I noticed a miss at the 35 to 45 mph range. I had a bad alternator and I replaced that and the miss is a lot less prominent. However I do notice a diffrence In the long term fuel trims b1 is about 5.5% and b2 is -1.6. Could this be cause by an ignition problem? I'm thinking it's related to the ignition system because after the alternator was replaced the miss got way less prominent .

 

if this miss is under "load" (read high gear, 35-40mph and you floor it), confirm you don't have plug arc on one or more plugs. Especially if you use the metal stock heat boots over the plug wire ends

 

I'll try that tomorrow.

 

It doesn't miss on hard acceleration. It also doesn't miss on closed loop. I described it as a miss before but its actually more of a surging.

 

Is this a totally stock engine? If not, what are the mods? What year 96 or 97? Please add a signature.

https://www.camaroz28.com/forums/lt1...nature-879835/

And this “surging” goes completely away when the PCM enters closed loop, typically after 206 seconds?

A misfire or exhaust leak before the O2 sensor on one bank can cause a false lean reading, and increase the LTFT's. There are 18 different LTFT's..... which one has the numbers you reported? +/-5% is not an unusual number, but the difference between bank 1 and Bank 2 can indicate an issue.

 

I have a le2 heads and cam, tpis 58mm throttle body the revised one with isolated iac passage, golen 383, vigilante 3600 stall, and torque head 24x system, kooks headers into a catted y pipe.

I checked for leaks and I have non where the headers bolt to the block. And the 02s thread right into the collector on the long tubes. The Ltft are all all over the place in fortunately they do not show blms with the 411 pcm at least not that I can tell.

I think I may have a bad 02 sensor I bought two new a/c delcos when I can get it on the lift I'll change them out. When I get on the high way they seem to get real close to each other but at idle at a light b1 wants to go to 25 and b2 goes to like -3.

I'm also concerned about one plug wires on the left bank it looks like the header may have compromised it.

 

YOU HAVE TO ADD A SIGNATURE. Your engine is so HIGHLY MODIFIED WITH THE 24X/LS1 PCM that it can change the responses to issues significantly from an LT1 with an Opti/LT1 PCM. If you want accurate help, that info needs to appear in EVERY post, and that is the purpose of the SIGNATURE. It automatically appends to every post. You said you were going to do this earlier, but didn't.

It also might have been a good idea to continue in your earlier thread, so people know the history of the problem, what may already have been suggested, and what you might have done in response:

https://www.camaroz28.com/forums/lt1...issues-887922/

I'm not trying to give you a hard time.... I'm trying to help you. Nothing will frustrate the knowledgeable members more than crafting a well thought out set of suggestions and fixes, only to find they were not aware of the specs of the engine they were working on. When you really think about it.... a 24X conversion is not really an LT1 engine any more.

 

I understand I have the other issues sorted out and I am just trying to figure put this mid range miss.

It's still an lt1 it just doesn't use the lt1 ignition system and computer. The nothing thing that changed on the engine from the opti is that the opti and ignition coil come off and you install the crank and cam sensors and swap the knock sensor for an odb2 one. All the other sensor are reused.

That harder part for me is understanding how some of the data is views in hptuner versus the odb1 software I used before.

I did change out that plug wire and it helped alot. I'm going to try changing the 02 sensors as well next. I still think one of them went had or maybe it got dropped or kicked while i was waiting to get all this done.


Ps. I tried to make a profile but I dont know how on a cellphone.

 

An LS1 PCM has many operating differences from an LT1 PCM..... it's a whole 'nother animal.

Don't want to argue about it..... up to you.

 

oh I agree with that. Though when you utilize it on an lt1 you dont use all of those "special perimeters"just cause the lt1 doesn't utilized them. I have read of other lt1s having very similar issues and alot of people say it happens when going into close loop. I dont believe that this issue relates to the ignition system. I think it is fuel related. So I'm going to try the 02 sensors first then try the MAF sensor. But since it runs fine in open loop I'm convinced it has to do with a sensor that only functions when it drops into close loop.

 

So a little update. We replaced the maf and the 02s that changed nothing. But after we changed those out it threw a code for the knock sensor. After changing the knock sensor the throttle response and drivability of the car got much better. We also installed a new iac which did nothing but it was only 55 dollars. The only sensor left on the car is the map everything else is brand new.

However I have been doing a lot of reading on this and have found a good amount of people who have had similar problems in both the lt1 and ls1 platform. Both seem to describe the problem as cam surge and it needs to be tuned out by the tuner. My guess is that this is the problem for the most part.

I still cant figure out why the two banks are not equal on bank one and two. But after all the changes they are much much closer