I don't know exactly how to explain this issue, but I'll try my best.

On two separate occasions I have taken my car to the dyno to get tuned. Everything is fine, until we try to turn up the boost. The stock wastegate spring is 7psi. When we try to turn up the boost and make a pass with the car, every time vtec engages the car studders and sounds like it has a miss or like the spark plug is blowing out. But if we turn vtec off it will rev past 5800RPM with no problem. It only happens when vtec gets engaged. We have tried everything.

The first time we tuned the car, we tuned it to 7psi and vtec would engage with no issue, but anything over 7psi and it would break up after 5800RPM. So now I was back at the dyno with a new block with piston and rods, and nothing else has changed but yet is doing the samething. It did this same problem on the stock b16a, and now it does it on my new block with piston and rods. I don't think it's anything mechanical.

My setup is as follows,
Car is being tuned on Crome Gold

Stock b16a Head, Just sent it out to get refreshed, new seals and resurfaced
stock b16a1 block
Eagle Rods
Wiseco 9-1 81mm pistons
custom mini ram manifold
3in down pipe
Hallman pro MBC
turbosmart waste gate
T3/TO4b 57trim 63a/r
tial bov
3in Kteller exhaust
3in MagnaFlow Cat
Vibrant Resonator
3in chambered turbo muffler
Walboro 255 fule pump
780cc Injectors


Things we have changed or tried

Distributor
New cap & rotor
Wire's
Plugs gapped at 25thou
moved grounds
GM 3bar map
run open down pipe
Changed ECU
Vtec Solenoid
OEM fuel filter
Turned the car over with the fuel line from the filter into a bottle 375ml in 5seconds at 40psi
Spark is 30kv
Plugs are gapped at .025
Vtec lobes are free
Zero back pressure from the exhaust
Timing is perfect (timing belt)
Igniter pattern is good
Injector control is good
TPS is good
MAP GM 3Bar at Idle .49v WOT 1.27v


Any help or insight would be much appreciated.


Modified by Boosted_Coupe at 8:49 AM 10/4/2007


Modified by Boosted_Coupe at 8:50 AM 10/4/2007


Modified by Boosted_Coupe at 7:57 AM 10/7/2007


Modified by Boosted_Coupe at 1:49 PM 10/8/2007


Modified by Boosted_Coupe at 1:49 PM 10/8/2007

 

I would start checking out the VTEC system itself. If you don't have an oil pressure gauge, get one. Mount it on the head on the VTEC pressure test port and make sure it's engaging with more than 50psi. Also check all the vtec dowels and o-rings are in place.

*edit* My bad, I wasn't reading carefully enough, listen to SOHC_MShue

Also, have you tried shifting the vtec engagement point downwards? It might give you more info about what's causing it. 25 thou is already pretty tight for just 7 lbs.


Modified by raene at 10:40 AM 10/4/2007

 

if it runs fine on 7psi, but gets worse when you turn it up and the fuel and timing are decent then it sounds like an ignition system issue. Gap your plugs down a little more and see if the problem gets better or worse. It may just be something in the dizzy.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by raene &raquo;</TD></TR><TR><TD CLASS="quote">I would start checking out the VTEC system itself. If you don't have an oil pressure gauge, get one. Mount it on the head on the VTEC pressure test port and make sure it's engaging with more than 50psi. Also check all the vtec dowels and o-rings are in place. </TD></TR></TABLE>

I do have an oil gauge, sorry should have mentioned that. Everything checks out on that end. The head has been taken apart and then put back together when i got it refreshed, so i'm not sure if it could be that.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHC_MShue &raquo;</TD></TR><TR><TD CLASS="quote">if it runs fine on 7psi, but gets worse when you turn it up and the fuel and timing are decent then it sounds like an ignition system issue. Gap your plugs down a little more and see if the problem gets better or worse. It may just be something in the dizzy.</TD></TR></TABLE>

I changed the dizzy, and the gaps were so close already that i don't thnk it would make a difference. But i will try it forsure. I pretty much changed the whole ignition system on the dyno and nothing changed it.

 

i had something similiar happen to me...turns out it was a clogged, earls fuel filter...but did the same things as you describe...ran fine on lower boost, but when i turned it up, it would lean out, studder, and act like it was misfiring....i swapped out the filter and its cured. something to look at anyways

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fast2camciv &raquo;</TD></TR><TR><TD CLASS="quote">i had something similiar happen to me...turns out it was a clogged, earls fuel filter...but did the same things as you describe...ran fine on lower boost, but when i turned it up, it would lean out, studder, and act like it was misfiring....i swapped out the filter and its cured. something to look at anyways </TD></TR></TABLE>

Swapped out the fuel filter? I replaced mine about 3years ago with an OEM one. I 'll check that out aswell.

 

what plugs are you running : #9's , BKR7E. etc

what gap have you tried : 15 17 25 27 28 30?

