Who has Tuned with no NB02s?

[HLxDrummer]

I've made a thread about this on 3Si but didn't get much attention. I've tried disconnecting the NB02's and tuning it out so I have full control over AFR but I've come accross a problem.

Under low RPM/high load it knocks like crazy even with a sane AFR and a couple of degrees timing pulled. If I plug them back in and go to stock tune (leaner and more timing) it may get a few counts of knock but nothing like with them disconnected.

I got better mileage with them disconnected and liked having control over the entire map but can't figure out what is causing the knock when I disconnect the NBO2s. Any ideas?

[DocWalt]

No idea, but good to see ya over here :)

[HLxDrummer]

Glad to see you here! I love all the sinking ship avatars lol. Props to Alan for doing this, I can't imagine how much work it must require!

[B-Man]

I've been running w/o O2's for awhile now. I get the same knock issues. I pretty much just ignore it. Mine happens under 0psi (vacuum) and with a 12.0afr, so I just figured it was phantom

[HLxDrummer]

I've been running w/o O2's for awhile now. I get the same knock issues. I pretty much just ignore it. Mine happens under 0psi (vacuum) and with a 12.0afr, so I just figured it was phantom

Interesting.. Mine happens from -8 inHg to 0 PSI at low RPM (2,100 and under). AFR and timing help mine a tiny bit but not much.

I think it's real knock because once I go back to stock tune/O2s it goes away. So it couldn't be a mechanical noise, right?

[B-Man]

What you're saying is actually making me concerned that it's not actually phantom knock. I do, however, get a lot of random knock (12-14 counts while cruising on the highway). How far are you pushing your afr? As far as I know, having the O2's unplugged do not affect the stock timing. I am not completely sure of that but I would imagine it would actually retard it if anything.

[HLxDrummer]

What you're saying is actually making me concerned that it's not actually phantom knock. I do, however, get a lot of random knock (12-14 counts while cruising on the highway). How far are you pushing your afr? As far as I know, having the O2's unplugged do not affect the stock timing. I am not completely sure of that but I would imagine it would actually retard it if anything.

Well here is my theory. Knock at low loads (relative to your 18 PSI on 13Ts) isn't very harmful and lots of cars experience it without blowing up. However, if I have to put strain on the engine I want it to be at WOT when I am having fun, not when I'm pulling a hill.

I also get knock here and there even when the stock tune but I drive at or under 2,000 RPM a lot.

At first I had the AFR around 15 at -8 inHg dropping to 14.5 at 0 PSI. Knocked like crazy. Gradually worked my way down to 14.6 at -8inHg and 13.8 at 0 PSI and still knocks even with 3-4 degrees pulled.

I've thought about this for months and can't figure it out. What else can the computer control that would cause this? Timing looks similar when I've looked at the Scanmaster. AFR obviously is monitored..

I would love to make this work though. I was AVERAGING 26-27 MPG with a (IMO) safe tune and had the top end nailed down nicely. The knock just scares me..

[B-Man]

First of all, I'd LOVE to get 26-27mpg. I normally get 17/22, but I'm a little heavy on the gas ;)

How high is your knock count? If you're still getting knock at that afr with that much timing pulled, it's gotta be something else. I usually go for 14.0 at 0psi and pretty much 14.7-15.0 under 0psi.

Are you using an EMU?

[HLxDrummer]

Well that is 50/50 city/highway and I either baby my car or stomp on it (usually baby it haha).
Knock is usually mid teens if I just maintain my speed up a hill but if I try to accelerate or give it any gas once it starts knocking it'll go to 28.

I would be thrilled with your AFR if the knock would just go away! I'm using an eManage Blue.

[DocWalt]

Bad knock sensor maybe? Does it have goo oozing out the top of it?

[B-Man]

Hrmmmmm

Mine, if I mash it when I get 14-15counts of knock, it goes away immediately. I do usually just keep it out of the under 2k range.

Since the EMB is pre-ECU, you're timing will be more advanced than stock. I really can't imagine it being enough (unless you have ungodly huge injectors) to cause this much knock, especially if you're pulling 3-4 degrees.

