o2 Volts drop at WOT!

[Benji]

I've had this problem for months now. I really need to get this fixed since it's starting to get nice out.

91 GSX. 190LPH, Ported 14B and o2 housing, MAF-T 1.3, Blow through, 3" GM MAF, Stock SMIC, Stock Injectors.

At WOT, the o2 Voltage drops between 0.02 to 0.08V. Weird thing is that there is not knock, timing is between 18-22 degrees. The car bucks at this point.

Starting problems are also present. It's worse after you drive it for a while, shut it off and restart it.

Changed the ECU, plugs, wires, Coipack, MAF-T.

Any ideas?

 

[Vegas Smith]

You could have a crappy connection on your fuel pump. Try doing a fuel pump rewire. vfaq.com

 

[Tyler_Baker]

O2 sensor, I had the same problem. It's not a fuel problem otherwise you would be knocking.

 

[DJ23GSX]

Originally posted by Tyler_Baker
O2 sensor, I had the same problem. It's not a fuel problem otherwise you would be knocking.

I was hitting fuel cut and not knocking. This sounds exactly like the problem i just had with my car. It was fuel cut because my boost was creeping to 17-18psi. How much boost are you running?

 

[kpt4321]

Fuel cut has nothing to do with knock. Hitting fuel cut without knocking is nothing abnormal.

My money is on a dead O2 sensor, or wiring.

 

[Benji]

o2 Sensor has been replaced with a Brand new one. It cycles (near) normal at cruise, only drops at WOT!

 

[DJ23GSX]

my car did the same thing even with a new 02 sensor my boost creeps up to 17-18psi and i get a pop. On my logger my timing was between 18-20* 0 knock and my o2's dropped to .02 i unhacked my maf and put the silencer back in my intake and put in the silencer that came with my n1 exhaust and now i have no boost creep and at 12psi i have no pop at all i am willing to bet its fuel cut. Do you have a boost gauge so you can tell us how much boost your running?

 

[awd4g63]

Be sure your ground is hooked up properly on your downpipe. My o2s would hit around .88 when I first got on it, but when I hit boost, I would fall right down to .02 or so. I hooked my ground up properly and it's running fine now. It's worth checking out, might save you from having to buy a new o2 sensor.

 

[Coldandafraid]

same thing happened to me. It was a bad O2 sensor. would cycle normally, then at wot, as I was rich, and the o2 volts approached .98v, any higher and they would suddenly drop to .02v, instead of going to 1.0v. I got a new O2 sensor, and fixed it.

 

[Benji]

I just can't see it being the O2 sensor still as I have replaced it. Anyone think of anything else this could be causing?

 

[DJ23GSX]

This is the third time I ask you HOW MUCH BOOST ARE YOU RUNNING?? I bet with your exhaust your boost is creeping at higher rpms and cause you to hit fuel cut. At what rpm's does your car buck?

 

[Benji]

I used to run about 15 psi but now the car bucks at 8 psi. It can be at any rpm point when this occurs as long as I am starting to build boost.

 

[DJ23GSX]

Do you have a boost gauge or are you going by the one on the dash? How do you run such low boost with 2.5" turbo-back exhaust?? My talon had 2.5" turbo back with a high flow cat and it used to creep to 16-17psi even with a hose going straight from the turbo outlet to the wastegate actuator.

 

[awd4g63]

Originally posted by awd4g63
Be sure your ground is hooked up properly on your downpipe. My o2s would hit around .88 when I first got on it, but when I hit boost, I would fall right down to .02 or so. I hooked my ground up properly and it's running fine now. It's worth checking out, might save you from having to buy a new o2 sensor.

Again, have you checked this out?

 

[Benji]

Originally posted by DJ23GSX
Do you have a boost gauge or are you going by the one on the dash? How do you run such low boost with 2.5" turbo-back exhaust?? My talon had 2.5" turbo back with a high flow cat and it used to creep to 16-17psi even with a hose going straight from the turbo outlet to the wastegate actuator.

I only creep a couple psi at really low temperatures. On a fairly nice day, I have very little to no boost creep!

 

[Benji]

Originally posted by awd4g63
Again, have you checked this out?

I have not yet, but will here shortly. Even though I can't see this being my probelm, it is definately worth checking into!

