Help with random/intermittent spark on recent engine install.
03-24-2012, 01:44 AM
#1
Help with random/intermittent spark on recent engine install.
To give some background I just completed an engine swap into my 88 Turbo. The car fired up easily the first 10 times I started it. But the engine has been popping alot (detonation) and running rough. Then today the car started up and ran for 10 seconds, then died won't restart. My afr light gauge shows extremely lean condition every time it ran.
After install engine has checked out at 145to 150 psi compression on all four cylinders. Fuel pressure shows 42 psi consistent. Spark plugs were new when put in, and now look black. But the confusion for me is that the afr show a very lean condition.
I unplugged all the spark plugs, and put the spark plugs iback n the wires while having them face upward. Testing at night shows random spark all over the place. Sometimes only one is firing. Next try will show two sparking strongly. Next, is one strong and two weak. Then trying it again shows three sparking weak. Nothing strong or consistent really.
Is this a decent way to check spark? I will try some of the test mentioned in my search to see if the coil is at 12 volts or not.
I am wondering if this is a DME or KLR issue? With the previous engine in the car getting spark and fuel was never a problem. It was bad rings due to an old engine and bad cleaning (me) that caused very low compression.
Any ideas of what tests this points too? Coil, or DME, or something else?
After install engine has checked out at 145to 150 psi compression on all four cylinders. Fuel pressure shows 42 psi consistent. Spark plugs were new when put in, and now look black. But the confusion for me is that the afr show a very lean condition.
I unplugged all the spark plugs, and put the spark plugs iback n the wires while having them face upward. Testing at night shows random spark all over the place. Sometimes only one is firing. Next try will show two sparking strongly. Next, is one strong and two weak. Then trying it again shows three sparking weak. Nothing strong or consistent really.
Is this a decent way to check spark? I will try some of the test mentioned in my search to see if the coil is at 12 volts or not.
I am wondering if this is a DME or KLR issue? With the previous engine in the car getting spark and fuel was never a problem. It was bad rings due to an old engine and bad cleaning (me) that caused very low compression.
Any ideas of what tests this points too? Coil, or DME, or something else?
03-24-2012, 01:33 PM
#2
What I have found with my testing today.
If I put an LED on either the green or black wire and ground the other end, when starting the car the wires will make the LED flicker. My understanding is that means the DME and KLR are working properly for each respective wire.
If I test the coil itself by pulling off the ground wire (green) and the coil plug at the distributor. Then put a spark plug into the plug I pulled off and ground it. Next I put a ground wire on the green coil wire. With the other end of the grounded coil wire and the ignition in the "on" position and tapping the negative battery terminal I get no love. Nada, no spark at all. I would guess this means I have a bad coil? Strange that I get some spark at the plugs though, it's just not strong or consistent.
If I put an LED on either the green or black wire and ground the other end, when starting the car the wires will make the LED flicker. My understanding is that means the DME and KLR are working properly for each respective wire.
If I test the coil itself by pulling off the ground wire (green) and the coil plug at the distributor. Then put a spark plug into the plug I pulled off and ground it. Next I put a ground wire on the green coil wire. With the other end of the grounded coil wire and the ignition in the "on" position and tapping the negative battery terminal I get no love. Nada, no spark at all. I would guess this means I have a bad coil? Strange that I get some spark at the plugs though, it's just not strong or consistent.
