hjdanzi

Hello guys... Im a tuner, not the owner of this car. It is a d16z6 boosted civic which came blown, and i did everything from scratch since january to fix it.

Now after sorting a lot, well... MILLONS of issues... the car finally behaves excelent for daily driving.. I mean... it runs really great!!! BUT... as soon as i wot it i feel a terrible misfire that wont let me rev more. It ALWAYS HAPPENS in 3rd, 4th and 5th gear and always after 4000 rpms. If i wot it in neutral or first or second it doesnt do it.

When it does it, you feel like a fuel cut/boost cut etc. Although there arent any cuts set there.

I know the problem is not in the tuning since im a neptune dealer, and im the one tuning it. Ive tuned plenty of d16 with turbos and never had this problems... Well... if i had it was just a common issue, like spark plugs, or wires etc. The thing is i have a lot of experience in it, so im not guessing with that...

I need this solved asap, and im very frustrated...

First the first...

The car:
Boosted 93 d16z6 18psi.
8.8 C:R.
Forged pistons, eagle rods etc. etc.
Rc 550 cc inyectors, walbro ... etc.
Tial 38mm WG
Hks ssqv BOV

What did ive check?
Ive already checked:

Compression and leak down test: ITS ALL GOOD and even across the board.
Lowering boost from 18 to 10 psi: Same Problem.
Wires, all hooked up nicely.

Ive already changed:

Sparkplugs. Ive tried ngk stock but heat range 7, iridium range 7, and also range 6 and 5 just for the heck of it.
Tried the following gaps: .025 .028 .030.. i ve also tried .022...

Its all the same.

New sparkplug wires.

New distributor, but not “tec” some chinesse I bought from ebay. Although I tried a friend original TEC distributor… the problem is the same.

Inyectors are firing good, they are brand new rc 550cc.. they all work fine. Ive already rewired all of them, tested them, and replaced the inyectors clips. Resistance is good.

Replaced the intake manifold gasket and the throttle body gasket.

NO VACUUM LEAKS.

Timing is synched at 16 (red mark) and synched with Neptune. The ignition timing is conservative… and fuel is conservative too.

I tuned to be at 11.3 at wot... tried also leaner and richer mixtures just in case. Im positive its not detonation.

I removed the NEW distributor and measured the resistance of each sensor and the ignition coil… they are all in spec…

No vacuum leaks, no exhaust leaks... the car behaves very well and this issue wont let me finish my work... Ive already lost money and a lot of time... IVE TRIED EVERYTHING.

Just for the hell of it, ive ordered a new distributor from xenocron, new sparkplug wires and new ngk range 7 plugs. (Ive already tried it... but oh well).

So please help me out what do you think? Ive tried everything, and im open to any ideas.

Thanks!

SovXietday

Have you tried swapping ECUs?

hjdanzi

First of, thanks for replying.

Actually i didnt. It didnt seem logic, but now that you mention it, ill guess ill try it. If it works, i wouldnt understand how is that possible but after trying almost all, seems reasonable.

Thanks for the input.

SovXietday

Haha, trust me I know all about chasing these kinds of problems. I really am just throwing out an educated guess at this point. I've seen ECUs do some weird ****, see below.

My first thoughts were the same as yours. Plugs too wide, coil/ignitor going bad, etcetcetc. You've covered everything ignition, and it's probably an ignition problem if you're getting the "fuel cut" feeling. Lean breakup is the only other thing that could be happening, but if you're getting a good readout on the wideband I'd say that's probably out. The only thing that could be possible would be that one of the injectors is messed up and you're getting a lean fire in one cylinder. How do the plugs look?

This car should have no issues at the boost levels, even if the injectors might be on the edge at 18psi (assuming you're running no smaller than a standard 50trim that is).

