MSefi.com read only forum (Jan.15,2018)

ok, i have a 3.0l v6 with 210cc high impedance injectors, MS-II 2.883b code

yesterday i was working on idle and free-rev tuning and after a couple revs, the motor stumbled and died. after trying to crank it over a few times, i was getting fuel dripping out the exhaust. switched plugs, charged the battery overnight. today, same thing when i crank over, 3 cranks and fuel coming out the exhaust. i pulled the upper intake manifold and the back bank has large puddles of fuel on the valves, front bank is fine.

I took a look in my msq and the PWM% was at 75 instead of 100% and length was 25.5. would this cause a bank to get stuck open when running? i double checked the wiring and there isnt a short or leaking injectors....

Do you have a stim? or rig up some other test light or meter to see if maybe there is some issue with the drivers on that side keeping those on? Also if you have a vacuum adjustable regulator does the vacuum line happen to go to that area? A leaking regulator can dump a lot of fuel.

unless something fried Thursday, the MS was working not only on the stim, but the car as well. the FPR is vaccuume controlled but it is on the front bank of the fuel rails. it is quite puzzling

IF the FPR goes bad you end up getting fuel though the vacuum line so thats why I was asking where that line goes into the intake. I had one that went into the throttle body but because of the slight angle the car was parked at it ended up hydro locking one cylinder. If the vacuum line happens to connect to the side that seems to have the extra fuel and the reg is bad that could explain all.

its possible, ill look into that.

check the pulse width at the injectors. compare bank to bank.

It may have a grounded wire on that bank holding the injectors open.

checking the injectors and their wiring is next on my list...once it stops snowing...

it was a rather sudden issue so *shrug* who knows

ok, i am trying to figure out what would have caused a sudden change in the amount of fuel injected into the motor. My issue suddenly started after a free-rev, and has plagued the motor since; puddles of fuel on the valves on both banks. some of my thoughts are:

1) fried injectors not responding correctly in run/start mode flooding the motor

2) bad vacuume source to FPR causing added fuel to be injected

3) some setting somewhere in MT causing obscene amounts of fuel to be injected.

other than that, i have no idea what it could be

If it was something in MT it would show up on a datalog. If you look at the options in MegalogViewer you will see an option for things like AE plus you would see the injector PW go up. If the PW is not going up its not the MT or other software causing the problem so you are back to electrical or mechanical issues.

if its a short in the wiring, would it have to be a short to ground for the injectors to open? and if i had a short, the injectors are on a switched 12v, so in start/run they have power. However, with the key on or off (not start mode) the injectors do NOT leak at all. its like before MS controls the injectors they are fine, but once MS fires them, they dont close...

would having them wired not in parallel or series affect the injectors? i have all 3 positive leads of a bank wired to a single switched 12v and the 3 negatives to a single wire to the relay board.

was reading through the injector part of the megamanual and found this:

Signs of an impending flyback failure are:

* MegaSquirt® will often require higher PWM% over time,
* The engine may start running erratically, especially at higher speeds and loads,
* the injectors may 'stick' open and flood the engine.

any way i can test to see if the flyback is dead?

shadowplane676 wrote:if its a short in the wiring, would it have to be a short to ground for the injectors to open? and if i had a short, the injectors are on a switched 12v, so in start/run they have power. However, with the key on or off (not start mode) the injectors do NOT leak at all. its like before MS controls the injectors they are fine, but once MS fires them, they dont close...

would having them wired not in parallel or series affect the injectors? i have all 3 positive leads of a bank wired to a single switched 12v and the 3 negatives to a single wire to the relay board.

That is a good assumption, and a short to ground on the trigger side of the harness would not necessarily be a likely problem.
I suggested it because it is one of those things that can keep you going in circles if you don't check for it, and it's a simple check. I would suggest doing the check and also wiggling the harness around while you do it just to eliminate it then move on. and check the actual pulse width at the injectors.

ok, today i did the following:

1) checked the impedance of all 6 injectors and got ~13.5-14 ohms.

2) checked the wiring to both banks of injectors, no shorts, nothing.

3) removed upper intake and with spark plugs removed, physically watched injectors as the motor was cranked over. I observed the front bank working fine as intended, pulsing squirts of fuel. the back bank (inj. 2 circuit) was going full bore all the time, even to a 4 SECOND spray after the motor was not turning over.

so, what would cause the injector 2 circuit to keep the injectors open 100% of the time even after the MS is powered down? mind you that they dont leak when the fuel pump primes the fuel rail at key on, only once you start cranking.

it does not short with the DB37 disconected

teh injectors only misbehave during and after cranking, on key-on the FP primes with no injector leaking.

i tested the standard flyback components and the PWM components, but have MS configured for high impedance injectors.

