This is a follow-up to my thread about the intermittent misfire at idle.

As I had suspected and hoped, some chimed in saying they had a similar problem that turned out to be a coil pack and did not throw a code, and no SES light.

So, can we agree that coil packs can sometimes malfunction and the SES light not come on?

Also, some suggested that I pull each plug wire off the plug until I found one that did not seem to make a difference in how the car runs, and that is my cylinder that is misfireing.

The problem with that test is that the misfire is not constant. Sometimes I will stop at a light for 30 seconds, it will misfire only ONCE while stopped at the light.

SO.... After my usual long-winded, and hopefully informative preface, here is my new question;

Does anyone know of a diagnostic tool that I can carry in my car with me that might stay plugged into the OBD port that will 'remember' or 'record' the misfire and later tell me which cylinder or (hopefully not) cylinders are misfiring?

I was just using the OBD port as an example. It can stay anywhere in the car. Maybe under the hood somewhere, wherever it has to be. I am thinking possibly something I could 'rent' or leave a deposit for, Etc.

As usual, thanks SO much for any tolerance for my long post(s), and thanks VERY much for any input.

 

after some quick searching, people are saying go to a shop with live scanners. you should be able to see 3-4 misfires within a minute or so

tl;dr, you're gonna need to get a hold of a decent scanner

 

There is also a coil pack testing procedure to test the resistance across the pins. Do a search and you'll find it.

 

There's coil / plug probe ( http://www.matcotools.com/ProductImages/COP963.jpg )
It will show a pulsing light when placing it's tip onto an ignition coil, which ever one is off beat would be seen. One of my mechanic friends actually uses a stethoscope. It's strange that its giving you no codes, OBII scanner would pick it up if you had a CES light.
In my case I had multiple misfires (with codes). To fix I started with plugs, then harness, ECU, and then finally replaced all coils. Once new oem coils were in, it went away and the car felt SO much better.

Good luck.

 

Did this just start happening? Have you noticed it getting worse? code should come up soon......but you could buy one coil for the front and one for the back...1,3,5 are in the back 2,4,6 are infront...backs are shaped different from what i remember....you could put one new one infront and drive,but keep your old coil just incase thats not the messed up one...if problem goes away you found it,if not put old one back and switch again with different one until your problem stops...also you could return one not needed to autozone after ...do one at A time...change your plugs with e3s while you're there...might as well,could be your problem

 

Generic live scanner will NOT give you misfire counts. However, almost all scanners are capable of giving you stored codes. It is possible that there might be stored code. Unfortunately, the problem that you are having, a cylinder specific code will take a long time before it will show up. Until that you will be getting generic misfire code such P1320. I had my scanner hooked up to the car and used to check the codes every single day. It took more than 6 months before I got a cylinder specific code. I had similar problem i.e. randomly misfiring but not consistent to run the cylinder drop test.

Having your own live scanner (given that now you can buy them under $100) is the best idea.

If you are not sure that your coils are all updated and new and if you are not sure you have correct spark plugs installed, just get all new coils and new spark plugs (check into Amazon/ebay for deals on OEM parts) and just replace them. It will not be cheap but in the end if you have to take it to a shop, that is exactly what he will do but will add 100% of markup on the parts and will charge you hefty labor.

- Vikas