Hi Wizard - Glad to see you again

Got the 4:1 disc in with the surrounding ring this time. My second hand FMU came without the ring for the 8:1 disc.

At WOT with the 4:1 disc from about 1 - 4k rpm its around 11 - 12 AFR and 4 - 6k rpm it's about 13 AFR. Might be a little lean but I've adjusted it up with the emanage as far as it will go. A 6:1 might be better perhaps?

Even so, heres the weird thing - the plot has thickened.

After installing my WB02 I let the car warm up to operating temperature and took her for a cruise. The backfiring was really severe from abour 3.5k onwards. AFR was about 13, which shouldn't be causing it to backfire.

I ended up turning the car off and turning it back on again and after that it was fine. I'm a bit bewildered by this.

Consistently the car backfires if driven from Cold to operating temp. Simply switch the car off and on again at operating temperature and it runs fine.

Odd? Or is this something someone has come into contact with before....

 

I'm changing the spark plugs tomorrow. I'll see if that makes a difference. My 2-step colder plugs are about 2+ years old now.

 

You probably should just use the one step colder plugs and make sure they are gapped correctly. Do you have the injector harness for the emanage? As for your problem the backfire could be from the plugs since they are 2 years old (2 steps colder maybe too much for your application) and have been introduced to such a rich afr consistently. Also check your injectors and injector seals.

 

Is the car backfiring (like actually making the loud Pop Pop Pop noise) or is it misfiring (weird uneven acceleration accompanied sometimes by a change in the overall sound of the motor as the uneven acceleration manifests itself)?

 

Thanks maxgtr. Going to pull the plugs out today and have a look. Failing the new plugs, I'll check the injectors. Yes, I have the injector harness for the emanage but it's currently not connected.

Nealoc187: Good question. I would assume it's a backfire because it pops. Sometimes it pops very quickly in succession - quick as in maybe 10 pops a second. It does lose power momentarily when it does this. Sometimes it will only let off one pop and carry on accelerating. Whatever it is, I doubt it's fuel now. Has to be something to do with spark for sure.

I have some second hand Deatschwerks 555cc injectors lying around. I need to test them first before I put them in though. It's been about 2 1/2 years since the previous guy used them.

 

Well, to my surprise the plugs at the back bank of cylinders were swimming in oil. Plugs were probably not tightened enough.

Cleaned it all up and put them back in again. Things are running smooth so far.

Still have an issue with the FMU...

4:1 disc is hanging around 13 - 14 AFR at 5 - 6k rpm with the emanage pushed as rich as it will go. Too lean for my liking.
8:1 disc is hanging around 8.9 - 9.7 AFR at 4 - 5k rpm and around 10.5 - 11 around 5 - 6k rpm with the emanage pushed as lean as it will go. Too rich and has a little bit of a backfire through the 4 - 5k rpm rev range.

I need a 6:1 disc!

 

If you have oil in there it's the seals on the valve cover leaking around the plug.

 

Crap. Don't tell me that! Another thing to fix

Might take it in the same time I get the 555cc injectors put in. Two birds with one stone.

 

If you do the spark plug valve cover seals and do the injectors you won't need the fmu.

If you decide not to, or up until that time, all you need to do is install the injector harness and it will allow you to add injector pulsewidth to bring you closer to your desired afr. Remember the black wire for the harness goes to ground.

 

I did the seals today. All done! Took me around 4 1/2 hours but I took my time not rushing etc...

Gave her a little detail too

I didn't change the injectors at all. I havent tested them yet - they're second hand, so I figured no point putting them in to try and then finding out they don't. Who wants to take the manifold off again. Bleh!

I'll be getting the 6:1 disc in the mail this week.

Guy from the dyno shop said I should be running 13 AFR not 12. Would you guys happen to agree?

 

Well here we go...

I got the 6:1 disc installed. AFR is bang on 12 all the way through the rev range. As you know I have fixed my spark plug tube seals. I put in new one step colder plugs and gapped them to specification.