 

[Talon_Got_Boost]

On my 90 Talon TSI AWD, I had replaced the o2 sensor with a brand new one...problem was I got one from Schucks. If you replaced your o2 with an aftermarket, get an OEM Sensor. My "new" Schucks sensor would not read fast enough at WOT and just fall out, especially up hills. I swapped out with an OEM O2 sensor and everything is fine now.

 

[Benji]

Here are some logs and files for everyone to look at.

Here is the first Log. Below you can also find a link to a picture as well as a txt file for easy viewing.

IDLE ONLY LOG

IDLE LOG

Time, Hz , RPM, IPW ,Knock, o2, TPS ,Timing
0.00, 50.38, 875, 2.56, 0, 0.78, 13.73, 13
0.13, 50.38, 875, 2.56, 0, 0.78, 13.73, 12
0.25, 50.38, 875, 2.56, 0, 0.78, 13.73, 12
0.38, 50.38, 875, 2.56, 0, 0.78, 13.73, 12
0.50, 50.38, 875, 2.56, 0, 0.76, 13.73, 12
0.63, 50.38, 875, 2.56, 0, 0.76, 13.73, 12
0.75, 50.38, 875, 2.56, 0, 0.74, 13.73, 12
0.88, 50.38, 875, 2.56, 0, 0.72, 13.73, 11
1.00, 50.38, 843, 2.56, 0, 0.68, 13.73, 12
1.13, 50.38, 843, 2.56, 0, 0.64, 13.73, 12
1.25, 50.38, 843, 2.56, 0, 0.33, 13.73, 12
1.38, 50.38, 843, 2.56, 0, 0.08, 13.73, 12
1.50, 50.38, 843, 2.56, 0, 0.10, 13.73, 10
1.63, 50.38, 843, 2.56, 0, 0.08, 13.73, 11
1.75, 50.38, 843, 2.56, 0, 0.08, 13.73, 10
1.88, 50.38, 843, 2.56, 0, 0.08, 13.73, 11
2.00, 50.38, 843, 2.56, 0, 0.10, 13.73, 10
2.13, 50.38, 843, 2.56, 0, 0.16, 13.73, 9
2.25, 50.38, 843, 2.56, 0, 0.23, 13.73, 9
2.38, 50.38, 843, 2.56, 0, 0.53, 13.73, 10

Picutes Link: http://www.mustangmods.com/data/71/idle.jpg

Notepad Link: http://benji99.homestead.com/files/Idle.txt

Next up: Cruising and WOT logs

Here is the WOT Log. Below you can also find a link to a picture as well as a txt file for easy viewing.

