Hmmm...Pulls strong to 4k than sputters to 7k and getting no o2 readings? Need advice

[95RedGST]

My car will run pretty strong till only like 4k than like die out it wont move anywhere after that, at WOT it basically runs like shit. I took it to the shop they hooked the computer up and im getting no O2 reading. So I replaced the front o2 sensor and im still getting the same error. Could this be why my car is running like shit at WOT? If so what could it be if I just replaced the o2 sensor and im still getting that same error?
Oh by the way I have 660's and 255 FP on stock t25 (putting bigger one on soon) It isnt really tuned but I cant tune until I get a o2 reading which I dont have.
Any advice is helpful, thanks.

 

[DSMJim]

Originally posted by 95RedGST
Oh by the way I have 660's and 255 FP on stock t25 (putting bigger one on soon) It isnt really tuned but I cant tune until I get a o2 reading which I dont have.
Any advice is helpful, thanks.

You have 660cc a 255 on a T25 but you do not mention any way of tuning that much fuel. Do you have an adjustable fuel pressure regulator to control the fuel pump and you have a SAFC to control those injectors?

If your lacking one or the other or god forbid both then your running so pig rich your O2 sensors can't get a reading because your out of their range. THey only read a small range (hense a narrow band O2 or the constant need for wide band O2 that we all want to use on our cars to tune them) and your air fuel sounds like it's completly out of wack and so far in fact that your O2 can't even read it.

Please give more details on your fuel system or complete your profile. If you want an answer give us the whole picture, it's pretty hard otherwise...

(why do people do this??? "Hi my car bogs, I have a turbo and 1000cc injectors, what is my problem? aargh!! )

 

[nowayout]

Your running rich. Cforrect it with a AFPR and afc.

If you pull you plug it will be completely black that means too much Fuel.

is your O2 reading 0 or 1.

I had the same problem when my car was running rich with 660 and 780cc.

 

[L2RTSiAWD]

I agree with everyone else.

You are running so rich it's silly.

 

[95RedGST]

I have a FPRL set at 41 psi and I do have a AFC tuned SOMEWHAT for the injectors. Everytime I bring it into the shop for a tune he tells me he cant tune anything because im getting NO o2 reading what so ever, he says my o2 sensor is bad or my ecu or some shit. I just changed my o2 sensor so it cant be that. My air fuel gauge doesnt read AT ALL, no lights or anything, im not getting any o2 response what so ever.

 

[CBgst]

Check your plug wires. If you know someone you trade with real quick that'll be the best way test them. I had the same peoblem and it was the wires. I'm not sure about the o2 sensor though it could have something to do with it. Check your plugs and see what they look like

 

[ninjanick]

Did you check your caps in the ECU? I've heard of some wierd results ie 0V on O2 if the caps are busted/need to be replaced. Try swapping the ECU out with a friends to see if that clears it up. But I'd check the caps if you don't have access to another ECU.

 

[95RedGST]

Ill check the plugs and wires, I got new wires a little bit ago but as for my plugs they are kinda old. Will a 96 AT GST ecu work for my 95 M GST?

 

[Coldandafraid]

same thing is happening to me. But Ive figured it out that it pulls strong until 30% throttle. Then O2 readings drop until at 40% throttle they bottom out. Then, if I turn up the fuel, I get hesitation. So, im guessing Im too rich, but why do I get no O2 reading?

 

[Amallick]

Originally posted by 95RedGST
.....Everytime I bring it into the shop for a tune he tells me he cant tune anything because im getting NO o2 reading what so ever, he says my o2 sensor is bad or my ecu or some shit. I just changed my o2 sensor so it cant be that. My air fuel gauge doesnt read AT ALL, no lights or anything, im not getting any o2 response what so ever....

Does the shop you bring it to tune with your cars o2 sensor? I would think that would be a rather inaccurate way to tune a car. When cars come in to us for a tune, we usually end up welding a bung into the exhaust somewhere and widebanding it. Narrowband was never too precise...

 

[95RedGST]

I dont see why I would get NO o2 reading, even in my air fuel gauge, its just dead, so im thinking its the ECU right?
If so would a 96 auto ecu work for a 95 man? Both gsts.

 

[turbotalon92]

Figure out why you are not getting any o2 readings and your problem is solved. Check the wiring from the o2 plug to the ecu, if you intercept it before the ecu and still get no reading, then you have a break in the wire somewhere. Sounds like that is it, because I am sure your shop is tapping the o2 wire at the ecu. Does this help? If your ECu can't see what the o2 readings are, it will not know what is going on fuel wise and fall into fail safe mode. No check engine light?

 

[95RedGST]

Yup my CEL is on and remained on after i replaced the front o2 sensor, brand new from dealer. But no gauge reading or o2 reading.

 

[95RedGST]

Bump