Rapid Backfire/misfire

[90 DGRZ]

I'll try to keep it short.

blacktop SR, exhaust, FMIC, hks t28, 10-11 psi.

I had a cage welded in my car (battery disconnected) about close to a month ago. A month BEFORE that, i didn't really drive the car at all since it's last event. when i got my car back from being caged, i took it around the block the day before an event, and it rapid backfire/misfires around 4.5-5k and loses power and stumbles. (sounds like back to back rapid gunfire) as long as i hold it WOT, it will do that, and eventually slowly make it way up the tach. Sometimes, like in second gear, it really won't stumble or backfire, it will just climb up the rpm range powerfully, then around 5k the power will seem to "flatten" out and will eventually pull to redline. but most of the time, it's the back fire issue. This only happens under load, the car revs fine in neutral.

The reason why i mention the car being caged, is because i really don't know if it's coincidental that it happened after being welded and it may be an electrical issue, or if it's completely a separate issue and it just happened to occur while being caged.

i am just now posting, because i've run out of ideas.
here's a list of what i've done or replaced, in order.

New spark plugs, gapped to about .28.
Coilpacks and grounds
Re-timed to double check timing
Igniter chip
ECU
Fuel Pump-Walbro 255
FPR
Injectors/injector seals
coolant temp sensor

the next thing i'm gonna do it pull the engine harness and go through it. i'm running out of ideas and am really hoping someone can help me. i'm becoming desperate.

thanks!

[DUFFM4N]

damn chuck, you always got the shittiest luck with your car :(

i love you

[s15specR]

I just posted in response to the same sort of thing, I've read about 20 of these threads because I'm having the same problem, the one similarity is that they all just changed plugs....

[90 DGRZ]

i know eddie...fml. when my car runs bad, it runs really bad.
i love you too. and freakin miss you. ass.


s15specr, yea the last time i kinda had a similar issue, it was a spark plug fouling out...but this time it wasn't. :(

[YoungGun]

Shit is weird fah real my dawgs.

[chibo]

Check your MAF and for leaks after the MAF.

[bardabe]

chuck i hope whoever welded your cage knew wtf they where doing, because you are supposed to disconect the battery ground, and put the ecu in a bag to keep it from touching any metal while they are welding if not. Bye Bye ECU

Other Than that check your Fuel Pressure make sure you have constant pressure and it's not droping all the way to redline. who Tuned your car?

[zenkicookies]

i agree with chibo,check the MAF. id also check the couplers just in case.

[90 DGRZ]

chuck i hope whoever welded your cage knew wtf they where doing, because you are supposed to disconect the battery ground, and put the ecu in a bag to keep it from touching any metal while they are welding if not. Bye Bye ECU

Other Than that check your Fuel Pressure make sure you have constant pressure and it's not droping all the way to redline. who Tuned your car?

the sr is basically stock, no tune here.
they knew what they were doing, he's welded many cages into FD cars and has alot of experience in fabrication, etc.
Even if it was the ECU, i already have another one in there that came out of a running car.


i'll try out a different maf tmw, but it doesnt seem likely that it's the maf...when i unplug the maf it does it's thing where it'll bounce around 3-4k and not budge. but i have nothing to lose, i'll try it.

[93sr20240]

I would say a coil pack but since you tried that......... I say dunno

[GSXRJJordan]

Other Than that check your Fuel Pressure make sure you have constant pressure and it's not droping all the way to redline. who Tuned your car?

I guessed fuel pressure first too, but he's replaced the fuel pump and the FPR with known-working ones. I told him to inspect the harness too for burns in the electrical tape/sleeve/etc...

I would say a coil pack but since you tried that......... I say dunno

I said that second - Chuck did you try wrapping the coilpacks with electrical tape too?

Also, MAF ground? Coilpack ground? I made a little grounding strap to ground all the coilpacks to the intake mani on my SR years ago, helped with some hesitation I used to have...

[Blackparade]

did you check for any boost leaks?
making a boost leak tester is easy and effective. try it out.

