2004 STI Possible TPS issue

[Bioya]

I was just talking to the guys at my old job. Im trying to get the actual test, but when I looked quickly, b1s1 IS a wideband sensor and the range is 0-8v. I can not confirm that yet, they are busy and I dont work there but ill get the actual test.

[klarowe]

How does that sensor look to you? It had a couple spots that were lighter and looked almost "dry" but I'm really not sure what its supposed to look like. Either way I ended up ordering a new sensor to make sure it would be here by tomorrow... and according to advance auto and a few other online retailers, it is the correct sensor for that car and that location. Seemed to be a little "inexpensive" to be wideband though (only ran about $90) but it has the same blue covering and looked identical...

[Bioya]

Ive never had good luck with aftermarket o2 sensors, always used OE.

The o2 looks fine, but.that doesnt mean much.

The troublesheet says do not replace the o2 for that code.
First step is to clean the MAF.

[klarowe]

I already ordered the sensor because I didn't want to take a chance of it being the issue and not being able to get it this weekend. It is a Denso sensor which from everything I can find, the OEM sensor is also Denso with the same part number so it SHOULD be OE.

I cleaned the MAF earlier in the week and it didn't seem to change anything. The only thing I did change (after the issue had already been going on, but before I actually got the engine light) is that I soldered the wire connection to the MAF for the Meth/H2O injection, and changed the connection by the pump to the opposite side of the plug so that I could remove the pump / tank assembly if ever needed. The only thing I'm thinking is that possibly the solder caused added resistance in the line and the ECU is no longer getting a proper signal; but that would be a long shot.

[Iant333]

I would double check the info you got about b1s1 being a wideband. For one i've heard 100000 times that it isnt.
The sensor looks 100% fine. I've seen a handful of failed ones and none of them had any visual indication of an issue.




I guess you will find out your problem for sure when you get the new one though. Just unhook the battery for a bit to clear the PCM memory before you put the new one in.

[KA_Killuh]

When I hear "OEM" I think dealership.  Freddy is a huge asset to this community, and he can get you the right parts at the right price.  I have worked in many dealerships (including Capitaland) and have never seen such a dedicated parts manager.  When I had my Subaru, I bought everything from Capitaland, including oil filters, coolant, nuts/bolts, gaskets, etc. 


Anyway, don't buy things like 02 sensors from Napa unless it's for your beater car.  This thing makes how much horsepower??  Don't cheap out on the details. 

End of rant.  Hope your car feels better.

[klarowe]

But what is the difference between a dealership purchased Denso o2 sensor or the exact same Denso sensor bought elsewhere? I agree that Freddy is a great asset and I don't know why I didn't think of it, but still, the same o2 sensor from 2 different sources shouldn't matter. Same with the spark plugs. I bought them from the dealer at $15 each when I could have gotten the exact same part numbers for around $10 each or less.They were just NGK plugs...

[klarowe]

But normally I would agree with you. On most other parts like that I prefer going to the dealership if I can't find the same part number.

[klarowe]

Well I'm not going to throw a party yet, but I think it's good. Got the new o2 sensor about an hour ago, went out and threw it in quick, reconnected the battery and went for a 2mile quick test drive. Tried like hell to get it to hiccup or mis and couldn't get it to do either. And it was much more predominant when the engine was cold. I don't want to jump to conclusions just yet because the ECU still needs to relearn everything, but hopefully the o2 sensor was the culprit. I'll keep you guys updated!

[klarowe]

Well I just had to run a bunch of errands so I was driving around for about an hour or 2 and it never once had a single stutter / hesitation / hiccup so I think its safe to assume all is well. She seems to be running a lot more smooth too. So glad it ended up being something "minor". Thanks for all your guys' help!!!

[hydrochloric]

Glad to hear it's fixed.


Still think it's a wideband...

[Iant333]

Glad to hear it's fixed.


Still think it's a wideband...

I promise you that it is not. Wideband o2's werent even invented until 1996. Your 99 RS didn't have one.

I did some research:

Basically some Subarus (STI) came with something like a half assed attempt at a wideband that only reads till like 11.5:1 and still outputs a narrowband style 1v signal. They are much better than most narrowbands which piss out around 13:1 but they aren't good enough for tuning with. I think the Bosch wideband I have on my RS says it will read to 9:1 which is rich beyond what any car should ever run at lol.



Anyways, nice to see the car is fixed.

[hydrochloric]

I promise you that it is not. Wideband o2's werent even invented until 1996. Your 99 RS didn't have one.

I did some research:

Basically some Subarus (STI) came with something like a half assed attempt at a wideband that only reads till like 11.5:1 and still outputs a narrowband style 1v signal. They are much better than most narrowbands which piss out around 13:1 but they aren't good enough for tuning with. I think the Bosch wideband I have on my RS says it will read to 9:1 which is rich beyond what any car should ever run at lol.

It's a '00, but I get the point.     It may not be a true wideband, but I know from reading the voltages from FuzzyCar, the front o2 puts out a way higher voltage than the rear (which is a narrow).  It sits at 1.3V (which is higher than a narrow should ever be, right?), IIRC, compared to about 0.4.  I also know it's listed as a Bosch Wideband, but maybe its one of these half-wides.

Anyway, I'll stop asking about it.  It runs, that's enough for me for now. 

[RedRoof2]

Do me a favor, Kenny.  Grab your ST and LT fuel trims now that you've got the O2 issue resolved and see what they are.   11% is a long way off and I'm hoping that's a result of a dead O2 and not improperly scaled squirters. 

[klarowe]

Will do. Thanks for the heads up. As you know, I've always been an offroad guy so I never really got into tuning and performance (since you really don't need a ton of motor with mild to moderate wheeling). All this shit is still foreign to me... lol. I'll try to get that tonight and let you know.