Still having 02 sensor/bad mpg problems. - 3000GT/Stealth International Message Center

BSAS3000GT · 09-10-2008, 09:47 AM

Hey, its me again. Im still experiencing 02 sensor problems, and bad MPG mostly driving around the city. I get an average of 12 MPG all city, and around 18 highway/city.

Since I dont have a laptop PC i had to borrow one from a friend to make some logs. I dont know how to post the logs here, so if anyone could help me out that would be much appreciated (Im logging with the HHH hybrid datalogger).

The problems that i saw were the following:

At cold start up:

-Before starting the car, the front 02 sensor was already at 0.03V, while the rear was at 0.00V
-After 30 seconds, the rear 02 began cycling. It cycled from 0.03V to 0.82V max.
-Even after 5 minutes, the front 02 was reading 0.05V, and was not cycling. (The front 02 sensor is new)
-The Mass air flow sensor moved back and forth from 44HZ to 50HZ every 5 seconds approx.

After the car gets to operating temperature, everything remains the same as described above.

While cruising:

-The front 02 comes to life, and it cycles from 0.11V to 0.83V. It doesnt cycle as fast as the rear one, and the graph looks more like a valley, not so sharp as graph of the rear 02.

I also did a log while the car was deacceleration (no brakes used, only engine), and the rear 02 sensor got down to 0.00V, while the front only went down to 0.07V and stayed there. Also, IDC and IPW went down to 0.

Im really lost because the front 02 sensor is new, I installed it around 6 months ago. Its a bosch replacement sensor if that matters. Any help is appreciated. I really need to get the car running right, now more than ever with the gas prices. Thanks again,

Manuel

Rom3BreaK · 09-10-2008, 10:10 AM

I'm having a very similar problem (but with the rear). I have no idea if I'm correct but I'm giving this a shot:

It seemed I was running richer since my clutch/tranny rebuild. Eventually the rear O2 wouldn't cycle correctly. I had also installed an ebc and bov...basically a bunch of stuff which had me messing with the vac tubing. It's my thought that I have a lot of intake leaks thus causing me to run rich which may have clogged the new O2 sensor upon replacement of the old one that stopped cycling.

I just bought a pressure tester figuring it might help me solve this problem, plus it's always good to pressure test anyways. I believe I read somewhere that it is possible to burn off extra carbon buildup on the O2's after a few wot runs, and I did notice that after I gunned it down the road once or twice it would come alive for a little while.

So yeah, I'm gonna pressure test when I get a weekend off from work (college during the week, so I'm not at home). If nobody has any other solutions for us, I'll just have to let you know how this goes for me.

Oh and very important, don't log for O2's soon after start-up. The system isn't warmed up yet and isn't using the O2's fully for a/f information yet. Run for five minutes or so before logging the O2's (this may be a liberal amount of time, basically the system needs to be brought up to operating temp).

BSAS3000GT · 09-10-2008, 10:24 AM

Quote:

Originally Posted by Rom3BreaK

I'm having a very similar problem (but with the rear). I have no idea if I'm correct but I'm giving this a shot:

It seemed I was running richer since my clutch/tranny rebuild. Eventually the rear O2 wouldn't cycle correctly. I had also installed an ebc and bov...basically a bunch of stuff which had me messing with the vac tubing. It's my thought that I have a lot of intake leaks thus causing me to run rich which may have clogged the new O2 sensor upon replacement of the old one that stopped cycling.

I just bought a pressure tester figuring it might help me solve this problem, plus it's always good to pressure test anyways. I believe I read somewhere that it is possible to burn off extra carbon buildup on the O2's after a few wot runs, and I did notice that after I gunned it down the road once or twice it would come alive for a little while.

So yeah, I'm gonna pressure test when I get a weekend off from work (college during the week, so I'm not at home). If nobody has any other solutions for us, I'll just have to let you know how this goes for me.

Oh and very important, don't log for O2's soon after start-up. The system isn't warmed up yet and isn't using the O2's fully for a/f information yet. Run for five minutes or so before logging the O2's (this may be a liberal amount of time, basically the system needs to be brought up to operating temp).

Thanks for sharing, it seems that we have the same problem. Try pressure testing and see if that resolved your issues. As for me, i dont have a single leak. I have pressure tested as many times as i could and fixed all my leaks, even the TB o-rings are new.

I will do some WOT runs and see if that helps a bit, thanks for the suggestion.

And about the 02 cycling at start up, they are supposed to begin cycling shortly after start-up. They should begin cycling BOTH around the same time, and thats my problem. The rear one seems fine, while the front one does not.

