91 Z not firing on no. 1 cylinder. - ZR-1 Net Registry Forums

terry mckeown · 04-06-2010

Hope someone can help. Last weekend took the Z out for the first time this year, been sitting in my cold garage all winter with stabil in the fuel. About 25 miles from home the engine started running rough. Even when I floored it it still was missing. Once home I started pulling spark plug wires and found #1 cylinder was dead. Pulled the sparkplug it seemed ok however the gap was about 45 thou. Regapped the plug still no difference however I am getting spark to that plug. I suspect the injectors. Last year I had the primary injectors tested everyone was between 12 & 13.6 except # 1 which was 6.3.
Since there is no one around here who knows how to work on the LT5, I have decided to pull the plenum myself and change the injectors. Here is where I need help. Gaskets, injectors, and what ever else I will need.
Who do I call for these items? I have decided on accel injectors as they are the best price. I also want to change the spark plug wires (red) there are bosch grey ones on the engine now.

1990 415 · 04-06-2010

I had a very similar situation last fall. My number 1 cylinder was not functioning. I had just pulled the plenum and when I was reinstalling it I somehow pulled off the wire to the primary injector on cylinder number 1. After I hooked it back up all was fixed. Before pulling your plenum carefully check to see if any of the wires to the injectors are loose. It might be that simple.

terry mckeown · 04-07-2010

No I did not correct the low reading injector, as the car was running real good. Thanks for the info. I have ordered the Accel injectors from Atlantic, have sent an e-mail to Jerry's gaskets. Tomorrow I will price the
wires at the local GM dealer vs the price on E-BAY. Again thanks for your help.

rkreigh · 04-08-2010

see www.zr1specialist.com

you can ohm out the injectors (warm car up) from the harness, chances are you'll find a dead injector

the old sniffer works good too, run the car and pull the plug, you can smell unburned gas if it's not firing

leaky injectors will make it rich misfire and a "weak spark" from a bad wire, coil pack can make it run on 7 too

the factory service manual is your friend here if you dive in, but don't do that plenum pull without first changing plugs

a plain old bad plug can happen and they look just fine, it happens

04-06-2010	#2
1990 415 Join Date: Feb 2009 Location: Canada Posts: 309	Re: 91 Z not firing on no. 1 cylinder. I had a very similar situation last fall. My number 1 cylinder was not functioning. I had just pulled the plenum and when I was reinstalling it I somehow pulled off the wire to the primary injector on cylinder number 1. After I hooked it back up all was fixed. Before pulling your plenum carefully check to see if any of the wires to the injectors are loose. It might be that simple.

04-07-2010	#3
terry mckeown Join Date: Apr 2008 Location: Cambridge, ON. Canada Posts: 14	Re: 91 Z not firing on no. 1 cylinder. No I did not correct the low reading injector, as the car was running real good. Thanks for the info. I have ordered the Accel injectors from Atlantic, have sent an e-mail to Jerry's gaskets. Tomorrow I will price the wires at the local GM dealer vs the price on E-BAY. Again thanks for your help.

04-08-2010	#4
rkreigh Join Date: Jan 2004 Location: Alex VA Posts: 1,087	Re: 91 Z not firing on no. 1 cylinder. see www.zr1specialist.com you can ohm out the injectors (warm car up) from the harness, chances are you'll find a dead injector the old sniffer works good too, run the car and pull the plug, you can smell unburned gas if it's not firing leaky injectors will make it rich misfire and a "weak spark" from a bad wire, coil pack can make it run on 7 too the factory service manual is your friend here if you dive in, but don't do that plenum pull without first changing plugs a plain old bad plug can happen and they look just fine, it happens __________________ 95 390 LPE ZR1 (505 rwhp) LSV = Lingenfelter Super Vette Twin Turbo 2003 Z06 (800 RWHP)

04-06-2010	#1
terry mckeown Join Date: Apr 2008 Location: Cambridge, ON. Canada Posts: 14	91 Z not firing on no. 1 cylinder. Hope someone can help. Last weekend took the Z out for the first time this year, been sitting in my cold garage all winter with stabil in the fuel. About 25 miles from home the engine started running rough. Even when I floored it it still was missing. Once home I started pulling spark plug wires and found #1 cylinder was dead. Pulled the sparkplug it seemed ok however the gap was about 45 thou. Regapped the plug still no difference however I am getting spark to that plug. I suspect the injectors. Last year I had the primary injectors tested everyone was between 12 & 13.6 except # 1 which was 6.3. Since there is no one around here who knows how to work on the LT5, I have decided to pull the plenum myself and change the injectors. Here is where I need help. Gaskets, injectors, and what ever else I will need. Who do I call for these items? I have decided on accel injectors as they are the best price. I also want to change the spark plug wires (red) there are bosch grey ones on the engine now.