HELP!, SR is undriveable My A/F ratio is all over the place!!*****Got VIDEOS****

[redsx13]

Like the post says, SR runs horribly, This issue renders my car undriveable and I have been dealing with this issue for over a year, I have spent thousands and thousands of dollars trying to fix it with no luck at all. I am just about ready to push this thing off of a cliff.

The videos i have are at 2000 and 3000 rpms, but car will act like this at all rpms, there is just no need to take that many videos. (note: i am holding the rpms very very steady, the tach is fixed at 2 and 3 thousand, motor is not revving)

2000 rpms (exactly)http://s279.photobucket.com/al...4.flv

3000 rpms (exactly)http://s279.photobucket.com/al...5.flv

Idle (if you notice, it takes a longggg time for the car to make it back to 14)http://s279.photobucket.com/al...7.flv


Modified by redsx13 at 2:56 PM 1/28/2009

[boro drift]

Looked normal to me, since the gauge is moving, it means the ecu is in closed loop and operating correctly. And the ratios at 2 and 3000rpm seemed good also.

[redsx13]

Looked normal to me, since the gauge is moving, it means the ecu is in closed loop and operating correctly. And the ratios at 2 and 3000rpm seemed good also.

really? it is supposed to fluctuiate like that? look at the one at 3000, you can even hear the motor strain when it moves up and down.

[fast_s13]

how far from your turbo do you have your o2 mounted

[redsx13]

how far from your turbo do you have your o2 mounted

its on the turbo elbow about an inch from the downpipe flange.

[pauliedrft]

AEM recommends it to be 36 inches away from the turbo...

[redsx13]

AEM recommends it to be 36 inches away from the turbo...

this my be true, but that doesent account for the fact that my car is undriveable, idle jumps around all over the place and misses at all rpms. The gauge just confirms the fact that something is wrong. and whatever is wrong is telling the computer improper information, so computer can't decide proper mixture at a set rpm.

here is what i haven't checked........

-harness (i tore mine apart, checked most wires with ohm meter and all looked good, maybe i missed something?)

-O2, would it really cause a problem this drastic?

-CAS

-iacv

any more ideas?

[gixxerbob]

if your wideband o2 sensor is on the turbo elbow where is the factory (narrow band) o2 sensor, the factory sensor is needed for the computer to function propperly. he first t hing i would do if i were you is mount the wideband sensor at the end of the down pipe and make sure the factory sensor is installed properly and works correctly.

if you have the factory sensor installed and correct then i would check fuel pressure or tps/maf..

what motor is it on? red top/black top/s14/s15. if it is a redtop does it have the upgraded fat o2 senor. what is your setup, aem ems? power fc, no tune....give me some info.

[burntricer]

this my be true, but that doesent account for the fact that my car is undriveable, idle jumps around all over the place and misses at all rpms. The gauge just confirms the fact that something is wrong. and whatever is wrong is telling the computer improper information, so computer can't decide proper mixture at a set rpm.

here is what i haven't checked........

-harness (i tore mine apart, checked most wires with ohm meter and all looked good, maybe i missed something?)

-O2, would it really cause a problem this drastic?

-CAS

-iacv

any more ideas?

DUDE!! seriously, replace your harness, you could easily have missed something small, a wire might be corroded inside the insulation!! trust me, your car is doing what mine did

[redsx13]

if your wideband o2 sensor is on the turbo elbow where is the factory (narrow band) o2 sensor, the factory sensor is needed for the computer to function propperly. he first t hing i would do if i were you is mount the wideband sensor at the end of the down pipe and make sure the factory sensor is installed properly and works correctly.

if you have the factory sensor installed and correct then i would check fuel pressure or tps/maf..

what motor is it on? red top/black top/s14/s15. if it is a redtop does it have the upgraded fat o2 senor. what is your setup, aem ems? power fc, no tune....give me some info.

Redtop, fat o2 sensor, I am running a power FC d-jetro, No maf. I will check fuel pressure tomorrow.

but let me assure you, it had this problem before i installed the power FC. The fc was installed to tune the car in hopes of getting rid of the problem.

DUDE!! seriously, replace your harness, you could easily have missed something small, a wire might be corroded inside the insulation!! trust me, your car is doing what mine did

well, i found a new one for 200$ but it is not converted yet, or i can just go with a used one and take the sellers word that it works,OR... i can find someone with an sr that it willing to let me try out their harness, but the problem with that is, i dont know anyone else in my area with an SR. what do you think?


