WARNING LONG STORY BUT GOOD TECH

I don't know if I posted it here but I went to Sacramento Test N Tune night with the intention to run big jets in my plate since we got the wheelie bars and the suspension setup figured out now to avoid wheelies...

The last time we ran these jets before the wheelie bars the car went 1.38 60' got the nose VERY high in the air, I pedaled it to bring the nose down but when I did that the TPS % fell below the preset value and the XFI turned the nitrous off and reset the timer for the progressive. So instead of having the full 300hp or so at 1.5 seconds into the run I had the full tilt hit at 2.5 seconds in instead.... Basically a whole lot of wasted time and power. I ran the car to the 1/8th mile and it went 6.05@117... I lifted at about 800' and coasted to a 9.54. The 1/8 mile converts to a 9.32 which is about what I figured it would run... But after I looked at the datalog and saw the spray turned on and off I was shocked it ran even a 6.0 and KNEW the car would be good for a 5.8x on a clean pass and possibly run the elusive 8.9x.....

So Friday the intention was to put the same jets back in and get out there and test with the intention of getting the 5.80 or better if we could. Weather was good, we got there early and setup and were like the 3rd car to get tech'd.... This is where the good luck ended...

We check the car over, everythings tight. Go out there to make my as usual motor pass to ensure car is tracking straight and to avoid complicating any possible issues with nitrous.. So I make a motor pass, car bogs out of the hole which is normal cause we have the front end strapped down so tight with limiters for the nitrous setup. So we've slowed it down on motor a bit. 1.6 60'... car pulled good thru 1 and 2 and when i pulled high gear it started missing. Not super bad but quite noticeable. So I lifted and ran 11.1@112... Came back and started scrambling to figure out what was wrong. Checked all the fuel pump wires and wires going to and from the fuel pump thinking it might have been fuel delivery related. Nothing amiss. Then I reached back and noticed that the distributor looked like it might have shifted. I have a yellow dot on the dist to make the #1 terminal apparent and it wasn't where it was before. So now the rotor could have possibly been out of sync with the motor if the cap rotated. Then for about 30 minutes or so the car would not start at all. So we pulled a valve cover to get to the dist holddown (which is halfway under the damn windshield!! DAMN 4th gens!!!) Finally i get it twisted to where I thought it used to be. Finally the car starts and we lock the dist down. Put it back together and go out to make another motor pass... This time it pulls clean but in high gear it misses slightly. I say **** it and i stay in it....

Runs 10.89@128 which is about what it usually runs. VERY WEIRD. It's missing but it's not down on power as evident by the trap speed. So i was confused at this point. A/F ratio was dead on. However it is reading at the wideband in the collector and not individual cylinders so it might be not recognizing one hole is missing or rich/lean. I talk to my tuner and he says he feels comfortable running the 150 cause it's obvious not fuel related. So we go out there and run the 150 shot. I didn't swap plugs and ran the warmup plugs that have been in the car for a few weeks. Car launches hard and goes 1.44 60'..... pulls hard and then misses again in high gear pretty bad but it's still accelerating. Runs 9.75@142.8 which again is right on par for what it usually runs on the 150 shot..... So i'm super confused as to why it's missing but still running what it usually runs and is not seemingly down on power at all....

I don't know why maybe from the pressure of wanting to beat my best time or having people there watching but I talk to my tuner and he says he doesn't think that running the 300 will hurt it, at worst it'll just miss like a motherf(*&ca cause of the increased cylinder pressure putting a demand on the ignition system. If it misses a little bit on motor or a 150 it'll DEFINITELY miss on a 300 shot. So we pull into the lanes. Leaving on a 150 shot progressing to the full 300 over 1.8 seconds. Fairly tame timeframe by all means and would be relatively easy to drive. I wanted to bring it all in in like 1.0 seconds but because of the miss I wanted to be out of first gear to give me time to shut it down. So i do my burnout, stage and launch and the car absolutely kills it out the hole. I see 1.390 light up on the board and I know I'm on a good pass. Right at the top of first I hear the motor's tone completely change and I know i'm on full tilt. I shift to 2nd and the car immediately goes REALLY dirty ignition wise, missing, crossfiring cylinders or something.... I shut her down way before the 1/8th mile. Probalby like 200 ft into the run it was aborted.... I was pissed... car hesitated slightly coming back down the return road but was idling just fine...

I get back home and yesterday I tear into the car. I initially set the motor and dist phased at 30 degrees BTDC. I line it up at 30 degrees and start pulling the stuff out of the way like the valve covers, TB, nitrous plate, etc to get to the dist. I pull the cap off and yeah the rotor is definitely off from my little yellow dot on the bottom of the dist signaling #1 terminal. It's off by like a 1/3 of an inch easy... XFI timing is locked out so it would have no effect on timing but would have an effect on possibly crossfiring cylinders. I pulled all the spark plug wires and found a slice on the #3 plug wire all the way down to the core of the wire. I don't know which could have been causing the missing but I'm imagining the slice could not have been good for it either way. So I ended up ordering a new cap, a brand new rotor, MSD 8.5MM wires up from my 8mm taylors I have now, and heat shielding and billet looms that bolt to the valve cover bolts to route my wires over the headers instead of under... I'm also going to spin the motor to 24 degrees BTDC and re-phase the dist there since that is the midway setting between motor timing and 300 shot timing. I run 24 degrees on a 150 shot, 32 on motor and 17 roughly on the 300 hit. My tuner said that it won't affect how the car leaves on the brake, nor will it effect really anything else other than giving me a bit more spark energy by the rotor being closer to centered on the terminal at maximum power output timing.....

