Hi all

I just purchased a 2001 SSEi. Car seems to be... decent. However, there is an issue that I'd like to get figured out. I've tried looking around on here and came to some conclusions of things to test/check/replace. Just wondering if anyone has any ideas on what may be the culprit for my specific issue.

The engine has a small shake/vibration. Other than that it runs great and sounds great, no knocks or anything. But I'm not sure exactly what is or may be causing the vibration. It doesn't matter if the car is warm or cold when I start it, it's always there. If I punch the gas, it'll bog, but if I roll into the throttle, it accelerates just fine. I had a shop take a look at it and he said it may be a plugged cat, but I don't think that's the issue. In my experience with plugged cats, there's a lack of power all through the power band no matter how hard you're pressing the gas. I'm thinking it may be a bad coil or ICM, or plugs and wires. But not sure if I should be looking elsewhere. The plugs are Autolite (I've heard NGK and Delco are safe bets, haven't heard anything on Autolites for the 3800). The wires are unknown brand but are 7mm. SES is on and the car threw/throws a "random misfire" code, as well as a couple evap codes. I haven't felt a misfire, and don't think the vibration is a continuous misfire. Feels less dramatic than a miss, though the issue may have caused the random misfire(s) that threw the code. The coolant and oil are clean, though there is a small coolant leak on the plastic elbow under the tensioner.

So, things I think may be the culprit:

-Plugs/wires
-ICM
-Coil
-Possible vacuum leak, though all the hoses I BRIEFLY looked at seemed good.

I unplugged the MAF and the car ran pretty much the same, rougher idle initially at startup though, as expected. Haven't looked at the MAF itself to see if it's dirty. Haven't checked fuel pressure, though I don't think it's fuel delivery. But who knows.

Anybody got any ideas on what else it may be, or how Autolite plugs seem to do in these engines, or if those would even cause the vibration?

Thanks for any help
-Matt

Its probably a coil or the ICM. Without shocking yourself, pull off the spark plug wires from the coils and see if the coil is making a spark. If you don't have spark on one coil, swap them around and see if the no-spark follows the coil or stays in the same spot. If it follows the coil, replace the coil. If it stays in the same spot, replace the ICM. If you have good spark on all the coils, replace the plugs and wires.

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Alright, so right along the lines of what I was thinking. Good. Thanks for the help. I'll try troubleshooting those some more and see if I can track it down.

Thanks!

Well, it's getting spark to all wires. Some might be stronger than others, though. Couldn't really tell just by watching the spark. hopefully it's plugs or wires. Or could the ICM possibly cause a weak spark to random cylinders at no particular interval or pattern?

The shake is enough to feel while sitting in the car. It idles at about 900 rpms usually, which I THINK is a little low, but not sure what it should idle at. A very few times, it idles at around 1000-1100 but then falls off again and the shake returns.

And yes, I shocked myself on 4 out of 6 wires.

I'm wondering how this turned out? Mine does the exact same thing, but it does so after new plugs/wires.

_________________
~SPACE~

It turned out to be a combination of poor plug choice and a bad injector/injectors. Swapped one injector that was throwing a code and all has been fine since.