BSAS3000GT · 09-10-2008, 12:33 PM

I also checked the injectors with the dataloger. When i shut off injectors 2,3,4 and 6, the car misses but the missing is similar in every injector. The missing in injector 1 is almost the same as 2,3,4 and 6, just slightly different. But the missing in injector 5 doesnt sound similar to the other injectors. It misses, but without great intensity. Could i have sticky injectors? 1 and 5? Both are on the front bank, thus maybe explaining why the front 02 sensor doesnt cycle so well. Thoughts?

BSAS3000GT · 09-11-2008, 07:08 AM

bump...

OhioSpyderman · 09-11-2008, 07:30 AM

Was the Bosch replacement Plug and Play?

Its not that hard to pull the injector and check them for signs of clogging (just make sure you don't lose those damned fuel line spacers!!!).

Bob.

BSAS3000GT · 09-11-2008, 12:30 PM

Quote:

Originally Posted by OhioSpyderman

Was the Bosch replacement Plug and Play?

Its not that hard to pull the injector and check them for signs of clogging (just make sure you don't lose those damned fuel line spacers!!!).

Bob.

Yes, the Bosch one was a replacement plug and play I bought from advance auto. It also shows the same behavior that the previous sensor did, which led me to believe the problem should be something else, not the sensor.

How can I check the injector? Just by looking a the tips and see if there anything there?

Also, how can i check the heater circuit for the 02 sensor? If i have a bad heater circuit, that could explain why the 02 doesnt cycle right after start up (like the rear one).

Thanks for the suggestions Bob, and I will try not to lose any spacers! Ive already gone through that with my base

BSAS3000GT · 09-12-2008, 09:24 AM

anyone knows how to check the 02 heater circuit??

And if i find the front 02 sensor heater circuit to be bad, can I run a jumper wire from the rear 02 heater circuit to the front one to see if that works? Can i damage something?

BSAS3000GT · 09-12-2008, 08:48 PM

I was talking to a friend of mine and he told it was possible that i had an exhaust leak before the 02 sensor, and thats maybe why the 02 sensor does not cycle so well. How could I check for exhaust leaks?

I had my front exhaust manifold replaced because it was cracked, maybe the new one is not torqued enough and it leaks?

OhioSpyderman · 09-13-2008, 05:59 AM

Maybe THIS will help.....

09-10-2008, 09:47 AM	#1 (permalink)
BSAS3000GT Argentine 3KGT Join Date: May 2007 Location: Miami Drives: 94 Red VR4 Trader Rating: (32)	Still having 02 sensor/bad mpg problems. Hey, its me again. Im still experiencing 02 sensor problems, and bad MPG mostly driving around the city. I get an average of 12 MPG all city, and around 18 highway/city. Since I dont have a laptop PC i had to borrow one from a friend to make some logs. I dont know how to post the logs here, so if anyone could help me out that would be much appreciated (Im logging with the HHH hybrid datalogger). The problems that i saw were the following: At cold start up: -Before starting the car, the front 02 sensor was already at 0.03V, while the rear was at 0.00V -After 30 seconds, the rear 02 began cycling. It cycled from 0.03V to 0.82V max. -Even after 5 minutes, the front 02 was reading 0.05V, and was not cycling. (The front 02 sensor is new) -The Mass air flow sensor moved back and forth from 44HZ to 50HZ every 5 seconds approx. After the car gets to operating temperature, everything remains the same as described above. While cruising: -The front 02 comes to life, and it cycles from 0.11V to 0.83V. It doesnt cycle as fast as the rear one, and the graph looks more like a valley, not so sharp as graph of the rear 02. I also did a log while the car was deacceleration (no brakes used, only engine), and the rear 02 sensor got down to 0.00V, while the front only went down to 0.07V and stayed there. Also, IDC and IPW went down to 0. Im really lost because the front 02 sensor is new, I installed it around 6 months ago. Its a bosch replacement sensor if that matters. Any help is appreciated. I really need to get the car running right, now more than ever with the gas prices. Thanks again, Manuel __________________ --> 1994 Mitsubishi 3000GT VR4 <-- Performance: 4.5" Air Intake W/3SX MAF Adapter, Red Aluminum Pre-Turbo Intake Pipes, Ebay Aluminum Y-Pipe, Greddy Knock-Off Type S BOV, Joe P. Boost Controller, Vacuum Reduction Mod, Clutch Assistant Delete, 3SX EGR Block-Off Plates, NGK Spark Plug Wires, NGK BCP-7ES Plugs Gapped at .36, In-Bay Fuel Pressure Gauge, Gutted Pre-Cats, 3SX Downpipe, Maximal Performance Test Pipe, HHH Datalogger Exterior: 99 Front End Conversion, 3SX HID's 6000K, Red Calipers, 20% Tints Interior: Cianci Fiberglass A-Pillars 52x3, Radio Gauge Pod 52x3, Water Temp Gauge, Oil Pressure Gauge, Oil Temp Gauge, Red/Black Shifter and E-Brake Boot, Pioneer DEH-P6800MP Stereo, 6x9 X-PLOD Rear Speakers Waiting to install: 3SX Braided Clutch Line 95 Base 3KGT TT Converted Part out PM me Last edited by BSAS3000GT : 09-16-2008 at 11:11 AM.