My daily driver drove fine for 6 months after I bought it aside from some random misfires and hiccups. I went to inspect it, couldn't get the OBD2 port to read. Found out that half of the ECU had been completely destroyed by water damage, and yet the car still ran fairly well. Amazing how well the car ran after dropping in a good ECU, considering I really had no complaints beforehand. Just a small bit of damage to the ECU and it could easily f up timing output. We all know how these ECUs jump from car to car to car and even the ones we get from Hondata are not new. Never know.

Accord Fanatic

Make sure that your fuel rail pressure is high and that you don't have volume problems when pulling a load at high rpms. pump, filter, etc.



brett pindell

DelSolMarine

hows the fuel pump wired?

hjdanzi

hahah i hear you!... Look, ill try swapping with another ecu... if that works... ill fly up there and do homo things with you just for happiness lol... nah, really... Ill try it, if that works ill make sure to paypal you some money so you can have some beers or something. I am dealing with this for about 1 month, day and night!.. its like you tried everything!!! and im so close to finish!!!! Ill give the ecu a chance... i will even change the ems if that helps. Thanks a lot man, ill keep you updated as soon as i have time to test it. THANKS!

Thanks for your reply bro. Do you know the thread size of the hole on top of the banjo bolt so i can do a custom fitting for my fuel pressure gauge? How would i know if i have problems at load etc? Is there any way to test it? All that i know is that my wideband is consistent at all rpms... It doesnt throw my tuning off. Thanks a lot for you help!

When i received the car, it was a mess since it had an electromotice unit wired up... Now i wired it the stock way... ITs 100% stock now, you know... from fuel pump to main relay, from main relay to ecu. from second circuit of main relay to inyectors etc. It primes good, and my a/f are quite good in all conditions... even when i get the misfire.. which obviously leans out the mixture, cause all the unburnt oxygen goes through the o2.


General Question to all of you: Do you think that i can get good wideband readings... like, as rich as 9's and still have low fuel pressure? Maybe im wrong.. but somehow ive always thought that if there was a problem with the pressure, the inyectors wouldnt be able to deliver so much fuel (like 10's or 11's) with low pressure? Am i wrong here?

To put it in another way.... LOW PRESSURE EQUALS TO LEAN MIXTURES?.. cause i dont have lean readings... it idles fine at 14.7.. i cruise at 13.8, moderate load at 13 and when the psi starts.. it goes from 12.5 to 11.3/1.

zfr7 sparkplugs gapped to .028 is about right? what plugs are you using?

Thanks for all your help... you pointed out some great ideas so far! Ill keep you guys updated!

0xenocron

Make sure the banjo fitting on the fuel rail and the fuel rail itself are compatible. I have seen people put a banjo fitting on a rail that needed a different end cap and this would cause your issue. If not compatible, just drill a hole in the fitting on the rail like it should be.

Hope that makes sense...

2k.civic.si

try gapping the plugs down further like 0.020 - 0.022 if that doesnt help try giving it some more timing in the top.

sleepencivic

gap them down to .018 i had to do the same on my set up and it cleared it up!

hjdanzi

It has an aem style fuel rail with the z6 stock bolts. How would i know if they are compatible? How would that cause the issue? Thanks a lot for you help bro.

Thanks man. Yes Ill gap them the most i can.

Do you think i will have idle issues or something like that? Thanks a lot for your time.

boostedBLUfg2

my buddy's boosted d16 had bad misfires until he gapped them down to .020, might wanna give that a shot

torres3030

Like xenocron said: Check the the bolt that goes to the fuel rail, that holds the fuel line coming from the fuel filter. If it's over tighten, since is crushed the car reacts like it has a fuel cut. I tell you this becuase it happen to me.