PS, I should probably change my sig since I haven't run 18psi since NG. I lowered it to 15psi because of really bad spikes. Shitty boost controller. *grumblegrumble*

[B-Man]

Bad knock sensor maybe? Does it have goo oozing out the top of it?

I'm not saying that it's for sure not a bad or overly sensitive knock sensor, but characteristics of a bad knock sensor are usually it knocking all the time.

[HLxDrummer]

I've considered that but it acts fine when I have the O2s plugged in.. I haven't checked it in a while though I'll have to take a look soon :)

[DocWalt]

I'm not saying that it's for sure not a bad or overly sensitive knock sensor, but characteristics of a bad knock sensor are usually it knocking all the time.

True, but not necessarily. Just something to check.

[HLxDrummer]

Hrmmmmm

Mine, if I mash it when I get 14-15counts of knock, it goes away immediately. I do usually just keep it out of the under 2k range.

Since the EMB is pre-ECU, you're timing will be more advanced than stock. I really can't imagine it being enough (unless you have ungodly huge injectors) to cause this much knock, especially if you're pulling 3-4 degrees.

PS, I should probably change my sig since I haven't run 18psi since NG. I lowered it to 15psi because of really bad spikes. Shitty boost controller. *grumblegrumble*

I haven't really gotten on the gas when it was knocking so I couldn't tell you what mine does under that situation.

I'm actually running stock injectors still and I'm needing to add anywhere from 5-15% fuel on the EMB so it should be retarding it if anything, right?

Is your car pretty similar to mine (in how it acts with the knock/etc)? Also, have you considered using a GM Boost Control Solenoid for a EBC? Pretty cheap..


Also, what do you think about trying O2 simulators? That would definitely tell us if it's the O2s actually being unplugged causing the problem.

[B-Man]

As a 7th injector? Eh, I've though about it, but heard it doesn't work all that well. If I'm gonna do it, I'm gonna do it right.

Have you checked for boost leaks? You should be able to just zero out your EMB map with stock injectors (or even lean it out up top).

[HLxDrummer]

Ya that's what I meant. Hopefully it works out well as I've just installed it this summer but haven't tuned it yet. I'll let you know how it works out.

I checked for boost leaks a while back and just had TB seal leakage. Replaced the seals although I don't think I fixed the problem (shitty seals). Plan to replace them again soon. With the O2s in I have it zero'd out but with them unplugged I needed to add some fuel to quell the knock.

I do think I found the some important information tonight. Put my "No O2" tune back on and unplugged them, reset the battery. Drove it and it drove great, no knock! A few miles later, the ECU threw the CEL and knock is back.. So it must have something to do with them being unplugged/limp mode. I think I may try this:

http://www.o2simulator.com/index.php?main_page=product_info&products_id=10&zenid=cbb91dce4b899a71e17a3003f681cb48

Just to keep the computer happy and hopefully keep the CEL away. I would just hate to waste the money and solder more crap into my car.

[a2j]

I will be running without O2s. but this topic is kind of scaring me now.
should there really be any legitimate knock on low/no boost? with the right A/F ratio and EGTs...

[B-Man]

If you're still using Airflow metering, I'd keep the O2s. I actually kinda of regret going MAFless.

[HLxDrummer]

I will be running without O2s. but this topic is kind of scaring me now.
should there really be any legitimate knock on low/no boost? with the right A/F ratio and EGTs...

With the stock ECU and a piggyback?

There shouldn't be any but something is causing it when the CEL comes on. I think if you can keep the light off (O2 sim or run a false signal from your wideband to it) it would be fine.


If you're still using Airflow metering, I'd keep the O2s. I actually kinda of regret going MAFless.

Well I think I fouled mine out from running with them unplugged for a while and I would like to make it work without them so I may try a little longer but if it doesn't work well I'll put them back. Definitely not going MAFless with the eManage after all the complaints I've heard.


What do you guys think of running a constant .48-.52V signal from the LC-1 to the NBO2s? Is it smart enough to see it's not sweeping from 0-1 or will it be happy with that signal?

[Chris@Rvengeperformance]

gatecrasher couldn't probably tell you better from looking at the stock code, but IIRC the stock ecu counts the number of sweeps passed that center value. It is worth a shot though.