[nieko]

cas?

and ground your coilpacks bro... it cant hurt

[GSXRJJordan]

cas?

and ground your coilpacks bro... it cant hurt

CAS isn't going to give a bad signal, unless it's improperly wired/grounded... it's a very simple device. That being said, if you have a chance to replace it with a known-working one, try it!

And yeah, grounding those coilpacks can't be bad. Doubt that's the problem though.

[nieko]

i think we need to stop thinking of the obvious right now....

just start changing EVERYTHING.

lololol

you havent changed CAS

so try it.

dont think youve tried changing mafs so try it.

just try EVERYTHING llolo

[charlie321]

Check the ground behind the head. And I second the CAS.

[bardabe]

CAS does make sence, try it why didn't I think of that. haha

[let5l1de]

just bring it to me chuck...

~m

[4x4le]

you can try to clean your cas with some sensor safe cleaner. If that dont work and a known good one does work but you have to give that back to your friend or something but it fixed the problem I can sell you a brand new cas with new cap and gaskets for cheap.

Good luck, its the small problems that give us the most grief.

[90 DGRZ]

did you check for any boost leaks?
making a boost leak tester is easy and effective. try it out.

the boost gauge doesnt show that it's leaking...and even if it was leaking a couple pounds, im sure my car wouldnt be running like to this extent.

I guessed fuel pressure first too, but he's replaced the fuel pump and the FPR with known-working ones. I told him to inspect the harness too for burns in the electrical tape/sleeve/etc...



I said that second - Chuck did you try wrapping the coilpacks with electrical tape too?



Also, MAF ground? Coilpack ground? I made a little grounding strap to ground all the coilpacks to the intake mani on my SR years ago, helped with some hesitation I used to have...

yea jeff thanks for all ur help, i wrapped those bitches good.
i'm gonna pull my harness as soon as i get a day off. and put new grounds to the coilpacks. i was gonna swap mafs with my roommate, but the plug on the maf side was wider on his than mine, so i couldn't test it today. i'm gonna get some sensor safe cleaner and clean mine...it actually looked dirty.

a couple peopl told me it could be my alternator??????

just a quick note: my idle voltage is roughly 13.5 ........ when i'm flooring it andd it starts backfiring/misfiring around 5k, the voltage drops to about 12.7.
normal, or should there not be a drop in voltage?


cas?


i'm gonna go grab one off of cody's old motor.<3

just bring it to me chuck...

~m

i will.

[GSXRJJordan]

Normal for there to be a voltage drop at full load, as long as it stays above 12.5V or so comes back up you're fine. I've run my car full out with a bad alternator and it didn't start bogging until 11.8V, and didn't actually turn off until 11.3V, FYI.

Clean the MAF, swap CAS, re-time, and hope for the best? Otherwise I'd be happy to inspect the harness for ya.

[BrokenWhite240]

Sounds like a MAF to me had alsomt the vary same problem with a swap I did. Reved in neutral fine and sounded awsome. As soon as I took it out and got up to about 5k I believe it broke up, stumbled, lost power, backfired..etc. Put a MAF in it and it fixed it..hope this helps.

[90 DGRZ]

finally my day off today. borrowed some maf cleaner and cleaned the bitch andddd...put a CAS from a known-working car. TDC, lobes out, timed it at 15 degs on second hash mark, whole nine, and still basically the same thing.

PLEASE anybody...help..im super desperate. i've really tried everything.

Do you guys think this happened during welding in the cage, or do you guys think it's pure coincidence? any other ideas??

[steve shadows]

If you are able to drive your car down to my shop on Saturday AM I will give it a look, just bring 80 bucks with you for the diagnosis fee I charge.
I will give you about an hour of my time and will pull out all the stops and give you my honest opinion. 99% of the time I nail the diagnosis.
I will check ECU, your ignition system with IR gun and with consult and with Voltage meter etc. I will also check your injectors and other parts as well
If you are REALLY DESPERATE I suggest you let me give it a shot rather than spending more money on replacing parts, let me give you my honest opinion.
I have a dyno apt at 12 PM but I can squeeze you in at 1045-11 ish if you want to come to the shop, we are located Canyon Racer Motorsports Home Page (http://www.canyonracermotorsports.com)

Either way

It sounds like

- Ignition System Failure
- Fuel System Failure
- Possible major vacuum issue.