WOT LOG

Time........Hz.......RPM......IPW.Knock...o2....TPS....Timing
254.66, 233.03, 2406.25, 4.61, 0.00, 0.10, 22.75, 31.00
254.78, 239.33, 2406.25, 4.61, 0.00, 0.68, 22.75, 31.00
254.91, 233.03, 2375.00, 4.61, 0.00, 0.70, 22.75, 31.00
255.03, 239.33, 2375.00, 4.61, 0.00, 0.25, 34.12, 31.00
255.16, 251.92, 2406.25, 6.66, 0.00, 0.04, 71.37, 24.00
255.25, 421.97, 2375.00, 9.22, 0.00, 0.02, 98.82, 22.00
255.38, 421.97, 2375.00, 8.70, 0.00, 0.02, 100.00, 21.00
255.50, 440.86, 2406.25, 8.96, 0.00, 0.00, 100.00, 20.00
255.59, 447.16, 2406.25, 9.22, 0.00, 0.02, 100.00, 19.00
255.72, 453.46, 2406.25, 9.47, 0.00, 0.00, 100.00, 18.00
255.84, 472.35, 2375.00, 9.98, 0.00, 0.00, 100.00, 18.00
255.94, 484.95, 2437.50, 9.73, 0.00, 0.00, 100.00, 18.00
256.06, 484.95, 2406.25, 9.73, 0.00, 0.00, 100.00, 18.00
256.19, 484.95, 2406.25, 9.98, 0.00, 0.00, 100.00, 16.00
256.28, 529.04, 2437.50, 10.75, 0.00, 0.00, 100.00, 15.00
256.41, 529.04, 2375.00, 10.50, 0.00, 0.00, 100.00, 16.00
256.53, 510.14, 2406.25, 12.03, 0.00, 0.00, 100.00, 13.00
256.66, 566.82, 2406.25, 12.54, 0.00, 0.00, 100.00, 11.00
256.78, 610.91, 2437.50, 13.82, 0.00, 0.00, 100.00, 11.00
256.88, 636.10, 2437.50, 14.34, 0.00, 0.02, 100.00, 11.00
257.00, 636.10, 2468.75, 14.34, 0.00, 0.02, 100.00, 11.00
257.09, 636.10, 2437.50, 14.08, 0.00, 0.02, 100.00, 11.00
257.22, 642.40, 2437.50, 14.59, 0.00, 0.00, 100.00, 11.00
257.31, 648.70, 2406.25, 14.59, 0.00, 0.00, 100.00, 11.00
257.41, 648.70, 2406.25, 14.59, 0.00, 0.00, 100.00, 11.00
257.53, 661.29, 2437.50, 14.85, 0.00, 0.00, 100.00, 11.00
257.63, 667.59, 2437.50, 15.10, 0.00, 0.00, 100.00, 11.00
257.75, 667.59, 2437.50, 15.10, 0.00, 0.00, 100.00, 11.00
257.88, 680.19, 2468.75, 15.10, 0.00, 0.00, 100.00, 11.00
258.00, 686.49, 2468.75, 16.64, 0.00, 0.00, 100.00, 10.00
258.09, 787.25, 2468.75, 17.92, 0.00, 0.61, 100.00, 10.00
258.22, 793.55, 2437.50, 17.15, 0.00, 0.70, 100.00, 11.00
258.34, 692.78, 2500.00, 14.85, 0.00, 0.02, 100.00, 11.00
258.44, 673.89, 2500.00, 14.85, 0.00, 0.00, 100.00, 11.00
258.53, 680.19, 2468.75, 15.10, 0.00, 0.00, 100.00, 11.00
258.66, 686.49, 2468.75, 14.85, 0.00, 0.00, 100.00, 11.00
258.78, 680.19, 2437.50, 15.36, 0.00, 0.00, 100.00, 11.00
258.88, 705.38, 2468.75, 15.62, 0.00, 0.00, 100.00, 11.00
259.00, 655.00, 2468.75, 14.08, 0.00, 0.21, 100.00, 11.00

Picture Link: http://www.mustangmods.com/data/71/wot.jpg

Notepad Link: http://benji99.homestead.com/files/WOT.txt

Here is the Cruise Log. Below you can also find a link to a picture as well as a txt file for easy viewing.

