hello, I just swap H/C/I along with the tpi harness and ecm, which all came from the same car.(92 z28 m5) it all went in a 89 rs that had a 92 lo3 set up the car is a 5 speed although it had a automatic neutral safety switch the tbi set would run great and the safety switch would work as a kill switch..after the swap this is my problem...the car will crank prime the fuel pump and it has spark.. but it will not start .. I checked the ohms on the injectors all check out at 16.8 I put an noid light on the injector connector and got nothing while cracking the car and just having the acc on??
also when I try starting the car the starter will click, sounds like a dead battery but its brand new???
where should I start??
is the safety switch a problem with my 5 speed ecm???
any help would be awesome!!!!
thanks for taking a look.

 

update****
while trying the test light(noid) the starter made a click and now the car will not crank and the fuel pump is not priming ??
could this be the ignition switch ??

 

anyone ?
please help a brother out


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VATS?

 

is there anyway of testing that ?
I bypassed it, and it was fine with the tbi set up ?


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You could hook up the security light and monitor it. How did you bypass it? With a PROM, or a hack? Those are the symptoms I believe, no crank and no injector pulses. It's been so long since I read thru all the ECM stuff, that I really don't recall what else might result in no injector pulsing besides a bad ECM or shorted/low resistance injectors.

If you had the ECM happy with the TBI, then it's surely something small. You have your negative cable hooked to the engine block, right? Anywhere else and you will cook things when you try and crank it.

 

I'll look into the security light, the dash is an 89 but everything in the car is 92, and yeah the battery is grounded to the back of the ac.? ill move it to the block would that help anything? could that be why my car stopped cracking


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You just want to be sure that the massive amount of current that flows thru the starter is only passed by wiring capable of carrying the load and/or engine block material. Try connecting the cable to the lower front accessory hole in the passenger side cylinder head. There should be a braided cable ground from the engine to the body also.

 

Are you talking about the header bolt ? or the front of the head ?


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I was talking about an accessory bracket hole in the front. You can use pretty much anything in the area that is solid to the engine.

 

505 304-4163 505 304-4163


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number not in service??

 

I have no idea how or whose phone number that is got posted

 

Ok update ! I made a noid light and plugged it into the injector connector turned the on and got nothing ... When one of the wires from the noid light fell out and grounded itself the light came on ? Same thing on both sides .. it would light up and that's about it..when I tried crankin it the light would not flash... We then supplied the test light with 12v and disconnected the ecm from the distributor and with the noid light plugged in I poked the purple/white wire and the fuel pump primed but the light didn't flash ?
What is the next testing step ? Also how do I know if the vats is bypassed ? I did bypass it when the car was tbi and it ran great ?

 

there are a couple ways too bypass the vats , one in the memcal/ eprom reprograming or with a hz modulator to the ecm. You didn't state what ecm you are using or how you bypassed the vats. was is just a resister wired in too bypass the cylinder pellet and key contacts? the 1227165 ecm tpi maf gets its passkey signal to b6 of the ecm. The 1227730 tpi speed density ecm gets its signal too f10 of the ecm. This can be measured in hz30hz 50-60%. the purple and white wire your talking about are you saying you back probed the reference high tach signal from distributor too the ecm ? how did you make a noid light led and 10k resister ?

 

Ok I made the noid light out of a license plate light bulb socket and bulb ...its a 730 computer and everything else tpi was out of that same car ... And I soldered in the resistors to the where the vats connects to the key tumbler..also when I checked the volts coming from the injector connector it was marking 20.2

 

I can't imagine the voltage being any higher than the battery. The injectors are hot when the key is on. The ECM grounds the injector to complete the circuit causing it to fire. If the light isn't flashing then the ECM isn't pulsing the injectors.

 

you have 20.2v feed too the injectors

 

I was using the meter wrong , 12v with the key on , the light will not come on when both wires are in the injector plug but when grounded it will turn on ?

 

the ecm provides the ground too pulse the injector. you need just a few things too get the injectors to pulse. distributor ref high the purple wire from the distributor sending a tach signal too the ecm, ecm grounds connected securely and clean. proper memcal installed and 12v to each injector bank. if all this is fine then look at the vats without the signal from the passkey module too f10 of the ecm you will not have injector pulse.

 

you can always try one of these.

http://www.ebay.com/itm/GM-VATS-or-P...c89c8f&vxp=mtr

 

injector bank? what is supplying the power to the injectors? fuse box?
ok i have the inj1 inj2 wires from the ecm hooked up the the fuse box.. is that right??