Unforunately the car is still misfiring occasionally around 4-5k rpm.

I am at a loss. The only thing I can think of now is coil packs. Is this a possibility?

 

Coilpacks could most definitely be a possibility.

 

did you change the spark plugs? if so to what plugs and what gap?

If my memory serves correctly, you're running a 2.62 pulley and no timing control?

I don't know every way a coil problem can manifest itself, but my coilpack problem was nothing like the problem you're having.

Anything more than 10-20% throttle resulted in constant misfiring throughout the RPM range, the car was virtually undriveable (a large part of the reason I got it for $1100).

 

2.62" pulley true - however through a intercooler setup, so only boosting 10.5 psi.

Yes, I have new plugs in. They're one step colder plugs with a 0.035 gap.

Tested my coil packs with the following results.. seems ok??

Results are in Ohms. 1-2 = continuity accross pins 1 - 2 with - being 1 and + being on 2. P = spark plug terminal
Coil Pack 1:

- +
1-2: 628
1-3: 703
2-1: 1
2-3: 833
3-1: 1
3-2: 824
1-P: 1
2-P: 1
3-P: 1

Coil Pack 2:

- +
1-2: 629
1-3: 708
2-1: 1
2-3: 818
3-1: 1
3-2: 829
1-P: 1
2-P: 1
3-P: 1

Coil Pack 3:

- +
1-2: 622
1-3: 700
2-1: 1
2-3: 820
3-1: 1
3-2: 820
1-P: 1
2-P: 1
3-P: 1

Coil Pack 4:

- +
1-2: 629
1-3: 709
2-1: 1
2-3: 832
3-1: 1
3-2: 829
1-P: 1
2-P: 1
3-P: 1

Coil Pack 5:

- +
1-2: 628
1-3: 708
2-1: 1
2-3: 838
3-1: 1
3-2: 827
1-P: 1
2-P: 1
3-P: 1

Coil Pack 6:

- +
1-2: 628
1-3: 717
2-1: 1
2-3: 861
3-1: 1
3-2: 838
1-P: 1
2-P: 1
3-P: 1

 

its possible your injectors are still not ok after the massive pressure spike you gave them when your FMU wasn't working properly? if its backfiring that means fuel isn't getting burnt.

when one of my coil packs died, i had what you described (10 pops in only a second or so), while accelerating mostly at 3 / 4 k rpm, but could be at any time.

Try taking off the supercharger and going for a run, perhaps this will give you more cause as to what the problem is? also i have a parts car if you want some cheap known working spark plug coils / injectors, give me a yell here or on MDU if you want me to send them up

 

Probably can't hurt to try a new set of coil packs. How much do you want for them?

 

I have found the testing the coilpacks can be misleading. I had bad coilbacks even though my measurements showed they were within spec.

Can you swap c. packs with a buddy and see if your problem goes away?

 

my wife has a maxima. I'll swap hers out this weekend mind you, hers have done 250,000 k's.

 

So I swapped the coil packs out of my wife's car.

Instantly I noticed a smoother idle, and all the misfiring went away.

Best of all I noticed a huge power increase.

But even better - my wife seems to run my coilpacks fine??! Things couldnt have gone better! Other than the fact I found that one of my wife's cars rear spark plug tube seals is gone. I just conveniently forgot about that though.... :P

Car is running good.

Thanks to everyone who chimed in on here to help me out. It is much appreciated!

 

... Oh.. I and I finally got some rims. They're Konig Netz 18x8's. What do you think???

 

nice looking car, what color are the rims

 

Nice ride man, wheels look great on it.

 

Thanks guys. I appreciate the comments.

The rims are a matt grey. Different, but I hate chrome and wanted something different. I like the mesh style rims too. I think they suit the Maxima (Or I30 as you guys would refer to it) down to a tee

 

Nice! I knew it!

Glad you got your issues resolved. Happy boosting.

Those new rims looks sweeeeet.

 

Thanks Wizard!

 

I really like this car

 

Haha, thanks dude :P I like it too! .. If that wasn't completely obvious