more DOHC issues

slow'n'steady · Post by **slow'n'steady** » Sun Jul 01, 2007 1:41 pm

I have grounds set-up like crazy at the moment, i will try to explain what i have going on for the grounds...

4guage going from the battery to the engine block, 4gauge going from the sme spot on the engine block to the strut tower and a 4gauge going from the engine block to the cradle. Also have an 8gauge going from the battery to the engie block, to the cradle then up to the battery box where it meets up with the ICM ground and is bolted to the battery box (as that is where my coils are. I mdidnt notice before but it was a llose connection and there was some paint in the way. I sanded it down to bare metal and got the biatch TIGHT. My buddy is bringing some jumper cables over so we can give it a try now... If nothing else there is a ground going from everything to everything else... Every ground cable is connected to the battery, strut tower, engine block and engine cradle at some point...

slow'n'steady · Post by **slow'n'steady** » Sun Jul 01, 2007 2:16 pm

Well, i decided to back track and try stuff that i have already tried...
I took the fuel pump fuse out and sprayed some carb cleaner in there and it started up. I had my buddy keep spraying and it did stay running. I checked the fuel pressure again and it was about 42 or so. Sound like injectors or what should i try next?

Aaron · Post by **Aaron** » Sun Jul 01, 2007 2:31 pm

Get a multimeter, and test the resistance between the 2 pins on each injector. I forgot the exact range, but the resistance should be between 11-14ohms IIRC. A friend recently had an injector go out in their Z34, and after testing the resistance, it was obvious that one had failed (The number was significantly off from the other 5).

slow'n'steady · Post by **slow'n'steady** » Sun Jul 01, 2007 3:50 pm

well, before reading this and finding out the easy way to do it...

I pulled the fuel rail off but left everything connected and had my buddy turn it over so i could visualy WATCH the injectors. 3 of the 6 didnt fire, i marked the injectors and marked the clips, then switched 'em around to see if it was the clips or the injectors. It is the injectors! 3/6 are bad and i gave my other set away like a douche to someone one fiero.com

What cars can i snag injectors off of that will work on the DOHC? i dont have a penny right now but figure i can snag a set of injectors and not feel to bad seeing as how i always way over pay at the local yard...

The Dark Side of Will · Sun Jul 01, 2007 4:11 pm

Series8217 wrote:Or at least put a ring terminal on the wire and screw it down properly somewhere...

EDIT: Wait a second... between the bottom plate and the battery tray? The bottom plate is NOT the ICM ground (though it might be grounded if there isn't ,uch thermal paste under the module). There is a wire coming off of the ICM power connector that must go to ground. Grounding the plate will not help you for any reason. Where does the power ground go to?

The plate on my Northstar coil pack was grounded with a HUGE wire (8 ga or bigger).

The Dark Side of Will · Sun Jul 01, 2007 4:14 pm

slow'n'steady wrote:well, before reading this and finding out the easy way to do it...

I pulled the fuel rail off but left everything connected and had my buddy turn it over so i could visualy WATCH the injectors. 3 of the 6 didnt fire, i marked the injectors and marked the clips, then switched 'em around to see if it was the clips or the injectors. It is the injectors! 3/6 are bad and i gave my other set away like a douche to someone one fiero.com

What cars can i snag injectors off of that will work on the DOHC? i dont have a penny right now but figure i can snag a set of injectors and not feel to bad seeing as how i always way over pay at the local yard...

Did you check this before?

If you have an extra injector connector, splice that into some jumpers and hook each one in turn directly to the battery. I've opened EVERY stuck injector I've ever come across by putting 12V DC to it.

Aaron · Post by **Aaron** » Sun Jul 01, 2007 4:31 pm

slow'n'steady wrote: What cars can i snag injectors off of that will work on the DOHC? i dont have a penny right now but figure i can snag a set of injectors and not feel to bad seeing as how i always way over pay at the local yard...

You petty much need the DOHC injectors, but any year will work. You'll want to stick with the same 6 though, so don't use 94-97 injectors and 91-93 at the same time.

