clwz28

I have replaced the opti,02s,walbro fuel pump,injectors,msd coil,and when the car has been run for a while ,it cuts out bad above 5500 ,any of u guys been here before.I am thinking maybye the ignition module ,no codes or anything?????????????????

MattSapp95_T/A

iTrader: (35)

I am having the EXACT same prob...ugh

Runs great up to 5500 and then crap....shift to the next gear and runs great to 5500 again..

New coil, ICM, opti, Plugs, Wires....

No codes...Good fuel pressure, regulator and pump...Plugs look good!

Good valve springs and hardened push rods...
car ran great for a while then one day it started missing then cleared up then it came back and I haven't been able to figure it out....

If i figure mine out I will let you know!

There are TONS of threads about high Rpm misses but no one updates them when they figure it out

boosted LT1

iTrader: (3)

The times I had trouble with upper RPM break up in a SBC it was always ignition. Cap, Rotor, wires, plugs, plug gap, coil.

I have not had an LT1 have trouble without boost...and an MSD box akways fixed the bust up. I would recommend trying autolite plugs and tighten the gap .005 to .010" from recommended, that will probably clear the problem, then I would put an MSD box on te ca and return to recommended gapped plugs.

The other common problem I have seen in an LT1 is poor ground at the drivers head. Make sure none are broken and the ground is making good connection. I rough the conection point with sandpaper.

Good luck

clwz28

My car will pull to 6200rpm until it gets warm ,then cuts out above 5500 ,has not done it all winter,now the temps up the problem is back,it all started at the end of last summer,but seems to be getting worse.

MattSapp95_T/A

iTrader: (35)

My Car has an MSD digital 6 box too...on or off it still breaks up...
All grounds are good...
Tried 2 different sets of plugs and closed the gap....

If you car will run to 6200 and then after warm breaks up after 5500 it is def not mechanical....

I just pulled my opti off again and am going to send it in for warranty and see if that fixes it....fingers crossed!!


Matt

collier341

iTrader: (5)

I had the EXACT same symptoms you described. I also had an MSD digital 6 box. I took it completely off and changed out my ICM and problem was solved. I've heard a lot of bad stories from those things.

If it's not that check under the hood at night and look for plug wire arcing.

RamAir95TA

iTrader: (2)

It's unfortunate how many people nowadays resort to the "throw new parts at it till it fixes itself" method.

Anyway, it's probably your ICM.

clwz28

I replaced all my other parts because they were oem,but I guess its time for a ICM.

MattSapp95_T/A

iTrader: (35)

Ive replaced the ICM too and checked the wires for arcing...also replaced the wires and plugs completely.....New coil as well....


Ive ran the car with and without the MSD and does the same either way..


I think it almost has to be a bad opti...


clwz28 - not trying to hijack your thread just figured we both have the same issue and maybe between the 2 of us we can figure something out...


Matt

stburgpete

I got a 94 lt1 have not had the problem yet nor have I seen it. You guys have got me interested. Hopefully you all figure this out.

Drew24

I have seen this happen a couple of times never to me but have you checked the spark and also i have herd about a clogged cat being the issue or could be a bad tune or pcm just some things you can check ill keep trying to pull up some info for you guys

clwz28

I put on a new ignition module last night and drove it last night,I think its fixed,so far so good,now my security light is staying on,at least it cranks.

MattSapp95_T/A

iTrader: (35)

Good I hope that ICM did fix it for you!!!

Unfortunately for me it didn't fix my issue...I sent my optispark back for warranty hopefully when I put the new one on it things will be good again!


I don't have any cats on the car (No Emissions Florida)
The tune has been in the car for a long time with no issues so I doubt that would be it...

Def thinking opti at this point.....

clwz28

Have you checked your maf,I did ,mine was ok,but they can cause simular probs.

MattSapp95_T/A

iTrader: (35)

No I haven't checked the MAF yet.... wouldnt it throw a code if the maf was bad??

clwz28

Alot of times they dont.

z28camaro1996

iTrader: (1)

mines doing that same thing.

z28camaro1996

iTrader: (1)

my opti is like 3 months old i get mine from oreillys where do yall get yalls?

MattSapp95_T/A

iTrader: (35)

mines from All Ignition

My buddy runs the same one with NO problems but mine has been horrible...


I have another MAF I will change it out when I get the car back together...

Matt