Ok so I havnt really pushed my car in a few months but in this few months of normal driving I have noticed that it seems like it has like half the power it should..

I didnt really think twice about it but then the last few days I have had the chance to really get on it, im talking WOT up to 130.. -But we were making runs thru 1st, 2nd, 3rd, and everywhere between and there is something wrong.. Im having a hard time breaking the tires loose from a stand still.. That should tell you something right there..

This IS on a private track BTW.. I dont condone that kinda recklessness whatsoever! End up killing someone BUUUUT..

Where do I start in regards to trouble shooting.. What info can I give you to help you help me??

Ive maintained this car the best I know how, and thats all info coming from this site so..

CURRENT MODS are just CAI, full exhaust (1.5" primaries into 3" back), and milzy's stage 1 tune.. Series 2 3800 SC btw..

Help me out here im starting to worry..

Heres a little info I got after a couple 1-2 and 2-3 runs.. Dont know if its of any help tho.. Ignore the HP and TQ graphs as I have not calibrated those readings yet..


Desktop Screenshot 2018.04.12 - 10.45.44.73.png

 

I sure I cant be much help on this one , but have you checked your catalyst convertor ? When I use to install engine's a long time ago we had to do back pressure test's on the cat too confirm they weren't plugged for the warrenty. Can't remember what the readings were but you might be able to do a search on it, or since your at a closed track you could remove the O2 and see if there is a difference besides the noise.

 

I probably should have went further into detail about whats done to my car.. My mistake on that.. Although, ive ran with this setup all last year with no problem......

Repaired UIM + LIM gaskets
Never run under 93 octane/ usually keep 100 in it.. I know this here makes a huge difference in power but I am familiar with it and have determined this cannot be the cause..
One or two step cooler plugs, cant remember
180 tstat
Cat and rear o2 removed.
EGR system removed
de-screened tbody
Boost bypass solenoid disconnected from boost side and unplugged (still controls actuator)

I think thats it right now.. Like I said, nothing is new except the problem.. I hope someone can give me some direction here.. I wanna go fast..

 

Do you have a way to monitor knock and AFR?

I see the timing advance scale, but I don't see anything about knock.

And in your LTFTs, your max value is pretty rich. I'm curious if the car is flooding you out at your power stage, or locking too rich when you go WOT.

 

I see a mod list, but nothing about pulley size.

100 octane, why? Unless you're running a tiny pulley, there should be no reason for that.

This isn't a mod. Put the screen back in.



The bad thing is that it's hard to tell anything from the gauges shown. A snapshot at WOT would be more helpful; most helpful would be a plot of the gauges through a pull. Issues I see looking at the gauges:
-it shows a max MAF reading converted to cfm of like 1900. No way is the engine moving that kind of air - that's 1000++ whp F1x blower airflow. Can you show this in Hz instead? Bad MAF?
-it shows very low throttle, low engine speed, but is showing +6psi. No way that's possible. Is this a converted reading or actual map value? Bad MAP?
-As Chibi mentioned, it's pulling a good deal of fuel in the long term trim. I wonder if something is giving bad data and it's over fueling?
- What is the WOT timing?
-Any KR at WOT?
-How about O2 readings?
-Any pics of the plugs?
-What are the compression readings?


I'd definitely stop beating on it through all the gears until you figure out what's going on though. You'd hate to destroy it trying to troubleshoot. You should be able to tell from just hitting WOT briefly if it's running right or not.
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Pull the plugs. They always tell a story.

 

Ok let me try to gather myself here and answer some of these.. Ill try to make this simple.. Ill try to get the info im missing ATM, later.

Using 100 octane because we put the 3.4 on sometimes.. Honestly tho, the 100 makes it run quite a bit better no matter which pulley im using.. Dont like knowing "it could be running better".

The 6.2 psi youre seeing, I have no idea what that is. Look one box to the right and thats the map reading (max 7.1psi). I didnt set this "arrangement" up on the tablet myself. It was just a quick thing done by someone else so I could take the pic of the info..

RPM was 5927 making 7.1psi at 100% throttle..

WOT timing advance is 13.5. -But here is something that concerns me... Looking over the timing advance im seeing a minimum of 0.0, thats not normal.. It never goes below 13.5 unless there is a backfire. A backfire will consistently give me a -10.0 due to false knock.. This "backfire" is only caused by an abrupt release of the throttle, from WOT...

Gonna measure KR later today.. Guess theres a few things I have to do with this app to get it to read correctly..

Ill get a pic of the plugs later.. I have changed them within the last 7k miles I know that.. How often would you recommend changing regular copper plugs? 10k?

