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Spark Plug gap and ICM


Kevin
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So this is a pic of the ICM, I checked resistance, and all show OL I just watched a video on checking it and it said if any of them show OL then the coil pack is bad. The other thing I was trying to find all though it may not matter is how low to set the spark plug gap (setting lower to make it idle smoother) if running this coil pack.

 

20221120_154648.thumb.jpg.09396f7d994cb41917da774124f9f2b4.jpg

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Welcome to the forum Kevin. I have never saw a coil pack that looks like yours on a Reatta or in a catalog. Could it be the wrong one for a 3800?

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Magnavox replacement, Jacobs maybe ? I would not set one of those over .045.

For more than you ever wanted to know, see here.

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Thank you both @Padgettand @Ronnie ok Ronnie that being said could that be why it sounds like it's misfiring, I had a leak down test done mechanic said it's misfiring on cylinder 6, and like I said previously I checked resistance across on terminals and each Coil reads OL.

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 The ignition is a waste spark system where two plugs fire at the same time, but with opposite polarity. #6 & #3 are on opposite sides of the same coil. If there is enough cable, switch the two to opposite sides and see if the misfire follows the change. What did the leakdown show? 

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Was the miss on #6 diagnosed by doing a leak down test?  That would be odd but if not, how was it determined that #6 is missing? Is it just missing at idle or is it missing when under load at highway speeds?

 

It would be good if you had another ICM and coil pack to try so you could rule out the odd looking ones you have being the problem. However, since all of the coils are reading OL, it would be unusual for only #6 to be giving a problem caused by the coils. It's strange that they all read OL. Have you checked the old coil pack to see what reading your get? Perhaps there is a problem with your meter or how the leads are connected. A miss on one cylinder would more likely to be related to a bad spark plug, or bad spark plug wire but it could be cause by a lot of other things.

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2seater, looks like we were posting at the same time. I think we are on the same page.

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AFAIR the coil primary side (ICM) is about 1100 ohms and the secondary (plug wire) side is near zero.

Is cyl 6 leaking down faster than the others ?

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So @2seaterfor your first question the mechanic did a leak down test and said cylinder 6 is misfiring. @Ronniethe old Coil pack and ICM I don't have, and my ohm meter is practically brand new, and @Padgett I don't know if it leaks down faster than the others.

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A leakdown test determines how well the valves and rings are sealing. The engine does not run during a leakdown test & is thought of as a reverse compression test. Results are usually in % (below 20% is generally good). To say it shows a cyl misfiring makes no sense.

See here.

Run do not walk.

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21 hours ago, 2seater said:

#6 & #3 are on opposite sides of the same coil. If there is enough cable, switch the two to opposite sides and see if the misfire follows the change.

This is very good advice. I recommend you give it a try and let us know the results.  Do you know any readings the mechanic got when he performed the leakdown test? OR a compression test that should have been done at the same time as the leakdown test?

 

All of he above would be helpful in diagnosing your problem. I wouldn't put much stock in a leakdown test as a way of diagnosing a miss  at idle unless a compression test showed a really low reading like when there is a burnt valve.

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+1. If I saw a lot of Mode $06 misfires in one or two cyl then a leakdown test (and a borescope) might be informative.

At this point I'd look more at logged parameters (TPS, IAC, RPM, MAF, Fuel Trims, O2 sensor,...) after running and having the problem.

This is an example of what TunerPro RT can show on an ALDL car. Right column is switches.

 

To work on a Reatta someone needs to understand this.

 

aldldisplay.jpg

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Agree it is aftermarket (are several) but not necessarily bad. I would change to a Delco, is a bolt in and more powerful.

Gaps:

Magnavox style .045 max

Delco                 .060

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