SCT X cal 3 issues

Mush-Hog · Oct 26, 2009

I have had my sct tuner for about 2 months now. Messing with it on and off. Been trying to cure some top end rattle from about 3500-6000 rpms. Better than it was. Took timing down from 0-2k down -2 deg. took timing from 2-4k down -4 deg. took timing down from 4-8k down -6 deg. Tuned for +8 a/f ration WOT. Running premium fuel strategy tune and 93 octane in the tank. SOB still rattles like heck on top under a good load. More powerful out of the hole but not so much up top, b/c i have to let off the throttle to stop the detonation.

BTW pinging not near as bad back in warmer weather. Could the cool air be leaning out the engine more, b/c of more O2 density.

Possible remedy..Add 4-5 gallons of 115 octane turbo blue to each tank to raise the octane? OR take more timing out of it?

Is it true that these tuners lean the a/f way out to try and get more power?

specs
4.6NPI engine
auto trans
4.10 gears
BBK CAI
comp xe274h cams/w spring upgrade
o/r x pipe

Dont say its the cam swap. Dosent ping on the 87 or 91 tune.

Thanks for help in advance.

wmburns · Oct 26, 2009

Is your MAF clean? A dirty MAF will over state air flow at low flow. At higher flow, it will under state. This causes the fuel trim to go from big negative values at big positive values at high flows.

If the MAF is dirty, the AF will lean as the actual air flow is greater than the MAF reports. The lean condition will be detected by the O2 sensors. The PCM will add fuel to compensate. There is a delay for this adjustment to take place. Obviously, this could cause pinging at high power levels.

Use the tuner to monitor the short and long term fuel trim. If you notice it going neg at idle and positive at load, then the MAF is dirty.

Use a cleaner made for MAF cleaning. It is fragile and easy to damage.

O2 sensors will respond slower as they age. If > 100k consider changing.

That's a lot of timing to take out and still have problems.

Fuel injectors could be clogged/dirty. I have had good results with injector cleaner services such as Ultrasonic Fuel Injector Cleaning and Flow Testing. Will make them as good as new.

I am sure that you have checked the fuel pressure.

Increased temperature of the air charge. If you CAI, is drawing in excessively hot under hood air this could contribute to pinging.

If the motor is running hot or on the verge of overheating, this can also cause pinging.

twogts4us · Oct 27, 2009

Cooler air typically does not create such a lean condition to cause pinging.
And yes tuners typically will lean out the OEM tune to make power. Understand that the OEM tune is somewhat rich to be on the safe side. The tuners will push you closer to the edge.
Does the problem disappear with the OEM tune? What mods do you have? Have you posed your situation to the folks at SCT and/or on their website's forum? I'm using a Diablo tuner, but I got a lot of help via Diablo's forum.

Mush-Hog · Oct 27, 2009

twogts4us said:
Cooler air typically does not create such a lean condition to cause pinging.
And yes tuners typically will lean out the OEM tune to make power. Understand that the OEM tune is somewhat rich to be on the safe side. The tuners will push you closer to the edge.
Does the problem disappear with the OEM tune? What mods do you have? Have you posed your situation to the folks at SCT and/or on their website's forum? I'm using a Diablo tuner, but I got a lot of help via Diablo's forum.

talked wirt sct, they said to seafoam it. putting in a wideband a/f gauge tomorrow to see exactly whats happening. On the oem setting even the 87 and 91 octane tune im good, on 93 tune is when it starts getting crappy.

Mush-Hog · Oct 27, 2009

wmburns said:
Is your MAF clean? A dirty MAF will over state air flow at low flow. At higher flow, it will under state. This causes the fuel trim to go from big negative values at big positive values at high flows.

If the MAF is dirty, the AF will lean as the actual air flow is greater than the MAF reports. The lean condition will be detected by the O2 sensors. The PCM will add fuel to compensate. There is a delay for this adjustment to take place. Obviously, this could cause pinging at high power levels.

Use the tuner to monitor the short and long term fuel trim. If you notice it going neg at idle and positive at load, then the MAF is dirty.

Use a cleaner made for MAF cleaning. It is fragile and easy to damage.

O2 sensors will respond slower as they age. If > 100k consider changing.

That's a lot of timing to take out and still have problems.

Fuel injectors could be clogged/dirty. I have had good results with injector cleaner services such as Ultrasonic Fuel Injector Cleaning and Flow Testing. Will make them as good as new.

I am sure that you have checked the fuel pressure.

by the sizing chart on the website you linked up, my injectors are too small. I need 24# and only have 19#s on the car, that could cause some trouble.

SCT X cal 3 issues

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