Hello, I have a strange problem with my b16a in my cx. Over the last 5 or 6000 miles I've noticed my fuel cutoff had lowered itself to 8200rpm. Now over the last few days its now at 8000rpm (Its a chipped p28 with a 8500rpm fuel cutoff). I didnt think a whole lot of it because I dont race this thing in summer anyways. Well now that its cooling down I would like to get this working properly. I have replaced the plugs, cap/rotor, and fuel filter. No change at all, still cuts off at 8000rpm. Its not my tach either, I know what its reading is accurate. If anyone has had experience with something like this, please chime in. TIA
-Globl

EDIT: Should have itterated that the ecu is throwing no cel and no codes present.


Modified by globlctzn at 7:33 PM 10/4/2003

 

any ideas? I'm leaning towards a wiring problem or something. The only thing that makes me not think wiring is that its not intermitent its like this every time I drive it.

 

ok 3 days and not even a guess from anyone?

 

alright heres a guess..... when you redline.. do you often hit the rev limit, cause if you do that can probably be hard on your tach. and when it bounces it could turn the needle on the shaft that actually spins the needle.. sort of confusing wording....

 

hook up a different Tach and see if the Redline's are the same

 

Thanks for both your replys

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">alright heres a guess..... when you redline.. do you often hit the rev limit, cause if you do that can probably be hard on your tach. and when it bounces it could turn the needle on the shaft that actually spins the needle.. sort of confusing wording....</TD></TR></TABLE>

I bounced off the redline a few times last year when burning out for a 1/4 run, but thats about it, it ran fine all spring with no racing and then kindof sudenly it started doing this.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">hook up a different Tach and see if the Redline's are the same</TD></TR></TABLE>

I did actually go through the trouble of putting my ex coupes cluster in there and it was about the same. Thing is I really didnt need to do that to tell it wasnt the tach, I know this car well and it is missing out on 3 or 400 rpms that make alot of power, even on the butt dyno its a very obvious difference.

This weekend I tried my jdm p30 from my b16 coupe and it was the same result (except i was throwing a cel for no k.s) Ive really covered all I can think of beyond going through the whole wire harness. Hopefully someone will think of something I havent tried, heres the list of what Ive done.

fresh oil/filter
cleaned air filter
changed spark plugs / cap and rotor and wires
swaped ecus
changed fuel filter (fuel pres is fine at 37psi)

the car truthfully runs excellent throughout the powerband till I hit 7900-8000rpm which sucks *** cause this is a b16 and needs every rev it can get.

 

how big of a difference did it make on the butt dyno?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 95excoupeMT &raquo;</TD></TR><TR><TD CLASS="quote">how big of a difference did it make on the butt dyno?</TD></TR></TABLE>

Pretty big difference, it doesnt seem to loose an ounce of power till 8000 then bam it feels exactly like the fuel cutoff, so I'm assuming something is telling the ecu to enagage the fuel cut for some reason. This thing used to pull like crazy all the way to 8400rpm so its pretty anoying.

 

well if you have tried another cluster and another ecu then more than likely it is in the wiring

 

Maybe one of your fuel injectors is starting to go out or your fuel filter is clogging and it can't flow enough to match the air intake at higher rpms.

Edit: obviously not your fuel filter because you changed that already. My bad.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Archidictus &raquo;</TD></TR><TR><TD CLASS="quote">Maybe one of your fuel injectors is starting to go out or your fuel filter is clogging and it can't flow enough to match the air intake at higher rpms.

Edit: obviously not your fuel filter because you changed that already. My bad.</TD></TR></TABLE>

I considered this also, all 4 seem to tick happily at idle (I used the screw driver to the injector technique to make sure each was clicking the same as the others). Does anyone think or know if one injector goes will it cause this kind of a problem? I dont seem to be running particularly rich in any cylinder according to the spark plugs. Maybe having the 4 of them sent off to be cleaned and have the flow recorded wouldnt be a bad idea.

 

next best guess would be the FPR, have you checked your fuel pressure lately? See what it's at and I would highly recommended getting a aftermarket FPR

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Ninja_Jc7 &raquo;</TD></TR><TR><TD CLASS="quote">next best guess would be the FPR, have you checked your fuel pressure lately? See what it's at and I would highly recommended getting a aftermarket FPR</TD></TR></TABLE>

fuel psi is at 35-37 without crimping the vac line, I thought that was sufficient for a relitivly stock b16a. I do have a b&m fpr laying around here somewhere, I'll try that next weekend.

 

I checked out this thread https://honda-tech.com/zerothread?id=419536 and I tried the same thing he did, I jacked the vtec selonoid off of my d16z6 and no change at all. I also did a compression test while I was at it and the motor pulled an impressive 215, 210, 210, 210 so I guess it looks like I'm not gonna find the problem unless I go threw the whole wire harness. The shitty part is that the ecu still shows no codes whatsoever, thats the one and only thing that makes me think its something mechanical, everything else points to an electronic problem. So once again if anyone has any tips on what wires could cause this. Are OHM loads important to our ECUS?

 

Assuming the motor is running just fine and the rev limiter is at 8000 RPM, I would recommend testing another OBD1 ECU, and see what that pulls.

Have you done anything as far as wiring of any nature, any removal of the needles on the gauges? Something simple has caused this.

Sounds like the tach is off by a couple RPM's, ignitor is not giving you accurate readings to the tach lead, or the voltage in the BLU wire at the dizzy to your tach is not accurate.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by poison &raquo;</TD></TR><TR><TD CLASS="quote">Assuming the motor is running just fine and the rev limiter is at 8000 RPM, I would recommend testing another OBD1 ECU, and see what that pulls.

Have you done anything as far as wiring of any nature, any removal of the needles on the gauges? Something simple has caused this.

Sounds like the tach is off by a couple RPM's, ignitor is not giving you accurate readings to the tach lead, or the voltage in the BLU wire at the dizzy to your tach is not accurate.</TD></TR></TABLE>

Yes I have swaped ecus, my tach is quite accurate also (its a JDM Pivot), and I have verified it with my digi timing light (has built in tach) and a ex gauge cluster. Not to mention the fact that tach shows a perfect 750 at idle vtec at 5500 where it always was before too. This isnt a tach problem.