boost issue backfire

[jonsparrow]

ok so iv searched all over the interwebs and found many people with a similar problem and they all had different solutions. only i have one different symptom which is why im going to post, so maybe some one will know whats wrong so i dont have to test 10 different things in the freezing cold.

the problem is:

when accelerating and just when the boost hits the stock wastegate setting it starts back firing and boost goes nuts. but not your normal back fire. sounds like a bee-r launch control. i can even feel the back fires through the floor board.

if i am boosting at 14.5psi when it hits around the 7-10psi mark (stock wastegate/turbo) it will start bogging for a second or two maybe longer then BAM it passes an boosts hard up too 14.5psi. if i run it at stock boost it just boggs when reaching full boost.

most people that have this issue say its bogging when it hits 0psi. that why i decided to ask, as mine is at the 7-10psi mark. could it be the wastegate is sticking? i think boost leak is ruled out because on high boost it will clear up and boost after bogging a bit.

its not the settings on the boost controller. i thought it was so i adjusted the gain and boost, an it seemed ok for like 5 min. then back to bogging. plus it does it at stock boost.

sr20det redtop
fmic
greddy bov
greddy electronic boost controller
apex'i SAFC (reset to stock to make sure that wasnt an issue)
recently changed plugs and fuel filter (so thats not an issue)
etc

edit: also RPM has nothing to do with it.

[ultimateirving]

ur rubber charge pipe is collapsing under extreme vacuum once the boost started to build its sucking the charge pipe closed.. See if that helps. =)
also is this on a t25? shouldnt really be running 14psi on that little turbo its not really efficient past 12-13 psi.. so ur blowing hot air into that motor.

If the waste gate was sticking then you would not be able to keep the boost below 14 psi it would always try to max out because there would be nowhere to vent

[jonsparrow]

upon initial inspection of the charge pipe, i dont think thats the problem. that thing is solid like a rock. a rubber rock. i dont see that collapsing. i will take it off later to inspect it closer to see if there are any cracks or anything. any other ideas?

[SamuelMSmith]

I have been having a similar issue with my gt28, but its only when I'm wide open throttle and at full boost. I get to about 45 50mph in 2nd and it starts halting itself like the engine is cutting off. I took out my sparkplugs to check them and the gaps were fine but they were black as hell. I cleaned them up and my car was fine for the first few pulls. I have heard it might be coils. I have a few more things to check but if I fix it I will let you know, and if you find anything that works please let me know?

Are you running rich by the way?

S14
SR20 Black top
Godspeed intercooler.
custom downpipe.
Blitz VD Bov

[ultimateirving]

thats good jon, some people dont have the big spring inside and it becomes extra floppy. Also check ur gap, for that setup you want bkr7 plugs around .025 gap to keep from blowout

[jonsparrow]

right now im gapped at .028. would that matter? its such a small difference. what exactly IS blowout?

@SamuelMSmith i will let you know when i figure it out.

[mhubble91]

Blowout is what occurs when the plug gap is too big for the application. High cylinder pressure can literally "blow-out" the spark, like a candle. Sounds totally far fetched but completely true ;)

[boost addict]

sounds kinda like what i had, what plugs are you running?

[ch1873857]

check plug gap and timing.

[jonsparrow]

im running NGK - BKR6E-11 at .028

[boost addict]

Try running a colder plug like the bkr7e's

[steve shadows]

If your plugs are really gapped at .028 then I would look at your fuel pump possibly dying or fuel system being clogged or lack of fuel, I would definitely turn down the boost to stock for now until you figure out exactly what's causing it.

There are a few things that cause this symptom though:

Loose or unbolted ground wires for the ignition coil packs (on back of head)
Injectors maxed out completely or dying fuel pump (less likely)
Boost leak or some sort of leak that is coming on under higher VE/Pressure
Loose connection, or shotty connection on Maf wiring or loose MAF
Loose connection or shotty wire connection on CAS plug/on the CAS itself
Loose connection or shotty wire connection on Injector output on main ECU plug on ECU
Corrosion on important connections on ECU plug @ ECU or elseware in the harness

First thing I do on any SR that comes in with shotty or harness pulled straight off front clip is suggest a brand new harness for the motor from Nissan or a used one in much better shape. Shotty harnesses cause the majority of the hicupps on our cars especially if the harness has been on the car for a while or never really inspected through and through...

Check'em out! too!

[jonsparrow]

thanks, i will check these things out and post my findings.

[SamuelMSmith]

If your plugs are really gapped at .028 then I would look at your fuel pump possibly dying or fuel system being clogged or lack of fuel, I would definitely turn down the boost to stock for now until you figure out exactly what's causing it.

