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Discussion Starter · #1 ·
Car started missing slightly on the way from the city of San Francisco. Dredded place to drive a Vette. The worst. You need a 4X4. Last time, I hit my exhaust there, resulting in header leak.

Would like assitance in developing a 1)fast diagnosis and 2)fast test procedures. Thanks.

Car missing.
1) Car revs up, although slower.
2) Lack of power; Possibly missing on two.
3) No overheating or fluid loss
4) No mysterious engine noises.
5) No Codes.

Me Thinks
1) Coil Pack?
2) Spark Plug wire?
3) Passenger side wiring harness may have fried on header?
4) Injector?
5) Fuel filter?
1,2,4,5 have only 5k miles on them.

Anything else?
 

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Grim, it's kind of hard to tell for sure but I would definately check the plugs. I know you are naturally aspirated but with the power levels you have on the 427, you may be running a colder plug and they can crap out on you in a hurry. I'm on my 5th set of plugs in the last year or so and I know it can happen.

The other thing to check would be the plug wires (possibly burnt or charred close to the header). The back two plugs on the drivers side are pretty close to the headers and are somewhat susceptible to the heat if you aren't running KoolSox.

Just some ideas....

Mike
 

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Discussion Starter · #4 ·
Will Check. Change plugs every 1,500 miles or so. Oil between 1,000-1,500. Running TR55's

Maybe Walbro pump is crapping out?

Mike, going to start with wires and coils first. Most likely, easiest to check or isolate.

Thanks.
 

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What type of fuel are you using? If it is bad or crappy the O2 sensors may have an issue with it. We had a problem last season with some 104 unleaded fuel. Missed like crazy along with loss of power. Changed fuel and all was well.

Tony #54
 

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Discussion Starter · #7 ·
Elf, I was wondering about fuel as well. I only use Chevron/Shell/76. Last Chevron.

Mike, never did the fuel gauge. Was going to do it, when I was going to do NOS. NOS is big no no here. Car Impound/Jail, in some counties. No good.

GR
 

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Grim, Do you have EFILive? or any other scan tool? If so log some scans dealing with misfire and go to the Cylinders with the most.
If you have one missing bad you can get false missfires echoing off the other missfires. I use that tool and it is great.
 

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Make sure you plug wires are fully snapped on. They should make a clicking noise as you attach them to the coil pack.
 

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Don't think an O2 sensor would have you missing...

I had an injector go bad (failed open), car felt flat as hell, would hardly get out of its own way. Mechanic at chevy thought it was a plug at first too.

It STUNK of fuel behind the car too, so thats an easy test.

If you have a scan tool, find out what cylinder its misfiring on, it'll help isolate the problem. If no scan tool, heres the ghetto way to figure it out: With the car running, get a test light with a pointed probe. Clip the lead to a good ground, then shove the probe into theplug boot, and ground out the wire. A good cylinder will make the engine run even worse, when you get to the bad one(s), the engine won't change.
 

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Discussion Starter · #12 ·
Computer found nothing wrong, except occilating rear O2's. Which we turned off. Still runs bad. Sitting at Synergy Motorsports in Fremont, going on the rack tomorrow. Will let everyone know.
 

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Discussion Starter · #14 ·
Update

Crispy Plugs wires #2 & #5. Now my fourth or fifth set. You can count this as part of your yearly maintanence.
Fouled the Plugs.

Retuning car. Mising at 3,200+. Me thinks to spark plug gap. Blowing out the spark. Rick now has it .060 vs. .047, that I had on the TR55's.

Opinions? Thinking about having him go back to .047 tomorrow.
 

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Grim Reaper said:
Crispy Plugs wires #2 & #5. Now my fourth or fifth set. You can count this as part of your yearly maintanence.
Fouled the Plugs.

Retuning car. Mising at 3,200+. Me thinks to spark plug gap. Blowing out the spark. Rick now has it .060 vs. .047, that I had on the TR55's.

Opinions? Thinking about having him go back to .047 tomorrow.
Grim,

Don't know if the plug gap thing is the problem. 60 mills getting blown out? If I am reading this right you have problems after leaving San Fran? Maybe the in town driving loosed up your air intake and the MAF is all over the place. I think I would try tighting up things under the hood first to see if thats it. You could also do what I call a manual load test to see if it's something else electrical. Pull a hill in one of your tall gears and load down the engine. If she bucks around under a slight load you may have other electrical items breaking down, (a coil pack, etc). Other than that I would pull the plugs and do a compression test and see if you may have some burnt valve's/seats. Just some idea's off the top of the head. Hope some of this helps.

D.J.
 

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Discussion Starter · #17 ·
Stroker Games. Now on Mission From God.

[/B]This is getting very personal. Rick(Synergy) and I are definitely getting mind foo-barred on this one.[/B]

One run. We had the car running under WOT under 6,500. Had a miss. Made peak power at 4,500, 434 rwhp/500lbs. rwt at 3,500 w/ a miss.. Straight downhill from there.

Motor is fine. No smoke, no noise, no fluid leaks. Fully built 429 with TPIS and Port matched Fast.

However,
passenger side cylinders just started running bad out of no where.(No power). Passenger side headers much cooler, throttle feel and computer read.

We replaced four coil packs off a Rick's 98 LS1. are these the same?

New GM Red wires.

Car never gets hot.

Put in his #42 injectors and fuel rail.

Checked Inside Throttle Body. You could eat off it. Assume MAF is good.

Compression is good(( same on two or three cylinders) and no noises. :)

No exhaust leak at headers.

Oil is clean and not fouled.

Checked each cylinder for spark. There is spark.

Check the little tiny wires on the injectors and measured. Pulse width is the same on three cylinders at least at low rpm.

Running TR5's .42 gap (Big motor) Variety of colors. Some clean, one black, one white. :-? #2 looks dry.

60 PSi after the 255 Walbro and fuel filter.

Cats look clean and don't rattle.

Replace Fuel Filter anyways?

Do the injectors need to be grounded?

What is the Valve on the driver's side fuel rail? Could this problem?

Thinking about changing both front 02 sensors. Rears are turned off.

Could in be the wiring harness? It looks okay and is away from the headers with heat tape.

Andy Green, Dave, Julio, DJWorm, Mike, Jayson, Ed, Lou? Need your guys help.
 

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I used the valve on the drivers side fuel rail to drain some bad gas one time. It may also be used for injector cleaner kit but don't know for sure. And speaking of gas is it good? Do you have a place to buy some unleaded race fuel around your place or is that what you are running? Pretty basic but did you check all connections to the intake and torque down the bolts to it. Are all of your ground wires making connection?

D.J.

Pray
 

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Discussion Starter · #19 ·
Rick's Father-In-Law was nice enough to come down. He is a Professional Electrician. Brought a portable scope with him. We were just generally irritated by the end of the day and perplexed.

Gas is 91 Chevron mixed from two stations. Thought of that as well.

And yes, I have prayed four times about this already.
 

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Grim Reaper said:
Rick's Father-In-Law was nice enough to come down. He is a Professional Electrician. Brought a portable scope with him. We were just generally irritated by the end of the day and perplexed.

Gas is 91 Chevron mixed from two stations. Thought of that as well.

And yes, I have prayed four times about this already.
Sounds like you guys are calling out the big guns on this one. Hopefully "Rick's Father-In-Law can shed some light on the problem, no pun intended. This type of thing is a PITA but you will get it. Long distance trouble shooting is a bitch.

I had a loose ground on the drivers side behind the head and it caused all kinds of problems. Took awhile to find that one.

D.J.
 
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