The PCM only "learns" a few things..... long term fuel corrections, learned IAC counts for idle at startup, and stores a low octane fuel flag. That's all.

 

My MSD instructions stated that the, as shipped, set-up should be 0*. And that there is a total of -7* to +7* of adjustment. I'll have to look at them again to see if they state which is CW or CCW. And that an adjustment should only be made to correct an initial timing error after installation, back to 0*.

 

That is correct. However, independent of the PCM tuning spark advance you could "play with" the MSD advance/retard screw (+/-) at the track and see if it improves your performance.

While I have though about doing this, I haven't done it yet. My car is really running great with the new MSD now (very consistent track times), so I haven't touched it yet.

WD

 

So just for the info:

Turning the screw CW retards the timing and CCW advances the timing.

Also here are the new test that i ve maid yesterday:

-Brand new wire
-New Delteq that was working on my last gm opti(now dead)
-New plug
-New msd pro billet

With the stock timing setting(2 1/2 turn out) the car idle bad and shake a little.If i give it some throttle the engin seems to shake even more and then when i let the gas off it makes the exhaust pop.

The more i turn the screw ccw the more the idle is great but it cannot be drive like that because it make backfire over 1k rpm.

If i turn the screw cw to the max the idle seems fine and i could drive with it but again some problem occur.

If im starting from a stop and stomp on the gas,the motor will have big hesitation until 1k rpm and then will run pretty stronght untill 3500rpm...At this rpm the motor will hesitate badly and never go any higher...

What can i do?

Thanks

 

That is the way I understand it also, BLM(block learn multiplier) and INT(integrator) are the only real learning functions that the ecm has the ability to correct(based on it's programming) Long term and short term fuel correct and learn, BLM(long term) and integrator(short term) are the only ones that learn, one affects the other to achieve optimum fuel trim(usually around the number 128 -130) again based on it's programming.

Re setting the ecm and driving the car 50-100 miles will not fix this problem.
DO you have a check engine light on?


IAC settings are a pre-set correct? IAC counts are a function of what the ecm has to have to aquire a set base idle speed.


I have seen and heard that if the cap sealing O ring on the MSD is not on the outside of billet bottom's "lip" it will cause these problems.

Are you SURE the plug wires are on correctly...it is easy to swap 5 and 7 on a small block Chevy...will have those symptoms.



Always Faster, gotta warn ya, some people in this thread(the one who has posted the most) have never even installed an opti, more or less a MSD opti or a Delteq, never had a running LT1 of his own. Be careful who you take advice from.


David

 

I don't believe the (+/-) 5 degrees of timing adjustment from the MSD is the solution to your problem. It's something else that is wrong with your setup.

Again, on my MSD Opti the rotor screws were loose and causing a problem. Therefore I recommend using thread-locker on the rotor screws and ensuring the screws are tightened correctly. Also, make sure the cap is not caught on the edge of the O-ring causing a deformity. With what I know now, I would never install an MSD Opti without first “completely” rechecking the assembly of the distributor.

Personally, I've done about 10 Opti installs over the years.

WD

 

I dont have any ses.

Im just trying to figure out something before tearing it down for the 20th time in the last month

 

Ok i ve got some new test and need some usefull "hints"...thats why im bringing this thread back.

Today i ve swap the ACCEL 8.8 wire that i ve made with the stocker that came with the Delteq.That didnt change a thing,same problem.So i put back my Accel cut to lenght on.

I ve put back the msd to the 2.5 turn out(stock spec for a ltx base).I ve also start the car and re-calibrate the IAC (with shoebox site method).It was still stumbling a little at idle.If you hear it quickly you maybe would not even realise the kind of small miss that probably happen once every turn of the engine.

When your giving comes throttle ,the motor shake badly.But here is the new interesting fact:

I was so pissed off because i was working everyday on this car since mid april and it would want to run properly so i floor it at idle just to see what kind of reaction it would have and then

After the 1750rpm mark it run pretty smoothly without any hesitation

So i took it for a small ride.From the 750rpm mark to 1750rpm it buck,shake hard has hell but again when i pass the 1750rpm mark it would run and pull really hard to the red line without any hesitaion or miss.And if im running thru all gear and just keep it over 1750rpm between each shift the car will reach high speed(over 120mph) without any problem...

So what could it be?

Thanks

 

lways Faster, gotta warn ya, some people in this thread(the one who has posted the most) have never even installed an opti, more or less a MSD opti or a Delteq, never had a running LT1 of his own. Be careful who you take advice from.


I put a disclaimer in there.


If there was some garbage the computer was trying to function with then if it resets it will go back to it's original set up and relearn what it is running with now.

I am not up to speed on all these computers do, but that is my understanding.

May be all out in left field


You don't know what I have installed so keep on running your pie hole.

 

Reguardless of what the book says or what people says, not all MSD optis will work out of the box without adjustment. Mine just for one was way out. The car did not have enough timing in it. After a few test passes around the house I had it dialed in.

 

I dont know what you have installed huh? Care to enlighten us? As to what you HAVE built or installed in the last 4 YEARS? Predictable response from you...you in living in the garage yet? LMFAO...oh yeh, when is the car(that's not yours) gonna be ready...or is THAT just another lie. I already know the answer Don't bother answering.

You should put a disclaimer in ALL of your posts.


I see you called Susan...I almost died laughing when she e mailed me...would you like me to copy those? I can put them up if you like, so you can see what SHE thinks about you.


The guy WITH a car(that runs)


David

PS Alwaysfaster, have you pulled the plugs? I bet you have a fouled plug,a plugwire problem or a cracked plug.

Also make sure you dont have a bent pin in the opti connector.

 

C mon boys dont start a fight here ok

I ll take comments/idea from everyone and see.

The wire are good,i ve swap them with my odler one(less than 60miles) and the same problem occur.

I will check for a bad spark plug but im really leaning toward the dang pro billet since the motor run perfect after 1750rpm...