injectors not firing when cranking
 

Hi,

My FC w/ LT8 suddenly died out of nowhere and wouldn't start back up. It will not start up anymore. I have checked and have spark and fuel pressure. The injectors fire in test mode, but they do not fire at all during cranking. Does anybody know what could cause this? I can post up whatever map you request of me.

Thanks so much for your time.

Jaime

^What he said....I couldn't figure out wtf the deal was to save my life haha

Any help is greatly appreciated. I'm at the end of my rope

what is the displayed fuel pulsewidth with the key on and while cranking?

try bumping the idle map up in the 0,5 and 10"HG ranges to add more fuel. also check to see where the TPS calibration is at, if it is below 0% it can cause wierd things to happen, you could also just adjust the TPS to read anything above 0% at all times which will eliminate the idle timing and fuel maps, the idle fuel map will still be used for cranking but not for idling so you can adjust it and it won't affect idle if you do. use the 1000RPM map to adjust the idle also if you do.

i adjusted my TPS years ago to just read something like 30% because i was tired of it constantly going in and out of calibration range.

Thanks, Ben!!! I will give it a shot tonight and report back. You are the man.

be sure the injectors are wired with + direct from the battery ( this IS how they should be ) .. suspect that you instead have IG power and it may be dropping out when cranking if IG relay or key barrel is faulty

check also for rev cut or boost cut thresholds that have been shifted down .. and last of all .. pull the cas and spin it .. see if the injectors click

if they dont,, you issue is cas wiring

TPS calibration was fine. tried bumping up over 0% and still no injector pulse. I don't think it's even trying to fire. Almost like zero fuel is even coming out. Pulse width was .76pw during cranking (not sure if that's the right figure)

revcut boostcut all normal (7500). I don't think the injector wiring is an issue since it's been running fine for so long.

Do you think it could be the cas? I didn't see an RPM reading on the microtech while cranking...but then again, I don't know if it's supposed to be at crk-RPM or not.

please help and thanks for the replies!

should be wired up off the back of the alternator and will always see battery voltage(some may say this is bad but w/e, mine has been this way for 8 years as have many others i installed and worked fine for many many years).


injector pulsewidth will show up as X.xxSt (i believe that is the appropriate abbrevaition for it) and is usually in the second row far right.

cranking speed may not show up, the yellow light on the microtech will flash if the CAS signal is working and probably is since it is registering "crank" on the handheld.

if it is really only injecting .76 then something is wrong with the cranking, coolant correction or idle maps.

you can try seeing if you can find a spare CAS, plug it in, turn the key on and spin it. you should hear the injectors firing.

should be wired of the BATTERY,, the alt is a no-no .. dont just take my word for it.. ask microtech themselves or just look at all the diagrams

it is on the battery and not just the alt for a good reason .. you may just think they are both live B+ .. but the alt is surgy A/C and the battery is a big cap with clean DC

on an ECU that cannot compensate for voltage changes,, this is more important than you think for consistency


all those with a micro.. idle the car,, turn on the lights,, and note the change in idle //// a good ecu will not do this,, and to limit this,, and incidental surges,, you MUST wire the micro from the battery

on the same vein .. those with the n350/ n370 onwards alts should take the time to wire the field to the battery ,, and not just to the b+ on the back of the alt
-- the factory didnt take that same shortcut for a very good reason

to the OP.. try the spin CAS trick.. it will register as crnk unless the motor goes past 400 rpms
but,, it should make the injectors click..
if they do,, but dont with the CAS in its hole,, then one of the cas wires has an earth fault
if they dont ( with cas out or in ) then maybe broken continuity of the cas wires
,, or burned drivers ( rule that out as yours passes test mode )

if you check your error codes,, expect you may be seeing a HOME or REF fault code

swapped out the cas and same result. I'm pretty sure it is stabbed correctly.

Starting to lose my mind here. I will plug my laptop in tonight and screencap all the maps and post them up.

well, there goes that idea. I think i just fried my serial to USB by plugging it into the ECU w/o the adapter.

Will post when i get a new one. fack.

seems like the injectors are firing but for some reason it is dumping 8+Ms of fuel during crank, wayy too much. should be around 3Ms or less so it's injecting 3 times as much as it needs to start. i have the cranking map adjusted to -99% in order to try and get it up and running to move around for now, cranking pulse is a little more reasonable at about 4Ms right now.

battery is either dead or the battery cables are fragged, engine is only cranking about 50RPMs at the moment when it came in. battery is on the charger.

Battery is brand new...but could have been killed from cranking/sitting.

i figured that since it looks new, it was pretty thoroughly discharged from trying to start it it looks like.

well it's not the battery so it's the starter or cables. connections are getting hot and tried 2 different batteries. result both times is super shitty cranking speeds, it cranked up fast one time and then went right back to being a lazy shit.

as soon as i get it in the shop i'm going to rip the starter out.

Sigh. That starter is probably less than 6 months old, too.