1G [1990] How to unplug coil pack?

[nelliott500]

I'm trying to do a compression test but I don't know how to unplug the coil pack. I'm following this thread to do the compression test and it mentions a clip on the connector but I don't see anything. I tried just pulling and wiggling it but it isn't budging. What do?

And just to clarify, this is the plug, correct?

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[thejollyrancher]

I'm pretty sure the connector has those yellow wires coming out of it. It's a big square plug

 

[nelliott500]

That actually makes more sense considering the smaller thing is only one wire. Not being near my car right this second, I don't remember anything else really looking like it plugged into the coil pack.

 

[pauleyman]

No thats not the plug and youre going to too much trouble. Pull the mpi fuse

 

[nelliott500]

Pulling the MPI fuse stops both fuel and spark? I was wondering if there was just a fuse I could pull. I found a few threads about compression testing and everyone said to unplug the coil.

 

[NHerron]

Check this link out, a little more detailed article.
http://www.dsmtuners.com/threads/compression-and-leak-down-testing.338152/

 

[thejollyrancher]

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Found a pic. Its not the plug circled, its the plug right on top. Black with red and yellow wires going in the back. Im pretty certain its the plug I suggested in my first reply.

Edit: Im certain. Pull the plug and crank the engine, bet you'll have no spark!

 

[helluvadsm]

What jolly rancher said, trust me, it's the top of those two, some are triangular though.
I owns me a 1g!

 

[DSM1G90]

Nah, just unplug the MPI fuse to keep the injectors from firing.

That's your big worry, not the spark plugs firing and those one can swing those away from the head.

Or, you can wrap each end of the plug with black tape-keep you from getting bit if you want to make it easy on yourself.

But undoing the plug for the coil isn't that all hard to do

If you do compression check with cylinders being filled with fuel by the injectors, that definitely will throw off a true compression reading.

 

[pauleyman]

Pull mpi fuse at battery. No fuel or spark because at that point there is no ecu. Yes this does reset your ecu.

 

[Morecowbell]

Yours is a 90 so the plug to the coil is a triangular plug. Real easy.

 

[thejollyrancher]

Sorry morecowbell. 90s have a square plug. I have a 90.

 

[nelliott500]

Check this link out, a little more detailed article.
http://www.dsmtuners.com/threads/compression-and-leak-down-testing.338152/

Good article. Bookmarked.

Thanks to everyone for the info. I'm heading out to do the compression test in a couple minutes once I warm up the car.

 

[Morecowbell]

You're right thejollyrancher! Got them backwards have a 90 and a 91 in the garage and got them backwards. 90 has rectangle plug. My bad.

 

[nelliott500]

Motor has 154k on it and is mostly stock.

#1: 140, 140, 190 (oil)
#2: 160, 155
#3: 160, 160
#4: 160, 160

Obviously #1 is worn out (assumed piston rings although oil test isn't 100%) but what do you guys think? #1 is still well above the service limit and the rest of the cylinders seem good to me.

 

[DSM1G90]

Did you let the motor crank a few times to get the highest compression before you push the button on the side of the gauge to lock the needle?

Did you do numerous tests per cylinder to get your best reading?

Best to be sure.

No.1 is a little tired than the others, but really nothing to get all excited about.

I have one of those readings also and just going to let it go until I really need to do an overhaul. Why bust up the block to get my 20 lbs back in one cylinder where I might as well do the full overhaul when the money is right?

-Good luck - DSM

 

[nelliott500]

I let the motor crank for five revolutions for each reading and I did two tests per cylinder (three on #1 because of the oil test).

I'm not too worried about it. I know they're supposed to be as close as possible but #1 is still well above the service limit. Eventually I'll dig into it but that's (hopefully) way down the road yet.