Standard
R33 - 226 ohms
R18 - 265 ohms
D6 - .5v
D20 - .5v
Q3 - .5v
Q11 - .5v

PWM
R30 - 253 ohms
R31 - 265 ohms
R34 - 251 ohms
R35 - 265 ohms
R32 - not present
R36 - not present
Q9 - .5v, 60K+ resistance
Q12 - .5v 60K+ resistance
Q10 - .6v
Q13 - .6v


also, Q1 and Q5 look fine and register open, all solder points are non-bridged. I inspected both sides of the board with a magnifying glass prior to installation in the car.

ok, i dont think the MS is at fault now. I switched the ground wires for the banks so the back bank was triggering off of the channel that was triggering the front bank earlier. SAME PROBLEM. this leads me to believe i have clogged or bad injectors on the back bank. i think they got clogged due to the old fuel and that the feed from the tank hits the back bank first before going to the front bank.

ok, spent the afternoon redoing nearly all the connections with solder and shrink tubing to eliminate any shorts, bad connections enc. But when i started her up, shes running so godawfully rich i cant figure it out for the life of me. i got a different set of injectors that looked fine when i turned it over without spark wires and had a good pulsing mist.

i can IDLE with a VE of ONE and an A/F of 7 to 8 :1, and it will hunt badly but still be running on a VE of ZERO; i cant figure it out. all the wiring is not shorted, is fine but i almost think those back injectors are not shutting again. *sigh* i an totally baffled now. it defies sense. unless there is something wrong with the injector circuits that i cant find or dont know about.

If you mess with the opening times, and go below 1.4, it starts to stumble and try and die, bring it back to 1.4 and it'll run a lil better but its still a crappy, rough, missing idle. changing the VE and req_fuel seem to have no effect on the motor at all.



heres some audio of it - it may help *shrug*

i cant seem to find the older code variants. can someone point me to a copy of the 2.3 code? thats what i was running before i upgraded to 2,883b and had this issue. i wonder if theres some difference between the codes that im missing and is screwing this up. its worth a try

i dont remember what they were, i didnt really read it as i moved my post over here. was a bit frustrated so wasnt thinking 100%. also figured i could reference it when i was more level-headed but i cant find the post anymore. think you could post it again?

btw, my apologies to everyone, i get frustrated with things when they dont seem to make logical sense, something i still have to work on..

Thanks Lance, ill try and answer what i can tonight and get the rest tomorrow hopefully.

Could you describe clearly and concisely what the problem is?
ok, what happened originally was:
pre-issue) ran well on 2.3 code, drove car round the block until EDIS wheel welds broke. re-welded wheel (properly) and...
1) upgraded to 2.883b code. was working on idle and free-rev acceleration enrichments when after revving the motor a few times, the motor sputtered and started running real bad.
2) Culprit was stuck injectors from 2 year old varnished fuel, since removed and replaced with 4 gallons 93 octane
3)Known good injectors swapped in to replace stuck/gunked injectors, idle has NOT improved, car now misfires badly, and is running extremely rich, even with VE of 1 or 0. Removing Vacuum line from manifold and/or FPR does not effect the motor. changing VE or req_fuel has no effect on the motor either. the only thing i can find that DOES effect the motor is the opening time, which, if it goes below 1.4 it starts hunting, reverting to 1.4 event it out somewhat, but misfires and over-rich condition prevails


you seem to be idling entirely on the opening time, which suggests the PWM parameters aren't right for you injectors, so I would review these very carefully.
from everything i have found, my injectors are high impedance (checked with DMM as well, 13.5-14.2 Ohms) 210cc flow, with similar opening times to the low impedance 3000GT injectors of .7ms each, totalling 1.4ms. MS settings are PWM% 100, Pulsewidth time threshold: 25.4, PW period: 66us

i will re download reload the .s19 tomorrow, and try and post a datalog soon, not sure if the one i have is good or not. will also try and trace the injector circuits

Lance,

I'm not quite sure what you mean about the 0.7 msec times totalling to 1.4. Injector opening times don't add, maybe you are saying the opening and closing time are both 0.7, and this adds to 1.4? If so, I don't think that's right, for MegaSquirt you want to subtract them (i.e., if the opening time and the closing time are the same, then the fuel pulse width is delayed by the opening time, but there is no net effect on the fuel pulse width). So I think we need some clarification of this.

they are added, .7 to open and .7 to close, which equal 1.4

do you have a fuel pressure gauge? I ask because it is possible that the regulator is sticking and allowing higher than regulated pressures
i have an adjustable regulator with a gauge i have yet to put in. i was thinking about this same issue today and will probably install this tomorrow if the weather cooperates

A backfire can also rupture the regulator diaphragm, leaking fuel directly through the vacuum hose, if you pull the hose off the regulator's vacuum hose off the intake manifold or TB, it should hold suction (and should not have gas in it, of course!).

i checked this yesterday, there IS vacuum through the MAP source hose to the FPR. i have a source Tee'd to both the FPR and the MAP source for the MS. only thing i can think of is that the part going to the FPR got pinched and isnt providing enough vacuum. i will replace this section anyways, as it is only 6"-8" long. there was no fuel in the line as well