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Discussion Starter · #1 ·
I'm having what i think is spark blowout in the upper rpms. say from 5k and up. Hard to explain the sound but it starts to feel kinda rough up till redline. From what i was told when i dyno'd last the lines started getting choppy up in those high rpms and that was why. Not sure if the two issues are even related or not. I just installed my NGK tr6's and gapped them to .40 but still seam to be having the same problem. My a/f was kinda lean in the lower rpm's but was safe in the upper ones. Before i had the MAFterburner adjusting my a/f but now that i got the Predator i'm using the Pulley tune and i zero'd out all my settings on the MAFterburner for now. It also did it before I got the Predator and after. I need to get it dyno'd with the Predator but from what i hear the Pulley tune should be pretty safe for me considering i'm just running the 3.10 pulley right now. I'm not sure if i need to change the gapping on the plugs or what. Any input or advise would be appreciated.

Current mods are:

Densecharger
Magnaflow X w/cats
Magnaflow catback
3.10 pulley
NGK tr6's gapped @ .40
Predator Pulley tune
MAFterburner (turned off for now)
 

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Not sure what to say, I have never had a fuel problem with my car, even running the 2.93 and no chip. I have always run NGK TR6's @ .035 - .040 I have ran them at both gaps and never had a stumble in the higer rpm's.

On your predator take a look at your 02 voltage and see if its dropping off alot from 5000rpm + if it does, this could indicate a lean condition. Your 02's should hang out around .90-.94v and stay steady. If it drops could be lean like into the low .8x area or high .7x area.

Not sure what to tell you, other than maybe recheck plug gap, make sure maf connection is tight etc. Coil on plugs. Good Luck and keep is posted.
 

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I too am having a similiar problem, but mine is noticable at low RPMs.

Sounds like a random mis. My car started it when I did all the mods. Could be the plugs perhaps. I'll be on the dyno tommorrow and will get it checked out.

Mine is most noticable at 2,000 RPMs. You can hear sort of a pop in the exhaust, and the engine will shudder. Not real bad, but its not normal.
 

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Eric, which intake kit do you have? Do you only notice this when your car is mainly cold, and it doesn't do it as bad when it warms up?

My 1st '03 was horrible about this at all times. It felt like a bad miss, like you described, in the low rpms cruising in a low gear. What was weird is that I hardly felt it in a higher gear cruising at lower speeds. My 2nd '03 I drive now doesn't do it hardly at all, although sometimes I do think I feel a slight miss. My car is basically bone stock, and it does it with or w/out tuning. I notice it when the car is basically cold, but when it warms up I don't think I notice it at all.

Oh, I wanted to add, thanks to the Predator I no longer have the surge or having to worry about the car going dead while coming to a stop, anymore!!! WOOHOO!!!

Sincerely...
 

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Discussion Starter · #7 ·
Thanks for the tips guys! I'll try to datalog the 02 Voltage and see how that is and if thats ok i'll remove the densecharger and put the stock airbox back in and see if that helps. I'll let ya know how it turns out.
 

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how much timing do you have in it? when on the dyno have someone watch the tailpipes too, it may puff out smoke up high if detonating.

.40 seems about right.
 

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Discussion Starter · #9 ·
Ok guys, i'm trying to do the datalogging on the Predator but i'm having a hard time finding where the 02 Voltage is? Which catagory is it under etc? And also i see where it shows the spark advance on it but what should i be looking for and would this help me at all figuring out what my problem might be?
 

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lifter213 said:
Ok guys, i'm trying to do the datalogging on the Predator but i'm having a hard time finding where the 02 Voltage is? Which catagory is it under etc?
O2 voltage can be found under the WOT fuel listing, as well as several others. Go to 'Show All' under that category and you will see it. It will be displayed in volts, naturally.

If you can't see it, go into Troubleshooting, and then do a Live Table Reset which will restore all the functions that you can't see or do not have, or if you're getting any message saying that it is incompatible with this vehicle (something to that sorts).

I hope this helps!

Sincerely...
 

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Eric Brooks said:
FYI

I put my stock spark plugs back in my car (gapped at 0.035) and my low RPM miss went away.

Car is noticably smoother, revs cleaner with the stock plugs vs. the NGK TR6s.
Yep, another reason why I will not use NGK's in my prior Lightnings and now my Cobra (and prior '03 Cobra). I had the same issue with NGK's in them, although not everyone does. I'll only run the Denso's when modifying.

Of course, you could have had a bad plug, too, ya know.

Regards...
 

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NGK TR-6s

SVT says that the NGK TR-6s are TOO HOT a plug for the 03 Cobra. The 03 Cobra came with three heat ranges of plugs. AGSF-32/22/12s. The NGK TR-6s = AGSF-32s. Mine came with AGSF-12s. I now running the Denso IT-24s with no problems. AGSF-12s=IT-22s.

AMB
 

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Re: NGK TR-6s

AMB said:
SVT says that the NGK TR-6s are TOO HOT a plug for the 03 Cobra. The 03 Cobra came with three heat ranges of plugs. AGSF-32/22/12s. The NGK TR-6s = AGSF-32s. Mine came with AGSF-12s. I now running the Denso IT-24s with no problems. AGSF-12s=IT-22s.
Excellent info, although I feel an IT24 isn't needed unless one is running extreme boost on the factory blower, but you're testiment that they work fine, so...

Thanks for posting this, AMB!

P.s. FWIW, my Dec. build '03 with YDH1 came with Motorcraft 22's.

Kind Regards...
 

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Discussion Starter · #15 ·
Ok I have an update..I pulled the plugs and regapped them to .35 but still having the same problem. I did the datalogging on the Predator but i dont have a clue which one tells the 02 voltage on the fuel listing. There seams to be alot of different things that have 02 in the description on the Predator. I guess i just need to get it on the dyno and see what the a/f ratio is doing. I can pull the Densecharger and put the stock airbox back in but i dont think that is my problem. Its only been doing this far the past month or so and i've had the Densecharger in for about a year now. I know this is driving me crazy though. :hammer
 
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