Engine cutting out at full throttle

[ridered494]

Alright so I have a 03 Cobra with 46,000 miles. I have been having a lot of trouble with it lately from replacing the clutch, battery, alternator, exhaust leaks and now the engine cutting out at full throttle. I have a 02 sensor out, I dont know which one yet, but could this cause the car to not run right at full throttle? I cleared the code when it came on not thinking that I would need it to fix the sensor. What are some possibilities that could be wrong?

MGW short throw
Spec stage 2 clutch
K&N intake
2.8 pulley with idler
Diablo programmer
Accufab throttle body
BBK headers, longtubes
Bassani exhuast

 

[Posi]

How old are the plugs?

 

[ridered494]

just replaced them probably last fall with NGK's becuase the engine was cutting out then to

 

[04cobra13]

check your plugs, and possibly your tune...

 

[Posi]

Checking the plugs is the easiest and cheapest place to start. Then maybe the tune if you've had this problem before.

 

[mofasta]

Wot miss

If you are able to data log let me know, use livelink if possible along with wideband A/F ,I'll give you the configuration file of pids I need you to run and I'll tell you the problem.:coolman:

 

[CAT600]

Alright so I have a 03 Cobra with 46,000 miles. I have been having a lot of trouble with it lately from replacing the clutch, battery, alternator, exhaust leaks and now the engine cutting out at full throttle. I have a 02 sensor out, I dont know which one yet, but could this cause the car to not run right at full throttle? I cleared the code when it came on not thinking that I would need it to fix the sensor. What are some possibilities that could be wrong?

MGW short throw
Spec stage 2 clutch
K&N intake
2.8 pulley with idler
Diablo programmer
Accufab throttle body
BBK headers, londtubes
Bassani exhuast

My engine was doing this on the dyno after I put the Mammoth kit on. Turned out that the TPS was seeing almost 8V supply instead of 5V, and the TPS sensor signal return to the PCM was going past 4.5V at WOT and cutting the engine completely, almost exactly the same as cutting the coil B+ wire at full load..... DEAD.

Daniel

 

[ridered494]

the only problem with that is that when I bought the car it already was tuned and dynoed or atleast thats wut I wsa told. So the question is will the o2 sensor have any link to this? I just changed the plugs maybe 4 months ago or somewhere around there so could they have gone bad again? And if I need to can I help the tune with my programmer or take it to someone?

 

[thomas91169]

whats the gap on the plugs? with those mods, im thinking it should be .028-.032, maybe a bit wider if its a Iridium. Which plugs are you running btw?

drive the car a bit, if the o2 sensor is dead, the code should come back in a few miles, and itll tell which bank and which sensor (front or rear) is dead. its usually always the front o2 sensors, as they are the only ones that would hve any effect on driveability when they go out.

 

[Posi]

the only problem with that is that when I bought the car it already was tuned and dynoed or atleast thats wut I wsa told. So the question is will the o2 sensor have any link to this? I just changed the plugs maybe 4 months ago or somewhere around there so could they have gone bad again? And if I need to can I help the tune with my programmer or take it to someone?

It's a $6,000 engine so pretty much never trust that it was "supposedly" tuned. I'm not saying it wasn't but it might not be a good tune either or just need to be tweaked. Did you get the handheld with it? At least find a local dyno and it'll cost you less than $100 to have them make maybe 3 pulls and datalog. You owe it to yourself and the car. When you think about it $100 is pretty cheap insurance.

 

[03cobra#694]

My engine was doing this on the dyno after I put the Mammoth kit on. Turned out that the TPS was seeing almost 8V supply instead of 5V, and the TPS sensor signal return to the PCM was going past 4.5V at WOT and cutting the engine completely, almost exactly the same as cutting the coil B+ wire at full load..... DEAD.

Daniel

What did you do to fix this,change the TPS?

It's a $6,000 engine so pretty much never trust that it was "supposedly" tuned. I'm not saying it wasn't but it might not be a good tune either or just need to be tweaked. Did you get the handheld with it? At least find a local dyno and it'll cost you less than $100 to have them make maybe 3 pulls and datalog. You owe it to yourself and the car. When you think about it $100 is pretty cheap insurance.

+1,000

 

[rotor_powerd]

Check your plug gap.

As it's been getting colder, my car has been blowing out spark on the really cold days. Gapped my plugs down to .36, and it's good to go.

 

[ridered494]

Ya I do have the hand held programmer. And I will have to get started checking some things.

 

[ridered494]

well i just went and programmed the front o2 sensor out and changed the tune from a 91 octane pulley tune to just a pulley tune on the programmer. I cannot figure out y it would be set up for 91 since everyone always uses 93. but the car is screaming now so we see if this fixed the problem. Also be4 when the o2 sensor was out my gas milage dropped from 17 to 12 so this tank should tell me if the sensor is really out. thanks for your help if you have any more ideas let me kno.

 

[Relaxed Chaos]

Nothing more dangerous to a boosted engine than a guy messing with his tune without knowing what he is doing.

Be careful.

 

[thomas91169]

well i just went and programmed the front o2 sensor out and changed the tune from a 91 octane pulley tune to just a pulley tune on the programmer. I cannot figure out y it would be set up for 91 since everyone always uses 93. but the car is screaming now so we see if this fixed the problem. Also be4 when the o2 sensor was out my gas milage dropped from 17 to 12 so this tank should tell me if the sensor is really out. thanks for your help if you have any more ideas let me kno.

umm, well since 91 is the minimum octane anyone would run, then using the 91 tune with 93 will only mean you are safer.

Id like to know what the timing and a/f curves are for both tunes before ****ing with them. I see a blown motor in the future if you are just swapping crappy handheld canned tunes on a whim. Those tunes really are only good for getting you from your garage to the nearest dyno for an actual dynotune session. Unless you have a wideband 02 and knowledge in tuning, take it to the pros.

 

[Evilspyderman]

umm, well since 91 is the minimum octane anyone would run, then using the 91 tune with 93 will only mean you are safer.

Id like to know what the timing and a/f curves are for both tunes before ****ing with them. I see a blown motor in the future if you are just swapping crappy handheld canned tunes on a whim. Those tunes really are only good for getting you from your garage to the nearest dyno for an actual dynotune session. Unless you have a wideband 02 and knowledge in tuning, take it to the pros.

+1,000,000

 

[jm@ReischePerf]

How do you tune a front o2 sensor out, I'm pretty sure the handhelds can only delete the post cat sensors? At WOT the o2 sensors should be out of the loop anyway, however yes, a bad front sensor will hurt mileage.