I posted a while back about something keeps failing with the MAF sensors I put in.. I finally got an AC delco, CEL went away, but the problem seems to still exist with it.. Its strange and hard to describe but it mimics a slipping transmission. Thats the best way I can describe it. I expect the CEL to come back anytime now over this issue.. Nobody can figure out why they keep failing..

My fuel mileage is horrible.. Driving like grandpa I can get a total 18 mpg.......

o2 sensor is brand new, rear o2 removed..

I bought a de-screened tbody is what I meant, the high flow ZZP one... Although whats the problem with de-screening the stock tbody? I did this in one of my other 3800s and it seemed to improve performance.. I mean the screen itself literally crumbled as I pulled it out..

I wouldnt know how to measure compression but the others I will try to get by tonight.. I gotta ton of crap to do today..

But with this, is there anything anyone could suggest or no? I know I really didnt add any more info here but rather made myself a little more understandable..

Thanks a ton for the help so far....

 

I guess it just seems crazy to me to spend the cash for 100 octane fuel, especially just for a 3.4". Even a few tanks could buy other mods to let you be able to run a 3.4" without race gas.

13.5 at WOT is very low, especially on 100 octane with a 3.4". Curious to see if that's being pulled by KR or if the tune just has no timing in it.

Are you talking about a legitimate backfire here or just exhaust popping?

It really depends if you've got the heat range matched up right. If the heat range is matched right, 10k could be fine. What I'm wondering is if you went too cold and they've started fouling out, especially if yiu hadn't been pushing it in awhile.

Also you need to 'read the plugs' anyways to see what they tell you about fueling and timing. Lots of help on that on Google if you're not familiar, but it's a pretty helpful data point.

​​​Definitely points to an over fuelling issue, perhaps related to the MAF problem.

It doesn't actually improve performance and causes issues with the MAF readings. If the car gained power from deleting the screen with no side effects, GM wouldn't have wasted the money putting one in.

Not to say a car can't be set up and tuned to run ok without one, but I sure wouldn't delete one from a setup where you can run one.

They rent testers at autozone. You just take out the plug, screw in the gauge and crank the engine. Can also do a leak down check too. I'm not thinking this is the root cause of your problem, but it's an important data point to tell if it's a contributing factor.

Its near impossible to be accurate given the limited info, but I'm really leaning towards a fueling issue. Bad gas mileage, low power, very negative trims, constantly failing MAF.

Might not be the only problem, but fuel certainly seems to be a common thread. Reading the plugs will give you another data point on fueling.
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Ok first, compression is good.. Thankfully..

Exhaust popping. Not an actual backfire I suppose..

Plugs look beautiful..

Im thinking whatever this is, is directly related to (or IS) whatever is causing my MAF to keep failing.. Its not oil from the filter and the whole intake looks clean like it should..

I know the timing is lower than it was before.. I was getting maybe 19.5 or 18.5 at WOT and 37.5 at idle.. NOW, its 12.5 at WOT and 20.5 at idle..

You said in my post about timing (it was a few months ago) that you wouldnt worry about idle timing (only WOT timing) but something is telling me it could help to consider this..

Mechanic said it would be $150 for a diagnostic analysis but I really cant spend that just to be told whats wrong with MY car.. Im sure you know the feeling..

Im worried im gonna have to start throwing parts at it and nobody likes that..

 

I'm just not sure how that would cause low timing. I also don't see how a MAF that is reading correctly (assuming it is and isn't really reading 1900 cfm) would cause issues before it failed. Have you confirmed you're getting a correct HZ reading out of the MAF?

I guess the upside here is that the system isn't particularly complicated- maf, pcm, wiring between, and grounds. Worst case you could just test and replace everything one by one.

I'm not sure what else you want to consider. My point before is that trying to compare your idle/cruise timing to 'normal' is impossible as it varies based on many variables. WOT timing is pretty straightforward as we know what it should be and what the general upper limit is. There really isn't much else to check here though- about the only thing you can do is see if KR is causing the timing pull, but otherwise your scan tool probably isn't going to tell you what else is modifying the timing. And it certainly shouldn't be showing a bunch of KR at idle.

I suppose you could check and clean the engine grounds as that could cause issues in the icm, pcm, and maf. Beyond that, there's no way to force the pcm to add more timing to check.

I do hate paying for someone else to do stuff for me, but I also won't get to the point of just dumping money into it with the shotgun approach. You need someone who knows what they're looking at to be able to see the scan logs. That should provide some good clues as to what to do next.

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