Vtec6000

Try another ecu, I recently had a problem with a car where it was miss firing at high rpm I changed everything including reverting back to oem injectors incase it was a problem with the injectors I was running but still the problem persist so for the heck of it I fitted a s300 installed ecu I had and put a quick 20min tune on it and guess what no miss fire!! so decided to pull my Moates Demon out of other ecu and fit into another socketed ecu and it ran 100% no missfire.

hjdanzi

Thanks man, ill do that. In your friend's d16, did it seem like a fuel cut? or like something else? Im asking because as you know there are many types of misfire... and this one is the case were you cant rev it anymore. Ill try gapping them smaller. Thanks.

Thanks for the input. To be 100% honest with you, if i recall right... it has a fuel hose attached by 2 mini screw clamps... you know the ones you use for the intercooler piping? but very small.

Ill try it bro, thanks a bunch.




Just for everyone to know, i didnt go smaller thatn .025 (up till now) cause ive tuned a lot of boosted d16 with almost the same setup. In my "logic" i didnt think that this car would do any difference, since in the others even with a .030 gap and same setup it didnt misfire. But now, since you all agree with that i will gap them as small as i can, and i will also change the ecu and even the ems if that helps. Im waiting till xenocron ships my stuff. Thanks a lot for your help... i feel so sad about this car... its like personal now.

SovXietday

Hahaha, if it works no worries.

I had to gap my plugs to .018 to get my car to stop breaking up really bad up top, but this is at 27psi on a decent sized turbo. My car ran fine with a .022-.024 gap at 18psi with no issues, so I don't know. It's worth a shot to try that too, that's an easy fix. However, my experience is if the car is breaking up that bad with a "normal" gap a smaller plug gap is only a short-term fix and the coil/ignitor is on it's way out.

hjdanzi

Well.. will see.. Do you know the banjo fitting hole on top of the fuel filter thread size? I want to buy a pressure gauge to test that, and i dont know what size of bung should i buy to fit it in that hole. Ive searched the helms and it instructs about the procedure but it doesnt state the hole's size. Hope that it made sense. Thanks again man! I dont feel so bad, after reading your answers guys... You give me ideas.

sleepencivic

mine are at .018 with no idle issues, ngk wires, new coil, cap, rotor and seal was replaced first and didnt fix the issue so i set them at .018 after talking with tuner and no issue since...and its been about 2 years. Its free and worth a try

DDTECH

Is there an exhaust on this car by chance..?

Cat?

piping? I'll explain on how you answer the question.

SovXietday

Nope, no idea. I just have a standard B&M fuel pressure gauge on mine, probably like 1/4" NPT or something. But considering you said your AFR readings are good I'm not seeing how losing fuel pressure could be your problem. If you lose fuel pressure you're going to go lean. Not only that, I doubt the banjo bolt would just stop supplying fuel suddenly?

I'm assuming you're thinking a cat might be clogged and exhaust can't vacate the ignition chamber at high load?

Turbo-LS

iTrader: (4)

Just for the heck of it, have you checked the readout of the TPS voltage? I tuned a car once that kept doing this and come to find out as i was watching the tables mid tuning every time we got fully into the throttle the tps was reading 0% and complete;y off the throttle the tps was reading 100%. guy had the wires crossed.

DDTECH

Cat clogged could be a problem however i was hinting towards something different..

Something i recently experinced on my own motor was, @ wot open header, i'd get alot of pinging @ lower rpms until vtec.. after vtec it'd go away. I custom built a res for it and put that on and it started to go away, after putting my full 3'' exhaust, it completely went away. After discussing with a few people i devoloped a theory that the engine wasn't properly getting rid of the gases from the chamber, the scavaging effect wasn't working, and the exhaust flow and tone needed some type of direction to exit the chambers.

You would think a big, High compression NA motor would like open header, mine does not.. something to think about.

@ 18psi you should be on NGK resistor 8's at least, gapped @ .025 or under. I think you should get the proper heat range first.. and understand the difference between non resistor and resistor plugs. if .025 doesn't work, go to .020. I just tuned a GSR turbo, bone stock that needed to be gapped to .020 @ 15psi.

These are things that should have been tested alittle more.

