Car won't start...not sparking till I let off the key! Plz Help!

[Spooled]

I've been having troubles gettin my car started with my new bank to bank speedpro system on it. I've had it running before and had one day of tuning on it while sitting in the garage a couple months ago. Now that it's cold out (30 degress) it won't start. I've changed the cranking fuel...the IAC start...everything. First off I better let you know it's a turbocharged firebird so i'm dealing with the GM HEI (external coil) ignition system. It's also got an msd 6a box and an accel supercoil on it. Last year i had DFI on it and I always noticed that it wouldn't actually fire WHILE i was cranking...it would just fire when i let off the key. Well, now since it hasn't been starting with the speedpro (once in a while it'll try to start when i let off the key but it doesn't) I took the coil wire off the distributor and put a plug in it to see if it was getting good spark. I unkhooked the injector harnass and proceeded to crank the engine while wathcing the plug. NO SPARK while cranking...NONE! THen i let off and it sparks once at the plug and at the same time I noticed an arc from the positive post on the coil to the wire boot. I kept trying it and it does this every time. There's no spark until i let off the key. Just wondering if someone could please help me out. I can't figure out why in the world this is happening. It's driving me crazy I wouldn't think the msd box would be bad or the coil b/c when that stuff goes bad it usually just quits working. I can't think of anything. I know it would start if i had spark during cranking (that always seems to help Thanks for the help in advance!

 

[Craig Smith]

The best way to narrow down the culprit at the moment would be to take the MSD stuff off and run just the Speed Pro and the HEI ignition. With HEI ignition, even if the ECU was to malfunction, the HEI module would still generate spark on its own as it would be in bypass mode. From everything you said, it sounds like either some type of wiring problem between the HEI setup and the MSD stuff or possibly a bad HEI module. Make sure that you are seeing +12V in the appropriate spots during cranking too - that can kill you in a heartbeat.

 

[steve h]

If that doesn't do it it could be the ignition switch has a bad contact in it. Or the wires on the starter are not on correct.One of the wires that goes on the big post maybe on the small post. I saw this on a friends car. She paid somebody to put a starter on it and they wired it incorrectly.

 

[NoviBlownGT]

is your msd connected to a switched power source that stays hot when you are cranking?....The speed pro also requires the same for its switched source. Seems like one of these things are connected to a switched souce that shuts off when cranking. Does your ECU go offline while cranking? Thats one way of telling if you have a good switched power to the speed pro. Just a few thoughts , hope it helps

 

[Spooled]

Well here's what went on today ( i didn't get much time b/c i was in a big hurry). I checked for power at the coil with the key on. NO power. I bypassed the msd and tried it...and there was power. But it still doesn't give any spark. The only thing i know now to do is check for ground at teh coil while cranking. If there is ground...then the coils bad...if there's not ground then the hei module is bad. I don't know whether the msd is bad at this point but i'm thinking it is. Is there any reason that could explain the msd failing and causing the hei module to go bad or vice versa? Any other explanations you can think of? Thanks alot for all the help fellas!

 

[Craig Smith]

Don't check for power or ground on the coil anymore! You will blow up test equipment if you do. An MSD ignition system applies several hundred volts to the coil primary, so +12 and ground checks are not a valid test. Look and see if you have an RPM signal on the main dashboard display while cranking.

I'm guessing at this point that there are wiring problems or you have ignition parts that just don't work together. Any time I've ever used an MSD box with an HEI distributor, I took the module out.

 

[Spooled]

There is an rpm signal while cranking. The car ran and ran pretty good about a month ago. That's the first and last time i've had a chance to tune on it. I wouldn't think it would hurt anything to check for ground at the coil as long as i don't have the + side of the voltmeter on the + side of the coil. I could tap into some other hot wire. If there's no ground...then the hei module has to be bad i'd think. IS there any way i could test the coil itself? Thanks for the help!

 

[Spooled]

Here's a little more info after I fiddled with it more today. The msd has good switched power going into it but the orange wire that runs to the positive side of the coil has no power with the key on. Like i said earlier, when i bypass the msd 6a box, the coil then has power when the key's on (I'm talking about power to the + terminal of the coil). But when i crank there is still no spark. THe only thing i can possibly think of is that the MSD box AND the hei module are BOTH bad. The msd isn't giving any power to the coil with the key on as i think it should. So when i bypass it, the ignition should be running off the hei module, but it still won't spark. IT should still produce spark even if the HEI is bad with an MSD box on there, right? Is there any way i can test the hei module, the msd box, or the coil to see if any one is bad? This is really frustrating. Once again, i appreciate all the help.

 

[Craig Smith]

I could probably help more if you described pin for pin how everything is hooked up.

I don't believe that you can check for power or ground at the coil with an MSD setup. I am fairly certain that you will never find either.

