maxont

what would cause a tpi motor to flood and not start? Injectors and fuel pressure regulator are good Timing is good... heres whats happening. The car will just crank and crank and not fire with the injectors plugged in, when i unplug the injectors and crank the car it will fire and run rough for about 5-7 seconds. I assume its just burning the unburnt fuel from the previous cranking with the injectors plugged in... any ideas?

91_z28_guy

I'M having the same problem so maybe we can get both of our problems solved.

maxont

Recently i put 8.8 accel rfi suppression wires on the car and this problem started short after... i tossed my old wires because they were old and bad... any reason why these new wires could cause my problem? "I'M having the same problem so maybe we can get both of our problems solved." Hopefully we can get it figured out bud, i know ive dumped to much money into this to just trash it.

tinymay

Hey MAX, you been going through the exact same symptoms I did and a couple of weeks ago, I even told you to check your ECM injector circuit. My post was #9 on https://www.thirdgen.org/forums/tech...-problems.html Anyways, you need to pull your ground off the battery, borrow a buddy's ECM and put your chip in it. Reconnect the battery, hold the gas pedal all the way down then try to crank it. When it hits, get your foot off the gas!! If yours is ailing like mine was, you'll be wearing a week long smile

By the way, before you do any of this, check your oil level. No kiddin', I drained 4 gallons of flooded gas/oil out of my crankcase. If you been playing around with a shorted injector circuit like mine you got WAY more gas blasting into the cylinders than you need. Please update!!

maxont

Ok just got back from family holiday stuff, im gonna try this today and see how it works... so basicly i just disconnect my battery, take another computer from a different car, plug it into mine and put my chip in it? then do the full throttle thing. So im guessing the ecm will reprogram my chip so it works right?
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o yea, and before i did drain my oil and found about 4 gallons of gas in it... so it sounds like this might just fix my problem. Thanks again i'll update soon.

maxont

Okay so i couldnt find anyone with the same ecm that i have so im going to have to buy one. Im now wondering if i should buy a new ecm or should i just buy a new prom? im not sure which way to go.... or which will guarantee me a fix. hope to hear back soon. thx

tinymay

If it is the injector switch circuit shorted, it's located on the electronics board of the ECM. Your chip is what tells the ECM what to do but if the board is fried, it can't do it.

I found an ECM at Advance Auto that done me in a pinch. Any auto parts store will have one though it may not be the direct "AC-Delco" replacement. I believe they are all alike except for how seal the electronics with that clear stuff. Anyways, I paid $79 for a "Cardone" replacement that is working fine, so far.

Just remember to unhook your ground from the battery before doing anything with the ECM. Wishing you luck, man. This could be the fix. Let us know.

91_z28_guy

Ok well i have my ecm ordered it should be here tommorow. I tested ym ecm and the injectors are not getting anything from the ecm so it has to be the problem with mine. Thanks for the help i will update tommorow when i have it in.

tinymay

One last thing to check... With all the injector wires off and measuring the injector ground wire to chassis ground, my old electronics 1227165 had a resistance of 1.5 kOhms. (1500) The new replacement (that works) has a resistance to ground of 88 kOhms. (88000) A big difference. If yours measures like my old ECM then you definitely need a new one.

That whole discovery about a month ago is described in this post:
https://www.thirdgen.org/forums/tpi/...off-major.html

maxont

well i measured the ohm resistance but i didnt read the part where they had to be off... measured 1.5omhs. so i went and got a new ecm thinking yay its gonna fix it... new ecm in and still the same deal...

when i measured the ohm resistance im not sure if i used the correct wire though.. exactly what wire is the injector ground wires... i figure maybe i have one grounding where it shouldnt be like in your post and it wasnt the ecm now. so i need to find that ground wire to figure out if that could be my problem. thanks

maxont

okay on 200k ohm setting im getting 1.8 with injectors unplugged. 1.2 when they are plugged in.
this is the new ecm

i know that the old ecm was getting 1.5 with the injectors plugged in

maxont

is there any way it could be my prom doing this? or could it be i got another bad ecm

maxont

another question... can i check the injector plug ins by voltage output or ohm resistance to see what they are telling the injector to do by what they are putting out?

tinymay

-Unplug all eight injector wire connectors.
-Turn your ignition key to "run".
-Measure voltage from one of the injector wires to a chassis ground. That wire is always hot. The other wire is the switched injector ground.
-Now measure resistance from the switched injector ground wire to a chassis ground. Should be a high ohm reading around 88000 ohms. If it is a LOT less, the ECM injector switch is shorted OR you have a grounded injector harness. Either way, very little resistance means it IS a ground causing the injectors to stay open and that is why it is flooding.
-To check for a grounded harness: Remove the negative from your battery and unplug your ECM. Now measure resistance from an injector ground wire to a chassis ground. If you get any continuity reading at all, your harness has a rubbing ground wire somewhere on the chassis. It can happen.

