I recently added cattman headers and now have the dreaded p0300 multiple misfire...did fuel pressure test and got 51psi...new coils+sparks and also did a seafoam treatment....still getting it...here are my symptoms

-Slight misfiring at initial start-up...I can easily tell by looking at the engine bay and watching the whole engine vibrate slowly....my exhaust system also bangs against those under-car braces becuz it's vibrating with the engine as it misfires...sometimes a blinking SES and a stored code in the ECM when i pull it manually thru the obdii scanner...

-Blinking SES during daily driving...won't go away until 15-30 seconds later...no matter what RPM you are in/what gear you are in...it still blinks

-Misfiring/knocking/pinging happens at low RPMs (1800-1900) and goes away by 2200...I only get this sometimes (thank God)

-Solid SES light if the misfiring code is stored more than 2 times in the ECM....I notice it doesn't blink anymore and just stays solid if my ECM picks up too many misfiring codes

I currently have 40k...before the headers my car had absolutely no hesitation/pinging/misfiring problems...In the past, I did read alot of vq35 owners get slight knock/ping alot low RPM...they say its normal...now I'm getting a similiar result but I'm sure its more serious becuz the SES is lit (which we all know is bad)....

please post anything informative, experiences, clues...thanks for reading

 

bump....somebody? anybody?

 

Who installed the headers. Could it possibly that something wasn't hooked up or that thought it was clipped and it had came undone.

 

He did .......

 

Did you check for vacuum leaks under the hood? Maybe a clamp on your intake is loose. If you're having these problems right after the install then it has to be that they didn't put something back the right way. If they took the intake off they may have not tightened one of the bolts or maybe an ignition coil isn't seated properly. I don't know what they took off to do the install so I can't narrow it down for you. But I would bet that it's something simple. It sucks that you were all excited to get headers and then have to experience headaches instead. Let us know how you make out.

 

For reference & a little background here's the root thread of this problem

http://www.foums.maxima.org/showthread.php?t=405560

 

I double checked all my connections...everything is on tight...no vaccum leaks either...it idles smooth as butter when it doesn't misfire...if i had a vaccum leak then it would misfire all the time....

Blackbird and Foobeca said something about the EGI harness....that could be a clue...I tried wiggling it around during idle and don't get a different exhaust tone...its shielded up fairly well too...no cracks or messed up wires under the hood...any other suggestions?

and plz no dumb/stupid comments....i've already tried two dealerships and they both denied my service...said my car is way too modified (even tho exhaust & intake would have nothing to do with it)....so I must diagnose this problem myself...it's not compression related becuz I did a compression test a week ago and got 210psi on all 6 cylinders....i'm sure its not ignition related becuz i have new sparks+coils all around...i'm pretty sure it's not fuel related either becuz I do register 51psi on the gauge...although I will do another fuel pressure test again just to double check...

any other clues?

 

have you replaced your oxygen sensors yet? do you have the NTB_03-023 TSB done? Have you checked your cat convertor to see if its plugged? check these and get back to me

 

I'm leaning towards dirty/fouled/defective injector(s). Check the pulse at each injector to rule out the electrical/computer side of it, then check each injector. I'd start by having your fuel system injectors pressure cleaned, about $125, not just sea foam. Good luck.

 

the injectors work great...at least electrically...I checked using a long blade screwdriver...all 6 of check tick nice and smoothly...

I tried doing some testing runs with an obdii scanner by my side....I drove to a city approx 25 miles from my house...I noticed that on the way over there...I only got the misfiring twice on the scanner...once at immediate start-up (can hear it misfiring by sound) and the other about 1 mile away from my house (slight powerloss at 2000rpms)...both were cleared immediately with the scanner...the remaining 24 miles I got absolutely no codes and powerloss....on the way back was the same result...except this time I only got one code at start-up which was cleared immediately too....no powerloss on the way home....

it seems as tho it won't misfire after the engine has been running for awhile

 

still running on my original o2's....don't need to replace them becuz they run fine...I unplugged them and it throws an SES...replug them back and it turns off....the lack of power TSB has been done to my car...new MAF+reprogram....and my cat is sitting in my garage...i'm running a test pipe right now...so no need to plug anything up

 

I'm still leaning towards injectors. Sounds like a problem with one of them keeping up in open loop operation right at start up. How's the power during WOT? Any misses? Did you ohm out your injectors? Do this right at start up and make sure they are all within .1 of each other. You've replace coils, plugs and compression checks out, so really injectors is all that is left (or a computer malfunction).
Allen

 

There's a voluntary recall for the cam shaft position sensor. My car threw a code two months ago (It's had the knock for 45k miles) and I had the sensor repaced under the recall. Since then, the knock has decreased. You may want to do a search for the recall and take it in under that premisis.

 

AFter beating on my car for a bit (reaching higher revs towards redline) and just working the car hard in general for 25+ minutes, my car begins sounds a bit different, idle a bit rougher. I never equated it to knock or ping but this thread had me wondering. Now that i have motor mounts, i can actually feel the difference too. The condition goes away if i take it easy for awhile, and it doesn't really seem to effect performance... No lights go off whatsoever.

