hesitation at low rpm and back fire
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From: Modesto, CA
hesitation at low rpm and back fire
I have freaking done everthing and still hesitates and back fires...I change spark plugs,oil,gas added octane...checked the tdc and the timing all seems to be perfect...but my car still seems to hesitate and is not throwing any codes....what else could it freaking be.... 
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From: Annapolis, Md, US
Re: hesitation at low rpm and back fire (yz125rider21)
if you have been using NOS mannnnnnnnn... maybe thats it !!! or maybe your not getting any fuel (i.e. need new fuel pump, or maybe a upgraded fuel system is needed..) what do your plugs look like ?
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From: Modesto, CA
I havent used nitrous on this motor they stole the kit right after I dropped in a new motor 9 months ago...I am getting fuel I took of rail to make sure...I just cant figure this out..i am about to take it and get is dianostic on it but I hate to fork out that money
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From: Annapolis, Md, US
Re: (yz125rider21)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by yz125rider21 »</TD></TR><TR><TD CLASS="quote">I havent used nitrous on this motor they stole the kit right after I dropped in a new motor 9 months ago...I am getting fuel I took of rail to make sure...I just cant figure this out..i am about to take it and get is dianostic on it but I hate to fork out that money</TD></TR></TABLE>
that doesn`t mean anything you have to check your fuel Pressure while it is operating w/ the fuel pump on... and if you look at your plugs they could tell you a whole lot...
that doesn`t mean anything you have to check your fuel Pressure while it is operating w/ the fuel pump on... and if you look at your plugs they could tell you a whole lot...
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From: Annapolis, Md, US
Re: (yz125rider21)
what did your old plugs look like ?
to check your fuel pressure you need a gauge, the guage mounts into the top of the fuel filter
- remove the service bolt, while holding the bango fitting in place
-attach the fuel pressure gauge
-** Start the engine- measure the fuel pressure with engine idling and the vacuum hose of the fuel pressure regulator disconnected from the fuel pressure regulator and pinched...
if you tell me what engine you have i could possibly findout what the required pressure is..
to check your fuel pressure you need a gauge, the guage mounts into the top of the fuel filter
- remove the service bolt, while holding the bango fitting in place
-attach the fuel pressure gauge
-** Start the engine- measure the fuel pressure with engine idling and the vacuum hose of the fuel pressure regulator disconnected from the fuel pressure regulator and pinched...
if you tell me what engine you have i could possibly findout what the required pressure is..
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From: Annapolis, Md, US
Re: (yz125rider21)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by yz125rider21 »</TD></TR><TR><TD CLASS="quote">plugs where a brownish color...but the gaps where bigggg...so I got new plugs and gap them to .041...cant think what else would be causing all this</TD></TR></TABLE>
if your plugs were brown you were leaning out.. check your fuel pressure i`ll look the specs up before the end of the day. it sounds as if you have a poorly chipped ecu/ tuned S-afc, or a bad fuel pump..
if your plugs were brown you were leaning out.. check your fuel pressure i`ll look the specs up before the end of the day. it sounds as if you have a poorly chipped ecu/ tuned S-afc, or a bad fuel pump..
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From: Annapolis, Md, US
Re: (035psi)
the fuel pressure should be at 35-41psi (240-279 kPa)..
-if the pressure is less than specified, check for:
--clogged fuel filter
--clogged or leaking fuel lines
--pressure regulator fail (do you have a adjustable FPR ?????? it may be out of adjustment )
-if is higher than specified check for
--pinched or clogged fuel return hoses or pipes
--pressure regulator failure
if your fuel system is in proper order check you MAP sensor next, if that is good... check your ignition system...
and DO- it in that order of process of elimination, or you could be fixing things that are in working order only to find out your skipping something.
-if the pressure is less than specified, check for:
--clogged fuel filter
--clogged or leaking fuel lines
--pressure regulator fail (do you have a adjustable FPR ?????? it may be out of adjustment )
-if is higher than specified check for
--pinched or clogged fuel return hoses or pipes
--pressure regulator failure
if your fuel system is in proper order check you MAP sensor next, if that is good... check your ignition system...
and DO- it in that order of process of elimination, or you could be fixing things that are in working order only to find out your skipping something.
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From: can't find parking in baltimore
Re: (yz125rider21)
its a bad o2 sensor.... almost guarantee
the only things that could cause those symptoms are:
o2s (thru 2-4K rpms)
map sensor
unless you have some rare expletive up.. but i doubt it
the only things that could cause those symptoms are:
o2s (thru 2-4K rpms)
map sensor
unless you have some rare expletive up.. but i doubt it
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From: Modesto, CA
Hey what would cause backfire out of the intake???...thats where it is coming from...we just timed it and everything and still getting bad backfire out the intake and hesitation on motor....also where can I get a fuel pressure tester at???my friend brought one over but wouldnt work with my honda...