09-10-2008, 10:10 AM	#2 (permalink)
Rom3BreaK Verified Seller Join Date: May 2007 Location: Northern CT Drives: Mitsu 92 VR4 Trader Rating: (7)	Re: Still having 02 sensor/bad mpg problems. I'm having a very similar problem (but with the rear). I have no idea if I'm correct but I'm giving this a shot: It seemed I was running richer since my clutch/tranny rebuild. Eventually the rear O2 wouldn't cycle correctly. I had also installed an ebc and bov...basically a bunch of stuff which had me messing with the vac tubing. It's my thought that I have a lot of intake leaks thus causing me to run rich which may have clogged the new O2 sensor upon replacement of the old one that stopped cycling. I just bought a pressure tester figuring it might help me solve this problem, plus it's always good to pressure test anyways. I believe I read somewhere that it is possible to burn off extra carbon buildup on the O2's after a few wot runs, and I did notice that after I gunned it down the road once or twice it would come alive for a little while. So yeah, I'm gonna pressure test when I get a weekend off from work (college during the week, so I'm not at home). If nobody has any other solutions for us, I'll just have to let you know how this goes for me. Oh and very important, don't log for O2's soon after start-up. The system isn't warmed up yet and isn't using the O2's fully for a/f information yet. Run for five minutes or so before logging the O2's (this may be a liberal amount of time, basically the system needs to be brought up to operating temp). __________________ 1992 VR4, Java Black Pearl paint ('04 STI) with combo '92/'96/'99 custom front end, Fittipaldi Force wheels, RPS Max pressure plate with street disk, P.I.T. BCU+ EBC, Gutted pre-cats, Greddy type RS BOV, K&N intake. Currently working a minimum wage job to get my 3s back to 100% (again) as well as pay for tuition....AKA the stereotypical proud 3si member.

09-10-2008, 12:33 PM	#4 (permalink)
BSAS3000GT Argentine 3KGT Join Date: May 2007 Location: Miami Drives: 94 Red VR4 Trader Rating: (32)	Re: Still having 02 sensor/bad mpg problems. I also checked the injectors with the dataloger. When i shut off injectors 2,3,4 and 6, the car misses but the missing is similar in every injector. The missing in injector 1 is almost the same as 2,3,4 and 6, just slightly different. But the missing in injector 5 doesnt sound similar to the other injectors. It misses, but without great intensity. Could i have sticky injectors? 1 and 5? Both are on the front bank, thus maybe explaining why the front 02 sensor doesnt cycle so well. Thoughts?

09-11-2008, 07:08 AM	#5 (permalink)
BSAS3000GT Argentine 3KGT Join Date: May 2007 Location: Miami Drives: 94 Red VR4 Trader Rating: (32)	Re: Still having 02 sensor/bad mpg problems. bump...

09-12-2008, 09:24 AM	#8 (permalink)
BSAS3000GT Argentine 3KGT Join Date: May 2007 Location: Miami Drives: 94 Red VR4 Trader Rating: (32)	Re: Still having 02 sensor/bad mpg problems. anyone knows how to check the 02 heater circuit?? And if i find the front 02 sensor heater circuit to be bad, can I run a jumper wire from the rear 02 heater circuit to the front one to see if that works? Can i damage something? Last edited by BSAS3000GT : 09-12-2008 at 09:53 AM.

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09-12-2008, 08:48 PM	#9 (permalink)
BSAS3000GT Argentine 3KGT Join Date: May 2007 Location: Miami Drives: 94 Red VR4 Trader Rating: (32)	Re: Still having 02 sensor/bad mpg problems. I was talking to a friend of mine and he told it was possible that i had an exhaust leak before the 02 sensor, and thats maybe why the 02 sensor does not cycle so well. How could I check for exhaust leaks? I had my front exhaust manifold replaced because it was cracked, maybe the new one is not torqued enough and it leaks?