View Full Version : lt1 stuttering problem

08-24-2007, 11:44 PM
I just bought a 1994 camaro 6 speed lt1 with 78,000 miles that had been sitting a couple months without driving. It has an aftermarket intake, tb and mas.airflow sensor. The car has not been tuned since these parts where installed.

The problem is, when going through the gears , hard throttle or normal driving, the whole car studders and shakes and wont rev past about 4500 rpms. I know it has old gas in it and the check engine light came on when driving but goes off when you restart the car. When in full throttle, it is very hesitant and I know it isn't normal.

If anyone has had any experience with this problem or might know what it is/how to fix, I would be very appreciative. Thanks

08-24-2007, 11:55 PM
clean your furl injecters and get a new fuel pump and filter good luck because with the few parts it has on it the car would not need to be tuned your disturbuter my be bad just a few suggestions

Sneakin Deacon
08-25-2007, 12:11 AM much for doing the easy stuff first huh?

go see what your code is. the computer stores it even if the SES light goes out. after that work from there. sounds like an optispark issue, but one thing at a time.

08-25-2007, 12:40 AM
ck your codes !!!! it could be a # of things
pm me !! with more info

08-25-2007, 12:45 AM
i would say possible opti problems

08-25-2007, 02:39 AM
alright ill be doing that tomorrow, I really appriciate the help, im kinda dissapointed however becuase I spent all my money just to buy the car in the first place

Sneakin Deacon
08-25-2007, 03:32 AM
well the good thing is, its a you can check the codes with a paperclip.

08-25-2007, 03:43 AM
put fresh gas in it for starters, 89 at least

08-25-2007, 02:36 PM
I threw a whole tank of 93 in yesterday and it seemed to help i guess time will tell

08-25-2007, 11:20 PM
I would definately lean toward opticrap. That was my issue. I had the same issue about the 4500 rpm nonsense. I would top out at 70 mph. I would first pull the codes brecause my friends car had a bad ground on the block and it acted simular. Sooooo, check codes.

08-29-2007, 04:30 PM
codes as well

also add some sea-foam to the gas tank

09-01-2007, 02:27 PM
Ok well cheak this out, I ran the code and it came up egr which really dosent explain much

09-01-2007, 05:18 PM
Cycle thru the tank of gas you have now and see if it clears up. Will it free rev past 4500rpm with out acting up? You said it has a aftermarket MAF try and unplug the MAF and see if it gets any better. I'm not far for you and off on monday if you cant get things sorted out.

09-02-2007, 03:01 PM
It will rev past that when its not under load but its not how it how should. Ive gone through 3 tanks of gas and no change the only other things i could think of were the injectors or the plugs and wires.

09-02-2007, 03:52 PM
Try driving it with the MAF unpluged, the PCM feeds mainly off of that at WOT, if you unplug it and go into speed density and nothing changes then at least you know its not the aftermarket MAF.

09-02-2007, 04:00 PM
a bud of mine had an lt1 with the same problem, he got some intake cleaner and it worked. Just disconnect your intake down to the throttle body and fire up your beast. Spray the cleaner into it and rev the car up. Use the whole can, and get ready for tons of black shit to spray out the back. GL

Sneakin Deacon
09-02-2007, 05:37 PM
sounds like typical hi side electrical in the opti going bad. compare the resistances and voltages at the opti with what GM specifies.

also, ignore eautocad.

09-03-2007, 05:16 PM
is that bad for the motor? please explain i would like to know because im considering it on my ls1

09-04-2007, 10:47 AM

my lt1 was giving problems similiar to that... it ended up being the sock (filter) on the internal fuel pump.... I would go through everything else that they say *first* like opti, because my fuel pump was not easy to get to.. and no fun at all...

my car got so bad after running for a little while it would start to break up even at idle.. if yours isnt doing that and only breaking up when reving it probably is opti...

09-04-2007, 11:32 AM
umm ur throttle body could be all gunk up or might just need to do a full tune up..its about 800$ in parts and 3 to 4 hours to do..have fun..

09-05-2007, 12:40 AM
will try

09-06-2007, 01:51 AM
im just going to take it somewhere becuase its starting to drive me crazy

09-07-2007, 09:32 PM
quick test, wait till night fall, the dead of night when its really dark. open your hood start your car....... make sure you are not in enclosed garage.. look at all your spark plug wires and see if they are arcing anywhere. raise the rpms up to the level the car stutters, and see if you can see any arcing. The wires should not be sparking or showing any glow whatsoever. Its a quick test and you dont even have to get your hands dirty

09-09-2007, 02:37 PM
ill try it tonight, a few people said it might arc in the opti

09-10-2007, 05:27 PM
o2 sensors...

09-10-2007, 05:36 PM
what did you come up with anything?

09-13-2007, 02:16 AM
Yea I acually found out I have no money, and im hesitant to tear it down myself becuase it is by far the nicest thing ive ever had. Im 90% the problem is in the opti, it basically runs like a vehicle with piss poor timing.

09-13-2007, 08:54 AM
the opti isnt that expensive..

Sneakin Deacon
09-13-2007, 10:10 AM
neither is a crank trigger conversion.

09-14-2007, 03:43 AM
lol I know there not much, but my funds are real low. As of tonight my car lags when you rev it up fast and i hear a sucking sound once its warmed up which seems odd. I'm basically waiting to sell somthing so ill have some money.

