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plz help.. v8 pulls like a 4 banger

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spunky602

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Discussion starter · #1 ·
hi guys.. my friend just bought a used 07 gt which has an unknown intake on it..
anyways.. the car pulls like a 4 banger but the power is not consistant.. and there is a check engine light(p0155) bank 2 sensor 1.. this is what we did so far:
changed oil
changed coolant
replaced spark plugs
replaced fuel filter
replaced fuel pump
replaced BOTH o2 sensors
checked the injectors

connected the battery.. drove for 30 mins and it still has no power and the check engine light came on with the same error (bank2 sensor1)

so i checked the timing with SCT device..
idle:40
full throttle it goes down as the rpm increases untill it hits 9 and stays at 9 for a while but from 6500rpm to 6750rpm it goes from 9 to 15 .. and thats when i can feel some power
i donno what the hell is wrong with this car and am tired.. please help
and the car appears to be tuned using an sct... a guy checked it with hp tuner and took a guess..
other than the power issue.. the car seems to be very normal while not in WOT
any help is appreaciated
 
Discussion starter · #3 ·
mrbigjeep said:
wow for all the money spent on those parts you could have had it correctly diagnosed and found the problem right away before replacing all that stuff.

anyway, good luck with it! they can be a pain
Click to expand...
i had it diagnosed by two mechanics and one tuner
thats why i changed and fuel pump and filter.. wasn't my idea
and they all told me to change the sensors as the ecu is throwing a directly related code
 
#7 ·
On the cheap, buy a new tune and measure the size of the MAF tube in MM to give to the tuner. The car isn't making 40 degrees of timing. Maybe it's commanding 40 degrees of timing. If so than you know that you need a new tune because that's the lazy way to tune so who knows what else is wrong with the tune.. Anything else done to the car? Exhaust?
 
#8 ·
the tune is definately whack but I think there is something else wrong as well. Idling and light throttle being fine and running crappy at WOT sounds like a plug or coil. What plugs did you install and what gap? How many miles on the car? Have you checked the intake tube and manifold for cracks/leaks?
 
#11 ·
I had a similar problem with inconsistent power. Turned out my intake was loose at the TB. Either check the intake or go back to stock.
 
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#13 ·
Cant help you much, but if you havent googled the code here you go.

02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

What does that mean?This code refers to the front oxygen sensor on Bank 2. The heated circuit in the oxygen sensor decreases time needed to enter closed loop. As the O2 heater reaches operating temperature, the oxygen sensor responds by switching according to oxygen content of the exhaust surrounding it. The ECM tracks how long it takes for the oxygen sensor to begin switching. It the ECM determines (based on coolant temp) that too much time elapsed before the oxygen sensor began operating properly, it will set P0155.

Shown here is P0155 obd2 code and a brief analysis on how it is fixed by testing the oxygen sensor heater circuits. Also, please check below the obd2 code listings.

P0155 Engine primary oxygen sensor heater circuit problem

On late 90s imports, you will see this P0155 especially if you have primary and secondary oxgen sensors. The primary oxygen sensors sit at the engine exhaust manifolds whereas the secondary sits at the back of the catalytic converter underneath the vehicle. In this set up, the primary sensors are used to monitor the engine performance and the secondary sensor is used to monitor the catalytic converter. In this code, one of the primary oxygen sensor is at fault and the way to check this is to monitor the voltage signal from the sensor signal wire if they are switching. You can also manually enrich the fuel mixture or make it lean by introducing fuel vapor (use propane gas to do this) in the engine vacuum line. When enriched, the voltage reading should go up around 0.9 v, like wise if you introduce a vacuum leak to make the mixture lean, the voltage reading should go down near zero.


If your oxygen sensor has 4 wires on it, it only means it has a heater circuit on it and it is used by the sensor to make the sensor more responsive to the demands of the engine. The heater usually is a separate circuit of wires that are use to supply power and ground to the heater element inside the sensor. To fix this code is normally done by replacing the sensor if they are more than 50,000 miles old (for older engines) and 100,000 miles for newer engines. If the signal wire does not switch, check the continuity of the signal wire from the sensor to your computer. ATS can supply you a detailed check up for the oxygen sensor for most automotive vehicles until 2005 models.
 
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#14 ·
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#15 ·
NastyStang113 said:
The car isn't making 40 degrees of timing. Maybe it's commanding 40 degrees of timing.
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why not? Its common to see real high timing at low load. I suspect either a vacuum leak, or a crappy tune.
 
Discussion starter · #16 ·
ok guys i have done what you suggested
got some parts from a friend
installed the stock tune + stock airbox and no luck
switched the throttle body with a 2006 gt and still no luck
hp tuner shows that my tps goes up and down at full throttle
it was fluctuating and peaked at 63% .. it was a 2nd gear pull to redline
and hp tuner still shows p0155 error bank 2 sensor 1 which i already replaced

oh and btw we had a hard time passing a hyundai veracruise today lol...
0 - 100 we were head to head with a gmc suburban
so its really bad specially in 1st gear
 
#18 ·
Reading about alot of similar problems, it could be a problem with voltage to or from the sensor, or something like a header leak. Myself, I would let a dealer handle that headache lol.
 
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Discussion starter · #19 ·
Seabee said:
Did you gap the spark plugs to the proper gap? Are all the vacumm lines hooked up? Check the maf wiring and harness.
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idk about gapping.. but my mechanic changed the plugs and it didnt help at all
maf is workin.. i disconnected it and the car died instantly
but vacumm lines?? the one going in the intake near the throttle body? if thats the one yeah its connected.. i just noticed some oil in the intake manifold while changing the throttle body.. donno if thats normal
 
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spunky602
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