Boryke

Hey guys.

I've been fighting a nightmare with this car. The car has 10,500 miles on it. I first got it and it was bone stock. I put on a halltech mf103 and took it out one night with my friends. Ran it hard on the highway a few times and I could feel it lay over in the upper RPM range... but nothing too serious.

I didn't worry about it much.

The next week I swapped the heads to AHP heads that were milled .020 and added a ported TB and ported LS7 intake manifold.


I sent the car to vengeance racing to get tuned, and they were unable to tune it. Massive KR in the upper rpms.

I got the car back and began looking for causes.

I've replaced:
MAF
Alernator (old one fan was dinging teh housing)
Plug wires.
Ran some 100 octane with the original gas that was in it for the tune and then filled up with Quik Trip 93.
Ran Mopar combustion chamber cleaner to remove carbon from pistons

I am still getting massive knock retard.

Here is a screen cap from my log session tonight.

Attachment 48365641

When I first nailed the gas, it didn't get any KR but the car was spinning so the car wasn't under heavy load.... I backed out and nailed it again. Immediately it tacked up to like 12 KR and I could hear audible detonation .


I am at a loss on how to fix this. It seems like something is majorly wrong with the car.

Mike @ vengeance told me the AFR looked great on the dyno when the detonation started, but I didn't get a print out.

tblu92

Typically when knock sensors fail----you will get excessive pinging---often without any codes--
If your tuner checked the WOT AFR ratio then it's not a lean issue---Without knowing how much timing they put into your engine it would be hard to say if there is indeed simply to much timing---
My guess since you had the intake manifold off--- either a pigtail was left un connected
OR you pinched a sensor wire---and lastly you have a bad sensor which is unlikely
You may research that when installing a LS7 intake if anyone changed the knock sensors to a LS7 sensor

Boryke

This is a LS7 car. 2006 z06.

The knock sensors are located on the side of the motor... not under the manifold.

total timing under WOT is right at 18 degrees and it's still pulling 12. I can hear audible knock.

tblu92

OK then I would suspect a knock sensor issue--- with only 18* of timing there is no way it should remove 12* of timing---

norris_83

You need to tune your vehicle properly!!! Your narrowbands are reading way toooo lean, don't blow up that motor and don't run it hard anymore.

PM me if you need a hand!

Boryke

This tune is from vengeance racing. I have not adjusted the tune.

norris_83

well since you have hptuners you should be able to adjust it. I saw your post on the hptuners forum.. post up your tune and lets have a look at it.

subfloor@centurytrans

Where exactly are you seeing lean narrowband readings???

subfloor@centurytrans

Uh yeah...the knock sensors haven't been under the intake manifold now for I don't know, 12 years!!!

subfloor@centurytrans

Go into the tune and pull out 10 degrees across the board (in both the low and high octane tables) from 1500RPM and up. The car will feel like a slug at WOT but if the KR is legitimate, you should see the amount of KR drop significantly. If it stays the same or close to it, then you need to start looking for something that's banging around loose in your engine bay.

I'd also recommend checking to make sure the knock sensors are properly tightened as I've seen loose ones cause huge amounts to show up in a scan.

jim2092

Or if he is seeing KR in the log and hearing "audible detonation", those milled heads may have somehow resulted in too high of compression. Compression test?

norris_83

800-825mv is lean! No doubt about it.

The narrowbands are controlling fuel in closed loop perfectly as you can see, so I'm sure they're reading correctly. 900-920mv is the typical commanded 11.8-12.5 afr .

I guess I've seen more then 2000cars and know from experience.

Check out my account just to reassure yourself

www.instagram.com/mep_q8

norris_83

post up your tune, thats the only way we're gona be able to help you out.

subfloor@centurytrans

Uh no, and for several different reasons.

The narrowband O2 sensors and (resultant STFTs) have absolutely zero effect on what's happening with the car at WOT, this is why wideband O2 sensors are used to do proper tuning.

A narrowband sensor has an extremely limited range as all they are designed to do is indicate whether the car is slightly above or slightly below the desired closed loop AFR value of 14.678 (stoich), but cannot accurately report by how much. In fact, your comment about how "900-920mv is the typical commanded 11.8-12.5 afr" shows just how much you don't know because narrowband sensors can't even read that low! If that were the case then nobody would ever need to run a wideband sensor!

Next, when the car goes into PE mode it also goes from closed to open loop at which time the fuel trims stop recording (indicated by all the fuel trims going to zero at WOT so once again, they have no effect at WOT.

The only very slight exception is that if the LTFTs are positive (indicating a lean condition) going into Power Enrichment mode then the computer will add some fuel but other than that don't factor in to controlling the fueling at WOT.

