She wont start :( Cranking Pulse, Vr sensor, Tach signal

[scorpio12]

After 5 years getting my project ready I hooked everything up, Engine cranks but wont "catch" and start. Everyone on this forum is extremely knowledgeable as ive been reading through posts for a while now and thought ide get some help.

Running edis 4 and MJLJ ( which i removed just to get her started and running in LIMP mode ie 10 degrees btdc) using edis PIP as a tach signal for megasquirt... 4 Cylinder engine...also running relay board

QUESTIONS
1) Ive switched polarity on the VR sensor and get a spark when cranking... will having the VR sensor the WRONG way still give a spark? or can i eliminate this as a problem?

2) Cranking pulsewidth at -40 on most documentation says to start at 88% required fuel..yet ive seen on some documentation to start it at 320% required fuel ...... which is it??

3)Im running 2 squirts alternating...is this best or best to start at 1 squirt simultaneous etc?

4) im running 2 injector banks... Bank one goes to "injectors 1 and 2" and is powered from only 1 of the INJ1 terminals on the relay board...is this correct or do i need to power this injector bank from both INJ1 terminals on the relay board?

Thanks alot guys..i thought ide post all my questions in one topic so as not to clog the forum...

[slow_hemi6]

With your computer and Tuner Studio connected to your MS do you see rpm on the dashboard gauge while cranking?

[scorpio12]

I see a tach signal while cranking of around 90-100 RPM

Ive also noticed that the sparks are dry even with very high cranking pulsewidths... Injectors arent opening ( even though tunerstudio shows a pulsewidth)

So I tested the injector voltage on the Relay board and its extremely low ???????
ie- When megasquirt is "off" the Voltage difference between INJ1 pin and INJ 12V = 13 volts
When megasquirt is turned "on" this same voltage = 0 Volts ( no pulse width- makes sense)
When engine is "cranked" the voltage is irregular, sometimes hitting 7volts, sometimes staying at 1-2 volt peaks ( never hitting 12 volts) ....Without 12 Volts the injectors im guessing will never open!!

What could cause very low injector voltage on the relay board , or megasquirt ecu ...ie why wouldnt it ground the injectors properly ? ???

[slow_hemi6]

I have not used the relay board but 12V to the injectors with the key off does not sound right to me. We try to supply the injectors from the load side of the fuel pump relay. Any way you can not diagnose the very short switching of the injectors with a multimeter. The readings will be all over the place as you have found. You can pick the flashing of a led test light, or to see whats happening properly you need a scope.

[scorpio12]

My mistake...its actually 0 volts between inj1 and inj12v on the relay board.... even with the fluctuations on a multimeter im not reading above 1-7 volts for the injectors... what on the ecu could cause low voltage for the injectors?

[slow_hemi6]

Makes more sense to measure with key ON between ground and INJ12v and then between ground and INJ1. You want near enough to 12v measured at both points. From there the MS injector drivers switch INJ1 and INJ2 to ground. This is only done for a matter of milliseconds at a time. A multimeter can not respond fast enough to show you anything meaningful. As I said earlier your eye will pick up the flashing of a led tester or you could use a scope.

[scorpio12]

Hi Luke I took your advice and found that the testing LEDs were flashing so I took it one step further and tested a spare injector and did get a spray of fluid when rpm signal was encountered .

My cranking rpm is very very low at 50-80 rpm and the engine still didn't start after wiring it all back up ?
I even rechecked cam timing
No idea how to test whether vr sensor is slightly off by a few degrees ... Because cranking rpm is very slow I'm only cranking for say 3 seconds and at 60 rpm that's not much fuel at all I can't even check edis is at 10 degrees btdc as it only has one ignition event per second at 50 rpm while cranking ... Ie 3 flashes of timing light in 3 seconds ....

I will try and attach a msq file and datalog of what I do have as soon as I'm home from work

[slow_hemi6]

Might have to get your battery on a charger as well. Doesn't sound like it has much charge in it with such a slow cranking rpm.

[scorpio12]

tune1.msq

low cranking pulse.msl

high cranking pulse.msl

Might have to get your battery on a charger as well. Doesn't sound like it has much charge in it with such a slow cranking rpm.