What year are your's currently? The 94-97 injectors idle a lot better, a very large amount of 91-93 injectors cause phantom stalling when you're coming to a stoplight. Now would be the perfect time to upgrade if you can, they are plug and play.

If you want to stick with the 91-93s, I've got a full set here you can have for $30 shipped. They all tested good.

The Dark Side of Will wrote: The plate on my Northstar coil pack was grounded with a HUGE wire (8 ga or bigger).

Weird, the 3.4's plate bolts right to the block, so I guess that's the ground. And the power ground is just a normal wire, no bigger (5 individual copper wires).

slow'n'steady · Post by **slow'n'steady** » Sun Jul 01, 2007 7:32 pm

The Dark Side of Will wrote:Did you check this before?

thats the "funny" thing. before i just popped off the UIM and looked into the ports to watch the injectors spray but i could only see the 246 bank injectors which happen to be the good 3. :thumbleft:

Some on old europe gave me a full set so between his and mine im sure i can get 6 good ones... Also i will try the 12VDC but i dont have any extra clips, i can just use a plain old wire cant I?

Aaron · Post by **Aaron** » Sun Jul 01, 2007 7:38 pm

It seems odd to me that not only 3 would go bad, but 3 on the same bank.

I think you should check the wiring while you are at it. Remember the 2-4-6 bank should be continuous with the 1-3-6 bank. There are two banks in the ECU, 2 wire outputs, then these wires merge into a single wire, and late split again.

slow'n'steady · Post by **slow'n'steady** » Sun Jul 01, 2007 9:13 pm

i checked the wiring already. Also when i got the motor, the injectors where in the bottom of the parts so it was prolly just "luck" that the 3 which where going bad ended up in the same bank. Lastly i did manage to get 1 of the injectors unstuck so i have 4 working injectors. Cylinders 1 and 3 have no injector...

Erik · Post by **Erik** » Mon Jul 02, 2007 1:45 am

slow'n'steady wrote:i checked the wiring already. Also when i got the motor, the injectors where in the bottom of the parts so it was prolly just "luck" that the 3 which where going bad ended up in the same bank. Lastly i did manage to get 1 of the injectors unstuck so i have 4 working injectors. Cylinders 1 and 3 have no injector...

they do go out and can really fuck with your mind when trying to figure out running issues..I have had several of mine go out in the past almost 4 yrs since I did my swap

Series8217 · Post by **Series8217** » Mon Jul 02, 2007 2:44 am

The Dark Side of Will wrote:
Series8217 wrote:Or at least put a ring terminal on the wire and screw it down properly somewhere...

EDIT: Wait a second... between the bottom plate and the battery tray? The bottom plate is NOT the ICM ground (though it might be grounded if there isn't ,uch thermal paste under the module). There is a wire coming off of the ICM power connector that must go to ground. Grounding the plate will not help you for any reason. Where does the power ground go to?
The plate on my Northstar coil pack was grounded with a HUGE wire (8 ga or bigger).

Interesting. Where is the coil pack bolted to normally?
The power ground for the ICM and coilpacks is a tiny little 16 gauge wire. Same size as the power feed. Why would the ICM plate need a ground wire more than four times larger than the power?!

The Dark Side of Will · Mon Jul 02, 2007 5:17 am

Series8217 wrote:
The Dark Side of Will wrote:
Series8217 wrote:Or at least put a ring terminal on the wire and screw it down properly somewhere...

EDIT: Wait a second... between the bottom plate and the battery tray? The bottom plate is NOT the ICM ground (though it might be grounded if there isn't ,uch thermal paste under the module). There is a wire coming off of the ICM power connector that must go to ground. Grounding the plate will not help you for any reason. Where does the power ground go to?
The plate on my Northstar coil pack was grounded with a HUGE wire (8 ga or bigger).
Interesting. Where is the coil pack bolted to normally?
The power ground for the ICM and coilpacks is a tiny little 16 gauge wire. Same size as the power feed. Why would the ICM plate need a ground wire more than four times larger than the power?!

