Go ahead and move this that's cool I expect it, but it's a post to get a couple experts to look at our stumble/hesitation/misfire/backfire problem which a few of us have posted key word AFTER testing/changing all the basic BS!...A few of us have done all of this stuff and still have the same problem and need some advanced help desperately.

Thanks

 

carbon on the valves there are some methods to clear this the one i do which stopped mine when i was stock was
1. pull injector fuses and pump
2. take the fuel rail off and injectors out
3. get a syringe and inject duralube inj cleaner into the ports
4. bump the engine over dont spin it it will hydrolock
5. then inject more into it
6. let sit over night
i had that same problem once and i did that no more problem and i gained alot of power back

hope this helps

there is also the shadetree mechnic method of getting the engine hot and pouring dexron III tranny fluid in the intake while it running...the detergents in the tranny fluid will knock the carbon off the valves but i am not sure if it will harm the o2s because it will soke like hell but will clear up.....or get them pressure cleaned

 

There are endless threads on "hesitation" on the LT1 Tech forum. Anyone who could contribute has already probably done so many times, since all of us frequent the generation specific boards. The few remaining people that might have been missed are going to be the engine builders, who focus more on the mechanical issues than on the computer controls specific to the LT1.

I'll leave it here for a while to see what happens.

 

yeah I've searched a lot of the endless threads on this one in particular and it's the same old basic stuff...which a few of us have done and gone beyond actually. Hopefeully something will turn up here soon. Appreciate all the help.

 

I really dont see the point. The stumble/hesitation/miss as it has been hashed out countless times in huge threads.

Why do i say this?

Reason being is everyone says "oh i have this sumble/hesitation/etc" exactly like everyone else is having. If no one ever fixed theirs then id say by all means lets nail this down and knock this out.

But people have fixed theirs. By anything from tuning/cleaning difrent sensors/seafoam/etc etc etc. I think everyone says they have the same exact problem but dont, hence difrent things fixing the problem for difrent people. If suggestions were given and you tried them and one fixed your stumble, it wont work for John Doe in NY who has the "same exact" stumble.

Therefor there will ALWAYS be people with this SAME stumble/hesitation. Via a search there is access to every thread that gives info of what a person did to fix there version of this issue. All a new thread in any forum is going to do is list more 'possible' things to clean or replace...

 

If I was a teenager that didn't know any better or had a clue about working on cars I'd agree. But I'm not and have searched the threads and do realize we are not all having the exact same problem, based on the search I narrowed the problem therefore asked for help on advanced. If that gets you wired up all I can say is move the post, just looking for some advanced help not how to use tech forums, well aware how they work already.

 

No where did i say anything about what forum this should be in or shouldnt.

You say that you have narrowed the problem... it may be benifical to list what has been replaced or swapped out and ruled out...


Oh and im not wired up, trust me

 

here is what myself and a few others have either replaced and or tested:

OPTI
wires
plugs
02 sensors
IAC
EGR
COIL
MAF
TB
injectors
fuel filter
fuel pump

and for now thats about the extent that I've gone to with no luck. again it's a high rpm (4000k) misfire/stumble/running rich/backfiring etc etc etc I am getting a multi-engine misfire SES light when this anomally occurs that will stay for a few minutes then clear itself up.

thanks for any help if anyone is able to.

 

Unless you have some kind of mechanical problem,ie:worn rings,valve guides and seats.It has to be an ignition miss.Are the wires routed properly?All running parallel?Away from other electrical sources?How is your engine ground contact?I am betting wires thou.Even new doesnt mean good,quality.My thoughts.

 

wires are routed correct, no interferences, headers or otherwise, it has been running perfect for 4 months and overnight this problem occured. tonight I'm going to check each MSD wire with a multimeter for resistance, the MSD's are 40-50 ohms resistance so I'll verify I have that. Aprreciate the help.

 

Any logs of the car by chance?

 

I bought my car used about 3 years ago. It had a stumble/miss at higher RPMs that we couldnt figure out. I just got used to living with it. Well, I ditched the OBD2 computer and put in a OBD1. And wouldnt you know it, the miss went away. I thought it was wacky. Figured I'd share.

 

man I really hate to change computers since it was working fine for so long. This car is super strong for no more than I have in it with boltons and I thought a bad tank of gas caused the problem because next day it ran like crap. I want to rule out fuel based on have a constant 43 psi under full powerband and load on the road with a fuel gauge, so the fuel pump seems fine. Until I check resistance on each wire I will not rule out the wires completely, but they are not arching at night while its running. Very faintly you can see #5 & 7 glow in pulses through the ceramic but no arching or anything. I don't think the PCM died overnight but who knows?

 

I wish, nope sure don't.

 

Well you could by an obd1 off the board for cheap, try it to see if it fixes the problem, and if not switch back to you old ecu and sell the obd1 you just bought.