Really hope that gets it done. Let us know...

maxont

trying it on my lunch, thanks much

91_z28_guy

Ok well i just installed the new ecm in mine and that didn't seem to be the problem for me either. I know i smell a strong scent of fuel still to. I did pull the motor and tranny out together maybe i snagged a wire while i was in the process of doing that.

maxont

Ok heres what i found.
-Measure voltage from one of the injector wires to a chassis ground. That wire is always hot. The other wire is the switched injector ground. ---- (KEY ON, ECM PLUGGED IN)i got .4v on the driver side and .4v on the passenger.
-Now measure resistance from the switched injector ground wire to a chassis ground. Should be a high ohm reading around 88000 ohms. (KEY ON, ECM PLUGGED IN) ---- (from the negative injector wires i got from .8 to .5 ohms on the driver side and Nothing on the passenger side.
-To check for a grounded harness: Remove the negative from your battery and unplug your ECM. Now measure resistance from an injector ground wire to a chassis ground. If you get any continuity reading at all, your harness has a rubbing ground wire somewhere on the chassis. It can happen. (KEY OFF, ECM NOT IN) --- i got .8 to .5 ohms on drivers side and 13.3 on the passengers side So... im guessing this all means i have some kind of short somewhere in my wires correct? *******EDITED THIS********

Reid Fleming

iTrader: (2)

Just out of curiosity, what are you injectors (all of them) ohming at?

maxont

all injectors are 16.2

tinymay

Yep, something is wrong. Definitely looks like an injector ground touching the chassis somewhere. That wire should be clean with no reading at all. Is this how you checked it??

Voltage
- With all injector connectors off the injectors, ECM connected, key on, all the injector hot wires to chassis ground should read 12 volts.

Resistance
- With ECM out, there should be no reading at all on the injector ground wires to chassis ground.

- The injector grounds are looped together in a bank of 4. The right side ground wires should read continuity to all the right side injector grounds. Same for left to left. However, with the ECM out, the right side injector grounds should have no reading at all with the left side.

Anything less than that, you got a rat bite or something in your harness rubbing on the firewall, strap or block. Be sure all the connectors are off the injectors before the test so there is no loop. At least, you are closing in on the problem.

maxont

Okay under new testing i realized i had the wires backwards last time. heres the new deal. KEY ON --- Injector hot wires on the passenger side have 12v. BUT on the drivers side they have 0v. Not getting any voltage what so ever. This is most likely my problem... what could cause this? KEY OFF, ECM UNPLUGGED --- Injector ground wires get no reading like they are suppose to. """"- The injector grounds are looped together in a bank of 4. The right side ground wires should read continuity to all the right side injector grounds. Same for left to left. However, with the ECM out, the right side injector grounds should have no reading at all with the left side. """" Not sure i understood this but i guess it doesnt matter now that i found out the 0v problem and that the ground wires get no reading like normal. Okay so what could be causing my voltage loss?

tinymay

Okay, a problem!! I know how glad I was when I finally found something wrong. I know you be smiling. There is a blown fuse AND/OR a grounded hot wire somewhere.

Repairing that fuse will get 12 volts back but the problem was zero volts shouldn't have fired your injectors into a gas blasting, flood situation. I don't see how it's flooding with zero volts.

Find your blown fuse or seperated wire and try to start. Never know.

maxont

YAAAAP PROBLEM FIXEEED!!!!!! So happy. There was a grounded hot wire inline with that injector side that was poping the fuse. i guess voltage loss sends the injectors into full rich or something. Thank you for all your help!!!!

tinymay

GREAT NEWS!!! Enjoy the ride...

91_z28_guy

Well just to let everybody know the ECM fixed my problem along with a shorted ignition coil wire. So i got mine back up and running to.
Thanks

tinymay

Excellent News, 91. This gonna be a GREAT Day.

I am still scratchin my head how yours and my ECM went sour. I cannot place my hand on any significant event... just smelling LOTS of gas every once in a while. Oh well... Glad to have helped.

91_z28_guy

Yes it is going to be a GREAT day!!! And your right i dont know how or why the ecm would go bad??? Not sure. I hope that its not going to be a consistant problem, but if it is then somthings wrong. But hey thanks for the help, it wouldnt be running right now if it wasnt for you and a friend.