Hunting Idle?

[aircrewjake]

First of all I would like to thank all of you that have put soo much time into this forum. And I assure you I have spent alot of time reading on here about the program, but I constantly get lost trying to find my answer already answered in another thread. I feel that I have learned alot, but there are still quite a few acronyms that are over my head.
I am going to be getting a bung welded on my exhaust for an LC-1 soon, but for now I just have my stock sensors to play with. Most of the time my car idles fine (about 70%) and then it will idle really high(2000rpms) or really low(between 500 and 800). I tried replacing the pcv, but that did nothing, the only other thing mechanical that I can think of that might be causing my engine to do what it's doing is maybe an vacume leak. I haven't seen it go into open loop yet, and there is possibility of my stock O2's being bad because they tend to flatline at idle, Another thing I've notice is that when the O2's flatline the engine commands an AFR of around 13to 1 and I've seen in past logs as high as 11 to one, but right now I am just wondering if anyone knows of a fix for the idle problem.
I am going to attach my file for logging on here in hopes that someone might be able to tell me where to go from here.
My Mods are Edolbrock RpmXT heads(prebuilt), Comp cam, comp cam pushrods, shorty headers, comp cams timing chain, and K&N in shock housing. (CA-54-424-11
Cam Style: Hydraulic roller tappet
Basic Operating RPM Range: 1,500-6,800
Intake Duration at 050 inch Lift: 212
Exhaust Duration at 050 inch Lift: 218
Duration at 050 inch Lift: 212 int./218 exh.
Advertised Intake Duration: 265
Advertised Exhaust Duration: 271
Advertised Duration: 265 int./271 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.558 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.563 in.
Valve Lift with Factory Rocker Arm Ratio: 0.558 int./0.563 exh. lift
Lobe Separation (degrees): 115, pushrods, shorty headers, comp cams timing chain, and K&N in shock housing.

[joecar]

ACJ, welcome to the forum...

A vacuum leak will do that.

I can't tell but it all does seem a little lean, but I can't tell from the log.

From your log, it looks like O2S21 has failed.

When the O2 flatlines, the PCM goes to open loop and gets the commaned AFR from either of B3605 CFOL or B3618 PE tables which might be why you see AFR 13; AFR 11 might be piston protection mode kicking in (happens when knock is prolonged).

Also, there's some knock, which suggests lean.

Cheers,
Joe

[aircrewjake]

Well I have been making some minor changes to timing around the rpm ranges that the engine tends to knock, and I fixed a fairly large vacume leak, but I still have several problems. I first one is uncertainty of the actual afr. I went to a shop to have the bung welded on so I could hook up the O2 sensor, but there doesn't seem to be anywhere to put it up stream of the catalytic converters. I was thinking of taking the right side cat off and welding the bung on on a bench. The problem with that is that you can't check the clearance of the sensor when you are welding on the bung on a bench. I was wondering if anyone has any pictures of where the bung is welded up stream of the cats.
I am also trying to figure out if my motor has out grown the stock injectors. I think that this might be why I have my ltft pegged at 25%. I am going to attach my latest logged data. So if anyone wants to take the time please do. thanks

[joecar]

ACJ,

In the scantool, at the bottom, is that your correct VIN and OS...?

Are you getting any DTC's...?

How many miles are on those O2 sensors...?

Do you have any more air leaks between the MAF sensor and the heads, and between the heads and the cats...?

How's your PCV, EGR, AIR plumbing...?

I think your MAF may be reading a little low, it might be dirty (don't use brake clean on it, use MAF cleaner).

What wideband O2 sensor are you installing...?

Cheers,
Joe

[aircrewjake]

The intake has a small leak around the block off plate I made for where the egr used to be. I disable the egr valve, but the leak is very small. The O2's only have 29000 on them. And thanks for the idea on the maf I'll give it a try.
This may sound like a stupid question, but what does DTC's stand for. Is is Trouble codes??
I am installing the innovate LC-1 Wideband O2 sensor. I have been seriously considering just removing the cats for now. If for no other reason then being able to put an O2 sensor on the mid pipe and be able to check the overall AFR on the engine instead of just one side at a time.
I have been able to eliminate most of the knock by introducing more air, but when I go WOT I still get 11.7 AFR and several degrees of knock retard. I think that it is the abuse management system kicking in, but I am not entirely sure. I'll attach My latest and greatest to this one. When I first got knock I was in too high a gear going up a steep hill and opened it up a little to see if that was possible a problem. That was where some of the knock is, but my main concern isn't when the motor is at just over 1000 and bogged down at 50 mph. My concern is when I go wot and I get knick retard and a commanded afr of 11.7 to one.

thanks,
jake

PS. Thanks again I really do appriciate the help. Thank you very much.

[joecar]

Jake,

Yes, DTC = Diagnostic Trouoble Code

The LC-1 has an extra output to simulate the narrow band O2 sensor...
You could just replace one of your front O2's and wire up the extra output to provide the signal (the connectors are cheap; you need a wire diagram).

AFR 11.7 would be piston protection mode and/or catalytic over temp protection mode.

But the wideband will show what is actually happening...

I think you still have air leaks, check your exhaust and cats.

Knock is bad no matter where it occurs... even if bogged at 1000 rpm.

Your spark timing up high may be too advance, you may want to bring it down to about 24 degress.

No worries,
Cheers,
Joe

[aircrewjake]

alright, my dtc's are all basicly saying that my egr isn't working. I don't seem to have anymore idle knock, but I still get knock at full thottle. Basicly what I'm trying to figure out is what makes my engine go into piston protection mode. I know it's there to prevent lean conditions, but I don't see that parameter in the tune tool. I guess this whole process will be much easier with my wideband O2 hooked up. for now I am slowly going richer and very slowly retarding my timeing. I have seen significantly less knocking around idle, but still I have the wot knock. So I am going to try some octane booster in this next tank and hopefully that will clear up the wot knock. At least until I can get my O2 sensor hooked up.