Gutless over 4500rpm

[crunchymilk55]

A fluctuating 02 signal is completely normal. When the car is under "closed loop" mode, that is, when you're not giving it much gas, the ecu and 02 sensor work together to keep the a/f where it needs to be. Once you give it some gas, the car will enter "open loop" mode, where the ecu just sends out a predetermined amount of fuel. Jumping all over the place does mean back and forth right?

[blk_srt]

Yeah, I have a log with the o2 signal and st fuel trim and such but I havent figured out how to upload it yet(just got it yesterday). What your saying makes scence and I really should have remembered that considering I just spend a whole semester talking about it lol.

[clipsekid99]

Would the crapped out o2 sensor throw a CEL? Cause I'm still getting shit gas mileage even though I am "tuned" with a safc, and I don't have a CEL. Would this be something to look into also?

[crunchymilk55]

Originally Posted by clipsekid99

Would the crapped out o2 sensor throw a CEL? Cause I'm still getting shit gas mileage even though I am "tuned" with a safc, and I don't have a CEL. Would this be something to look into also?

Who did your tune? I've seen first hand some shops, even some of the good ones, just remove some fuel at higher rpms and call it a "street tune" An 02 sensor usually doesn't send out a CEL. My suggestion is to go ahead and replace the 02 sensor, it's around 50 bucks, and could be a reason your car is not performing right. What do you mean by "shit gas mileage", are you on the turbo alot? The T25 is damn hard to stay off the turbo on.

[clipsekid99]

Originally Posted by crunchymilk55

Who did your tune? I've seen first hand some shops, even some of the good ones, just remove some fuel at higher rpms and call it a "street tune" An 02 sensor usually doesn't send out a CEL. My suggestion is to go ahead and replace the 02 sensor, it's around 50 bucks, and could be a reason your car is not performing right. What do you mean by "shit gas mileage", are you on the turbo alot? The T25 is damn hard to stay off the turbo on.

Well, 3 days a week, I drive ~13 miles both ways to school, and the usual driving around and to work which is 3 minutes from my house. I don't push it really. Most of the time I try to watch the boost gauge and not accelerate fast enough for the needle to pass 0 into the boost range.

EDIT: Which o2 sensor would it be? The one in the cat, or the one in the o2 sensor housing?

[blk_srt]

So I went to put in my O2 today and it came out great but I went to put the new one in and it was totally different so I took it back and after 15 minutes of trying to figure out why its not right we look it up in a book and apparently the previous owner had swapped a 98 engine and wire harness(w/eprom ecu) into my 95 so the sensor changed, went from $50 to $125

[clipsekid99]

http://www.oxygensensors.com/ Are these guys any good, or should I just go to satan and get an OE one?

[crunchymilk55]

the ones they sell at car parts stores work fine. I believe denso has one that can take leaded fuel even.

It's the 02 sensor in the 02 housing, the sensor on the downpipe just makes sure the cat is there.

[clipsekid99]

Alrighty then. Thanks crunchy.

[crunchymilk55]

Originally Posted by clipsekid99

Alrighty then. Thanks crunchy.

no problem

[xavier3jr]

you know ur car crunchy lol much respect

so pr_ricer did u ever get it changed? what happend?

[blk_srt]

I'm waiting on the o2 to come in still. The one I got was for a 95 but apparently I have a 98 motor with a complete wire harness and the sensors changed in 97 so instead of having the right one for $50 in my hand I had to special order the right one and it was $100 and it wont be in untill tomorrow. Funny thing is since my car is running rich hard core I dont have a misfire at idle problem lol. hopfully it will be in tomorrow and I'll throw it on quick and let you know if that solved the problem

[blk_srt]

Today I did a boost leak test and found 3 major leaks and my system would only hold about 5 psi. I fixed those and it held all the way to 19psi and I got it on the road and it studdered really bad untill 4500rpm(exact oppsite of before lol) So I get on the highway and it just flys. I must of had this leak since I got the car becuase I never remember it being that fast. Anyway I made it about 5 miles untill I relized why it was acting funny still, I forgot to plug in the mas lol. after that it ran fine but it idles really high(1600rpm) with the mas unplugged it was idling smooth at about 950rpm, I thought it was kind of weird that it idles better without the mas. Could there be sometehing wrong with it?

[crunchymilk55]

haha I have to admit I forgot to plug in the MAS once, that was fun!

I'm glad you ran the boost leak test. Here's the deal, you were running SO rich while you had that leak, think about how much air you were losing if you could only hold 5 psi, think about how hard your turbo was overworking...boost leaks are killer man. Eventually your ECU got used to running to rich. Unplug your battery and leave it for about 10 minutes. This will reset your ECU and force it to relearn now that your air/fuel values are closer to what they should be. This will fix the idle to, the car's ECU will relearn what it needs to. It might take a while though, if the idle is still to high, adjust via biss screw. You could have been leaking so bad that the car was grabbing extra air through the boost leaks at idle, and the ECU figured out how to make it idle at 950.

O yeah, don't try to be a badass and change the 02 sensor while the car is still hot. I thought I could do it, bad decision.

[blk_srt]

lol, I know the feeling, I accidently brushed my hand against the manifold after driving it for a half hour. Didnt blister, just fried the skin like kfc lol