lt1 with issues
 

i replaced the opti, coil, and plugs. 130,xxx miles.

it takes a couple seconds to start, it bogs/hezitates under 2000 rpms

im thinking fuel issue? hopefully not uneven cylinder compression. any thoughts?

Fuel pressure is easy enough to check.

What kind of plugs and what gap did you use?

i forget what brand, but they were iridium. the sticker above the radiator said one gap and haynes said something else so i gapped them right in between i dont remember them being very far apart

Yuck. I would ditch the iridums. But thats not here or there.


What kind of opti and can you check fuel pressure?

Does it do it all the time, or just when hot?

might have carbon buildup

thought it was mandatory to run platium plugs in our cars.... i could be wrong but last time i did my plugs i was sure that i was told to only run platinum plugs.... with that said on a side note what plugs you run matt... got any recomendations for my build... was thinking either just going with good ole delco's or maybe some NGK's i donno...

opti is gm performance, it does it just about all the time. i know some other people that run iridiums with no issues.

hmm sure sounds familiar, my brother had a very similar issue , replaced everything from the opti to the computer and come to find out...it was the dam fuel pump.

yeah check your fuel filter and see how old it is... 130k mile fuel filter could be bad lol. just throw a fuel pressure gauge on it and see where the pressure goes.

.035

i only run NGKs in my DD and "weekend driver"

but they have to be platinum right?? i was told this from many people early on in my lt1 career ahah...

People will often say platinum plugs for the LT1 because they are generally a PITA to change, and platinum plugs are supposed to last much longer (although that's a whole different debate).

- Justin

i replaced my fuel filter in june. i think the plug gap was .04 or .045. the sticker on the car says .05

holy big gap!

regap them to .035 lol

Yea, but if you have LTs, spark plugs are a breeze...
Def re gap them... the huge stock gap is for emissions.. and that is silly.

yeah i got some paceupsetters so it wont be hard

Then switch em out for some NGKs.

And Brandon, I run autolite 103s I think...

anyone know what they have theirs gapped at?

.035

.035 here as well

Stock gap of .050" is fine for stock cars, but once you delve deeper into performance territory, .035" is more desirable. I picked up 3mph on my 383 from switching to .050" to .035". I am running copper NGK TR55s.

Definitely check your fuel pressure. A fuel pressure test gauge is a must-have for any LT1 owner's toolbox. Key on, engine off pressure should be around 43psi. With the engine running it should drop to around 35 or so, then slowly rise with throttle position.

You can also pull off the vacuum line off of the fuel pressure regulator to see if the regulator is still good (if fuel comes out, it's no good). If the rubber diaphram in the FPR is torn that can cause issues as well.

check your mass air flow sensor (other words un plug it to see if the car runs better)



why does everyone thing it the spark plugs ??

no not true everyone says that becasue they dont wont to change sparkplugs

How old is the fuel filter? Didn't see any mention of that being changed?

How does it run above 2,000 RPMS? Did you check all your hoses for any vacuum leaks?

How old are the O2s?

Check if the spark plug wires are crossed and one is going to a wrong cylinder.

Is it possible to get the timing wrong? Is there any timing adjustment in the opti or is it keyed in a fixed way to the camshaft? If it were an old-fashioned distributor, I'd say that it sounds like not enough advance.