spark plug wiring for 1990 v-6
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spark plug wiring for 1990 v-6
my friend has a 1990 camaro with V-6. Unfortunitly she took it to a Midas shop for plugs and wires. It ran fine when she took it in and now she believes they have routed the wires incorrectly from distributer to plugs. I have looked for a diagram showing what plug on the cap is for which cylinder but have not come up with anything. She wants to be sure that this is her problem before returning the car to Midas. If somebody can e-mail me a picture I would greatly appreciate it. Thanks alot.
Meeboboy Meeboboy@hotmail.com
Meeboboy Meeboboy@hotmail.com
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Joined: Jul 2001
Posts: 3,931
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From: Palm Bay, Florida, USA
Car: 95 E-150 & 07 Kawasaki ZX-6R
Engine: A slow one & a fast one
Transmission: A bad one & a good one
Axle/Gears: A weak one & a chained one
I'm at school right now and they blocked all email programs.. I made a paint image up for ya real quick..sorry for the sloppiness. Now I can't get to my Hayne's manual right now to double check because, like I said, I'm at school..but this is my best guess and I THINK it's right.. If it's wrong though, someone please feel free to correct!
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Joined: Mar 2000
Posts: 13,414
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From: Central NJ, USA
Car: 1986 Firebird
Engine: 2.8 V6
Transmission: 700R4
The "engine" diagram is 100% completely right. The distributor cap, unfortunately, isn't 100% correct. Only part correct about it is the firing order (1-2-3-4-5-6). The #1 terminal of a distributor cap can start ANYWHERE on the cap. Once you find #1, you can find where the rest of the wires go.
Here's something that I posted a long time ago, January 31, 2001. I got scared for a sec- I couldn't find it, I thought maybe the message was too old and it got erased because of age... luckily I found it! So instead of putting the link to that message, I'll quote the message itself. That way it'll be around for a while...
.......................................................................................
Here's something that I posted a long time ago, January 31, 2001. I got scared for a sec- I couldn't find it, I thought maybe the message was too old and it got erased because of age... luckily I found it! So instead of putting the link to that message, I'll quote the message itself. That way it'll be around for a while...
.......................................................................................
Originally posted by TomP
Alright. Here comes an explanation as to "why the #1 plug wire is NEVER in the same spot on a distributor cap".
-----------------------------------------------------
Okay- there's two things that spin as regards ignition timing: The distributor housing and the distributor's rotor. There's one major thing that needs to be addressed for ignition timing: The distributor's rotor must be in the firing position for the #1 cylinder when the #1 cylinder is at top dead center.
Here's why "you can never tell where a #1 plug wire should be on a distributor cap by looking at it's position in the engine bay."
The distributor housing ITSELF, cap and all, can be rotated!!
(Ugh, how do I explain this without pictures...)
Say I have two 2.8l engines, "A" and "B", both of which I've set their #1 piston to TDC of the compression stroke. By saying this about TDC, this means that the only engine part I need to concentrate on is the distributor.
Say I've pulled their distributors. Now, say I hold both of the distributors so the spark module connections face to the firewall.
Say I use white-out to mark the passenger-side-most terminal on engine "A"'s distributor cap to be the "#1 cylinder".
Say I label the driver-side-most terminal on engine "B"'s distributor cap to be the #1 cylinder.
I now drop the "A" distributor into engine "A". I make sure that when the distributor is fully seated, the rotor points to the extreme passenger-side-most terminal on the cap.
I now drop the "B" distributor into engine "B". I make sure that when the distrib is in the motor all the way, the rotor points directly to the driver's side.
Now, I install the distributor caps.
Engine "A"'s distributor's rotor is pointing to the passenger side. It lines up with the #1 cylinder mark I made on the distributor cap, which was the terminal pointing to the passenger side.
Engine "B"'s rotor points to the driver's side, to meet exactly with a distributor terminal.
On both engines ("A" & "B"), I now run the spark plug wires clockwise. I use the mark I made on their caps as a reference for the #1 plug wires, and therefore, ALL of the plug wires. Looking at the top of the distributors, the wires coming from the cap are:
-----------------------------------------------------
"Engine A", rotor pointing: <<----
...2...3...
1....c....4
...5...6
-----------------------------------------------------
"Engine B", rotor pointing: ---->>
...5...6... "Engine B"
4....c....1
...3...2
-----------------------------------------------------
Both engines are now timed, as I first said, so that the distributor's rotor must be in the firing position for the #1 cylinder when the #1 cylinder is at top dead center.
And this is why you can not determine where the #1 plug wire should be in relation to anything in the engine bay, other than the #1 cylinder's piston position (TDC).
Does this do it? If I confused anybody, let me know. I could've shown it with two pictures much easier.
