Sick Cobra

[frank5o]

My car is acting up on me.....I need help.

I just recently put a JLT CAI on, along with a 2.8 pulley and 100mm idler.
Problem is that at higher RPM's (4500-6000) it misses badly.

The car has a Mac off road H, Mac welded in mufflers, and a diablo preditor pulley tune installed. My car has 42,xxxx miles on it and was stock for almost all of the miles. My car was built in june of 02, so I'm under the impresion that it has the coldest plugs installed already. I've never changed the ignition wire's, or fuel filter, or plugs. Basicly, the car has never had a tune up. Before the 2.8 and JLT was installed the car just had a preditor performance tune and off road H. With this set up, the car stumbled at high rpm before, but nothing major. I could never get the miss to repeat on a back to back run. Now with everything installed the car has developed a bad miss. It pulls really hard up to around 4500 and then just loses all the power and sort of boggs down. Some times it surges at high rpm. In both cases the car lose's a large amount of power. Also, the miss has seamed to have gotten worse with the cold weather. The boost gage dose not move around when this happens, leading me to believe it's not a belt slip problem . I think it could be a fuel problem, or maybey ignition? I know I need a good custom tune , but in the mean time could it be something simple.

 

[SickBlackMach]

Man, get some new plugs and a good tune!

 

[Venomous01]

You need a tune now! Do NOT get into boost until you get a tune. You have probably already detonated a few times and may have already damaged the motor. Get a dyno tune ASAP and change your plugs.

 

[frank5o]

I pulled out a few plugs today, and they are pretty dark, but not damaged. They look old. I'm gonna park it, and replace the plugs with motorcraft 22fm1's in a couple days, we'll see what happens. I gonna get it on a dyno soon, I'm just thinking that it's the plug's at this point.

 

[knowfreed0m]

You need some NGK plugs and a Custom Tune ASAP!

 

[Steel Horse]

NGK TR6's at stock 35gap

 

[sambandit]

Probably not plug related.... You are probably running either lean or rich and you are in need of a custom tune... Let me know if I can help.... You could have one in about 20 minutes!

 

[EJ23]

You trying to blow the car up?? GET IT TUNED NOW!! IT'S NOT THE PLUGS.
Your A/F is probably 14-15:1!! :nonono:

 

[frank5o]

SAMBANDIT, what do I need to connect my pred to computer, and what's the price for all of this........My local tuner guy is a sct guy and I don't want to buy another tuner.

 

[sambandit]

$100 bucks for a lifetime custom tune. If you check out www.milehidyno.com and visit the private custom tuning forum, you'll see a thread which explain everything and gives you the part numbers you need to buy the cable and adaptor from Radio Shack.

 

[frank5o]

Cool, I'll check it out....Today I installed new plugs (12fm1's) gaped to .35. The original cold plugs that were installed in the car. I also re-installed the pred pulley tune and added 1% of fuel from 4000k to 7000k just incase it was lean before. The car now pulls smooth all the way to 6000rpm in 1st thru 3rd gear. What do you guys think? I plan on geting a tune as soon as possible. SAMBANDIT I'm wondering how a downloaded tune is much better then the Preditor pulley tune?...since my car won't actually be on a dyno for the tune. No bashing intended.

 

[frank5o]

After some searching on this forum. I think the problem I was having was spark plug blowout. How come nobody said anything about that?

 

[SCcobra4me]

Seriously, you need to quit driving your car until you get a tune. The only place you should be driving it is to the dyno.

 

[95YellowGTBeast]

After some searching on this forum. I think the problem I was having was spark plug blowout. How come nobody said anything about that?

you could have spark blowout due to addind the cai...but you also will need a tune bc the maf transfer is now different than when it was! which will cause a lean or rich condition in your case it maybe a rich condition cause it not to have enough timing to ingnite the fuel correctly, which may correspound with it having spark blowout.

Nick

 

[frank5o]

I was thinking spark blowout becuse of adding 2.8 pulley, and becuse my car had the original factory plugs (4 years old, stock gap). I will get a tune guys, but I really think from reading about other people's spark blowout issues, and how there cars were acting, that my car was doing the same thing, surging at high rpm, missing ect, ect............ Since I installed the plugs , the car pulls cleanly all the way thru, in 1st thru 4th. Have the preditor pulley tunes been known to be really bad? I was under the impression that the canned tunes were to rich causing lower performance, not blowing every bodys chit up.

 

[95YellowGTBeast]

yea you should have spark blowout with the stock plugs...get a set of tr6'a or tr7ix

 

[jm@ReischePerf]

I was thinking spark blowout becuse of adding 2.8 pulley

Yeah it was pretty obvious from the beginning of the thread. Stock plug gap plus 4 years of erosion widening the gap furthur. Then add a bunch of boost, spark blowout was a no brainer. I would recommend getting the tune from sambandit though, it's killer deal for $100. If you insist on using the Predator tune for now, like I am, I would modify the 4-7K fuel band to at least 3% rich and the 2-4K to 5% rich for now until you can get it on a dyno or get your own wideband.

 

[frank5o]

jmproductions, thanx for not overreacting. I'm going to get a dyno tune on tues. I'd like to go to sambandit for a tune but my thinking is that it will need to get on a dyno anyways just to be safe, so I'll just do everything at once on the dyno. I'll post the results after its done. Right now the car feels like a monster! The prospect of it running even better is exciting. Later.

 

[jm@ReischePerf]

jmproductions, thanx for not overreacting.

Oh no I don't fault you at all man, you're just trying to get a solution to your problem. I was just kind of surprised that no one mentioned blow-out until you did. Yes definitely post your dyno numbers when you get them.

 

[frank5o]

Ok got the car tuned today......First of all when the car was stock it put down 390 rwhp on a dynojet (corrected #'s).... Now this shop I went too today use's a Clayton chasie dyno (eddy curent). First pull with the previously stated mods (canned pulley tune) was 380rwhp and 350rwtq with the AF going really rich, averaging around 10.5 to 11.0. Then after about 5 pulls the tuner got the car up to 405rwhp and 390rwtq with the AF staying around 12.0. The boost was good staying around 13psi. The car feels real good, defnitly better then when stock. My ? is why are the numbers so low? Has any one had experience with a clayton dyno? Oh ya and the tuner said I was pegging my maf above 5900rpm, and the car would put down more with a diablo mafia. WTF?