The coil pack bolts to the cam cover, which is isolated from the head & block by the o-ring gasket and rubber grommets on the valve cover bolts.

Yes, it does need its own ground, but that should only be necessary for when it loses a plug wire and has to return spark through the block rather than the other tower on the coil. I'm not sure why it's that big.

IIRC the power & ground wires at the connector are 14ga.

Mach10 · Post by **Mach10** » Tue Jul 03, 2007 10:30 am

Aaron wrote:Here I was thinking the C203 was inside of the car all this time.

*wipes egg off face.*

I'll have my crow medium rare with a side of ketchup. :salute:

Nothing wrong with that connector either, though. Humidity gets a little funny inside the car (especially in northern climes with rapid heating + cooling), and the temperature swings around like crazy; but I've NEVER seen one of those connectors in rough enough shape that it didn't work properly, though.

I'll double my vote on dielectric grease. As was mentioned, the grease does NOT conduct electricity; what it does is eliminate air from around a POSITIVE connection (positive = good, not charge)and seal it against humidity, moisture etc., so it won't tarnish, rust, or oxidize.

Dielectric grease doesn't improve a bad connection, it helps prevent a good connection from going bad.

slow'n'steady · Post by **slow'n'steady** » Tue Jul 03, 2007 1:19 pm

To be honest i put some grease on the C203. I pretty much thought the same as Mach10 and also i go fishing alot so i drive on dirt and gravel more than a few times a week. But i did take it clean it all up and tighten the females.

Mach10 · Post by **Mach10** » Tue Jul 03, 2007 1:34 pm

hehehe... tight females rock.

I'm more than a little concerned that you aren't able to read codes off the ECM... That in of itself screams wiring problem, since the damn thing still tries to fire the injectors--and so obviously hasn't suddenly become a charred lump of PCB.

Good find on the injectors, though... Try what Will suggested to open them up. Soaking the injector ends (and filling the bore) with a penetrating oil might help to keep them open. I'm hesitant to suggest a strong solvent at the risk of eating the insulation off the solenoid... But i'm reasonably sure SeaFoam should be safe... And I've had great luck with that particular product. :salute:

Aaron · Post by **Aaron** » Tue Jul 03, 2007 7:54 pm

Mach10 wrote: Nothing wrong with that connector either, though. Humidity gets a little funny inside the car (especially in northern climes with rapid heating + cooling), and the temperature swings around like crazy; but I've NEVER seen one of those connectors in rough enough shape that it didn't work properly, though.

Nope, nothing wrong at all. We now have 4 that have all caused issues, 1 of those without any human interference. And mine looked in great shape, it wasn't rough at all. It plugged in like normal, just didn't connect half the time.

The Dark Side of Will · Tue Jul 03, 2007 8:17 pm

Do you know what a normal one looks like? Were the pin retention hinges in place? It's translucent, so you should be able to see whether the pins are in place or not.

There are dozens if not hundreds of those metri-pack pins on every GM car built for a 15-20 year period. The pins work like gangbusters. The potential problem is the connector shell not retaining the pins with enough force to mate them or the pins being misaligned and not mating properly. Either of these should be EASY to see with the connector connected.

Aaron · Post by **Aaron** » Tue Jul 03, 2007 8:19 pm

The Dark Side of Will wrote:Do you know what a normal one looks like? Were the pin retention hinges in place? It's translucent, so you should be able to see whether the pins are in place or not.

Yes I do, yes the retention plates were in place, and the pins were in place.

Mach10 · Post by **Mach10** » Wed Jul 04, 2007 9:29 am

Your enthusiasm for quality control is impressive; if we had a whole team of you working on an assembly line, we'd have cars that would NEVER break down... Or wouldn't ever finish production...

It's a 20 year old connector, and there is nothing intrinsically wrong with it. 4 bad connectors out of how many cars made? 350,000 or so? Pretty piss-poor sample there, bud.