I could continue but I already made my point.

tblu92

Excellent reply of how it works !!!!!!!!

As someone else said----I would try removing 10* of timing at WOT areas and then see if you are still getting any knock--or still hear audible knock----If so then you have a knock sensor issue as I said earlier when they fail your engine pings all the time no matter what
could be wiring--broken or over tightened when installed pinched wires
I 'm curious to see what the fuel trims are at P/T as well----If they are positive it's lean at P/T

norris_83

Ummm, firstly, I never said they have any effect at WOT. They are a just a sensor. With the limited log shown above, that was the only thing I could comment on. You do need a Wideband to tune WOT, if you think you don't then you should order a remote tune from me

A narrowband does have limited range your right. That's exactly what it shows, if its slighty rich or slighty lean. I never said you could accurately see the AFR from the narrowbands, but with 800-820mv on a narrow band, that is running lean.

Again I said, from my experience on a naturally aspirated car, 900-920mv typically runs between 11.8-12.5AFR. What I've seen from my "experience" is running WOT with 800-850mvs reads around 12.9-13.8 on a wideband. That by no means is an accurate reading, it's a limited range

Who was talking about closed loop and open loop above? I think I know the difference between both of them.

My statement was, the fuel trims seem to be doing their job properly before going open loop, meaning the sensors aren't worn out or "lazy". So they should be reading well.

Again, who said anything about the fuel trims controlling open loop WOT? I was talking about the readings on the Narrowbands since that's all I can see from the log.

I really don't see your point

subfloor@centurytrans

You should probably quit now because every time you open your mouth you just make yourself look worse. I was going to write "quit while you're ahead" but that hasn't happened yet.

The problem this guy is having is KR at WOT, not part throttle. Whether the car is crazy rich at part throttle, crazy lean or doesn't even have O2 sensors at all has no bearing on the issue at hand. You just don't seem to get that because in one breath you admit to knowing narrowband sensors have limited accuracy yet you follow it up with an idiotic statement about how "900-920mv equates 11.8-12.5 AFR and 800-850mv equals 12.9-13.8". I'm not sure how many times I have to say this - one has NOTHING to do with the other. If in your "experience" you've seen those values on the narrowband while the car is at WOT it's a coincidence nothing more.

See that little green line called TPS showing 88%? If you knew how to properly read a scan you'd know it means WOT and with it a couple things happen - the car transitions from closed to open loop, it's now in Power Enrichment mode and the stock narrowband O2 sensors no longer contribute to the proper fueling of the car. I don't even have narrowband O2 sensors in my car but with a wideband I'm able to get the WOT AFR dialed in extremely well. I looked at the scan he posted on the HPT site but even without having done that, the screenshot he posted above is more than enough information to indicate the KR is only happening at WOT which makes all your incessant droning about the stock O2 sensors a complete waste of time for everybody reading this post with the intent of trying to help.

To the OP - I'm sorry this got off on such a tangent but the last thing you need right now is bad advice telling you to chase down things that aren't even close to helping you find and/or fix the problem, and that's simply what I was trying to prevent.

norris_83

The only person making themselves look worse is you trust me. Read through what I wrote and don't make assumptions.

Exactly, so why are you getting confused?

Who on earth is talking about closed loop?! IF I said an idiotic statement, I'm just glad I tune myself and would never have to deal with you since your so blind sighted by what you read from your Tuning School Book

OMG, do you seriously not understand what I am saying?

The O2 sensors look lean.

Nothing about the O2 sensors commanding WOT fuel, nothing about the car not being at WOT, nothing about whatever you a are rambling on about, nothing about KR, nothing about wasting everybodys time. IF you can't hear someones advice, then don't give any!

My god, your arrogance blows me!

ZZMike

Please listen to the subfloor on this one.

Especially if VR tuned the car and achieved a satisfactory AFR, but had to abort testing due to KR. Something else is going on here besides a lean problem.

schpenxel

There is some gross misunderstanding going on in this thread. norris has said maybe 1 out of 10 things that he's been accused of, and by a vendor no less. Jesus Christ.

We all know narrowbands aren't used in PE. We all know they can't accurately say much besides "you're leaner than stoich" or "you're richer than stoich". No one is disputing that, nor has he said that a single time.

The point is, that typically narrowbands will read closer to 900mv when in the ~11.5-12:1 AFR range. Is it 100% consistent? Of course not. The point being is seeing them closer to 800mv is an indication, a very rough gut check if you will, to see if it's likely leaner than it should be.

Obviously a wideband is really required for WOT tuning.

I agree with everyone else--pull 10 degrees out everywhere and see what happens. No change=something banging around or knock sensor messed up or something. Significant change=it was likely real knock.