 

[Spooled]

Well I'll do my best to describe it better for you. I did find a way to test the msd box so i'm going to run over and try that in the morning. Ok, here's how it's set up:

The distributor has two connections in the back of it (drivers side is a 2 pin and passengers is a 4 pin). The 4 pin is plugged straight into the FAST wiring harnass. The two pin plugs into the msd "quick connection harnass" i got with another 2 pin that looks just like it that comes from the factory firebird wiring harnass (these two are the ones that pluged straight into the coil in the factory setup). One turns into the red wire of the msd (switched power) and the other is the white wire (which is what gives the ground signal i believe). Then those two (red and white) run into the msd box and out come a black and an orange wire. They both run to the coil (orange to positive and black to negative). The only other wire on the msd box is the large red wire (constant +12). It's hooked to the battery. It's getting good switched power (I checked). And like i said, with the msd box wired up, it shows no power at the + terminal of the coil, but when i bypass the msd box it shows full voltage at the + terminal (but neither will cause it to spark WHILE cranking). I don't know if that's the kind of description you were looking for but that's about all i can tell you. i know it's very hard to fix problems over the pc but thanks for trying. I'll report back on my msd test tomorrow and let you know what happens. THANKS again !!!

 

[Spooled]

I went back this morning and "tested" the msd box by unhooking the white wire (what senses the ground from distributor and causes spark), and it's working fine. That means the msd box and coil are working fine. I would think that means that the HEI module is needed to produce a ground signal for the msd to feed off of and therefore it is bad. I'm going to call msd now and ask them about it. Isn't that what you would infer?

 

[URSPANKED]

I'm certainly no electrical system expert, but could it be that your starter solenoid is faulty, so that it doesn't relay the power through it as you're cranking?

 

[Spooled]

The starters almost brand new. And i've checked for power at the msd while cranking and it's fine. After calling msd today the guy said if it's a 4 pin HEI module, it IS needed but if it's a 5 or 7 pin module, it's totally bypassed. I don't know which mine is. There's 4 pins on one side and 2 on the other. I'm hoping it's a 4 pin. I'm going to do more research to find out. If it's a 4 pin then i should just be able to replace it and be back online Hopefully

 

[Spooled]

Well it's an 8 pin HEI witht he two connectors coming out the back of the distributor. The guy from MSD said i have to have that to make it spark. I'm thinking it's bad. It's only 25 bux from autozone. I'll try it this coming weekend. I sure hope he's right!

 

[64duece]

I've had a similar issue

I never use the factory GM module. Just pull it out and use the supplied wires from MSD. My problem was voltage related. I had an input wire connected to a source voltage that went low during cranking, when I realeased the key, it would spike up and almost start the car. I'd really check there first. I found it by checking the output trigger signal and found it to be low enough not to trigger the MSD. I believe it was 3V. I changed to a solid 12V input and wham...problem solved.

 

[Spooled]

It has to be used. It's an 8 pin module with the two electrical connections sticking out the back of the distributor. The msd has to have it to send a ground signal so it knows when to fire. There are now wires that msd sends to bypass it. There's only two wires coming from the pickup into it. If i bypassed it, the speedpro wouldn't have any rpm input. The speedpro has a 4 pin connector that plugs into the back of the distributor and that's how it gets an rpm input. But now that i think about it...there is still an rpm reading while cranking. I wouldn't think there would be if the module was bad. Damn, i thought i had it figured out. Craig...is there any way the hei module could not be sending a ground signal to the msd but still relay an rpm to the speedpro? Thanks again

 

[Spooled]

Here's a pic of the same kinda distributor i have. The 4 pin connector on the pasengers side plugs right into the speedpro. The two pin on the drivers side goes to the msd box. One of them is the ground refernce from the pickup. I don't think it's sending ground to the msd box but it must be sending a signal to the FAST b/c i'm seeing and rpm input.

 

[bobbyp]

I had the exact same problem (except on a ford). It ended up
being a votage drop problem. I solved it by putting a push
button starter switch that bypassed the ign key switch. The key switch still has to be on the "on" position for fast to fire off.
When cranking, do you get a communication error notice on
your laptop?

 

[Spooled]

No, i get no communications error. I'll try the new hei module this weekend. I think that's what it is. I HOPE!

 

[SingleTurboIroc]

Originally posted by Spooled
Well it's an 8 pin HEI witht he two connectors coming out the back of the distributor. The guy from MSD said i have to have that to make it spark. I'm thinking it's bad. It's only 25 bux from autozone. I'll try it this coming weekend. I sure hope he's right!

i'm 99.99999999999999% sure you have a bad module

go check my reply in the other thread

---Also, as another side note. i used to have an MSD setup

JUST LIKE YOU

the module went bad and i couldn't get the car to start. Before it went bad, the car didn't want to start a lot, but couldn't figure out why until i was

90 MILES AWAY AT US41

ouch was that a tow bill