Does this having anything to do with the topic here?

BTW, i have headers and most of the boltons to be had if this is any indication... Yet i've noticed it since i've done headers about a year and half ago.

 

Already got all 3 sensors replaced under recall....besides these sensors will not make your car misfire...it will only make yer car go into limp mode....how do I know? becuz one of the sensors went out on me n my car drove like ****...then got it replaced

 

sounds like a good theory....no misfiring at WOT or during daily...thats granted if I clear the SES with my scanner after start-up....becuz thats when it usually misfires...about 15 seconds after start up....

I did ohm my injectors awhile back...all 6 of them read 0 OHMs....the FSM says it has to be in the 13-17 OHM range...but I dunno why mine came out to be 0 OHms....blackbird said if everything reads 0...then something is shorted and the car won't start at all...but mine starts up very easily

i'm thinkin something electrical too....some pplz threw out the suggestion EGI harness...does anybody else know any further details into this?

 

They can, according to the FSM

 

Nope..I have the FSM right in front of me....

Improper spark plug
Insufficient Compression
Incorrect Fuel Pressure
Injector Circuit is open or shorted
Injectors
Intake Air Leak
Ignition Secondary Circuit is open or shorted
Lack of Fuel
Drive Plate or Flywheel
Heated Oxygen Sensor 1
Incorrect PCV hose connection

 

Read the section on them....

 

I've read the misfiring section throughly many times....doesn't mention a single thing about cam & crank position sensors....besides I already know how it feels to run on a broken camshaft position sensor...it runs like ****...but it DOES NOT misfire....

tomorrow I'm going to do a fuel pressure test...i'll keep ya'll posted

 

When did you replace the plugs and coils? Did you use stock plugs? Did you do this yourself? I wonder if a plug has rattled loose....You need to find a good mechanix.

 

if you have a miss a good scanner shoud tell you which cylinder is missing a narrow it down to coil injector or plug

 

when you replaced your plugs, did you gap them?

 

yup..0.044 inch...it came out of the box at 0.035ish

 

You arent supposed to.....they should be pre-gapped to spec

 

When did your car start misfiring? Was it the second you installed the headers and took it for a ride?

 

nope...mine came at a different gap...apparently vq35 spark plugs don't come pre gapped...my vq30 did though....

it doesn't really matter now...i know i am running the correct gap....

 

yes...but the first time it misfired was becuz it was related to fuel....if you read the link that Nmexmax posted..you will get into the details....but to sum it up for you...my MAJOR misfiring problems have now been solved....it only misfires a little now...i still have alot of power unlike before

 

i found out something new earlier today...i disconnected both primary oxygen sensors and turned the car on...SES for both o2's came up...but the weird thing i noticed is, i didn't get the misfire that i usually get at start-up....i turned the car on & off a few times and still no misfire....drove it around for miles...absolutely no problems.... ....

plugged in bank 2 sensor 1 with the bank 1 sensor 1 still being disconnected....i started to get the misfire at start-up again.....so i was like, cool i'm narrowing it down to something...i disconnected bank 2 sensor 1 and plugged in bank 1 sensor 1....and no misfiring at start-up....drove it around...no misfiring still...so i was like SWEET!

i'm going to conclude bank 2 sensor 1 primary o2 to be the problem...becuz everytime that sensor is plugged in i get the misfiring....but the rear primary doesn't seem to do anything....

Nmex i remember you told me in the other thread that both of primaries aren't connected? the baby blue ones that is....how is your gas mileage?

 

I told you about the oxygen sensors....

 

I know you told me...but my original misfire was related to fuel....if i had followed your advice and bought two new o2's after the cattman header install....i would have been even more pissed and angry cuz I just blew another $200 on something that didn't work...and indeed the o2's would have done NOTHING to my car after the cattman install....becuz my whole misfiring issue is FUEL related...

if you car has a jacked up o2 sensor...it is NOT going to make your car run like azz....my car literally ran like azz...it was so bad that it became a hazard to drive on the street....accelerating to 40mph literally took a good 20 seconds....but you still insisted that it was my o2's....and you also insisted that my secondaries had to be plugged up behind the bpipe and not simulated....again, secondaries have NOTHING to do with anything to the engine....i confirmed it with MANY people and even a couple nissan techs...they even said that if your primaries went out...it still should be driveable...mine was not...

 

Hey Steven,
I got the misfires after having the custom turbo kit installed. I was getting pretty much the same behavior as you - p0300 code right after starting up in the morning and then a possible solid SES light a little bit into driving it. The blinking SES would happen to me when I was cruising it in 6th gear at about 2200 rpms...

last week, we replaced all the 1-step colder iridiums with the factory plats and swapped out 2 coils that were reading below specs... I haven't gotten the blinking SES yet, but I have gotten the p0300 still though. I've only driven the car for a couple of days since last week, cuz i was having the exhaust manifold gaskets replaced to get rid of exhaust leaks.