98integralsB18

I'm not sure if this has been covered but if it is a stock fuel pump it might not be supplying enough fuel to the rail. Just a thought. I remember my single cam had a stock pump when I went to get it tuned. I wasn't getting enough fuel and it wouldnt go past 5000 so I swapped pumps and it was fine.

hjdanzi

Of course ill try it man. After all the things i did to this car... thats a MUST. Ill def. do it, once xenocron ships my other stuff (new dizzy new wires etc.) THANKS A LOT FOR YOUR ANSWER.

It has a half exhaust setup. No cat, and piping is 2.5". I know it should at least be 3"... but its 2.5" The wastegate has an open dumptube 2". Thanks a lot for your time and help. Its deeply appreciate it.

Thanks man, and yes my readings are ok... and no, i doubt the banjo bolt will cut fuel... and i highly doubt fuel pressure is low.

hahah thanks man! Yeah, i laugh cause i thought that too... but not only i checked it like 10 times but ive also configured it on Neptune. It has an option were you set up close tps voltage 0% and wot tps voltage 100%.. and my readings are fine... in fact as soon as i do koeo it reads 0%, then if i wot it it reads 100%... thanks a lot bro!

Hey man. Regarding the piping as i said its 2.5... i know it should be 3" minimum, but my customer doesnt have a penny now. (we had to do millon of things to the car)... regarding the resistor plugs.. i dont see why i should use them. NOW, im not saying you are wrong, but ive tuned a lot of boosted hondas... and even at 380whp heat range 7 iridium gapped to .025 worked fine... zero detonation. everything smooth. Im using now iridium range 7.. and the problem doesnt happen at 18psi... it even failed at 1.7 psi... like i was going at 3.5k (light cruising) and wot it.. and as soon as it went to 4k at 1 or 2 psi (like for a split second) boom.. didnt go anywhere.

I understand what you are talking about the heat range... but lets assume im using range 8... why do i need resistor plugs? my wires already have a resistor on it... well... even the stock wires have one... now, eCtune and hondata work well with resistor plugs due to the radio frequences compatibilities that are found with those ems.... but on the other hand.. neptune is not known to work well with resistor plugs... so i dont understand that part of your point.

So... We agree on even colder plugs... like heat range 8... we agree about the gap.... i will go as small as i can, and make my way up if that helps. But i dont understand why is so crucial the use of resistor plugs in this build... Ive tuned more aggresive cars, and didnt have any problem. Could you elaborate a little more?....

And again.. maybe the exhaust is 2 small.

Thanks a lot for your time and help. I really appreciate it.


Thanks man. Yes that is right.. but im using a 255 walbro fuel pump and its more than enough for this engine. Thanks a lot though.

DDTECH

Think of it like this..

When you turn on a garden hose, and hold your hand infront of it, it builds up right? When you move your hand it shoots alittle futher on the initial hit. This is what a resistor plug does, it has alittle more *** behind it, to jump the gap, hence the name, "resistor" plug. Non-resistors are fine too, however they lack that "***" behind it to jump the gap sometimes, this is one of those times that i would consider switching to a better heat ranged plug, gap it down, and try a resistor.. I too am a tuner, as you can see from my sig, i tune eCtune and neptune as well, i was a beta tester for both... Something to think about is reading the plugs properly.. that comes into play it sounds as if you haven't read the plugs yet. I'm not questioning your ablitiy, but i'm saying that if you aren't reading plugs, you aren't going to be able to tell whats really going on, if you need help reading your plugs i'll be happy to explain over the phone if you'd like.

The dump tube may only be 2'', but you should have something flared out to 2.5 or 3''.. money may be tight, but you can get a 3'' dump tube for cheap somewhere... I think your exhaust is hindering your performance some, but it isn't whats causing your problems.


Some cars can make 600whp on ngk 7's.. others can only make 260 on ngk 8's, such as my motor..
Plug reading is very important...very important.