this value for the TPS Flood Clear. If this value is set too low then you will not get any fuel during cranking. If you set this value too high, then you won't be able to press the pedal enough to trigger the Flood Clear.

chucker

iTrader: (4)

Good advice. But I think this is an answer to a separate problem.

I’m not trying to stop the injectors from injecting fuel during cranking. I’m trying to stop the single spark event at power-up. If that single bastard spark is eliminated, so would be the cold-start pop. Momentary spark interrupt could solve this, yes?

Braineack

iTrader: (62)

fix your leaky injector.

richyvrlimited

iTrader: (1)

I don't think it's a leaky injector, mine does this sometimes too, had my injectors tested, they don't leak, period. I still get an intake backfire occasionally

paul

iTrader: (21)

tested by whom? I am starting to doubt the practices of IR. Gonna send mine to Witchhunter or Cruzin Performance from now on.

richyvrlimited

iTrader: (1)

An Injector cleaning company in the UK ASNU Fuel Injector cleaning by post..

chucker

iTrader: (4)

What's your guess, then?

richyvrlimited

iTrader: (1)

it's a 'feature'

wayne_curr

iTrader: (8)

After reading through this thread, it doesn't appear that anyone figured this out.

So this just started happening to me. Started happening after I went turbo. I installed my 550s and ran them for a couple of weeks without this happening. Not sure if they're related. There is seemingly no ryme or reason to the pops except that it doesn't happen if I rev the engine and kill it at like 3k.

Also along with this, sometimes my car does not crank on the first try. It does like half a crank and stops as if something is in the way. Injectors are 550s cleaned and flow tested by injector rehab.

I am running fairly rich right now...perhaps way too rich? At about 13:1 afr at idle.

Savington

iTrader: (31)

I get this on rare occasion. Maybe once every 50 starts. Always cold. Twice it's been big enough to foul a plug; car ran like crap for 30 seconds then came back normally.

wayne_curr

iTrader: (8)

I'm curious if this might have something to do with me jumping FP and GND instead of running the fuel pump wire off the MS.

And I notice this plug fouling thing too. Totally runs like crap for a few seconds.

richyvrlimited

iTrader: (1)

too much fuel in cranking settings.

Laur3ns

I don't understand this either. I get it now the weather warming it seems, can be anything between parked for 3 hours and a couple of days. Fouls a plus sometimes indeed.

We need to figure this out dammit.

wayne_curr

iTrader: (8)

That would make sense, just loaded a new msq not long ago and didn't change my cranking settings. I will investigate this tomorrow.

As for the popping, no fracking clue. It startles me when it happens, then it smells like someone lit several matches.

JohnW8

I had this happen while I was calibrating an o2 sensor and gauge. I had to power up the LC-1 and XD16 a couple of times and when it popped the engine didn't rotate. I assumed it was fuel vapor leaking into the exhaust from an open valve and being ignited in the pipe by the hot o2 sensor.

DXO

iTrader: (2)

+1, My car didn't start this until I installed a WB with a heated sensor.

Joe Perez

iTrader: (8)

Not figured out? We know that the MS, when configured as we do, sparks the plugs at initial powerup. So either fuel remains in one or more chambers at shutdown due to the engine not rotating through a full cycle to clear it, or a small mount of fuel drips out of the injectors and finds its way into one or more chambers after shutdown.

Which suggests that in your case it is due to the engine not rotating through a full cycle after you shut it off, thus leaving some fuel in one or more of the chambers (said fuel having been injected on the last squirt prior to shutdown) which subsequently ignites.



Cranking fuel has nothing to do with this. The pop in question occurs before cranking begins.



Every time you powered it up, the MS squirted priming fuel. If you didn't crank it, that fuel stayed behind and drifted into whichever chamber had open intake valves. Then you turned it off, and then when you turned it on again, pop.



I don't see why this is such a mystery. If you want to make it stop, either make sure that the engine turns a full cycle (two rotations) at shutdown (add rotating mass, or blip the throttle before you turn the key), or wire your spark outputs to be inverted so there's no spark at powerup.

wayne_curr

iTrader: (8)

Ok, it still does it even if I rev the engine a bit before shutdown. I must be dealing with leaky injector(s) issue(s). I dont have a light flywheel or anything and my idle is high to begin with so i'm pretty sure its getting 2 revolutions before shut down even if I dont blip the throttle before killing it.

As long as the pop isn't damaging anything, i'm fine with it. The only adverse effect I seem to be dealing with are fouled plugs making the car a bitch to start sometimes (runs on 3 cyls til the plug comes back to life).

Just swapped out the plugs with some bkr7e's and gapped them to .025. We'll see what happens I suppose.

Quick question: Are leaky injectors due to the injectors themselves being rebuilt improperly, or due to a poor installation by myself? Or are RX7 550s just kinda leaky and shitty to begin with?

Laur3ns

I had brand new RC 550s installed by a pro, so unless that **** is know to leak I doubt it's that. Joe's explaination about inverted outputs seems correct. The fouling is the only issue I have with it.

Mach929

iTrader: (3)

i still et this occasionally as well. i don't understand what you mean by making the engine go a full cycle after turning it off, how are you supposed to do that? by hand?

the problem is that ms fires the plugs when turned on, is there any good reason for it to do this?