Would anybody be willing to review my data log and pinpoint a hard start/rough running problem?
https://www.mediafire.com/file/eyx94...22982.csv/file
Scanned using Scan9495
I am aware of the DTC 36 and 41, im curious as to if the data from the log corresponds to opti failure, or a bad ground, or whatever. just looking for input
Note, the first 200 seconds are start, warm up, and light driving.
Note, there is a massive exhaust leak on bank 1 that is not contributing to the running problems.
As for symptoms, the car takes about 15 - 20 seconds of cranking before it will start, then it will run like s*** all the time no matter the temp. with a significant vibration and power loss, my butt-dyno estimates it is producing maybe 150hp. As it warms up it will develop a slight miss every minute or so at idle, and when I am pulling away from a stop it will miss really bad then pull away without issue until I come to another stop. I don't notice any significant jerking or power loss during the misfire events. Ive swapped PCMs with my other car to no effect and tested the ICM and coil.

 

I'll take a look. No guarantee that the problem can be found. From just a quick look at the download, would have been helpful if you had the scan data for cranking the engine, if that is one of the problems. The second frame of data shows the engine has been running for 26 seconds. Also shows it was started “warm”, coolant at 129°F. Does the extended cranking before it finally starts occur cold, hot, or both. Also interesting that both fans have been commanded on.

What is the elevation above sea level where you live? Barometric pressure appears to correspond to about 5,000 feet.

Where is the massive exhaust leak? If it's before the. O2 sensor, it will cause problems with the A/F ratio.

Might take a while before a detailed look. At least two people in front of you.

 

Thanks for taking a look, I appreciate it. the extended cranking time happens regardless of the temperature, other than the miss at idle that turns into a significant bang when i pull away from stops there's no performance change as the temp changes.
The altitude here in Santa Fe is about 7,000 feet, and the temp was about 40 degrees. so its reasonably accurate. I swapped MAPs with the brand new one in my other car and it didn't change anything.
The leak is right at the manifold, but its been there since i bought the car. the rough running is a new problem that doesn't exist normally even with the exhaust leak.
I'd be happy to provide another short log of the cranking and startup.

 

Are you planning on fixing the exhaust leak and do you know what's causing it? It has to be effecting performance in some way.

 

Let me look some more at what you've done already. Might have some other suggestions. In the meantime, please read post #2 here:

https://www.camaroz28.com/forums/com...-guide-886891/

If you run another log, PLEASE attach it to a post in this thread. Do not upload it on Mediafire. My PC security software had to block what it described as "a dangerous web page". I won't try Mediafire again. I had already downloaded it to my iPad, and will continue to look at it there, but it gets too awkward. Best if you attach a copy of the the existing log to a post here.

If I had to guess which side had the massive exhaust leak based on the data log, I would say it's on Bank 2 (passenger side). All long term fuel trims are close to or maxed out, adding 25% extra fuel in response to a perceived lean condition. Then the short term trims are adding even more extra fuel. Definitely a major problem on Bank 2. Might be worth pulling a plug or two on Bank 2 to see if they are showing an excessively rich condition, possibly due to a "false" lean condition.

 

Thanks for taking another look, I agree with everything about the fuel trims but its been an ongoing issue, I'm concerned about the new symptoms, I'm not even sure if the data log can accurately reflect them. But in a nutshell the car has about 150hp according to the ol' butt dyno and it vibrates like a **** especially as you get up in the RPM. Plus the 15 - 20 seconds of cranking before it will fire right up and the DTC 36. The leak is the number 8 rear-most manifold bolt and it broke inside the head before I bought the car, its essentially impossible for me to repair without pulling the head off and replacing the manifold so I've left it alone. It hasn't caused me any problems so far believe it or not. Ive checked all the plugs already, number 6 and 8 were darker than the rest but nothing really bad.

When I get the next log this weekend I will post it here as an attachment

Shouldn't a "lean" condition sufficient to max out the fuel trims cause a CEL? I know the leak is there but I'm not getting a lean code at all.

 

The O2 sensor codes are NOT set by the LTFT value.. There are three codes for each O2 sensor in OBD-1. The PCM looks at the O2 sensor readings:

- If the sensor readings are stuck between 350-550mV for 60 seconds, it sets an "open circuit" code.

- if the sensor readings stay below 200mV for 50 seconds, it sets a "lean exhaust" code

- if the sensor readings stay above 750mV for 50 seconds, it sets a "rich exhaust" code.

If effect, in response to a PERCEIVED (could be "true" or "false") lean condition, the LTFT's can add as much as 25% extra fuel, and as long as the O2 sensor reads are moving up and down like they are supposed to, there is no code. And the STFT's can also add even more fuel, without triggering a code, as long as the O2 sensor readings keep moving. If it's a false lean, caused by an exhaust leak before the O2 sensor, the extra fuel is in fact, creating an excessively rich condition, adding fuel that bank of the engine doesn't need.

 

Very common for the rear bolt to break off. The easiest fix is to switch to aftermarket headers that don't use that bolt hole. I went with mid pacesetters (emissions) and it was an upgrade and fixed the leak. I sure there are lots of info if you search the old thread on this site.

 

Thank you for explaining that. but circling back, Would a dead optical sensor throw the DTC 36 and cause the excessive cranking? I read that the car can run exclusively on the low res signal, just not well.

 

Any chance you can shoot me a link? Ive had trouble finding parts that definitively specify that they dont use the rear bolt hole.... unless none of them do....

 

I did a lot of searching and they all say manifolds use outer bolts and headers use inner bolts. It's been so long since I did it, I can't find the info online anymore that's specific. I'm hoping someone else came jump in and have that info. I've had my Camaro for 22 years and the internet isn't as user friendly as it was years ago.

 

Alright I mean I’ve seen pictures of a lot of pacesetters, h*okers, Edelbrock, all sorts of different headers from different brands and the ones I’ve seen all look to me like they have a bolt hole on the outside of the #7 and #8 ports. I’m just assuming that means they use the outermost bolt hole.

 

If you look at the cylinder heads there are 8 holes and aftermarket headers use 6 bolts on each side. There are 2 holes right next to each other on the ends. The end ones are not used on headers as far as I can tell on any aftermarket version. If you look at the pictures of the ones your looking at buying you will see what hole they use. Look at images of stock exhaust manifolds and they use the outer one.

 

Thank you I looked at the stuff you said and I understand now. I already have a set picked out lol.

In other news, sorry for the delay. Got super busy with work. But I ended up swapping the opti last week before getting another log in and it cleared up my problems. Runs pretty good now, even with the exhaust leak. Just posting this for anyone else that may encounter a similar issue.

 

Thanks for updating your status. So many people just disappear without posting there solution. I remember the broken bolt being annoying but not affecting the cars performance. I just had to fix any issue it had and upgrading to aftermarket headers was a no brainer. It was an easy job and I just used clamps to hold it together and took it to a muffler shop to weld it up. Hardest part was cleaning the heads throughly to put new gaskets on and fitting them through the tight engine compartment which took several tries to get the right angle. If you don't have emissions I recommend long tube for the best HP gains.