Modified by redsx13 at 6:38 PM 1/29/2009

[Justin35ll]

The ratios don't seem that bad, the way it works is the O2 sensor fluxuates about every half a second making it go lean, rich, lean, rich, lean, rich and so on.Stoichometric a/f ratio is 14.7:1 so a flux from 15.5 to 13.6 doesn't seem to crazy to me. So basically it is impossible to have a steady a/f ratio readingWhy is the car undriveable?

[burntricer]

its really easy to convert it, like super easy, if you can use a soldering gun and heat gun, then your set. i did it in like 4 hours.

[boro drift]

Yup. The fluctuation is the ecu trimming the injector pulse width to obtain a specified air/fuel ratio.

[redsx13]

The ratios don't seem that bad, the way it works is the O2 sensor fluxuates about every half a second making it go lean, rich, lean, rich, lean, rich and so on.Stoichometric a/f ratio is 14.7:1 so a flux from 15.5 to 13.6 doesn't seem to crazy to me. So basically it is impossible to have a steady a/f ratio readingWhy is the car undriveable?

-Car is only boosting around 4-5 psi

-idle has noticeable issues (tends to search up and down, and drops after revving) I do have atmospheric bov, but that would not account for searching idle.

-Very rough, almost sounds like its missing (around once every five seconds)

[jdm_master_X]

check your fuel pressure regulator and check your injector insulators/o-rings. at what rpm ranges does the motor start scavenging?

[Kansei240sx]

DO NOT REMOVE YOUR ENGINE HARNESS OR ANYTHING UNTIL YOU PROPERLY DIAGNOSED ALL CIRCUITS PROPERLY. This can cause alot of money to go down the drain.

Remove your coolant temperature sensor for the ECU. Get a pot of water warmed up to engine operation temp, around 170-190 degrees and place the sensor inside the water, check the resistance of the sensor.

Or if you can have the car running it works too.

Disconnect the sensor and check for these values specifically. *F Resistance68 2.1-2.9122 0.68-1.00176 0.30-0.33

I've seen several SR's not even start or idle rough and stumble all over the place because this sucker is dead.

Check the grounds on all your major sensor inputs and make sure that the voltage reads less than 9mv (.009v), if it is above this value, the sensor needs to be regrounded. To do this, a wire needs to be run from the pin on whatever sensor it is to a new ground.

[redsx13]

DO NOT REMOVE YOUR ENGINE HARNESS OR ANYTHING UNTIL YOU PROPERLY DIAGNOSED ALL CIRCUITS PROPERLY. This can cause alot of money to go down the drain.

Remove your coolant temperature sensor for the ECU. Get a pot of water warmed up to engine operation temp, around 170-190 degrees and place the sensor inside the water, check the resistance of the sensor.

Or if you can have the car running it works too.

Disconnect the sensor and check for these values specifically. *F Resistance68 2.1-2.9122 0.68-1.00176 0.30-0.33

I've seen several SR's not even start or idle rough and stumble all over the place because this sucker is dead.

Check the grounds on all your major sensor inputs and make sure that the voltage reads less than 9mv (.009v), if it is above this value, the sensor needs to be regrounded. To do this, a wire needs to be run from the pin on whatever sensor it is to a new ground.

i actually replaced the computer coolant temp sensor with the working one on my KA24 in hopes it would fix the problem, it didn't. I will go back and check all grounds, and i will let you know what i find.

[Kansei240sx]

SR20DETs are super picky about the grounds.

Did you test the coolant temp sensor like i posted?

Also, where do you have your MAP sensor located? Is it supplied by a vacuum off of the intake manifold, and if so do you have an in-line filter on the feed line to the MAP sensor or is it open to straight incoming pressure changes off the vacuum line.

[redsx13]

SR20DETs are super picky about the grounds.

Did you test the coolant temp sensor like i posted?

Also, where do you have your MAP sensor located? Is it supplied by a vacuum off of the intake manifold, and if so do you have an in-line filter on the feed line to the MAP sensor or is it open to straight incoming pressure changes off the vacuum line.

I checked the coolant temp sensor, its good. .49ohms at like 140*F

my map sensor has no filter, but like i said, the motor ran the same all stock.