So to any of the LT1 masters out there anyone got any ideas on what they think could have been the cause? The split in the wire would explain the miss but not the car not wanting to start for 30 minutes. We checked for spark when the motor was being rolled over in the pits by plugging a new spark plug on the wire and touching the plug to the block while cranking it.

 

no idea... coil?

 

Bad coils can cause problems when they heat up, but work fine up until that time. Could have anything changing on the crank trigger? Maybe it somehow getting a flase signal? Probaly not the case just thinking outloud..

 

Its an HVC II Coil which is what pro stock cars use so i can't imagine it would be dead this quickly..... I'm leaning towards the cut wire but not 100% sure. Guess we'll see tommorrow when my new cap/rotor and wires come in...

 

A wire cut to the core causes lots of issues, all exactly as your describing. The miss, cross firing, etc. Since the spark energy will follow the path of least resistance, it will go anywhere but the plug especially on a 300 shot run. I'm willing to bet my paycheck you'll be fine once the new cap and wires are on the car.

 

The wire could be arcing off to anything, as mentioned before (path of least resistance) depending on where it's split - it could be arcing on to the body, block, etc. I know mine was doing that a few weeks ago (wire was split).

 

yea but the starting problem?

 

That's where i'm confused. The arcing would cause a definite miss. that i'm completely agreeing. My car not starting, nor even PUFFING Like it was gonna start was completely weird. It just stopped trying to start for a good 20-30 minutes.... I'm hoping that the distributor was off of being phased enough to cause that...... but again i'm just grabbing at straws.

I highly doubt it's the coil as that would have killed all the spark not just one or two cylinders.... no way my car would go 143 in the 1/4 with a bad coil..... i'm still shocked that it went that fast with a possible lagging cylinder if I had a bad wire...

I'm willing to think that the cap/rotor/wires will fix it cause that's where i'm thinking the problem lies... I hope... My stuff comes in today so we'll see..

 

If the rotor was not in sync or phases in that would be your starting problem......


How would pulling timing not matter how it leaves? a 1.44 60' on the brake? wtf?



I sure as hell wouldn't shoot dope if I had a misfire....that will blow he bitch up faster than it going lean(within reason)

Why do you think people take the pill out of the limiter on gas? a misfire when that cyl is filled up with fuel and gas....not pretty.

 

Make sure you change all the spark plugs too. A small crack in the porceline can cause misses that aren't that noticeable at idle but really show in upper rpms. Also, after you get everything back together check the entire ignition system in the dark to make sure there is no arching from the wires, plugs, cap, coil, etc.

I had a similar starting issue and it turned out the spark plugs were too cold and fowled up to the point where they got soaked and the car wouldn't start. However, yours sounds like a timing/phase issue.

 

Regardless of the misfire and whatnot, that thing moves out! Congrats on that!

 

Thanks guys... Okay here's what I found upon inspection...

Did what I usually do and started the car in the dark. saw no errant spark going anywhere. My wires are taylor 8mm wires with heat shielding on them from MSD. Let everything cool down and took the upper part of the motor apart so i could get to the distributor. removed all the wires and pulled the cap off... Rotor was out of phase about a 1/3 of an inch from a yellow dot on the distributor bottom plate signifying #1 contact (so i can tell when the cap is on where #1 is).... I rolled the motor to 30 degrees BTDC which is where we set it up when the motor was built to verify. Yup sure enough it's off....

Reinspected the wires when they were off the car. #3 cylinder wire has two deep cuts in it seemingly from heat initially causing the rubber to be brittle. The cuts went all the way to the core. It wasn't shooting or arcing at idle but i'm sure at full load it might have went sideways right into the header tube instead of into the plug.

Rotor cap terminals have a little brazing on them which is to be expected. The actual rotor itself looked like ****. Rust colored and whitish red on the end indicating at least a bit of moisture had gotten in from the car sitting in my garage and not being started everyday.

So I replaced the cap and rotor with new pieces, upgraded my wires to MSD 8.5mm race wire with MSD Pro guard heat wrap (basically looks like garden hose with fiberglass inside). I also ordered R&M Industries wire looms to route my wires down the side of the valvecover vertically instead of horizontal so we can still change plugs easily. The looms look like this only mine are anodized blue



Overall they came out REALLY good and I definitely like the look at how they came out. We're gonna hit the track tonight to make sure everything is good...

 

I have my wire going under the header and up the back..... everything is easy to work with. I have 2 of them zip tied to the dipstick, and some cushion clamps on the 1/4-20 holes in the block on the other side, it worked out slick. I went to MSD wires too. I am going to stick with those.

your rotor being out of sync would have thrown off your fue curve timing, everything..... do you lock it out in the pcm and check it with a timing light? I remmber I had to do that with a gen7 dfi and dual sync dist.