 

 

the injectors get there power from the fuse box, you stated in a earlier post you verified power to the injectors.

 

yeah just making sure, now the wires are running off the connector under the pass side dash.. should i take pictures??
also is vats a possibility and will that product work for my ecm?

 

I answered your questions on post #20

 

 

Yes yes ! I will start on it tonight ill be back for updates

Thanks !

 

ok tonight I'm going to check all wires to ensure all is well... BTW when i got the harness i had to hack it from the connector on the fire wall the seller would not let me take the firewall connector c100 i think??
is it possible that i hooked up the power sources wrong ???? maybe causing the injectors not to fire??

 

on post #14 you verified 12v to the injectors, on post 15 I told you how to confirm the signal from the passkey. The only other thing needed to get injector pulse is a tach reference pulse from the icm on the purple and white wire on pin D8 of the 730 ecm. you can easily test to see if the ecm is getting power and grounds by seeing if it will go in field service mode bye jumping a to b on the aldl.

 

ok, I checked the purple/white wire by giving it 12v power the fuel pump primes and what not... i also checked the back of the ecm my probing the injector ground wires (green/blue) the test light lit up when the key went to on and then turned off while cranking ?? i will be ordering the vats bypass from ebay>> ??? I'm not running a VSS box .. I just left that alone .. its the stock tbi stuff??

 

you might need to consider a new ecm since you just put 12v on the 5v tach circuit.

 

Now, if the light comes on in both terminals, reconnect your test light to injector harness, and disconnect the 4 way distributor connector. Momentarily touch the connector with the purple/white wire with a test light hooked to 12V, if the injector light blinks the problem is a bad ignition module. If there is no blinking light, disconnect the tps and repeat the test. If the light blinks, replace tps. No blinking light means you'll need to make sure the fuel pump runs for its two second priming period. If the fuel pump checks out okay, reconnect all your injectors, turn the ignition off, disconnect your ecm, turn the ignition key back on, and probe terminal D15 with the test light connected to a hot power source, if the light comes on, you'll need to wires to injectors (green/blk or blue/black) being shorted to a voltage source. If they are okay, the ecm is at fault.

click here to go to SES and Engine will not run troubleshooting flow charts

i got this from chevythunder ... its the third or fourth page ??

 

http://www.chevythunder.com/ses_chart_a3a.htm

I don't agree with applying 12v power to the tach signal wire.

 

Could it be the ECM ?? It wasn't flashing from the injector ground and while all connectors disconnected the test light would light up and then when any injector connector was connected the light would turn off key being in on position ??

 

you could have a shorted injector. you should be using a vom not a test light.

 

The injectors ohm out ok ?
Could the ignition switch cause problems ??

 

Thanks for all the help
This is just driving me crazy ! Lol

 

I bought a ECM should be in by the 29th I'll give another update also what acc can I hook up the ECM to ?? To ensure it has 12v on run

 

the car was originally a L03 you can use the ecm fuse line that powered the tbi 1228746 ecm.

 

How would I use my 746 ?? I got another 730 on the way

 

I never said to use a 746 ecm You asked where to get switched power too the 730 ecm.

 

ok the ecm came in today... the vats wire from the harness was hooked up to a 12v wire from the c207 I made a boo boo I will be testing tomorrow morning !
could the hot wire have messed up any thing in my ecm?
I grounded the battery to the frame?

 

if your using the frame as your battery ground make sure you have a large ground strap going from the frame too the block. The passkey signal output was hooked too 12v ?

 

Yeah the pass key I made a mistake but fixed it as for a ground strap I don't have one , I will get one in the next hour or two I'll be back with updates

 

Ok with vats fixed no crank and with all the injectors unplugged the ecm grounds and when even one gets plugged in the ground stops working?? This is the the key in on position , and using a test light

 

sounds like you may have more boo boo's maybe in c100. If your engine is not cranking you need too look at the starter interrupt relay and park neutral switch connections.

 

Ok I'll check that out, to bypass the nss it's the green and purple wire together ?
Also I have a t5 set up but still have auto dash wiring ?? I say this because of the nss under the shift plate ?? Does the ecm have a pin for the nss it's a t5 prom and harness

 

the ecm only has provisions for a park neutral switch. On a manual transmission this input is left open. The neutral safety switch wires are yellow and purple. You might double check your main ground and ground strap connections or move the ground too the engine.

 

First of all what harness are you using? U are using a 92 tbi harness right?