There are a few things that cause this symptom though:

Loose or unbolted ground wires for the ignition coil packs (on back of head)
Injectors maxed out completely or dying fuel pump (less likely)
Boost leak or some sort of leak that is coming on under higher VE/Pressure
Loose connection, or shotty connection on Maf wiring or loose MAF
Loose connection or shotty wire connection on CAS plug/on the CAS itself
Loose connection or shotty wire connection on Injector output on main ECU plug on ECU
Corrosion on important connections on ECU plug @ ECU or elseware in the harness

First thing I do on any SR that comes in with shotty or harness pulled straight off front clip is suggest a brand new harness for the motor from Nissan or a used one in much better shape. Shotty harnesses cause the majority of the hicupps on our cars especially if the harness has been on the car for a while or never really inspected through and through...

Check'em out! too!

I have Greddy NGK iridium 8s, would that make a differiance?
that and im running really rich. you can see it from my spark plugs(Black as hell) would that help narrow it down? I think i have a leaky injector.

[jonsparrow]

ok so i found something.

on the back of the head driver side there is a ground with with a very small plug on it. the plug is kind broke and not plugged into anything. where is this ground supposed to go? its a pretty short cable so it cant go far. im guessing it was always broke and it finally slipped off of what it was connected too. its one of those flat braided ground wires if that helps.

thanks

[jonsparrow]

any one? i know there are a few people here with sr20's. (sarcasm)

[boost addict]

yea i took that off my sr, dunno if your suppose to or not but its for a ka. i havent had a problem without it

[jonsparrow]

hmm... back to the drawing board.

[jonsparrow]

:cry:
well i pretty much checked every thing minus using a multimeter. plugs are tan, maf is clean, there are no grounds on the back of my head except that one thats not plugged into anything. the harness for the coil plugs does have a ground going to the intake manifold. the ecu has no codes.

also it seems to have changed. now instead of the backfires it did its just a steady bbbuuurrrrr type noise when its bogging. im going to do a boost leak test and if thats all good, i might just order a new harness. if the problem is still there ill get a new fuel pump. if the problem is still there im going to cry.

i have a new head and a bunch of other parts waiting to go on, but i dont want to do that till i figure out whats wrong with it now.

its weird cause if feels totally fine untill boost climbs then every thing goes to hell. uhg... any friendly folk in central jersey wanna help a guy out?.

i think im gonna go ahead an order a harness anyway. who ever did this swap did a extremely terrible job on it.

[boost addict]

Don't order anything you don't have to unless you know forsure. Did you try a different plug?

[jonsparrow]

no i didnt try different plugs, mainly cause the threads are really messed up, an thats why i have a new head waiting to swap. so i didnt want to ruin the threads on new $40 plugs only to have to buy them again. maybe its a sacrifice i have to make. i dont see why that would be the issue if i have new plugs in, but range 6 instead of 7, but i didnt have the problem before, so why would it just show up out of no where?

[jonsparrow]

you know what... i think i have a clogged cat.
im gonna order a test pipe.

[boost addict]

This same thing happened man, don't even get the irdiums this time then. Itll only be like 25 then or something. I bought my car and it didn't do it, then all of the sudden it started. Changed to different plugs and it stopped

[jonsparrow]

ok ill give it a shot. thanks.

[jonsparrow]

little update, had to order plugs online cause no parts stores around here carry them for some reason. i checked the cat...its gutted, so thats not the issue. plugs should arrive thursday. while under the car i noticed two grounds above the exhaust that were not connected to anything.

[jonsparrow]

well i changed the plugs...still the same problem....

:bash::bash::bash::bash::bash::bash::bash::bash::b ash::bash::bash::bash::bash::bash:

[ultimateirving]

man sorry to see your still struggling with this, if i was in jersey id come over and take a ride!

as far as that wire on the back of your head, i have a small cable coming off my back of my head thats grounded to the chassis.
the description still sounds like boost is escaping somewhere, but if you pressure tested your pipes and no leaks not sure what else to say. I know i had a chitty BOV that was leaking wreaking havoc under boost.

[SamuelMSmith]

hey man my buddy has an 01 prelude and he had a the same problem as you and I sorta. He bought a new 02 sensor and he is fine now. I bought one but not put it in yet. I figured its worth a shot. Ill let you know my results.

[jonsparrow]

yes please let me know.

