Pretyflywiteguy

I don't drive my car before it's warmed up about a quarter of the way so i don't know if it does it when it's cold. Basically It hesitates a little bit if i give it some gas between 1k and 2k. If i ease into the throttle it doesn't hesitate but if i get on it, as to beet an unseen car, it does. Opti going bad? O2's? i change plugs and wires and double checked everything two days ago.

TIA

LoStOCeAnZ63

my car does the same thing 1-2000 rpms it doesnt do anything but if i take off at 2,000 the ******* thing will burn the tires down the street id also like to know what it is that is killing my power down low

Pretyflywiteguy

bump anybody?

EDIT: maybe it's a 94 thing

jd783

my 97 does it also

i420tom

iTrader: (11)

it may just be a 94 thing as mine does the same for as long as i have owned the car and i cant fuc$%& figure it out. I also get a slight backfire thru the intake if i blip the throttle from a stop or while in low rpms

i420tom

iTrader: (11)

i have replaced the whole ignition setup with an msd distributor new plugs a delteq setup brand new gm 02's any many other in hopes of fixing this but have not suceeded. I am going to pull off my performance pully and fix a little intake leak and see if that helps, if not i will then try a top end fuel injecton service or new SVO injectors, oh yeah i did the lt4 knock sensor and descreened the maf then bougght bigger ends and pcmforless all new exhaust and yet still does it. only have 70k on the car, with brand new head gaskets and intake gaskets, did tb bypass and relocated the air temp sensor and go an K&N FIPK. still doing it to this day!!!!!! hopefully my intka eleak will fix it , how do i have a leak with new gaskets you ask? I put a damn breather on the passenger side cover valve cover replacing the fresh air hose, dumb idea

mybluez28echoes

iTrader: (12)

Opti my friend, opti is ur problem, LT1s are known with this issue, the opti goes bad especially if yours is still the stock one. I replaced mine when I had the same problem and it's fine

Burning Rubber

iTrader: (1)

I have the same problem with my Freshly rebuilt 96. and i have replaced everything but 1 o2 sensor and the opti

nomoneyz

iTrader: (15)

My 95 does this also. Im still on the stock opti too at 116,xxx miles.

Pretyflywiteguy

well ****.. i'm not gonna bother with it until my car won't start because i'm cheap and lazy

WhyHelloOfficer

iTrader: (5)

Not trying to be a dick -- but if you're looking for help, punctuation and organizing your thoughts better will help people be able to read what you post, and be able to help you out. Just keep that in mind for future posting
MSD Distributor or MSD Cap and Rotor? A lot of people have done a cap and rotor, and have ended up having to back in there and change the whole thing out.

How is it stumbling? Up top? Down low? Throughout the RPM range? Can you go WOT?

For everyone else with issues:
How new is the ignition coil? How new is the wire going from the opti to the ignition coil? Did you use dielectric grease in your spark plug boots when you did your plug wires? Did you make sure your plug wires are routed correctly and are not burnt or cut on pulleys (along the passenger side)?

There are quite a few possibilities that I think a lot of you should look into. Getting a new opti-spark isn't always the solution. Some people have a factory opti last them 140,000 miles. Other guys have had one last 80,000, and the new one fails in 1,000 miles. I hate to say it, but it is hit or miss -- you just have to be thorough with your trouble shooting.

One thing that a lot of you need to look into if you are having a hesitation/stumbling/missfire/running rough/breaking up issue. Look along the passenger side of the intake manifold -- there is a wiring harness that looks like this:

It is the harness that goes from the PCM to the optispark. A lot of the time the harness as it goes down along the front of the block and plugs into the opti, it will be corroded and cracked from heat, moisture, and just being old. Take a look at that, because it very might well be your culprit. A lot of people don't look into it, but realize after they are replacing their opti that it needs to be replaced. Do it once, do it right.

Pretyflywiteguy

it only stumbles down low, between idle and 2-2.5K RPM. Everything else is fine. I didn't grease the wires though, whats that help with? the heat? I don't want to change my opti which is why i posted to see if it could be something else. I'm strapped for cash right now.

