well im at a loss on this one. car starts fine and idles pretty well at cold start...only a little putt putt can be heard in the exhaust. then once it warms the idle suddenly drops, then starts to climb slowly, goes to where it should be then drops again...each time it seems like its going to staul and eventually does. car seems to run fine the rest of the time. also once it stauls i hear a humming from the iacv, when i unplug it the hum stops, then when i plug it in again it clicks and humms again. once i turn the ignition off and turn it back in the on position again the humming is gone.

ive measuresd the voltage during idle and it holds steady at 14.5 volts and drops to 13 when the idle drops.

also measured the map sensor voltage and it reads 1.09 - 1.23 volts when warming up, then .90 - .93 volts then begins to fluctuate with the idle as expected between 1.50 - .90 volts

i also pulled the plugs that i recently put in and dont really see anything at all

cylinder 1
http://www.imagestation.com/pi...3.jpg

cylinder 2
http://www.imagestation.com/pi...0.jpg

cylinder 3
http://www.imagestation.com/pi...6.jpg

cylinder 4
http://www.imagestation.com/pi...c.jpg

this fluctuation is kind of drawn out in its cycle...not fast paced like a vacuum leak. also this is an obd2 b18b running off an obd1 p75.

ive tried new dizzy, map sensor, checked tps, clean iacv....just getting frustrated

 

forgot to mention i have a b16 tb on this motor so its not the fitv

 

sounds like a problem once the iac takes over?
i would check the iac.

 

u know anybody with a good working IACV? try theirs and see

 

ive already tried 2 different ones so far....same exact results....im going to get new plugs and wires...and also bleed out the coolant at the ect just to make sure there are no airpockets messing that up....also going to get a stuck fpr and see what that does

 

today i did plugs, wires, replaced fpr, bled coolant, tried a 3rd iacv, did timing, replaced map sensor, tested tps

still same problem

 

ok here is the latest...i have gone over everything at this point, then today going on someones suggestion i unplugged the o2 sensor. the idle problems all seemed to go away. only problem i had was when i got off the gas all my lights would dim noticably and when i was driving and pushed the clutch in and stopped at a light the car let the idle drop to much and died. wondering if the problems could stem from someting not regulating the voltage of the electrical system? or from a faulty o2? do o2s go bad without throwing a code?

 

What kind of motor setup do you have?

 

obd 2 b18b with basic bolt ons in a 98 hatch running off of an obd1 p75

 

it wouldnt hurt to try another o2 sensor. have you tried it yet?

 

no i havent bc im so tight on money right now.....the 2 things im targeting are now the o2 sensor and possibly the alternator

 

also does anyone know why the secondary o2 sensors ground wire, signal wire, and heater wire all run into the car harness.....i was checking some things and found that on the 98 ex harness these wires go to the ecu, but also run to the green plug on the engine harness that plugs into the car harness.....wondering why???

 

so they dident run one harness throughout the whole car. ease of installation.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rainforest &raquo;</TD></TR><TR><TD CLASS="quote">so they dident run one harness throughout the whole car. ease of installation.</TD></TR></TABLE>

no the question is what does the 2nd o2 sensor affect in the car....the wire s for that sensor go to both the ecu (which is on its own plug iin eks), and then it goes onto the car harness. why would the sencondary o2 sensor go through the car harness as well???

 

so i was watching the fuel pressure today when the motor stalls..and i noticed that just as it dies the pressure shoots up to that of wot....so i then removed the hose from the fpr to the im and i plugged the im hole and left the fpr one open, so the car was getting more pressure at idle.....and it seems to stop the problem.......

i have tried 2 other fpr and i have the same problems when everything is hooked up so im wondering if this could be a sign of a fuel pump dieing or what.....pressure is coming up just how it should according to a helms at idle ut likei said when i trickthe fpr to think it runig wo he ca ems to dle fine.....any advice??? btw there is a enom fuel pump on this car

 

did you check for vacuum leaks? or maybe the Evap/fuel return system has issues. what about your PCV? does it rattle when you shake it (it should - if not, replace)?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ( o )( o ) &raquo;</TD></TR><TR><TD CLASS="quote">did you check for vacuum leaks? or maybe the Evap/fuel return system has issues. what about your PCV? does it rattle when you shake it (it should - if not, replace)?</TD></TR></TABLE>

brand new pvc, no vaccum leaks and the evap system has been removed

 

im wondering if its the alt bc last year my old one died and i needed the car the same day....no parts stores had any and then i got one, but it wasnt for my car...they gave me the wrong one, but i had no choice so i grinded out the mount holes and got it to fit and such and ran it like that....but im wondering if even since the alt was for another honda motor if the voltage regulator is different....i have a feeling the guy at the shop gave me a d series alt, but im not sure....in any event the plug fits perfect, but im still having the idle problems and im trying to figure this all out....so far this is the only thing i can think of that i have transfered from the old motor to the new motor that could be causing this.;....and i honestly cant remember if this started at the same time as i changed the alt last year

 

try a different computer, i onced had a p28 that had no iacv control what so ever so the car never idled on its own, it was a nightmare until 1 day i changed the ecu, so worth a shot.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by chameleon &raquo;</TD></TR><TR><TD CLASS="quote">try a different computer, i onced had a p28 that had no iacv control what so ever so the car never idled on its own, it was a nightmare until 1 day i changed the ecu, so worth a shot.</TD></TR></TABLE>

so that would mean i would need another chipped ecu if running hondata...?
wondering if i can run a p30 without retuning?

 

narrowed problem to voltage regulator or fuel pump

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bleedblue94 &raquo;</TD></TR><TR><TD CLASS="quote">narrowed problem to voltage regulator or fuel pump</TD></TR></TABLE>

how'd you figure that?

 

hooked a voltage gauge up and it wasnt charging the way it should have been....to high then too low = voltage regulator....then i chaged the fuel pump the same day just bc i wanted to....one of those fixed it, but my money is on the voltage regulator

 

you just replace the alt? or can you just buy this one piece?

congrats on fixing your idle issues...

 

honestly just go to autozone ...pay tyhe cash for a duralast alt with a lifetime warrenty...