Hi Luke, ive had the battery on charge each evening before a day of cranking, Volt readings were 12V- 13 V at start of day with voltmeter... either way Ive found a better grounding point right up on a starter motor bolt and has given me much better cranking power...100 or so RPM

Guys here are my msq file and data log of two different starting attempts... one at 88% pulse width for -40 degrees temp ( 1/3 rd of that for 71 degrees temp) and another at a ridiculously high pulse width of 300% recommended fuel in an attempt to flood the engine ( still no fuel soaked spark ).....

Injector Impedance measured at 13 ohms ( high Impedance)
Injectors 50lbs/hr @43.5 psi
4 cylinder engine with firing at 1342.... edis unit is labelled so triple checked spark leads are to the correct cylinder
VR sensor only fires spark (used timing light to test) in one orientation, so i assume vr is correct( tried both ways regardless...no luck)

the KPA spikes coincided with backfires and / or "puffing" noises from the engine...... cant see fuel puddling in exhaust or any black smoke...... still couldnt start it.....let me know if you see anything that may gives hints...thanks again guys

[slow_hemi6]

Backfiring tends to be sparking at the wrong time. With the engine at TDC does the VR sensor line up with tooth No9?

[scorpio12]

Backfiring tends to be sparking at the wrong time. With the engine at TDC does the VR sensor line up with tooth No9?

Yep double checked it again today and it does line up....the backfires are more of a strong puff of air then a strong flame backfire and not all the Time if that makes sense. Noticing Any irregularities on my msq file or cranking log?
Thanks

[slow_hemi6]

Have you got good fuel pressure to the injectors?

[scorpio12]

Have you got good fuel pressure to the injectors?

I'm getting 43.5 psi reading off my electrical fuel pressure sender...the mechanical sender on the for reads slightly lower at 37 psi..... So I might bump this up and try it..... Do you see anything in the datalog or msq file that looks wrong?

My req fuel is 6.3 is this too low?
4 cylinder engine
1984 cc
50 lb/hr injectors

[slow_hemi6]

Are you sure they are 50lb injectors, source part No? Have you tried to increase the required fuel in steps to see if you can get it to catch? Have you any aerostart so you can give it a good spray and see if it will try to start. That will tell you if it is just short on fuel. Is your fuel rail and FPR all stock equipment for your engine and stock locations?
Not that it should be an issue with getting the engine to fire up but have you thought about changing from B&G code to MSnsExtra 029y4 firmware?

[scorpio12]

IM SOOOOO PUMPED!!!! SHE WORKS!!!!!!

looks like there were two problems

1)- i used a testing light to see if all sparks were getting voltage during cranking....they were
But this wasnt good enough
I pulled all spark plugs...1 and 2 had no fuel on them.....3 and 4 had fuel...which told me that injectors 1 and 2 were not working...or more likely, INJ1 wasnt giving enough or any power while INJ2 was feeding injectors 2 and 3..... so my megasquirt or relay board couldnt power INJ1 and INJ2 for whatever reason.......so i switched to " Simultaneous 1 squirt" and powered both injector banks off INJ2 ....this shouldnt be an issue as on a V8 there is the same current draw across these 2 INJ 2 terminals........ The car wouldnt start but i managed to get fuel on the sparks when i pulled them out .......

2) I noticed on the datalog that whenever i had a kpa spike( attempted fire) there was an instantaneous drop in RPM...as opposed to an assistant spike in RPM....this told me that that combustion event was at that moment fighting against the rotation of the engine.....ie it was STOPPING the piston from moving at all......ignition timing must have been 180 degrees off ....so going on a hunch i completely flipped the ignition wires so that 1 and 4...swapped with 2 and 3...Completely opposite to what was marked for a 1342 engine!.....go figure???!
and VOILA!!!!

Thank you sooo much guys...its taken me a week of cranking and p[roblem solving but she starts....next step the TUNE !!!

[slow_hemi6]

Good news. Keep in mind the extra029y4 firmware though, because the 12 x 12 maps give more control over your tuning.

[Craig C.]

Hey guys, Im having the same issue with my Ms2, am also using edis 4 for ignition. I tried your solution of switching spark plug wires around but then realized a have no spark at all using a timing light. I have a question about the twisted shielded pair wire out of the db37 pin number 24. It says to use that wire as well as pin 36 to go to edis 4. im assuming to use the white wire from pin 24 but what do I do with the black one?

[woznaldo]

Did you ever work our why INJ1 (or INJ2) wasn't working? I'm having a similar problem.