Whats your timing at when it crosses over?

what is the AFR's when it crosses over


I call its switching over and getting to rich and the timing is changing dramatically.

 

I'm with fast2camciv, sounds like you've got a fuel delivery issue.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boosted_Coupe &raquo;</TD></TR><TR><TD CLASS="quote">

I changed the dizzy, and the gaps were so close already that i don't thnk it would make a difference. But i will try it forsure. I pretty much changed the whole ignition system on the dyno and nothing changed it.</TD></TR></TABLE>
Hmm like others said maybe its fuel then. Your tuner should be able to tell. Although one time i tuned a big power boosted car that had some sort of grounding issue. It would misfire right at vtec engagement no matter where it kicked in at. We tried everything and then finally he put some extra grounds throughout the engine bay and it actually cleared things up completely.

 

Well now i have tried putting a new fuel filter in, and just for ***** and giggles i tried and new vtec solenoid. They both didn't make a difference. I'm lost on this one guys.

My Walboro 255 Isn't as loud as all my friend's pumps. I hear it come on, but nothing like when my friends start there cars. Maybe it could be the pump?

 

what are your AFRs when it starts to brake up?
when my car was having high RPM breakups it was the dizzy. replaced the dizzy with another i had, reset the timing and BAM.

make sure your dizzy's bearing isnt stiff

i remember when i was having my other car tuned on the 240cc injectors it did the EXACT same thing (minus the vtec portion cuz it was on a d15). the afr's appreared to be good as well, it was strange.
the moment i got some 450cc blue tops in there the car ran like gold

makes sence that when the engine engages vtec and needs more fuel it starts to buck because its not gettin it

360cc is small on a d15, and you are running a B!!

 

I'm using 780cc, so the injector size should be more then enough. I changed my whole dizzy and it did the samething. I'll try to find out what my AFR's are, but i ddn't tune it. I'll have to call up my tuner.

 

Bump..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boosted_Coupe &raquo;</TD></TR><TR><TD CLASS="quote">Bump.. </TD></TR></TABLE>

Change that fuel pump and see what happens. Definitely sounds like you're leaning out.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boosted_Coupe &raquo;</TD></TR><TR><TD CLASS="quote">I'm using 780cc, so the injector size should be more then enough. I changed my whole dizzy and it did the samething. I'll try to find out what my AFR's are, but i ddn't tune it. I'll have to call up my tuner.</TD></TR></TABLE>

yeah 780cc is good, i have no idea where i got 360cc from! hehe

with all the money you invested in that motor i wouldnt run it up again without a wideband to monitor your AFR's

a local honda head said there are huge timing issues with chrome and p28 ecus... ?? you running both? (works at the local honda dealer and apparently went through a few B's because Crome wasnt applying the changes made to the timing maps... all word of mouth, but i'd check it out carefully)

 

your problem sounds alot like what i experienced over the weekend. i was tuning my friends fully built setup:

84mm sleeved LS/VTEC setup
itr cams w/ springs/retainers
3" open dump
PT70 turbo
Precision intercooler
1000cc injectors

I was tuning the car in crome. in the lower rpms the car would run clean! I had vtec engage at 4600 rpms and at about 7K rpms the car would break up pretty bad. the air fuel was perfect at 11.5 across the board. i changed timing values as well but still had the same problems. i tried everything: new plugs, gapped them tighter/bigger, new plug wires, new distributor, checked all the grounds, started a new CROME program... but nothing worked. i got fed up and decided to put in a previous uberdata tune in this car that i did last year where the car made 620whp. as soon as we made a pass with uberdata the car ran clean w/ zero break up issues. there is somethign definitly wrong with CROME. i even put in the script that john Cui made that would allow me to pull timing past 15* but still nothing. Im thinking this might be a P30 based ROM problem. im gonna retune the car on sunday with a P72 based rom and see if i still get all this misfire

 

What ECU were you tuning with? P28 or P30. The really weird part about this is, I tried my friends ECU out, which is also a p28 and he also just got tuned by the same tuner the week before. And it did the exact samething on my car, but his run's fine.

His setup is a bit different then mine, but we are using same injectors, same tuning program, and pretty much the same tune. My tuner was basing my new tune off of my friends tune, and changing whatever needed to be changed.

My friend's setup is an LS vtec turbo,
Mine is a striaght b16 turbo.

 

ecu wouldnt matter. i always tune on a P72 ecu

 

Sorry, changed up my question abit..

 

Bump.. Anyone else run into this problem?

 

marked... im currently having this problem too.. i cant figure what the heck is going on either...

 

So it's sounding more like a software issue.. Because so far everything is checking out fine.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SPOON_BeIgHtEeNsEe &raquo;</TD></TR><TR><TD CLASS="quote">marked... im currently having this problem too.. i cant figure what the heck is going on either... </TD></TR></TABLE>

What is happening with you're setup?

 

Bump *Help*

 

Check your base timing with a timing light and make sure it is synchronized with the ECU.