Note, of course, that sure, GM may make these cars' distributor's point all the same way. But after previous owners and garage work, the position of the #1 plug wire on the cap compared to parts in the engine bay should never be taken for granted.
Alright. Here comes an explanation as to "why the #1 plug wire is NEVER in the same spot on a distributor cap".
-----------------------------------------------------
Okay- there's two things that spin as regards ignition timing: The distributor housing and the distributor's rotor. There's one major thing that needs to be addressed for ignition timing: The distributor's rotor must be in the firing position for the #1 cylinder when the #1 cylinder is at top dead center.
Here's why "you can never tell where a #1 plug wire should be on a distributor cap by looking at it's position in the engine bay."
The distributor housing ITSELF, cap and all, can be rotated!!
(Ugh, how do I explain this without pictures...)
Say I have two 2.8l engines, "A" and "B", both of which I've set their #1 piston to TDC of the compression stroke. By saying this about TDC, this means that the only engine part I need to concentrate on is the distributor.
Say I've pulled their distributors. Now, say I hold both of the distributors so the spark module connections face to the firewall.
Say I use white-out to mark the passenger-side-most terminal on engine "A"'s distributor cap to be the "#1 cylinder".
Say I label the driver-side-most terminal on engine "B"'s distributor cap to be the #1 cylinder.
I now drop the "A" distributor into engine "A". I make sure that when the distributor is fully seated, the rotor points to the extreme passenger-side-most terminal on the cap.
I now drop the "B" distributor into engine "B". I make sure that when the distrib is in the motor all the way, the rotor points directly to the driver's side.
Now, I install the distributor caps.
Engine "A"'s distributor's rotor is pointing to the passenger side. It lines up with the #1 cylinder mark I made on the distributor cap, which was the terminal pointing to the passenger side.
Engine "B"'s rotor points to the driver's side, to meet exactly with a distributor terminal.
On both engines ("A" & "B"), I now run the spark plug wires clockwise. I use the mark I made on their caps as a reference for the #1 plug wires, and therefore, ALL of the plug wires. Looking at the top of the distributors, the wires coming from the cap are:
-----------------------------------------------------
"Engine A", rotor pointing: <<----
...2...3...
1....c....4
...5...6
-----------------------------------------------------
"Engine B", rotor pointing: ---->>
...5...6... "Engine B"
4....c....1
...3...2
-----------------------------------------------------
Both engines are now timed, as I first said, so that the distributor's rotor must be in the firing position for the #1 cylinder when the #1 cylinder is at top dead center.
And this is why you can not determine where the #1 plug wire should be in relation to anything in the engine bay, other than the #1 cylinder's piston position (TDC).
Does this do it? If I confused anybody, let me know. I could've shown it with two pictures much easier.
Note, of course, that sure, GM may make these cars' distributor's point all the same way. But after previous owners and garage work, the position of the #1 plug wire on the cap compared to parts in the engine bay should never be taken for granted.
Supreme Member
Joined: Jul 2001
Posts: 3,931
Likes: 0
From: Palm Bay, Florida, USA
Car: 95 E-150 & 07 Kawasaki ZX-6R
Engine: A slow one & a fast one
Transmission: A bad one & a good one
Axle/Gears: A weak one & a chained one
Tom, that makes sense. But guess what? Once again, my "trusty old" Hayne's has the exact diagram I drew up here in it. :P Fortunately, it did prove correct for me...but I'm beginning to distrust this book... Although it DID list the correct cap diagram for an un-tweaked engine....
You know I was sitting there for 5 or 10 mins trying to decide if my engine diagram was correct or not...I was POSITIVE about the cap.
I couldn't remember if it was passenger to driver, and upward, or if it was straight up each side....but the first sounded like it made much more sense to me..I couldn't imagine all the cylinders on the passenger side firing and THEN all the cylinders on the driver's side firing!
You know I was sitting there for 5 or 10 mins trying to decide if my engine diagram was correct or not...I was POSITIVE about the cap.
I couldn't remember if it was passenger to driver, and upward, or if it was straight up each side....but the first sounded like it made much more sense to me..I couldn't imagine all the cylinders on the passenger side firing and THEN all the cylinders on the driver's side firing! 
Supreme Member
Joined: Jul 2001
Posts: 3,931
Likes: 0
From: Palm Bay, Florida, USA
Car: 95 E-150 & 07 Kawasaki ZX-6R
Engine: A slow one & a fast one
Transmission: A bad one & a good one
Axle/Gears: A weak one & a chained one
If only two are swapped, yes..but it'll run like holy hell...I accidentally swapped two wires at the cap before and started the car...shook like a mother but it still ran, misfiring on 2 cylinders. But any more than 2, maybe 3, and I doubt it'll run at all.
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