[jonsparrow]

maybe this can help.
also i noticed i felt one of the backfires in the throttle pedal. the throttle cable bracket is a little loose though so ya...
41TuFxDPU2k

[KaminaSan]

That doesn't seem like fuel cut, or lack of fuel, but more like ignition to be honest. If it was fuel, your entire care would jerk back and forth... happened to me before.

I would say start at the basics. Rip out that SAFC piece of junk, and start from there. I had the same issue on my car once, and it was a bad coilpack. It struggled getting into any boost for me though.

Like I said, rip out the SAFC, try different coilpacks, get a fuel pressure gauge and let us know.

[jonsparrow]

just throwing the video on page 2. only have 1 friend with an sr an he is dropping his car of at a shop in NY tomorrow. just my luck. im gonna do a closer inspection of every thing tomorrow, if all else fails, i guess ill just order a coil an start swapping them to see which one is wrong. maybe ill just order 3, i already had to replace one not too long ago.


41TuFxDPU2k

[unknownkris_s14]

Damn I feel for you man. When there's a problem and there doesn't seem to be a solution. Goodluck

[jonsparrow]

iv read some where then when the top of your coils get a little orange that its time to change them. if thats true i think i know the culprit. can any one confirm this? can you guess which one is new?
do you think i should replace the other 2 as well or just the really orange one?

edit: i ordered 1 coil. hopefully i can get away with that. ill replace the others later after i confirmed the issue.

http://i27.photobucket.com/albums/c192/jonsparrow/coil.jpg
http://i27.photobucket.com/albums/c192/jonsparrow/coil2.jpg

[SmokeCircle]

Does it smell of fuel at all when your misfiring? or after driving while misfiring? check around the injector for any residue forming. I had an issue similar to this and it was my injector leaking through the top of the injector. I couldn't even tell until after a few weeks of messing around, when the residual fuel started to hold dirt and dust that i could see.

[jonsparrow]

no there is no smell of fuel an the injectors are clean around them.

[S13-RB25]

Mines doing the same exact thing except its a rb25 in a 92 coupe. Ive tried coils, crank angle sensor, fuel pump, plugs, tps, checked boost leaks, replaced the mafs, checked the knock sensors, replaced the fuel filter, fuel strainer, regrounded the ecu, grounded all the coils. Pretty much everything with no luck. Used to run awesome at 13 lbs. Then it started this mess after i put iridium plugs in it. Which i swaped back out. I think that was just a coincidence. I'm at a loss as to what the problem is because i feel ive done just about everything i could think of. So I'm not sure what to tell you on yours. :-/

[SamuelMSmith]

See mine is much different. Mine almost seems to cut off when i hit full boost wide open. Ill try to post a video after work, and possably change out my O2 sensor and try again. Are you running rich?

-also something to try is disconnect your battery for 5 or so min and then drive and see if it does the same thing. If it does stop, it will come back. but that seems like it would point to your O2.



sorry didn't see the second page.

[jonsparrow]

Mines doing the same exact thing except its a rb25 in a 92 coupe. Ive tried coils, crank angle sensor, fuel pump, plugs, tps, checked boost leaks, replaced the mafs, checked the knock sensors, replaced the fuel filter, fuel strainer, regrounded the ecu, grounded all the coils. Pretty much everything with no luck. Used to run awesome at 13 lbs. Then it started this mess after i put iridium plugs in it. Which i swaped back out. I think that was just a coincidence. I'm at a loss as to what the problem is because i feel ive done just about everything i could think of. So I'm not sure what to tell you on yours. :-/

that dosnt make me feel good lol.
also i order all the coils. hopefully they will arrive this week. an i pray thats the problem.

at samuel. i will try that tomorrow thanks.

[JDMRIDDAZ]

u need to check coils with a multimeter...if there above 1k resistance there bad
also u need to check voltage to the coils..running
also the ecu
constant and
switched power...
mine did a hiccup at wot..and full boost
but it the injectors bein pushed 100%...
13-14psi is best..and if its a manual boost controller its not fully accurate
i swapped ecu from stock to mines stage 3...and its the same...injectors
this happened w 4 t25 i had and a gtir t28 with s15 front housing...

[jonsparrow]

i have returned with good news.
installed splitfire ignition system.
problem solved.
praised the lord.
:2f2f:

[ultimateirving]

woot woot! awesome man! so glad to hear you got it fixed. hows the car pull now?

[jonsparrow]

thanks! it never ran so nice. as soon as boost kicks in, tires are spinning. an it just pulls an pulls like there is no limit. except there is a limit with the factory ecu lol.
so happy this problem is fixed. i got so many parts sitting here waiting to be installed.