Voltage drop and miss in vtec

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autox19

Member
Stock b16a with a hondata ecu. Warbro 255 pump. Misses when in vtec. Turn vtec up high enough to not engage and runs up to 7k no miss. Had this issue before and adjusted dead times to fix. Log shows running lean and voltage drops to about 10 amp when on vtec.
Right now leaning towards toasted fuel pump as the engine us using the stock fiat x19 gas tank that was for a carbed and has to pull the fuel up to the pump. I have a fuel injection tank on its way with the feed on the bottom as well as i am relocating the fuel pump down there as well.
Posting here in case someone has other thoughts. Ran well for over a year. Started slight miss on vtec and was constant in under 10 miles.

Odie
Fiat x19 b16
 

CAFROG

Honda Minion
VIP
Check the screen on the VTEC solenoid. Could be a fuel pump issue but weird that a carb pump just now becomes insufficient. Check/change spark plugs.. .maybe cap/rotor too.
 

autox19

Member
Screen, cap, rotor, plugs, plug wires timing, were all done last year. ( about 200 miles) but will check the screen as it is an easy check.

Odie
 

Briansol

Admins
Staff member
Admin
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Is your tune looking at o2? Knock?
 

autox19

Member
Maybe simple....like grounds are loose?
good thought! because I will be relocating the fuel pump I will check. The real crappy part about this is changing the gas tank, because of course you never have to change a tank unless it is full. and yup, mine is full. Fiat made this extra tricky as it is more vertical than horizontal so I pretty much have to empty it before removing or it will tip over on removal. Unlike most carr that are horizontal and you can balance them on a floor jack.

Odie
 

autox19

Member
Picked up the second one. Will let you know how much my arm hurts after.
Tank came in yesterday. Car is up on jack stands (yes i checked and they are not on hf recall :) ) should be starting the process tonight
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Odie
 

TurboMirage

That’s how you get ants
VIP
i used one of these in the past (for a lawn mower, not a car)
Fluid Siphon Pump

took a lot and boy was my wirst tired, but it worked.

hindsight, should have gotten one like this: Multi-Use Transfer Pump

the first one is what i used... just sucked the gas up and out to the end and stuffed it in a gas can. i only pumped it for a minute to get it up out of the tank it was easier to hold vacuum once at that point lol
 

autox19

Member
Cake. The second one ran about 1 gal a min. The syphon happens on the push which was nice. I expected to pull up to pull the fuel.

Odie
 

autox19

Member
update, not good.

googled and seems like the common answer is I should have 14v and I have 12.2v that drops to about 10v at higher then 5k RPM. I replaced the alternator once but am now seeing that I should have went with OEM. I am having issues finding an OEM alt. I am really perplexed on why I am not spitting out full voltage. I have because I have heard about bad grounds, I actually have many grounds, 2 from engine to body, 1 form trans to body. the ECU ground is solid but I am contemplating running a wire from there to the chassis as well. this voltage drop coincides with a miss according to the datalog so I would like to figure out the voltage and see if the miss goes away. The miss has come and gone and various things I thought fixes it. Dead times, inline fuel pump pulling instead of pushing, etc. I unfortunately did not log when it worked so I dont know if the voltage was low at that point as well

thoughts? ideas?

Odie
 

Briansol

Admins
Staff member
Admin
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yeah, you should be seeing numbers nearer to 14 at non-idle rpm.

did you do anything to pulley size? it sounds like it may be getting under-driven.
 
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autox19

Member
yeah, you should be seeing number nearer to 14.4 at non-idle rpm.

did you do anything to pulley size? it sounds like it may be getting under-driven.
interesting thought. I didnt think of it until now, but, there was a pully change. albeit it would spin the alt faster. the original crank pully was chipped when I got the engine. I bought a new old stock one off of ebay. it was a bit larger but because of how hack the rest of the engine/car was I figured it was wrong on the car and this one was right. maybe I should google what the diameter of the pulley should be.
The alternator is also newish (less than 500 miles) but I cant find my receipt to tell what it was I put on there.

Odie
 

Briansol

Admins
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It could be the pulley on the alt itself is too big, resulting in it not spinning fast enough (like the rear cog on a bike). Is it for a b16 like from a del sol?
 

autox19

Member
Cant see how it can be much smaller. Also why would it go down at higher rpms then? Might have to do a quick little drive to get a log. I am also thinking it is possible that the alt mighht be at fault even though its "new". Got a total miss match when i google on what to use. And i cant locate oem.
 

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Briansol

Admins
Staff member
Admin
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Honda Part No.:31100-P30-033 is the correct unit you should have if it was an OEM obd 1 from a del sol.
 

autox19

Member
interesting, the other thread pointed out Battery. I did even think of that. because I the battery is probably past the point where it should probably be changed anyway, I might just go with that first. it is end of season and the car is going into storage insurance soon. as well as I dont have a garage to work on it once it is cold, it might be a bit of time in-between my responses. Although, by jan1st I am supposed to have my new 36x48 barn done so.....

Odie
 
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