Sneakin Deacon
09-14-2007, 03:49 AM
so out of everything we have suggested testing/measuring...what have you done? and what were your findings?

09-14-2007, 08:30 AM
sucking sound?

09-15-2007, 03:41 AM
sucking like a vac leak but I cant find one. I pulled every wire off the plugs and opti to cheak for corrosion, plugs and wires look new, I looked for arcing nothing, I wanted to cheak the injectors and fuel presser but I havent had time, and still the only code that comes up is the egr. Anyways its going in tomorrow unless I find something stupid in the morning

09-15-2007, 12:51 PM
get a can of carb cleaner and spray it around the intake manifold gaskets, plenum gaskets, and anywhere else you may have a leak, especially where the manifold meets the block deck.. see if your idle changes while you are spraying it around those areas, if it does, thats where you have a leak.

09-16-2007, 12:49 AM
Did you pull the plugs and what did they look like?
The sucking sound is just the cold air intake, but the rubber elbows tear on the bottom and the silencer tube could fall off.
You won't be able to tell from the exterior that the opti is crapped out.
One other thing, in my experience vacuum leaks don't just effect at high rpms.
Is this the white car in the pic? Looks real nice

09-16-2007, 03:37 AM
lol yea thats the one, its pretty sweet thats why I want it running nice and strong, I acually talked to the guy I bought it from today and he said the opti, plugs, and wires were replaced a little over a year ago. However that was only about 700 miles ago on the engine.

Quinn Racing
09-17-2007, 06:59 PM
get a new car !!!!!!! piece of crapp!!!! camaros

09-17-2007, 08:07 PM
SWEET! most helpful reply yet!!! ....Was that worth it?

09-17-2007, 08:08 PM
hey dick! you could give me your lt1. I took it in and they hooked my car to the computer and said it was my injectors

09-17-2007, 08:10 PM
hope they are right.

09-17-2007, 08:25 PM
yea me to i really dont hve money to waste, if i pull the rail and injectors i can turn my engine over and see if there working right?

09-17-2007, 08:51 PM
there is actually a specific way to test them.... But i would check all the wiring to them first... how did they diagnose injector failure>?

09-17-2007, 08:59 PM
He tried all the injector wires and they were fine, i guess the guy said that it was unlikely that the opti would be bad soon, he put his money on the injectors i guess there are little screens in them and when they clog they are done for good. He had my car on his computer for a while but i dont know if the opti/ignition would give off wierd readings if they were bad.

09-17-2007, 10:40 PM
didn't you say it had aftermarket injectors?

09-18-2007, 02:19 AM
no there stock

09-18-2007, 10:02 AM
Here's a couple of links that may help.
WitchHunter Performance - Injector Cleaning & Flow Testing Services (

I would sure try changing the fuel filter filter first or see if someone has some low mileage injectors for cheap to try. I have some extra o-rings if you need them.

Do you still have a cat?

09-18-2007, 04:33 PM
thanks for those, also it still has the cat

Quinn Racing
09-19-2007, 02:46 AM
naw really i was just kidding about the piece of crapp!!! thing bad ass car very clean but it looks like you ve got plenty of things to be checking so better wake up early and get to checking it out peace ttyl good luck!

09-19-2007, 04:10 PM
I know you are on a budget, gutting the cat is free. OBD1 has no after cat O2 sensors and you will see a few hp too.

Gutting procedures(must be strictly followed - haha):
(1) Unbolt & remove exhaust from back of cat
(2) Take a hammer or small sledge with a piece of rebar and beat the crap out of the honey comb crap inside the cat
(3) Shop vac or pull out the pieces (This takes about an hr)
(4) Start car before installing catback to make sure you get all the pieces out and to hear it with no muffler
(5) Install catback

09-19-2007, 08:02 PM
ok ill do that tomorrow, thanks

09-25-2007, 08:01 PM
ill fix it for you for cheap

09-25-2007, 10:31 PM
Any news?

09-25-2007, 10:36 PM
those aftermarket dist r junk out of the box call me

09-26-2007, 08:25 PM
No matter what the problem is... why is the first thing anyone reccomends to do is gut the cat?? That is so old.. Dyno your late model car with a cat, waste your time gutting it, and dyno it again.. Prove the horsepower gains, guaranteed its not worth your time. Unless its clogged dont mess with the cat.

09-27-2007, 10:20 AM
You need to reread. Gutting the cat was not the first thing recommended and is more than likely not the fix, even though it could be clogged. It is free and smokesalittle has no fundage. It will give you some hp. I can't tell you how much because gutting the cat was not the only mod I did between dynos(+27hp, +35tq). By itself, it improved the sound and I could feel a little with the butt-o-meter. The problem is ignition related (opti, wires, plugs, coil).

09-27-2007, 09:40 PM
I appreciate it guys it goes to GM tomorrow I have a family friend there, I've got two other buckets of bolts to work on and sell and I dont want to play trial and error with the camaro becuase it frustrates me. Ill let you know what they say

09-27-2007, 09:49 PM
That wasn't towards you personally B4C, all i was saying, most threads that start with some sort of Driveability concern, end up with somone saying GUT THE CAT! meanwhile its the problem 1% of the time. Late model cars gain little to no horsepower by gutting the cat.. research it, its been proven many times.