Chuck Dean

Still trying to get to the bottom of it...

The car will run fine if it's started cold. Once it reaches operating temperature it will totally change. It will all the sudden start misfiring constantly (like bububububububub). It's more noticeable under load. The ECU throws misfire codes. Sometimes for more than one cylinder.

The fact that it runs okay until it reaches operating temp is what puzzles me. I'm guessing that it is a bad o2 sensor since your car doesn't start to use the sensor until the car reaches op. temp.

Can anyone think of other possibilities? Perhaps something due to oil or metals heating up that would somehow cause my car to stop running normally?

primeredbeast

sounds like it might be dizzy get your ignition module tested out

Vtec92Civic

so by the car going *bubububububububu* that means it's miss-firing, or is that just a sputter?

Nid Styles

O2 would just make it run richer. It's got to be in you Ignition syatem like stated above.

flymecourageous

i don't think it's the o2 but i would check the gaps on your spark plugs ,maybe tighten them up a litlle.play with timing to advance, retard try different settings and run it .sounds like you're running hot to me .peace

R@mon

what size injectors?
some times if you run a very large injector, the o2 sensor will try and make the car ideal at a 14.7 af ratio which is very hard with larger injectors. because of the small time they have to be open and the time they take to open

Chuck Dean

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93h22a4 &raquo;</TD></TR><TR><TD CLASS="quote">what size injectors?
some times if you run a very large injector, the o2 sensor will try and make the car ideal at a 14.7 af ratio which is very hard with larger injectors. because of the small time they have to be open and the time they take to open</TD></TR></TABLE>

I'm doing the AFC hack with DSM 450's. I've been running this setup since July03.

I've been leaning towards a leaky/inconsistent injector. When I had the misfrie I took out the injectors and tested them. All four sprayed find but two of them showed fuel surface out of the tip when I pressurized them. The cylinder that misfires the most frequently moved when I moved injectors.

Perhaps when the o2 sensor is active, the 'bad' sensor isn't able to hold idle any more.

Also, about the misfiring sound. It's entirely consistent. But it feels and sounds like you're runnig on less clinders. The exhaust pulses out instead of being a steady flow.

Chuck Dean

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nd_styles &raquo;</TD></TR><TR><TD CLASS="quote">O2 would just make it run richer. It's got to be in you Ignition syatem like stated above.</TD></TR></TABLE>

If it is ignition why would it run fin during warmup but go to **** when it's done warming up. Something else, it takes a long time after it's been acting up for it to act normally again (a few hours or more).

I am using a MSD ignitiion module, coild and cap. I've checked the spark. I replaced the spark plugs. Which turned pitch black with carbon deposit after one use.

So confused.

JonGP4

check ur compression when warm, since cly expanded when warm, its possiable ur rings are worn and there is to much blowby..
just throwing suggestions

Chuck Dean

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JonGP4 &raquo;</TD></TR><TR><TD CLASS="quote">check ur compression when warm, since cly expanded when warm, its possiable ur rings are worn and there is to much blowby..
just throwing suggestions</TD></TR></TABLE>

200 on all four

pgpunkguy

are your o2 sensors heated or non-heated?

if they are heated than, your o2 sensor definately have nothing to do with it, since it only takes a few seconds to heat up... but as others have said, it sounds like an ignition issue or fuel injection issue...

Chuck Dean

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pgpunkguy &raquo;</TD></TR><TR><TD CLASS="quote">are your o2 sensors heated or non-heated?

if they are heated than, your o2 sensor definately have nothing to do with it, since it only takes a few seconds to heat up... but as others have said, it sounds like an ignition issue or fuel injection issue...</TD></TR></TABLE>

??

They are the stock o2 sensors on a 99 OBDII GSR. I was under the impression that the ECU doesn't use them until the car reachs full operating temp.

pgpunkguy

i believe your o2 sensors have a heating circuit that heat them up to operating temps (o2 sensor operating temps) within seconds...)

on non-heated sensors, the ecu compensates but running rich until the sensors warm up from engine exhaust gases...

regardless, i'm 99% sure yours are heated, so it shouldn't really be an issue...

Chuck Dean

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by pgpunkguy &raquo;</TD></TR><TR><TD CLASS="quote">i believe your o2 sensors have a heating circuit that heat them up to operating temps (o2 sensor operating temps) within seconds...)

on non-heated sensors, the ecu compensates but running rich until the sensors warm up from engine exhaust gases...

regardless, i'm 99% sure yours are heated, so it shouldn't really be an issue...</TD></TR></TABLE>

Can anyone verify this. I didn't think the o2 sensor was used until the 'car' reached operating temperature.

egchan

4 wire o2 sensors are heated, which means whenever the key is on, whether the engine is on or not, the o2 is getting hot. these were on all integras 92 and up i believe. the 2 wire o2s are the ones that need exhaust gases to get them hot before they fully begin to work.

Chuck Dean

So back to the problem... If it's not the o2 sensor, what else would cause the motor to <U>constantly</U> misfire after the motor warms up. If you pull the plugs, the misfiring cylnder has a wet spark plug. I've moved the injectors to different cylinders and the misfire seemed to follow the injector. Which would indicate a possibly bad injector. But why would it only mess up after warmup??????

Chuck Dean

Can anyone make sense of this. I don't want to dump my money into new injectors if that's not even the problem.

To make it a little clearer. The car runs fine during warmup. The car doesn't even have to warm up all the way. If I stop and then start the car up again it sounds like the car is running off three or less cylinders and it's consistant. It's a drastic change. That is how it usually happens but it can also happen in the middle of driving. In the middle of cruizing it can just totally switch to this 'misfiring mode'. It always throws a misfire CEL and sometimes it's in more than one cylinder. The car has to sit for several hours before it can be driven again without contantly misfiring.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by primeredbeast &raquo;</TD></TR><TR><TD CLASS="quote">sounds like it might be dizzy get your ignition module tested out</TD></TR></TABLE>

How can I test for this. I don't have my ignition parts with me but I could have them shipped up here to me. Is there a way to test the ignition module? It's the MSD sci.

Please somebody help. This is my daily driver. I'm basically without a car right now.

Chuck Dean

bump

PariahBoardshop

hey bro, did you end up finding anything out?
i am going through a similar problem and would like to know what you ended up doing.

Curtis Gibson

having same issue but leaning toward plugs coils or maf mass air flow sensor but now fuel pump entered the equation due to a few no starts until primed

DaX

iTrader: (1)

Hi Curtis. Bumping a 16-year-old thread is generally frowned upon. Also, Honda does not use a MAF.

wunfstgsr

Just here to get a free post

P.S this can very well be the symptoms of a bad ECT sensor!..