Ran into a few problems while tuning

I finished the air dam last night and figured id try to lean the top end out just by 2% on the afc. I figured wrong, I should have just left everything like it was. It ran a little leaner than I would have liked it to be like 13:1 so I changed it back. But instead of changing it back and leaving well enough alone, i figured I'd change the settings on the NEO from pro (16 rpm points) to easy (8 rpm points) Well when I did that, it erased my settings. I had the correction factors written down, but not the rpm points. So I reprogrammed 16 rpm points between 750 and 7200 rpms. Then I took it out for a drive and it was a decent tune, but I could have sworn I heard some detonation. It sounded like somebody was ballin up a piece of foil. Now the afr's were 12:1 and under and no timing being pulled. The strange thing is it doesn't do it in 1st gear or 3rd. Just second and only around the 6k rpm range. Anybody have any ideas?

So after i thought I detonated, I did a compression test. Now I've never done one before so I have nothing to compare it to. But from left to right on the valve cover its 125, 125, 160, 160. What kind of shit is that. Oh and plugs looked good and I looked down at what I could see of the piston and didn't see any apparent damage.

Lastly, today I was trying to fine tune it, and still the same stuff was happening, but i noticed around 6-7k my afr's will jump to 13:1. Even when I richen up the top end considerably it doesn't fix the problem. I'm almost thinking the 550's and the rewired 190 are running out of steam. But 20 psi on a 16g shouldn't make them do that. Especially seeing as like 2 days ago everything was running satisfactory. Any comments or advice please?

I've been doggin this car too much trying to fine tune it, and the combination of no progress and potential speeding tickets after topping out 3rd are really pissing me off. I hate to be raggin this car out for nothing.

Need a rebuild for sure.

Need a rebuild for sure.

Well I wasn't wanting to hear that, but kind of expected it. I won't be doing a rebuild for a little while. You dont think that one night of possibly detonating could have done that much damage do you?

What do you think about the sound that I heard? How bout the fuel system? I find it really hard to believe that I'm maxing that out. On a side note, I'm not burning or leaking any oil with mobil 1 10w30 even with those sorry compression numbers.

Low compression doesn't always lead to oil burning/consumption. When detonation wrecks stuff, it usually goes big (holes in piston/block, holes in head, etc). I find it hard to believe that detonation is what caused your problem.

How many miles on the car? Maybe it's just worn out.

That is true. It could be worn out. It has 104.5K on it as of now. The previous owner had a brand new head and transmission installed by the factory, but as far as I know the bottom end is still the same as it was back in 98. Really though I was able to hold my own with a LS2 a couple weeks ago, so even if it is worn out I'm still happy with its performance. It still runs good as of now, the only thing that makes me second guess it is that detonating sound in second gear from 6-7k rpm. If it comes down to needing a rebuild I dont mind, but I'd like to know for sure what it was that I did so I don't do it again on a freshly rebuilt engine.

Did you add oil to the cylinders to see if compression increased. This will tell you whether its the rings or could just be a valve or headgasket.

No I sure didn't try that. Is that what they call a wet compression test. How much oil would I have to add, and what should the compression numbers look like when im done.

Yes, that's called a wet compression test, but they don't work as well on flat topped pistons versus dome styled pistons, the oil just takes up more space, therefore increasing pressure numbers. You can sure try it though, it can't hurt anything. About a cap full in each cylinder will do just fine.

Ok well I took it out again to do some more logs. Got home and I figured Id change the plugs. Went to start it up and it kept dying. Checked the codes and its got multiple cylinder misfire, and a P0340, the chiltons manual says no cam signal at pcm, and cmp sensor circuit malfunction. So maybe I have a bad Cam position snesor. It wasn't loose but I messed around with it, cleared the codes and it fired right up. This time the idle wasnt near as choppy as it had been. I just figured it was normal because of the cams. It seems to run fine now but I don't feel like driving it and having it cut off on me. Anyway Im going to go see if I can test it and see if it needs to be replaced. Any suggestions?

Keep us updated. Hopefully that's all your main problem is, but those compression numbers aren't too healthy. But you'd probably get away without a re-build for at least another year I would guess if the cam sensor has in fact shit the bed.

Yeah man I'm not even sure what to think. Everything tested out fine on the cam sensor. Car seems to run fine. It's just that 6500-redline has that detonation sound, and for whatever reason around that rpm the afr's jump to 13:1. I messed with it all day today and couldn't come up with anything. Only thing I can think of is that somehow the fuel system isn't up for the boost challenge, which is strange because everything was fine a couple days ago. I've got my wally 255 laying around so I think I might just throw that in, along with a fuel filter swap. After that, I will definately be seeking a professional tune, since obviously I dont even come close. The only thing that sucks is that the closest AWD dyno is almost 2 hours away.

That is soo lean man you gotta aim for 11:1 or richer.

That is soo lean man you gotta aim for 11:1 or richer.

That is what I was going for but it's like no matter how much I richen up the top end on the SAFC it'll still lean out almost like the fuel system is't able to handle it. But I know it has to. The only thing that sucks is I have to get the rpm's up to nearly red line to even see. By then its hard to watch the rpm's, wideband, and the road, and look out for cops at the same time. I'll probably mess with it a little bit more today.

Well it sounds to me like maybe your fuel pressure isn't rising with boost. That would explain for no matter how much fuel you add it doesn't richen up. Are you using the stock fpr? maybe base fp is off.

Yep, I'm still using the stock FPR. I am getting a CEL for a fuel pressure solenoid. But I looked it up when I first got it and most people did't seem to think it was that much of a problem. Maybe I should just go ahead and get an aftermarket FPR seeing as I'll be installing the walbro 255 within the next few months anyway. Do you think that sound i was hearing (like balling up a piece of paper or foil) could be detonation at 13:1. I've heard it on other cars but this car sounds like a bunch of sand is getting kicked up and hitting the front of the car. Only at the top of 2nd gear though.

Since this, I did the wet compression test. Boosted the 2 problem cylinders from 125-150. I read that there should be at most 15 psi difference between the 4. I've got 35 psi difference. I just don't see how they can be so off, and what I could have done to cause this.

2nd edit - I was reading up and saw that you need to have the throttle plate open for a compression test. So I went out and did it again. From right to left
cyl 1 - 165
cyl 2- ~163
cyl 3 - 130
cyl 4 - 130
So the numbers are a little better, but still shitty, I read that if your compression raises with the wet test then the rings are trashed. Oh and on a side note. DONT try to start the car up right after doing the compression test with the throttle plate open. All that fuel is chillin in the cylinder and when you do go to start it over bang. I thought somebody shot off a shot gun. It made my ear ring and I wasn't even near the back of the car. Anyway I took all of the sparkplugs out and I'm letting the fuel evaporate before I go to start it up.

those compression ratings don't merit an engine rebuild. As for the FPR I say you might as well can't hurt and will be needed soon anyways.
That paper you heard definitely sounds like detonation and 13:1 is plenty lean to be knocking under almost any boost conditions. If your plugs are out right now. Go over them with a magnifying glass see if you can see and metal particles on them. When you detonate small pieces of the pistons vaporize and condense on the plug. The metal is a tell tale sign that you are detonating.