Missfire will be seen as lean spikes, if you gaps is in check perhaps a little dielectric grease on all coil connections can help.

Last resort: Borrow someones coils and slave them in there to see if thats the cause

 

can the OP please plot the throttle position with the rest of the data?

 

It shows 40-50% in the Log as I see it.

 

I do that to check spool up on occation and to repoduce a hiccup I was feeling in lower gears

 

a couple things to think about.

First off, the NGK Iridium IX BR8EIX plugs are 6.50 a piece and the best plug you can buy for the 4G63.(of course, choose your heat range wisely)

Did you check your gap when you checked your plugs?

One of a couple things could be happening. First i will state some facts; a misfire will show up as a lean spike on the wideband with the proper sampling. What i'm seeing in your log looks more like a lean condition, which is causing a misfire like stutter.

Did you try adding fuel in that area of your fuel map? I'm assuming you have your closed-open loop crossover set properly.

You are lifting the throttle, and the injectors should shut off after their initial over-run cutoff(if you completly lift off the throttle and engine break while still in gear).... but you are not lifting the throttle completly, you are going from 100%tps to just under 50%.....it's possible that the areas of calculated load in that range could be too lean and need to be richened up. If this is true, you might not ever see these cells in open loop...you might normally be passing these cells in closed loop, which will tune for 14.68:1. You see, the ECU stays in open loop for a second or so after you go below the open loop threshold.

Get some new plugs, gap them properly and re-tune all areas of your fuel maps.

Force open loop, and re-tune. This will take this factor out of the equation.

CJ

 

There should be absolutely NO need to gap the stock plugs on a nine. NONE
Second In order to properly diagnose the problem you need to know the exact AFR at the point where the log begins and the point at which it meets its demise around 17.5. (What the plot indicates)
If you are at partial throttle, there are a few things to concider here. First and formost the time delay between pre and post throttle. Injector duty, closed or open loop and actual load at the time of incident.
I-tune is correct however on one key point. FORCE open loop at all times and datalog. That means throttle and load. I think you may be able to eliminate some of this by INCREASING your closed loop throttle and load points.

My two cents. But honestly It would not be an issue for me as every time I drive and shift I am around the 3-4000 rpm point of the power band. There are better ways to check for spool up characteristics.

 

As the plug wears, the ground strap and the electrode wear. This loss of material on these pieces increases gap. If the plug wear is significant, the gap can be opened up a good bit.

NOW, with aftermarket plugs, other than OEM(which are NGK iridiums), you will need to gap the plug. All engines are different and all set-ups will not perform the same, this difefrence will require a difference in gap.

Even if you are still using the stock plugs and are usings elevated boost levels and non-stock set-ups...you WILL need to re-gap the plugs, no matter if they are OEM or not, because gap requirement will change as your power levels and set-up changes.

CJ

 

whoops i feel like an idiot, TPS is on there. just looked different as the scaling when i plot it, it is usually the highest in the graph.

 

NGK Iridium IX BR8EIX fit the 8 not the 9. the 9 has a different plug due to the redesigned head. while I agree it could be the plugs I am going to drive conservatively for the next week and richen up the spool up range that I am hitting during the event a little. and see if that helps. I do plan on changing the plugs, it just may take a week or two til I can.

just to be clear I do logged pulls from the 2200 range to catch the full spoolup event on log. I can be at full boost before 3000 rpm depending on my tune. and since I do autocross on a stock clutch wot at 2500 rpm at the start is not unusual

thanks for the help every body, give me a week or two and I will post back up what resolved the issue

 

The EVO 9 NGK PGR7A plug(as does the EVO 8 IGR7A-G plug) directly cross refferences to the NGK Irdium IX BPR7EIXstock #4055(the P is for protruded electrode). I gave you a BR8EIX plug, which is one heat range cooler and is the non-protruded electrode version. this plug will work just fine.

Here is a pic of the two......



this is a BR8EIX NGK Irdium IX plug(NGK stock#5044), non protruded electrode



This is the same series of plug, but the protruded electrode version. NGK Iridium IX BPR8EIX(NGK part#6684)

The BPR8EIX plug is a direct replacement for the PGR7A plug, only it's one heat range cooler. You can run either protrueded "P" or non-protruded elecrode just fine.



CJ

P.S. The difference between the OEM 8 and OEM 9 plugs is what the electrode is made of.... The 8 is a laser Iridium tipped electrode, and the 9 has a laser platinum tipped electrode. I'm not sure why Mitsubishi choose a new plug made of a inferior metal to iridium...but they did and thats the difference.

 

iTune...you always have very informative things to say. I always learn something when reading the troubleshooting threads

 

Yeah, he's a good guy

 

FYI - the NGK's are racing plugs and expensive as hell ($30/plug)....your best bet is Denso's (IKH24's - 1 heat range colder)....the main diff between 8 and 9 lugs are the length...due to the mivec heads, the ix plugs are longer, thus evo vii plugs will not fit in there...been there, done that.

in terms of the op issue, can you please post your mivec maps...improper settings (i.e. too aggressive ramp) can cause this hesitation in cam transition...if its modified change back to stock and try it out.

 

All the NGK Irdium IX plugs are about 6.50-7.50/plug, depending on where you buy them. You should be able to pick up any of the NGK Iridium IX plugs i listed for about $29/set. They are by far the best option when it comes to plugs.

CJ

 

Thanks! I'm here to help you guys out! Although there are a few undesireables on here that think i know nothing...(vendors....shhh!)

CJ