BurrowsRacing33

I recently replaced my 2.8 with a 3.4 in my 85 Firebird race car. After reading the forums on the 2.8 to 3.4 swap I put all the bolts on from the 2.8 on the 3.4 and replaced the coil pack with the 2.8 distributor. We cannot get the 3.4 to start, after checking a few things we figured out that there is no spark. We replaced the ignition coil and still no spark. There is power going to the coil and power coming out of the coil to the distributor. We then put a new rotor, distributor cap and plug wires on it and still no spark. I noticed the crankshaft piston sensor plug in just dangling there but can't find a place to plug it in on the 2.8 wiring harness. Is there no spark because the crankshaft piston sensor isn't hooked up? and if that is a possible reason for no spark then is there a place on the 2.8 wiring harness to plug it into? Or do I not need the sensor because we took the coil pack out and replaced it with a distributor? If I don't need the sensor for it to spark then what would be the next most likely reason for no spark, possibly an ignition module? I'm stumped racing season is coming fast its 2 weeks away and my car isn't running Thanks in advance.

Kingsobieski

So long as you're using 100% of the electrics from the 2.8 then it shouldn't matter if there's additional unhooked sensors from the 3.4. Check on the back of the block to make sure you connected all the ground wires.

Six_Shooter

iTrader: (2)

The crank and camshaft position sensors have no use using the 2.8 (or even 3.1) electronics.

If you have no spark, it's one of 3 things, no power (12VDC), bad coil, or bad ICM (Ignition Control Module). The ignition system will still provide spark even without an ECM in the car, this is part of the base timing and limp home mode.

You can check for signal to the coil, by using a DMM set to AC, and connecting between a ground source and the coil negative. You should see 1 to 3 volts while cranking, if not, there is no trigger to the coil.
You can also use a test light and watch for the test light to flash, but this method hasn't been overly reliable for me.

drdave88

iTrader: (3)

Just to make sure here, you're using the 2.8 intake manifold setup/throttle body, distributor, fuel injector rail, wire harness, etc. right? You only used the 3.4 block/heads...everything else was from the 2.8? Let us know exactly what you re-used from the 3.4 and what you carried over from the 2.8.

BurrowsRacing33

Thanks guys for the information. I'll have an ignition control module this after noon so i'll install that and let you guys know what happens.

BurrowsRacing33

I replaced the ignition control module and still no spark. So I tested for a signal to the coil like you guys said to do and it looks like the coil is not getting triggered. Now what do I do? Thanks for your help.

Six_Shooter

iTrader: (2)

The coil gets triggered directly from the ICM.

Is there a small harness missing that gets plugged in between the dizzy and the coil?

BurrowsRacing33

I got confused with the wires because there was a black and a red I figured the black was negative but I followed the black wire and it goes to the tachometer. So I tested the red and there is power. Sorry about that. But I dont know what to do now the car has a new distributor cap, rotor, plug wires, ignition control module, ignition coil and new spark plugs and still no spark. I'm not sure if this will change anything but sense the car is a race car it has a push button start with an ignition switch. So if I was going to start it I would turn the key, flip the switch to turn the ignition/battery on and push the button to start it. I also have separate switches for my fan and fuel pumps not hat has anything to do with spark i'm just saying that the electrical system isn't 100% stock. So do you have any more ideas for whats wrong here? Thanks again for your time its greatly appreciated.

OrangeBird

iTrader: (1)

From what I read here , I get two ideas .

First , have you checked the pickup coil located in the distributor ? I have yet to see mention of it in this thread , and from your above list I believe that to be the only part of the ignition system you have yet to replace .

And second ,

If the pickup coil ain't it , then ya got something wired wrong . Do the folks here that are tryin to help ya a favor and post a picture of the wiring you've got hooked up to your distributor and ignition coil . You know , the old "A picture is worth 1000 words" (well , Ok , Maybe 995 words due to the present state of the economy )

batsibf

here might be something when checking you ground make sure you use a ohm meter and go from unpainted place on your block not the grounding strap to a unpainted spot on you frame. some people when painting there blocks paint the ground locations and then the blocks are not grounded and no spark

BurrowsRacing33

I did paint my block so that would be something to check but I'm pretty sure that I sanded the ground locations down before I reconnected them. What kind of reading would I be looking for? I have been told that if I don't have all the grounding wires hooked up it could prevent me from getting spark. So If that is true then it makes sense because I just about replaced everything in the ignition system. So I'll mess around with ground wires this week. My father and I are done messing around with this car, if it isn't running by this weekend we have made plans to pay a guy to come out and get it going. Good thing it is only a back up car my main car will be a 1994 firebird we just have to get the rest of the money up for it so in the mean time I need to get this car going so I can run at the practices. Thanks for all your guys's help if I have any more questions I'll let you know.

batsibf

mine is 0.4 right now I would look for something under 1 ohm the lower the better