EDIT: It hesitates from a slight roll or stop at those RPM's

WhyHelloOfficer

iTrader: (5)

Dielectric grease just helps with conductivity along with keeping moisture out. It is usually a good rule of thumb to use it anytime you do new plugs or wires. That's why it is sold at any DAP or local parts store as "Tune-up Dielectric Grease."

Have you pulled any plugs and checked them since your issues started? Make sure they aren't fouled?

Start the car at night with the hood open and make sure none of the wires are arching. That could be why you possibly aren't getting enough spark to the cylinder.

Also -- I hate to say it but double and triple check your plug wires and their routing along with all of their connections. I had a set of magnecores ($$$ really expensive wires) on my car I had just put on, and I had some mid-range missfire issues about 3 weeks after I installed them. I swore up and down it wasn't the wires, but when I pulled them out one by one and checked them, sure enough three of them were burnt/cracked. I was positive I routed them correctly, evidently not well enough.

Are you wires over the valve covers or through factory locations? If they aren't OTVC (especially on the passenger side) its possible they got caught on the serpentine belt, or burnt through the factory routing as well.

Also, take a look at that wiring harness I put the pic up of. A lot of the time that can be causing hesitation/stumbling issues as well.

Pretyflywiteguy

Oh never heard of it. The wires are in like factory and I made sure before ending that day that they weren't touching the belt. I'll double check them for burns and stuff tomorrow. I know the car is running rich which is why i thought about the o2's being bad becuse that causes some hesitation to correct?

Gun5

iTrader: (37)

my cars hesitating on idle now 750 to 1000 anything over its fine..... only doing this after last nights rain wtf?

WhyHelloOfficer

iTrader: (5)

Usually hesitation/miss/stumble issues are caused more by ignition than O2s -- but if they are factory then it definitely wouldn't hurt to check.

If the car pulls fine at WOT, and runs well when it is cold, then that could very well be your issue.

You car basically runs in two different modes, open loop, and closed loop. In open loop (When the car is warming up, at WOT, or when a SES light is on) the car is running off of a table of pre-set parameters for all of the sensors. It is not actually taking readings of anything and is going by what it is pre-programmed. When car is in closed loop (when it is warmed up) it is operating on all of the readings from the sensors, and adjusting how it is running accordingly. The O2s are constantly sending signals back in closed loop to the PCM so that it can adjust its a/f so that it can stay in a safe rang e while you are putter-putting around town at mid-range rpms.

If it is only happening while the car is warm, and only at mid-range -- then I'd say unplug your O2s and see how the car runs all the time. It will eventually throw a code, but if it doesn't hesitate at all then that should tell you it is the culprit.

If you do happen to need new O2 sensors -- do not get them from a local parts store or a DAP, especially the bosch O2s. They do not send readings quickly enough, and people usually end up having to replace them again anyways. Save yourself the hassle and purchase ACDelco O2s from the dealership. They are usually anywhere between $45 and $58, so make sure you need them if you're buying them. If you are under the impression that they have never been replaced, it probably wouldn't hurt to put new ones in. With factory manifolds it isn't too hard to do, just get the car jacked up and make sure you've let it cool off well.

Pretyflywiteguy

alright well thats my plan for the weekend, thanks man i appreciate it.

WhyHelloOfficer

iTrader: (5)

No problem -- I'm down in Orlando for spring break this week from school in Gainesville. If you need a hand with anything let me know, just shoot me a PM.

Gun5

iTrader: (37)

my car hesitates cold and warm.. brand new bosch O2's - had the whole car retuned last week but after last nights storm like i said its hesitating

WhyHelloOfficer

iTrader: (5)

If the bosch O2s are working for you, then by all means keep running them. I've had bad luck with them, and I know of others who have had issues with them as well.

If it was running fine since the storm, just let it sit. Sometimes LT1s, well, cars in general can be finicky. I had to drive mine through some heavy rain one time and it had a rough idle. Sometimes you get some moisture in places and it just takes time for it to dry out. I've also sometimes just unhooked the battery for the night and hooked it back up in the morning and that has solved issues as well. Sometimes just resetting the pcm and letting the car sit can help.

It sounds like a new motor and you were in good shape last week, I don't think anything could have really gone wrong. Sometimes moisture going through the MAF can cause bad/wrong readings, but the day after you should be alright.