CRUISE LOG

Time........Hz.......RPM......IPW.Knock...o2....TPS....Timing
418.81, 138.56, 2625.00, 2.56, 0.00, 0.10, 19.61, 37.00
418.94, 138.56, 2593.75, 2.82, 0.00, 0.06, 19.22, 36.00
419.09, 138.56, 2593.75, 2.56, 0.00, 0.10, 19.22, 36.00
419.22, 138.56, 2593.75, 2.82, 0.00, 0.16, 19.22, 36.00
419.34, 132.26, 2593.75, 2.56, 0.00, 0.64, 19.22, 36.00
419.50, 132.26, 2625.00, 2.56, 0.00, 0.70, 19.22, 37.00
419.63, 132.26, 2593.75, 2.56, 0.00, 0.49, 19.22, 37.00
419.78, 132.26, 2593.75, 2.56, 0.00, 0.06, 19.22, 36.00
419.91, 132.26, 2593.75, 2.56, 0.00, 0.16, 19.22, 37.00
420.06, 132.26, 2625.00, 2.56, 0.00, 0.10, 19.22, 37.00
420.19, 132.26, 2593.75, 2.56, 0.00, 0.61, 19.22, 36.00
420.34, 132.26, 2593.75, 2.56, 0.00, 0.72, 19.22, 37.00
420.47, 132.26, 2593.75, 2.56, 0.00, 0.57, 19.22, 36.00
420.59, 132.26, 2625.00, 2.56, 0.00, 0.31, 19.22, 36.00
420.75, 132.26, 2625.00, 2.56, 0.00, 0.08, 19.22, 37.00
420.88, 125.96, 2593.75, 2.56, 0.00, 0.10, 19.22, 37.00
421.00, 132.26, 2593.75, 2.82, 0.00, 0.21, 19.22, 36.00
421.16, 132.26, 2593.75, 2.56, 0.00, 0.70, 19.22, 36.00
421.28, 132.26, 2593.75, 2.56, 0.00, 0.72, 19.22, 36.00
421.44, 132.26, 2625.00, 2.56, 0.00, 0.29, 19.22, 36.00
421.56, 132.26, 2593.75, 2.56, 0.00, 0.08, 19.22, 36.00
421.72, 132.26, 2593.75, 2.82, 0.00, 0.18, 19.22, 36.00
421.84, 132.26, 2593.75, 2.82, 0.00, 0.63, 19.22, 36.00
421.97, 138.56, 2562.50, 2.56, 0.00, 0.68, 19.22, 36.00
422.13, 132.26, 2593.75, 2.56, 0.00, 0.68, 19.22, 37.00
422.25, 132.26, 2593.75, 2.56, 0.00, 0.06, 19.22, 36.00
422.41, 132.26, 2593.75, 2.82, 0.00, 0.08, 19.22, 36.00
422.53, 138.56, 2562.50, 2.82, 0.00, 0.25, 19.22, 36.00
422.66, 138.56, 2593.75, 2.82, 0.00, 0.70, 19.22, 36.00
422.81, 138.56, 2593.75, 2.56, 0.00, 0.66, 19.22, 36.00
422.94, 132.26, 2562.50, 2.56, 0.00, 0.08, 19.22, 36.00
423.09, 132.26, 2593.75, 2.82, 0.00, 0.06, 19.22, 36.00
423.22, 132.26, 2562.50, 2.82, 0.00, 0.18, 19.22, 36.00
423.34, 138.56, 2593.75, 2.82, 0.00, 0.61, 19.22, 36.00
423.47, 138.56, 2562.50, 2.82, 0.00, 0.72, 19.22, 36.00
423.63, 138.56, 2562.50, 2.82, 0.00, 0.70, 19.61, 36.00
423.75, 138.56, 2562.50, 2.82, 0.00, 0.41, 19.61, 36.00
423.91, 138.56, 2562.50, 2.82, 0.00, 0.10, 19.61, 36.00
424.03, 138.56, 2562.50, 2.82, 0.00, 0.16, 19.61, 36.00
424.16, 138.56, 2593.75, 2.82, 0.00, 0.66, 19.61, 36.00
424.31, 144.85, 2562.50, 2.82, 0.00, 0.70, 19.61, 36.00
424.44, 138.56, 2562.50, 2.82, 0.00, 0.53, 19.61, 36.00
424.59, 144.85, 2593.75, 2.82, 0.00, 0.08, 20.00, 36.00
424.72, 144.85, 2593.75, 2.82, 0.00, 0.12, 20.00, 36.00
424.84, 144.85, 2562.50, 3.07, 0.00, 0.57, 20.00, 36.00
424.97, 144.85, 2562.50, 2.82, 0.00, 0.68, 20.00, 36.00
425.13, 144.85, 2562.50, 2.82, 0.00, 0.55, 20.00, 36.00
425.25, 151.15, 2593.75, 3.07, 0.00, 0.10, 20.00, 36.00
425.41, 151.15, 2562.50, 2.82, 0.00, 0.63, 20.00, 36.00
425.53, 151.15, 2593.75, 2.82, 0.00, 0.55, 20.00, 36.00
425.66, 151.15, 2593.75, 3.07, 0.00, 0.43, 20.00, 36.00
425.81, 151.15, 2562.50, 3.07, 0.00, 0.29, 20.00, 36.00
425.94, 151.15, 2562.50, 3.07, 0.00, 0.64, 20.00, 36.00
426.09, 151.15, 2562.50, 3.07, 0.00, 0.68, 20.39, 36.00
426.22, 151.15, 2562.50, 3.07, 0.00, 0.33, 20.39, 36.00
426.38, 157.45, 2562.50, 3.07, 0.00, 0.08, 20.39, 36.00
426.53, 157.45, 2562.50, 3.07, 0.00, 0.53, 20.39, 36.00