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From: Annapolis, Md, US
Re: (MonkeyMagic)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MonkeyMagic »</TD></TR><TR><TD CLASS="quote">its a bad o2 sensor.... almost guarantee
the only things that could cause those symptoms are:
o2s (thru 2-4K rpms)
map sensor
unless you have some rare expletive up.. but i doubt it</TD></TR></TABLE>
and what is your reasoning for it being an o2 sensor?
you can pick up a fuel pressure ( tester) gauge at any generic autoparts store for cheap..
make sure your MAP sensor, and TPS sensor wires are not switched.... and i`m not sure if the the idle control valve wires can reach the IAT sensor (on a D-series) but, make sure those two are not swtched also..
if you bought a Ohm meter and a helms it would take you 15mins to find the poblem with their process of elimination procedures..
the only things that could cause those symptoms are:
o2s (thru 2-4K rpms)
map sensor
unless you have some rare expletive up.. but i doubt it</TD></TR></TABLE>
and what is your reasoning for it being an o2 sensor?
you can pick up a fuel pressure ( tester) gauge at any generic autoparts store for cheap..
make sure your MAP sensor, and TPS sensor wires are not switched.... and i`m not sure if the the idle control valve wires can reach the IAT sensor (on a D-series) but, make sure those two are not swtched also..
if you bought a Ohm meter and a helms it would take you 15mins to find the poblem with their process of elimination procedures..
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From: Modesto, CA
I am literally having no luck with finding a fuel pressure tester here in my town...anybody have a pic what the fitting looks like...cause my friend has a gauge tester but not the right fitting for imprts....
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From: Northridge, CA, USA
Re: (yz125rider21)
bump???
im having the same problem on my zc single...
i have no low end power and it bogs, but anything after 3k its pure power...
i changed my o2 still no difference...
the guy at autozone suggested cap and rotor replacement which i have not yet done...
i had a friend tell me that he had the same problem and it fixed itself after 3 weeks...
hopefuly someone here can give us the cure...
im having the same problem on my zc single...
i have no low end power and it bogs, but anything after 3k its pure power...
i changed my o2 still no difference...
the guy at autozone suggested cap and rotor replacement which i have not yet done...
i had a friend tell me that he had the same problem and it fixed itself after 3 weeks...
hopefuly someone here can give us the cure...
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From: Modesto, CA
Re: (BaYoNAiM)
hey have you smog th zc in cali yet?....i havent but once car problem is fixed i am do for smog...I was told zc is legal in cali and passes smog...so it better past smog and not have to deal with a freaking ref lol....i will kill my ref in my town he a major ******** 
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From: b00sting my D16s, SoWis, USA
Re: (BaYoNAiM)
Well lets assume that when it was stolen, it was redlined a few times. Lets assume that they possibly floated (and bent) a valve or three. So... have you tried a compression test? Leakdown test? A bent valve could definately let the engine backfire, since the intake manifold is essentially open to the cylinder when it fires.
The other issue, as said, could be the o2, or leaning out. When I was in the process of tuning uberdata, I had an odd lean spot around 2.5k. It was spuratic since when cold, it wouldn't correct using the o2, and sometimes it wouldn't corrct due to extra load. It would stutter, but not backfire. Backfiring into the exhasut is a rich condition usually, fyi. Adding octane booster won't help if it's getting too much or not enough fuel.
Also, when I put my 780's in, simple scaling wasn't enough, so it was running 15-17:1 air-fuel ratios till I added fuel. I bucked along like a mechanical bull.
ALso check your coil, they have a tendency to either die instantly, or slowly. At the very least, check in the dizzy cap for orange dust, signifying a dying dizzy bearing (that heat kills the sensors).
The other issue, as said, could be the o2, or leaning out. When I was in the process of tuning uberdata, I had an odd lean spot around 2.5k. It was spuratic since when cold, it wouldn't correct using the o2, and sometimes it wouldn't corrct due to extra load. It would stutter, but not backfire. Backfiring into the exhasut is a rich condition usually, fyi. Adding octane booster won't help if it's getting too much or not enough fuel.
Also, when I put my 780's in, simple scaling wasn't enough, so it was running 15-17:1 air-fuel ratios till I added fuel. I bucked along like a mechanical bull.
ALso check your coil, they have a tendency to either die instantly, or slowly. At the very least, check in the dizzy cap for orange dust, signifying a dying dizzy bearing (that heat kills the sensors).
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