98 civic dx only mods are intake and exhaust (done before i baught it)

at idle my short term fuel trim is like 40 and long term fuel trim is 13 so its addling a CRAP LOAD of fuel. normaly i would think vacume leak but my idle is fine its at about 650-670.

so what could be the problem... think low fuel pressure would cause this?

IAT 86*F
TPS 9.3
MAP 7

 

well got back from school and popped a new code, it was 86*F and it was adding a lot of fuel soo driving it home at like 50-60 degrees outside it popped a lean code tryed to compensate for the cold air and couldn't do it i guess.

what i dont understand is the 8 in.hg of vacume at idle when it should be closer to 20 i would think if the map sensor was bad it would be adding fuel then poping a rich code case the engine didnt need it. so it adding that much fuel and still poping a lean code confuses me.

it idles fine at 670-700 rpm i checked that idle screw and its all the way in if that matters at all.

any thoughts would be helpfull.

 

How are you getting this information?

 

matco md1042 scanner why? got any info on what it could be?

 

So are you guessing it's dumping fuel? Just asking because it sounds like you don't actually know what you're looking at.

 

ok ill rephrase it, its asking the car to dump more fuel i have no reason to doubt it isnt but its not out of the question.

 

Start by looking up the term "closed loop".

 

don't have to its when the computer takes full control of fuel management based of pre determined events programed into the ecm.

 

You're the one describing what seems to be a normal condition and trying to make it out to be more than what it is.

And you have YET to post what the code was that prompted you to plug up the scan tool in the first place. Saying it was a "lean code" isn't really accurate and people have been known to misread codes and scan tools.

 

a normal condition? how is LTFT of 40 (40% additional fuel from standard) a normal condition.

normal would be 1 to 5 in either direction + or -

um when under neither the code po171 and po170 says bank 1 lean and fuel trim problem its kinda hard to misread what its saying.

 

Why don't you quit arguing and try a new map sensor ? Or hook up a vacume gauge and see what it is really reading

 

i would start with your tps u said 9.3? ohms or volts

 

rented a vacuum hand pump from parts store and tested the map sensor, spec says .8 volts is 25in.hg so i sucked it to 25in.hg and it as i gradualy did it it gradualy went down to .8v sooo i called local matco tool guy and he sayed the scanner is only reading the voltage from the sensor and at that perticular voltage would equal matcos pre determained vacuum and that sometimes them and snapon get the wrong specs.

so ya at idle i have .8v which is over 20in.hg which means all good


tps 9 ... i would asume thats ohms but wasnt sure so i busted out the multi meter and at closed throttle it read about .55 or .6 volts cant remember then went all the way to 4.3 volts WOT i set it to record minimum voltage and it had .55 so it never fell to 0 so i assume all good.

the only thing i can think of is a vacume leak or not enough fuel pressure its saying its lean asking for more fuel and the pumps not putting it out. im going to rent or buy a fuel pressure tester from the parts store tomarrow.

 

^^ Is this the same person?

 

no this is his cousin hes at my house right now is there a problem? im the one helping him with his car.

 

what is your ect temp ? and are your oxygen sensors hooked up ? why where you looking at your fuel trim in the first place ? for a check engine light ? if so please list the code's in the order they are on the scan tool

 

Sorry for a dumb question but is the car running poorly? And if you pull the plugs what do they look like?

http://www.hondacivicforum.com/forum...de-45-a-58760/

 

ok ok umm well i finally said screw it and took it to a shop for them to plug the big scan tool into it.

the previous owner who put the headers on put the down stream o2 sensor in the header and left the up stream sensor just hanging in the engine bay.

so bought a new o2 sensor (just in case)pluged it into the upstream conector and put it in the header and just took out the down stream and everything is honky dory

 

information like that would be helpful in the FIRST post, not the last.

 

If your fuel trims are adding fuel, it is either compensating for un-metered air(ie vacuum leak) or the readings it is getting from a few sensors is wrong. The pcm doesnt just "dump fuel" in open loop the car ignores readings from the 02 sensors. Once the car warms up and switches to closed loop it looks for readings from the maf, and oxygen sensors.a oxygen sensor does not detect unburned fuel (hence the name oxygen sensor).It mesures the amount of oxygen as it passes by it. If the amount of air in the exhaust stream is greater than the amout measured by the maf, it compensates by adding fuel with STFT. After the STFT reaches a certian amount(%) it will add to LTFT. LTFT stays in your KAM and will not reset when you turn your ingnition off. STFT does however. Judging by the fact that your LTFT's are up, it is a problem that has been ocuring for a while. My first guess would be a vacuum leak. The best/quickest way that i have found to find a leak would be with a can of brake clean/shop solv. Turn the motor on and pop the hood. Take your brake clean and start spraying it around all your vacuum areas, intake gaskets etc. If there is a leak, the motor will speed up. Obviously because you are adding more"fuel" to the mixture. If this is the case, you can locate the leak, fix it and then reset your KAM to reset your ltfts. Hope this helps

 

ya i would have liked to have had that info in the begining to

 

And i just saw that you fixed your car after i wrote all that.

Ill leave it up for someone else who has issues.

 

nice post slow boy but honda's don't have a maf . and kam is a ford term for keep alive memory

 

I wonder how anyone could have missed that if they actually were looking under the hood. I would say it would be next to impossible.

 

idk maby cause the connector is in the front top part of the engine bay and on aftermarket headers the o2 is like idk 3 feet away past the rear of the tranny?