Hello Everyone i'm am currently against a really weird issue and i thought some of you might have encountered something similar or you could shed some light in this case.

I had the car staying in the garage for almost 9 months. In the meantime i've built a header. So i do an Oil/Filter Change, Clutch Change, Header Swap, Battery Swap and Roll it out. Car Starts up Immediatly, Idles smoothly, Cruises below VTEC like Before. BUT when VTEC engages Full Throttle AFR goes down to 9.9 and slowly working it's way up to 13 moments before the limiter. Previously the Car was tuned at 12.5 throughout VTEC. When i try to hit vtec half throttle car misfires like hell at 14.5 AFR.

Things i've checked :

-Cap/Rotor ( Inspected and Cleaned )
-ICM ( Swapped a known working one)
-Coil ( tested found to be OK)
-MAP ( Swapped a known working one )
-TPS ( Measured and Checked for Blind spots )
-Cam Timing ( Checked )
-Valve Lash ( Checked )
-VTEC Solenoid ( Checked - Mesh Filter was Clean )
-Spark Plugs (Changed)
-Header ( Swapped a Hytech Small Tube - Same AFR/Misfires )

. I just came back from vacation and i'll start some more troubleshooting soon but i was wondering do you guys have any clue as to what could be causing this ?

 

was this header swap from OEM to aftermarket?

 

was the original header the car was tuned for a hytech small tube? if not, then the car just needs to be re-tuned.

i also encountered an issue with a friend's car. he doesnt drive it much, and the car was tuned probably around 1.5-2 years ago. i finally talked him into throwing it back onto the dyno, and the entire thing needed to be completely re-tuned again. he didnt change a single thing...

 

^^
thats where i was going with it

 

Nope the Car was tuned with a DC 4-1. But to clear things up i did street tune AFR's alone at 13.5:1 and it was still performing poorly from crossover 5.500 till 7.500. And that was where AFR's with the previous map went into normal range.

 

did you try and re calibrate the O2 sensor?

 

Ye i recalibrated twice i thought it was weird too..I will do a Compression Check, Clean Injectors, and Swap a whole Dizzy and check how thing go from there. I am really Curious though as to WHY its so low on power after VTEC crossover.

 

What's your setup?
What's the air fuel and timing during crossover?
What's the Vtec engagement RPM?

 

GSR Block,PCT Pistons,Blox C's,P30 IM,70mm TB,Precision 680cc,PW0 Ecu tuned on BRE. Car was running Smoothly prior to getting parked for 9months in a row. 5500 Crossover, VTEC Ign is at 27* in BRE and AFR's where 12.5 through VTEC Before this Weird behaviour began. Car was tuned on a DC 4-1 the only things that changed was Header and Radiator.

 

old fuel?

 

ok, but you street tuned it yourself just recently to 13.5? raise your vtec to 5800 and see if it still does it once your air fuels are ok

 

Yeah i street tuned the AFR's and tried Increasing the Crossover rpm even at 6500 i would get a bog till 7500. :/ I'll do a Compression test this week..this thing is way too weird. fuel was fresh, fuel filter was new. Could it possibly need MORE timing with a better Header than a DC ?

 

It's hard to say, but 27 sounds like its nearby. If your afr is within 12.5 to 13.5 during the bogging, then it's probably not the tune. Did you get a chance to log the tps and map when it's bogging?

 

If the TPS is calabrated correctly with a multi meter, then it should be fine.

 

Can you datalog

 

AFR goes rich because of misfire

Swap with a known, good distributor

 

Unfortunatly i can't datalog. I contacted Innovative about false rich reading due to misfire and they replied that a misfire will only cause false lean readings.
I am really confused.

 

Thinking about it again, Innovative is probably correct.

Misfire would leave free, uncombined oxygen

Do you have an OE Distributor

 

Ye Dizzy is oem. Aftermarket made in Japan Cap/Rotor. I'll get a known working one tommorow then re-install the previous header and give it a go.

 

good stuff

 

Problem Persists. I am Seriously considering picking up a sledgehammer and "fix" the damn thing lol.

I Swapped the Dizzy and the problem persisted.
I Did a Compression test and its 260-265 all around.

The only thing i haven't checked is oil pressure. Could inactivity have clogged something or ? i don't know...

Any insight anyone ?

 

Do u have another set of injectors to try?

 

Unfortunately no. But the current injectors are disc type so I doubt something is wrong with them

 

try another MAP sensor

 

Check oil pressure switch for vtech. And connecton/ wiring...