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Hi everyone.

 

Been having this issue for the past few months. On some humid morning, when I start the car, the tac sits at idle for a few sec and then the engine starts coughing every few secs. If I put it in neutral, it's a little better but still stumbles every few secs. When I hit the gas, I feel like I only have 1/2 the power from stop but when the RPMs go above 2500 or so, all 4 cyls kick in.

I got the CEL a few times, Cylinder 1 Misfire Detected. Once the car warms up, the car runs smooth, as usual.

 

I changed the sparkplugs. The wire seem to be in good shape, still soft and looking good. Any ideas what else the problem might be?

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Hi,

 

Misfiring can be caused by a problem with sparking or fuel mixture issues. Fuel mixture can become a problem either through a defective injector, insufficient air or insufficient compression.

 

I doubt that air is the problem, so the one to rule out is compression (stuck valve?). Put a compression gauge on it and make sure the cylinder is okay.

 

Taking the ignition route, yes, plugs and wires are important (did you check the gaps on the plugs? are they OEM? are they sufficiently torqued down?) but there are a couple of other items in the chain that could be a problem - coil pack and ignitor. Unfortunately, those are difficult for the DIYer to diagnose. Same for a injector.

 

My approach would be to check compression, then the ignitor, then coil pack and finally, injector. Assuming, of course, that your plugs are correct and wires are the right kind (resistor/non-resistor?). Also, use a good fuel system cleaner, in case you've got a clogged injector. When was the last time you replaced the fuel filter?

 

Multiple paths, I know, but you can address them one at a time and hopefully, find the culprit. My '96 once came up with a #2 misfire, which turned out to be a spark plug that had worked itself loose. Ever so slightly, but that was enough.

 

Regards,

Adnan

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Hey, thanks for the reply.

Didn't do the compression test but I do run a bottle of injector cleaner every oil change - 1.5 months. I first got the misfire code a few months ago but replaced the plugs right after with NGK Coppers, pregapped to .044 but I still checked and they were.

I guess the next step would be to do a compression test and see.

 

Thanks.

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FWIW:

I had similar problems on a 96 Legacy and one time it turned out to be the plug wire (which "looked" fine but wasn't) the other time it was the coil pack.

 

Bill

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97subaruGT,

 

Sorry to hear about the problems. I recommend you first ensure the grounding is in order. Check the contacts at the battery terminal and the ground points on the car. Perhaps add a couple more ground wires (8-10 gauge) to the intake manifold, and see if that smooths things out. I did it on mine, and it is much less rough on accelerate and idle. Then if electrical sources are solid, you can confidently diagnose the rest (MAF, solenoid, etc). Check for air leaks after the MAF. If air isn't metered it can mess up your fuel mixture ratios.

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I had the same problem with mine when I bought my 97 GT 2 months ago!

 

I had missfire in 2 cylinders and the engine was running like crap. The reason the guy sold it so cheap he thought the engine was shot.

 

The first thing that went trough my mind was the coil pack or plugs then it turned out to be the intake gasket was ripped! cost me $12

 

Got some WD40 and started spraying arround the intake and as soon as I got close to the problem the engine started to run smootly.

 

The moron sold me his car that he tought was a 96 and its actually a 97

got it for $3000 and spent less than $200 to put it on the road.

 

I'm Loving It.

 

 

just my 2 cents

 

Laz

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Hey everyone, back again.

 

This morning it was raining and the engine ran like crap again when cold and wet.

I replaced the sparkplugs and wires but the CEL for Cyl 1 came on again when the engine started stumbling. Once again, once it warmed up a little, the problem went away.

 

How complicated is it to remove the coil pack? What would be causing this problem - a bad gasket and some secondary ignition goin on?

 

Thanks.

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Hi,

 

It sounds like it's time for the infamous "Arc Test". I have a restoration project, a '67 Austin-Healey 3000 and this car also suffers from mysterious ignition issues. Here's a test that works on that car:

 

Make sure it's nice and dark outside. Pop the hood just enough so you can see inside. Start her up and look under the hood. If you are having HV leakage, you'll see stray arcing going on in places. Any strays mean your plugs aren't getting enough voltage.

 

This may help you localize the problem. As for the coil pack, it's right on top and about as easy as anything to replace.

 

Regards,

Adnan

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