Today I pulled the codes after driving it to work and even though the SES wasn't lit (1st trip codes) I had gotten p0138 and p0158 - both O2 sensor codes.

What's weird though, is that I replaced one of my front O2 sensors with a Walker O2 sensor and then wired BOTH front O2 sensor harnesses to this one O2 sensor - so the ECU is getting the exact same reading for both the front O2 sensors... so I wouldn't think that I would be having O2 sensor issues... I think tomorrow though, I'll try your test of disconnecting the front O2 sensor harnesses and drive around a bit and see if I get the p0300 code...

I've checked for vacuum leaks on my car... everything is tight. I've had the intake manifold off multiple times, to change plugs, check so see if injectors were leaking (per FSM) etc... Right now, I've got a brand new intake plenum gasket, so it's not that... All my coils are tightened down and lubed with dielectic grease... It's not the headers causing the problems for Steven - I had the cattman headers installed for months before doing the turbo and I never once had a problem...
We checked the EGI harness too... wiggled it around and listened for any change in idle... nothing. Looks like my harness is good too. Tony and I also did a compression test and everythings a-ok. My Apex'i fuel pressure gauge is rock steady at 51 psi also...
I've replaced my MAF with a 2000/2001 one and did the thermistor swap. I don't think there's anything plugging up my RT cat - in fact, I'd imagine that it's pretty blown out by now after running the turbo now... It's definitely not affecting my power (340whp).
My injectors were brand new. SFR installed 48lb Accel bosch type injectors.
Mine sound fine too... I can feel each of them ticking away... I noticed that I would get the 1st trip code after starting up in the morning too... and you're right, after running it for a while, I wouldn't get an immediate p0300 like in the morning - not to say i didn't get one later on, just not immediately.
any instructions on how to ohm them out?
I had the dealership check service comm on my car and there are no active campaigns... So all TSB's were done ( I hope )
P0300 is a "Multiple/Random Misfire" - which means it doesn't indicate a specific cylinder with a problem.
I replaced my original plugs with 1-step colder NGK iridiums gapped to .036. I just put back OEM plats - gapped to .034 or so... no difference. I'm thinking of putting the iridiums back in and gapping them down to .025 or so...
I'll try the same thing with my car and let you all know what happens... hopefully I'll have some good news too...

 

UPDATE:

Disconnected the front O2 sensors today.... Codes 031 and 051 - but no 0300! No misfires....

Tony and I believe that when the O2 sensors are connected, the ECU is overcompensating and making the mixture too lean. We tested this by disconnecting the O2's while the car was running... My AEM WBO2 went to about 12.8 AFR - then, when we re-connected the O2's, after about 1 minute (maybe the time it takes for the O2's to heat up?) the WB started to fluctuate from about 14 to 16 AFR and the car would start missing.... Unplug the O2's and the AFR went back down to about 12.8 and no misfires. (When you disconnect the O2's, the car defaults to a super rich setting)

On Steven's car, it could simply be a case of the extra flow that the headers are allowing, causing the car to run leaner... I never ran into this problem though... and shortly after installing my headers, I had TS flash the ECU (one of the things they do is make the mixture a little richer).

Now the question is, how to rectify this problem... I'm wondering whether or not TS can flash my ECU into having a richer mixture, or maybe O2 simulators (although I hate to go that route)

Whatever I do, I need this to work with my e-Manage too... maybe the Autotune add-on for the e-Manage....

Comments? Ideas?

PS - Good find Steven!

 

haha so you got a funky acting sensor too Roy? pretty hilarious....i would have thought your car would be misfiring becuz of the custom TC kit....i mean after all...it is throwing in alot more air than stock

good theory u got there....but don't we run super rich with headers? n/a vq35 that is....IIRC, when a vq35 ecu finds out the motor is running too lean (i.e. exhaust,intake) it will do it's best to protect the motor by throwing in alot of fuel for safety...true or false?

Roy are you planning to buy a new o2 from Frank?

 

just came back from a couple of spirited runs through the canyons....had alot of fun...the whole time my front (bank2) oxygen sensor was disconnected....on my way over there my gas mileage pretty damn good...i only lost quarter of a tank in about 75 miles....remember this is with spirited driving involved....if i had driven 75 miles of pure highway cruising at 65-70....i'm sure i would have broke into 100 per quarter of tank....

i'm going to run without the oxygen sensor from now on...see how my gas mileage is then go from there....

 

Adding the headers will make your car run leaner:
http://forums.maxima.org/showthread....t=headers+lean
http://forums.maxima.org/showthread....t=headers+lean
http://forums.maxima.org/showthread....t=headers+lean
http://forums.maxima.org/showthread....t=headers+lean
http://forums.maxima.org/showthread....41#post2810341

I don't plan on getting new O2's... I already installed a brand new one (see earlier post)

 

Roy are you planning to simulate your primary o2's? I heard simulating the primaries would be the same as having the car with disconnected o2's....except no SES light...

Still getting good gas mileage from running no front o2 sensor....picked up my scanner tonight to pull codes...only got two codes, both of them 0051....no misfiring codes stored in the ECU