If it is a vacuum issue I can assure you 100% we will find it. I have a special smoke machine type of vacuum tester which NEVER FAILS, in fact we find leaks that people never knew could even exist and get cars running in amazing shape just by checking the vacuum system

If it is your wiring harness then your whole harness is trash and you need to buy an entire new harness and also check all of your grounds and check for charring or any other wear.

I would let me give it a shot first though lmk if you are interested if not I understand.

-PM me for details

[90 DGRZ]

Thanks Steve for your input, and i'll be contacting you when i have time to take my car all the way down there, it's quite a drive for me since it's not registered and stuff. between work and moving out the end of this month, i wont have time for a couple weeks.

any other inputs?? :(

[steve shadows]

well if you I will drive up to where you are and check it out personally

[YoungGun]

This shit sounds like

BAD DAT DAT DAT DAT DAAAT DAT.

[steve shadows]

This shit sounds like

BAD DAT DAT DAT DAT DAAAT DAT.

thanks for the technical explanation my friend...:barfkiss::keke::redxd:

[PacificDrift_Nick]

this guy is a bad person and the Nissan gods are punishing him

[steve shadows]

well let him know I can come up and look at this thing in person on Sunday afternoon if he is fed up and wants a solid opinion on this thing

[consouler]

This shit sounds like

BAD DAT DAT DAT DAT DAAAT DAT.

lolololol yea it does

[0wn3r]

i had the exact same problem down to the T. go get a bottle of MAF cleaner and spray the sensor and the inside down real well

problem solved

[90 DGRZ]

i had the exact same problem down to the T. go get a bottle of MAF cleaner and spray the sensor and the inside down real well

problem solved


i did that already...

fail at reading...lol

thanks guys, any more?

[BrokenWhite240]

Did you try replacing the maf like I described earlier with one that is known to work perfectly. Most times when a maf is bad maf cleaner doesnt do shit.

[GSXRJJordan]

i did that already...

fail at reading...lol

thanks guys, any more?

Wiring Chuck, wiring.

Swap upper harnesses with someone.

[0wn3r]

well wtf did you clean it with? did you actually take off and spray the sensors? i'm telling you, I had the SAME EXACT PROBLEM.

[steve shadows]

apparently he is not desperate enough yet. haha

the funny thing is 7 out of ten times I fix this type of issue within like 10 minutes of showing up its alwasy something super simple/stupdi

[let5l1de]

apparently he is not desperate enough yet. haha

the funny thing is 7 out of ten times I fix this type of issue within like 10 minutes of showing up its alwasy something super simple/stupdi

true enough.

But I am wishing its a broken or collapsed valve spring(s). If it is floating valves, I can build chucks engine and get him the extra power hes always wanted. Not quite M. Essa power but enough for now.

Might as well build the rest of Team Mulsannes engines since everyone is having problems.

Barrow my hoist and bring me your engine... and Codys and Teddys.

1 1/2 weeks left chuck.

~m

[steve shadows]

lol nice.

As long as you send him to me for mechanical / boots controller tune up on my dyno you can handle the rest of his mess.

;)

[90 DGRZ]

Wiring Chuck, wiring.

Swap upper harnesses with someone.

i swapped coilpack harnesses with my roommate, but nothing. me and gary pulled the entire motor harness earlier today before work to go through it just in case, to rule that out. tmw's another day, we'll see how it goes.

well wtf did you clean it with? did you actually take off and spray the sensors? i'm telling you, I had the SAME EXACT PROBLEM.

it may be the same symptoms, but it might not be the same problem. i cleaned it with electrical sensor/maf cleaner spray. did you think i just dusted off the top of the maf or something? yes, i actually took it off and sprayed the actual sensors.

apparently he is not desperate enough yet. haha

the funny thing is 7 out of ten times I fix this type of issue within like 10 minutes of showing up its alwasy something super simple/stupdi

i'm pretty desperate, but at the same time my wallet is desperate for money too, lol. 7 out of 10 are good odds, but i might just be 3 out of the 10 that really has ridiculous issues. as u can tell i've ruled out many possibilities.

thank goodness cody has a spare motor i'm bumming parts off. thanks cody!


true enough.

