Viper/Saleen1

Took the Jeep to the dyno yesterday to dial-in the Split Second map sensor box and the timing for the meth/water injection. Got the thing running mostly 11.5-12.5 ratios until 5200rmp then it climbs to around 13.5-14 up to redline 6000rpm (on the high side) but I usually shift at 5300rpms. I don't like it in that range but we considered it reasonable.

My question is: after running it on the strip, I burned off the tip on the #8 cylinder and the plug tip "folded" on the #5. It did the SAME THING two weeks ago on the same cylinders using 30lb injectors; we just upgraded to 34lber's. All the other plugs looked fine. I'm wondering if maybe the plug wire for each of these cylinders may not be supplying correct current? I'm going to switch the wires for the #8/#6 and the #5/#7 just to see if the condition moves to the next cylinder. If so, I'd suspect a bad wire and/or injector on that cylinder. Also, my air/fuel monitor does not indicate a lean condition when I'm running down the track. Any further suggestions???

BTW; ran 12.70 and short shifted 1st gear at 3500rpms due to loose track....)

Birdieman4

How are your plugs gapped? Also, what kind of A/F ratio guage is on it? Is this Jeep n/a? I might consider updating the entire distributor/rotor/wire setup. A company called Jacobs speciallizes is street stuff, and makes some excellent components.

Derf00

http://www.gnttype.org/techarea/engine/plugs.html

Viper/Saleen1

55 looks and finally some discussion......My Jeep has been upgraded with Crane ignition box for the supercharger, MSD wires, Mopar Performance Computer, Split-Second map override box, air/fuel LED monitor light, etc. The only thing I can figure is that I will have to go back to the dyno (again!) and try and make the A/F ratio maintain below 12.5 all the way through 6000rpms. Then, add the meth/water injection and see how it does.

For the life of me, I just don't understand why only 2 out of the 8 cylinders is having a fuel issue. I asked everyone I could at the track to look at the plugs and the dyno sheet for opinions; mostly carbo-setup guys who don't have much to do with injectors. Once I get the dyno numbers as close as possible, will install the iridium plugs ($8.00 each) that are for use with methonal injecting. I have been using NGK1283 plugs; not sure of the temp on these but was recommended by KRC Performance in Florida where I get all my goodies for the Jeep. The gap is set a .38/100.

On Sunday, the Jeep ran 8.0 in the 1/8th mile with 1.72 on the 60-foot; very close to 12.5's or slightly less in the 1/4....serious power but need to get it SAFE first.

PolkThug

Are you on the stock fuel pump still?

Viper/Saleen1

Stock intank pump but has 2nd pump for FMU with the supercharger; putting 35psi at the fuel rail. If it were delivery of the fuel as a problem, I'd think all the cylinders would be leaning out.

Birdieman4

First things first. You need to start pinpointing the problem. First thing I would do is put a fuel pressure guage on and see what it reads while bringing the rpm up from idle. If you stay at a consistant 35 psi, then I think upgrading your fuel pump might help. The pressure should be building with more rpm. If it stays steady, then it is entirely possible the pump is bad or going bad. Addressing your potential lean issue might fix everything. Is this jeep injected? Your plug gap looks ok. Did you play 'musical wires' with the plug wires yesterday? I would seriously consider a digital wideband A/F ratio guage vs the LED analog one. Those analog ones are very unspecific, but the dig wideband is dead on exact. I look at it as cheap insurance for your motor. And they are pretty cheap now, under $300.