LT1 intermittant miss....

[mrvette]

really bad at idle, skip maybe one or two cyl....then smooth out, and then skip one/two.......sometimes bad enough to kill engine, especially if I in neutral then put it in gear.....engine stumbles/dies....unless I really quick on gas.....

I did the plugs, wires seem fine and up top easily seen, cap/rotor look ok,.....

any clues?? cap/coil/button?? or maybe ign chip/control chip?? or sending coil under it all that takes pulling the dizzy and popping it all apart??

[snide]

Broken plug in cylinder #5.

[Black94lt1]

Opti?

[mrvette]

Originally Posted by Black94lt1

Opti?

NO, LT1 induction is modified for HEI up top in back......EGR was bypassed/blocked off long ago, still sealed, PCV valve temp disconnected, capped off, no change.....steady fuel pressure adjusts from 30-40 psi at speed under load, sounds/feels fine....just the damn skipping at idle,

[StaticCling]

I'd start with the Distributor Cap and Rotor

[SubZero]

vac leak, injectors?

LT4 swap

[Mr.Bigg]

If it gets better after it warms up the o2'S can be bad and not show a code. While your under there pull the knock sensors and do a proper flush you won't believe the crap in there. Just pinch the connectors with your fingers to disconnect.

[mrvette]

scanner sez O2 is switching back/forth rather quickly.....lean/rich back and forth....fluids are a nice clear green, not cloudy at all.....

I going to try all the dizzy parts tmrw while dinner is being cooked.....one at a time, just bought them ALL except wires......

[Mr.Bigg]

How many miles on it? Headers?

[mrvette]

It does have headers, H pipe back to Magnaflows in rear, I don't hear any header leaking.....I have not taken a temp reading on the tubes yet, maybe I do that tmrw...I have an IR gun for that.....

[Mr.Bigg]

If the knocks have never been pulled it is full of crap. A bit of a design flaw. Even if you pull the hose you will have a gallon or so still in there and will most likely need to poke around in there to break the crap out. Between old or upstream leaks on o2's and blocked knocks it could do what you are experiencing.

[mrvette]

pulled the coil outta the cap, and surprise, looked like moisture in there....WTF?? maybe it could have been oil mist....at any rate, cap, rotor, coil, chip and it seemed to run much better....drove it around quite a bit, not purrfect, but better....

so I going to measure the pipes and look around tmrw...

[mrvette]

Originally Posted by snide

Broken plug in cylinder #5.

HOW Clair-voyant of you......I got disgusted and found a sealed container of 24 lbs injectors in the shop.....decided to try them, pulled the old ones out and found that two of them came out with little plastic tip on one of them, and another one left it in the manifold hole...cyl#5 of course, went to pull it out, and it fell down into the head, since 6 others had preceded it, I cleaned up everything and put in the 'new' injectors.....Fat ones this time not the skinny ones that were in there.....

I dunno watt to do now, so going to just run the engine in hopes those plastic parts about the size/mass of my little fingernail will just burn out and the engine will settle down.....the thought of tearing it all down for a valve job is just BS at this point.....

It makes me wonder if I installed those injectors, or someone did a swap on me......long story behind that thought......

[mrvette]

Dug this one up, and really weird, I added a fuel filter, stainless, inline with the 3/8 fuel line up top next to engine have one back at the tank on suck side of pump.....rubber hose, properly clamped, obviously.....

I was thinking the remaining rough idle was due to dirt in the line, really grasping at straws.....so adding the filter has improved the engine to the point that knock on wood, over the last two daze it's running like GREAT!!!!

but the mystery IS, why.....wonder if it somehow smoothes out the line pressures with the batch firing of the injectors....really grasping at straws now.....

maybe the filter has some air trapped in it?? and that cushions the pulses??

[DJ_Critterus]

Originally Posted by mrvette

Dug this one up, and really weird, I added a fuel filter, stainless, inline with the 3/8 fuel line up top next to engine have one back at the tank on suck side of pump.....rubber hose, properly clamped, obviously.....

I was thinking the remaining rough idle was due to dirt in the line, really grasping at straws.....so adding the filter has improved the engine to the point that knock on wood, over the last two daze it's running like GREAT!!!!

but the mystery IS, why.....wonder if it somehow smoothes out the line pressures with the batch firing of the injectors....really grasping at straws now.....

maybe the filter has some air trapped in it?? and that cushions the pulses??

Maybe the filter was clogged? Please tell me you're not filling up at the RaceTrack station by your house

[mrvette]

Originally Posted by DJ_Critterus

Maybe the filter was clogged? Please tell me you're not filling up at the RaceTrack station by your house

NO, off Blairmore, GATE, mostly and the filters are clean/clear /new even....I been fighting this crap for a while now, I am tempted to go to the BP near me when filling up again, and getting ethanol free, piss on the cost.....tried higher grades, no difference but not ethanol free, yet.....

thing is, the way I drive it, sometimes less than 4 miles for quite a few trips/out-back....engine not even warm by time home....so ~10 mpg really sux....18 gallon tank lasts about 2 months though.....

NEED a 130mph run over the Buckman......

[Mr.Bigg]

Pull the vacuum line off the FPR and smell for fuel as well.

[Old Ben]

Originally Posted by mrvette

NO, off Blairmore, GATE, mostly and the filters are clean/clear /new even....I been fighting this crap for a while now, I am tempted to go to the BP near me when filling up again, and getting ethanol free, piss on the cost.....tried higher grades, no difference but not ethanol free, yet.....

thing is, the way I drive it, sometimes less than 4 miles for quite a few trips/out-back....engine not even warm by time home....so ~10 mpg really sux....18 gallon tank lasts about 2 months though.....

NEED a 130mph run over the Buckman......

A run on the interstate would probably help. Not at 130 though.

[DJ_Critterus]

Originally Posted by mrvette

NO, off Blairmore, GATE, mostly and the filters are clean/clear /new even....I been fighting this crap for a while now, I am tempted to go to the BP near me when filling up again, and getting ethanol free, piss on the cost.....tried higher grades, no difference but not ethanol free, yet.....

thing is, the way I drive it, sometimes less than 4 miles for quite a few trips/out-back....engine not even warm by time home....so ~10 mpg really sux....18 gallon tank lasts about 2 months though.....

NEED a 130mph run over the Buckman......

The taxman...err....cops monitor the Buckman heavily now.