weird issue with #2 #4 pistons not firing

[89irocz]

ok Getting ready to send my classic fast b2b back to have it checked over.

Here is whats going on. 89 camaro sbc factory HEI. I put new heads on the car and start it up and notice a miss. #2 #4 pistons are not firing at all. Plugs look brand new. I check spark yup got spark. I pull both conectors for those two injectors and have 12 volts and used a light bulb to test. Both connectors flickering well just like the others. Last maybe those two injectors are dead? I pull both injectors and move them to 6 and 8 and move 6 and 8 injectors up to 2 and 4. Start car up and let it run for a minute and guess what pull the plugs and 2 and 4 still not firing. I pull the valve cover and valves are working fine. So this seems impossible, why when i make a change the car breaks some random other part. The worked great before the head swap.

FAST is going to check the injector drivers to see if they are week but they admitelly find it very odd.

 

[HighPSI]

Verify the number of cylinders is 8 in the fuel calc parameters

 

[89irocz]

I checked it tonight and it still is at 8 as the program should be.

This realy has me stumped

 

[Chuck Leeper]

Valve lash is??

 

[89irocz]

double checked valves just to be sure 0 lash

 

[Chuck Leeper]

double checked valves just to be sure 0 lash

done a compresion test?
I'm wondering about "weak drivers".. Usually something like that is kinda like being pregnant.. Either you are or UR not. Drivers work, are shorted, or open....
U used a light bulb for a noid??

 

[89irocz]

I used a light bulb and it flickered just like the other 6 pistons. I did have to pull the head a month ago due to leaky head bolts after installing the new heads. I noticed then both 2 and 4 were perfectly clean not a hint of carbon. Compresion is fine. I spoke with FAST tech and he said the drivers usauly work or don't and since its a batch it should leave 4 cylnders dead.


If by the end of the day tonight I can't figure anything out I will pull the ecu and send it back to FAST.

 

[89irocz]

After taking a closer look tonight all my valves are out of adjustement. I can move the rocker arms up and down almost a 1/4 inch. Also after letting the car run for about 10 minutes the plugs are carboned up on 2 and 4. Tommorow we will readjust the valves and should be good to go.

 

[Chuck Leeper]

Ok

Valve lash is??

Glad you found it! Now go spin the tires!

 

[89irocz]

Still broken

My valves were out of wack but got them adjusted correct. What I have done in the last few days i put 8 new plugs in and new wires and cap and rotor. I get gas into both 2 and 4 so the only thing left is for me to send the ecm back.

 

[89irocz]

Well the ecu checked out fine. I got my ecu back today and #2 and 4 piston will not fire still. Plenty of fuel, injectors opening. It must not be getting spark under compresion but why? What on earth could keep 2 and 4 from never firing not even ounce. Can anyone point me in the right direction?

 

[UR50SLO]

Sounds stupid but verify 18436572 firing order on cap/cyls.

What were the actual compression numbers on all cyl?

If you've got a air compressor you'll want to back the intake/exhaust rockers all the way off on 2&4 and then put shop air into the cyl. This will show where your leak is. Could be bent valves... could be valves not seating could be rings.. could be head gasket not sealing between the two cyl.
Putting shop air into there is going to verify if it's sealed up or it's not.
Is this a TPI engine?
What's the history? build ect... need some more details there.
Sorry your having such trouble.
~Scott

 

[Chuck Leeper]

"It must not be getting spark under compresion but why? What on earth could keep 2 and 4 from never firing not even ounce. Can anyone point me in the right direction?"

Simple check: Put a timing lite on 2&4.. does it flash?
As Scott suggested:
Do a leak test, and while UR there, do a compression test on all 8.
18436572!
Has this engine ever been run, prior to the problem????

 

[89irocz]

the engine is just a bsaic 355 with trw pistons. Car ran fine last winter. I pulled the heads of the car, it sat all summer and I put another set of heads back on the car recently so I could drive it. I'm going to do a compresion test this weekend.

 

[HighPSI]

Simple check: Put a timing lite on 2&4.. does it flash?

X2

 

[89irocz]

some more info found today. This is my first time doing this so I'm learning as I go. Keep in mind this engine ran fine 8 moths ago. I pulled of the heads let it sit for months and then bolted on a brand new set of iron heads. Yes I used new head gaskets.

First I got a timing gun today and verified both 2 and 4 are firing timing light was flashing just like pistone 6 and 8 so we are good there.

Next I pull plugs on 2 4 6 8 to check compresion and here is were it gets confusing.

piston 2 reads 84psi let it crank for about 7 seconds

piston 4 reads 0 psi yes i re did it 10 times and it will not read anything on the gauge.

Piston 6 reads 90 psi and piston 8 reads 90psi.

Both spark plugs for 2 and 4 still have never fired not ounce and look brand new. So what do you guys think? I do not have air in my garage so no leak down test. I would of thought 6 and 8 would be atleast 115 psi?

Guys I just got my new dart little m 406ci longblock with dart 230 heads yesterday its sitting there just need to drop it in, but I wanted to figure out what is going on with this engine first. I also got my turbo 400 and converter. Anyone want to buy a built t56 and mcloud twin disk clutch?

 

[Chuck Leeper]

"piston 2 reads 84psi let it crank for about 7 seconds
piston 4 reads 0 psi yes i re did it 10 times and it will not read anything on the gauge."
Gasket blown between 2&4...

 

[89irocz]

Just seems odd the car has no drive time at all just 10-15 mintues of garage time I havn't even set the timing yet.

 

[UR50SLO]

That's where putting air down the two holes will answer your questions (with rockers backed off.)
You said it was a different set of heads too... could be issues with valves you were not aware of.
Find a air compressor. It'll answer your questions real quick.
~Scott