426.66, 157.45, 2562.50, 3.07, 0.00, 0.68, 20.39, 36.00
426.78, 157.45, 2562.50, 3.07, 0.00, 0.39, 20.39, 36.00
426.94, 157.45, 2593.75, 3.07, 0.00, 0.10, 20.39, 36.00
427.06, 157.45, 2562.50, 3.07, 0.00, 0.23, 20.39, 36.00
427.22, 157.45, 2562.50, 3.07, 0.00, 0.64, 20.39, 36.00
427.34, 157.45, 2562.50, 3.07, 0.00, 0.21, 20.39, 36.00
427.47, 157.45, 2562.50, 3.33, 0.00, 0.23, 20.39, 36.00
427.63, 157.45, 2562.50, 3.07, 0.00, 0.68, 20.39, 36.00
427.75, 157.45, 2562.50, 3.07, 0.00, 0.12, 20.78, 36.00
427.88, 157.45, 2562.50, 3.33, 0.00, 0.12, 20.78, 36.00
428.00, 163.75, 2562.50, 3.33, 0.00, 0.10, 21.18, 35.00
428.16, 170.05, 2562.50, 3.33, 0.00, 0.06, 21.57, 35.00
428.28, 176.35, 2562.50, 3.58, 0.00, 0.04, 22.75, 35.00
428.44, 195.24, 2562.50, 4.10, 0.00, 0.06, 22.75, 34.00
428.56, 207.84, 2562.50, 4.35, 0.00, 0.10, 23.14, 33.00
428.72, 214.13, 2562.50, 4.35, 0.00, 0.18, 23.14, 33.00
428.84, 214.13, 2562.50, 4.35, 0.00, 0.70, 23.14, 33.00
428.97, 220.43, 2562.50, 4.35, 0.00, 0.66, 23.14, 33.00
429.13, 220.43, 2562.50, 4.10, 0.00, 0.47, 23.14, 33.00
429.25, 214.13, 2562.50, 4.35, 0.00, 0.08, 23.14, 33.00
429.41, 214.13, 2593.75, 4.35, 0.00, 0.14, 23.14, 33.00
429.56, 220.43, 2593.75, 4.61, 0.00, 0.66, 23.14, 33.00
429.69, 220.43, 2562.50, 4.35, 0.00, 0.74, 22.75, 33.00
429.81, 214.13, 2562.50, 4.10, 0.00, 0.70, 22.75, 33.00
429.97, 214.13, 2562.50, 4.10, 0.00, 0.35, 22.75, 34.00
430.09, 214.13, 2593.75, 4.10, 0.00, 0.06, 22.35, 34.00
430.25, 214.13, 2562.50, 4.35, 0.00, 0.61, 22.35, 34.00
430.38, 214.13, 2593.75, 4.10, 0.00, 0.74, 21.96, 34.00
430.50, 207.84, 2593.75, 4.10, 0.00, 0.76, 21.96, 34.00
430.63, 207.84, 2593.75, 3.84, 0.00, 0.74, 21.96, 34.00
430.75, 201.54, 2562.50, 3.84, 0.00, 0.66, 21.96, 34.00
430.88, 201.54, 2593.75, 3.84, 0.00, 0.33, 21.96, 34.00
431.03, 201.54, 2562.50, 3.84, 0.00, 0.20, 21.96, 34.00
431.16, 195.24, 2562.50, 3.84, 0.00, 0.66, 21.96, 35.00
431.28, 195.24, 2562.50, 3.84, 0.00, 0.43, 21.96, 34.00
431.44, 195.24, 2593.75, 3.84, 0.00, 0.51, 21.57, 34.00
431.56, 195.24, 2593.75, 3.84, 0.00, 0.68, 21.96, 35.00
431.69, 195.24, 2562.50, 3.58, 0.00, 0.47, 21.96, 35.00

Picture Link: http://www.mustangmods.com/data/71/cruise.jpg

Notepad Link: http://benji99.homestead.com/files/cruise.txt

One more and that's it for now.

Here's a link to the complete TMO Log. So if you have TMO ... you can view this: http://benji99.homestead.com/files/BadTestLog.tlg

You should also check out this huge log pic: http://benji99.homestead.com/files/LongLog.jpg

Or download the complete log as an excel spreadsheet: http://benji99.homestead.com/files/BadTestLog.xls

 

[Tyler_Baker]

Originally posted by Talon_Got_Boost
On my 90 Talon TSI AWD, I had replaced the o2 sensor with a brand new one...problem was I got one from Schucks. If you replaced your o2 with an aftermarket, get an OEM Sensor. My "new" Schucks sensor would not read fast enough at WOT and just fall out, especially up hills. I swapped out with an OEM O2 sensor and everything is fine now.

, Never buy electrical parts from CSK auto, I know, I work for them. I too put the Borg Warner O2 sensor in and it died in three days, so I bought one from the dealer, and haven't had any problems. Good luck.