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Old 06-16-2020   #1
mmkkpro
 
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Default Compression test

Hi guys, I am doing a compression test, what should I do about the plug wires? Should I put a plug on each wire or is there a way to kill the ignition system? I have read that I'm not suppose to start/run the engine without a plug or spark tester installed, could damage DIS.
Still have the miss, sounded good for a short time, but back doing the same thing again. Very frustrating. Thanks.
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Old 06-16-2020   #2
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Default Re: Compression test

I think I found it, suppose to disconnect the crankshaft timing sensor. Thanks.
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Old 06-16-2020   #3
tf95ZR1
 
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Default Re: Compression test

From our own Paul Workman, 2009:

"Be sure to put a battery charger on the battery to assure uniform cranking speed between tests. And, pull the "inj-1" fuse (open passenger door & find fuse near the center of the fuse panel). This will shut off the fuel and prevent it from flooding the engine, and or getting into that expensive oil!"

This is what I did. I have never heard of disconnecting the crankshaft timing sensor. I just let my spark plug wires hang (not close to any ground). Good Luck!
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Last edited by tf95ZR1; 06-16-2020 at 06:20 PM. Reason: Wanted 2
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Old 06-16-2020   #4
mmkkpro
 
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Default Re: Compression test

Thanks tf95ZR1, the FSM says to disconnect the crank sensor, I did the battery charger and held throttle plates wide open, didn't think about FP1 though. It's running again. Here are the numbers warm and dry, I didn't do the squirt of oil. I have new wires, coils 2nd set of new plugs, injectors, fuel filter, my fuel pressure is good, I'm missing something, I'm starting to think IH gaskets are bad, would cause a lean condition. I got compression, fuel, and fire, guess I will recheck everything.
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Old 06-16-2020   #5
Ccmano
 
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Default Re: Compression test

What compression tester are you using? Your numbers are low. If your near sea level you should be ~210 psi. If your using a Harbor Freight tester throw it away. I went through 3 before I came to the conclusion they all read low. I bought one from NAPA, low and behold, I had good compression. Its only tool from HF I have ever found to be bad.
H
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Last edited by Ccmano; 06-16-2020 at 08:39 PM.
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Old 06-16-2020   #6
mmkkpro
 
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Default Re: Compression test

Not sure CC, I have had it for many moons. I am at sea level, Holden Beach about a mile off the water as the crow flies. I do need to update it, I put new plugs in after the compression test, drove her a couple miles, felt good. I'm going to take her out on hwy 17 after work tomorrow, see how it does. If I could listen to or drive one that's right it would give me an idea of what I'm looking for. I will stop and get a better tester also and test again. Wish I knew more about its service history, being that it sat for many years, I knew it would need a lot of finesse, I appreciate the help!
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