But I am wishing its a broken or collapsed valve spring(s). If it is floating valves, I can build chucks engine and get him the extra power hes always wanted. Not quite M. Essa power but enough for now.

Might as well build the rest of Team Mulsannes engines since everyone is having problems.

Barrow my hoist and bring me your engine... and Codys and Teddys.

1 1/2 weeks left chuck.

~m

Mario, i'm moving back to the 626 after the 30th of this month, so if it still isn't up to par by then, i'll swing it on by ur pad. i'll be literally right down the street from you.

[let5l1de]

Mario, i'm moving back to the 626 after the 30th of this month, so if it still isn't up to par by then, i'll swing it on by ur pad. i'll be literally right down the street from you.

Sounds good chuck. I'm looking for a shop in our area to make this legit. Not that I can't build engines in my garage, but the mess... So I'm serious about building for the team. Send me the old sr's

lol nice.

As long as you send him to me for mechanical / boots controller tune up on my dyno you can handle the rest of his mess.

;)

Sounds good to me. I might just swing by one day and check out your shop. Actually, I might be in the area tomorrow around 2 or 3.

~m

[0wn3r]

no, just alot of idiots seem to want to use brake cleaner on their MAF.

my guess is it's somewhere from your battery to your MAF.

[DALAZ_68]

have you check the TPS ... MehSilvia is having horrible bog issues, similar to urs...he already figured out it was TPS he checked voltage and it was horribly wrong...change he TPS...

im pretty sure that can be it...

since it affects air/fuel mixture...

him being N/A and u boosted could result in diff results

[90 DGRZ]

yehhh. replaced tps and reset it. :(

[steve shadows]

Still sounds like the right person hasnt really diagnosed it honestly man, no offense.

It can only be so many things. The car is a mechanical object. 1+1 = 2 everytime.

If you can get the car down to LB ill only charge 40 bones and ill give it a check and give you my honest opinion.

eitherway I would check compression AGAIN and AGAIN and AGAIN

Also if you wiring harness has ANYTHING WRONG AT ALL that you can see, like shotty wiring or grounding shroud or crap or any butt connectors I would throw it i the trash and get a new harness in better shape or better yet just get a brand new wiring harness and start over. This was the best thing I ever did on my last S13, I just ponied up and almost all of the intermittent electrical bugs were totally gone forever, car ran a lot better

[bardabe]

just kinda thought about this, whats your battery voltage under load?

[GSXRJJordan]

...If you can get the car down to LB ill only charge 40 bones and ill give it a check and give you my honest opinion.

Best $40 you could possibly spend. Remember when I had you drive all the way out to my place to look at my S13 back in the day? Lolz.

Problem is, he won't be able to easily get the car down to Long Beach.

just kinda thought about this, whats your battery voltage under load?

High 12's I think he said, unless I'm thinking about someone else I was helping. Coulda been Nick I was talking about batt voltages with.

[yokotas13]

Maff
turbo blown
leak

ive had the symptoms that you had with all three.
or coilpacks, but youve checked that.

[dros]

I had the same issue...I cleaned the MAF and did nothing,changed the MAF and the problem was solved!I hate it when such things happens!Good luck!

[DALAZ_68]

just kinda thought about this, whats your battery voltage under load?


High 12's I think he said, unless I'm thinking about someone else I was helping. Coulda been Nick I was talking about batt voltages with.



just a quick note: my idle voltage is roughly 13.5 ........ when i'm flooring it andd it starts backfiring/misfiring around 5k, the voltage drops to about 12.7.
normal, or should there not be a drop in voltage?


is tha the info u guys were lookin for?


hows the idle?