[HLxDrummer]

gatecrasher couldn't probably tell you better from looking at the stock code, but IIRC the stock ecu counts the number of sweeps passed that center value. It is worth a shot though.

Man that's a bummer.. I guess I could try just .5V constant or maybe make the "window" for the scaling huge (instead of like 13AFR/1V-16AFR/0V or whatever make it like 8AFR/1V-22AFR/0V so it has no resolution. It would probably still alter the trims over time though but maybe it I center it around my ideal cruising AFR it won't change much?

[HLxDrummer]

Does anyone know if the ECU throws a light for the heater circuit or because it's not getting a signal or both? If it's just the heater, I could plug everything back in and just cut the signal wire..

[HLxDrummer]

Anyone?

[KeithMac]

Don`t know off hand, best bet is to measure the resistance on the heater coils and wire a resistor in of the same value to try?.

I`ve been running for years with no 02 and no CEL.

[SilverJester]

HLxDrummer:
I'm assuming you have a 2gen since you're throwing a cel? I disconnected my NB02's and I don't have your issue. But I'm using MAFT-pro and I have a 1g so no cel.

What if you just feed one of the LC-1's outputs to the ecu (in place of where the NB02's were) and change the scaling so that is either pegged rich or lean. The ECU will give up trying to adjust with fuel trims after a while when it realizes it can't change the AFR and just go into open loop. Or would that cause a cel also?

[HLxDrummer]

I actually have a 1G (1993). Drove home this weekend and confirmed that once it throws the CEL that it knocks worse. So the ECU is doing something so actually make knock worse for some reason.

I think instead of wiring in a resistor I would just snip the signal wire and leave the heater circuit in tact. I'm not sure if that would solve the issue or not though.

I considered pegging it rich or lean, but then my airflow corrections will be huge. I also tried leaving them plugged in and putting in a ton of correction to max the trims but that was a PITA and didn't really work.

Looks like I'll try snipping the signal wire and if that doesn't work wire in some O2 simulators even though I would prefer not to..

[SilverJester]

I actually have a 1G (1993).
Weird...maybe a late model 93?



I considered pegging it rich or lean, but then my airflow corrections will be huge.
If the ecu can't make the trims get close to 100% then it will give up and just go into open loop (same as unplugging them). Of course the downside is that if you reset the ecu it will have to "relearn" that it can't correct the trims before it goes back to open loop (but that shouldn't take more than 10-15mins of driving).

[B-Man]

I don't know why people think 1Gs don't throw CEL for o2s. Both my '92s have done it.

[KeithMac]

Well I`ve done 2 years or more with no o2 near the car and no CEL.. Must be ECU specific.

[SilverJester]

I don't know why people think 1Gs don't throw CEL for o2s. Both my '92s have done it.


Well I`ve done 2 years or more with no o2 near the car and no CEL.. Must be ECU specific.

Yeah it would be interesting to figure out why some 1g don't cause a CEL and other do. Mine doesn't throw a CEL, but I forget what yeah my ecu is from (I had t replace my original one cause the caps went bad).

[RL7]

Have you logged your AFRs before and after the CEL to see if there is any noticable difference? It is likely that the ecu uses a different fuel and timing map in "limp mode". I would suspect that it would run richer with less advanced timing. If this was the case, you would want to re-tune after the CEL was thrown if you were going to run this way. I'm running a 91 car with a 95 engine and a 93 ecu and I have no CEL with the O2s removed. I do have slight knock (usually 1-3 counts) right around 2k rpms under low throttle. Right now, I'm running a pretty safe map that is rich across the board. I tried to richen it up more at the 2k light throttle area and it didn't solve the problem (it may have reduced it though). I'm starting to suspect that it may want to be right around stoich there for whatever reason. I'll probably try to lean it out there to see what happens.

Which maps are you using with the e-manage? I use the Injector, the MAF correction, and the "Acceleration" map. I try to keep most of the corrections to the Injector map to minimize any unpredictable modification to timing. You can't put any negative values on that map though. You may want to juggle corrections from one map to another (if possible) to see if it has any effect.

[HLxDrummer]

Ya, my AFRs are the same. MAYBE .1 AFR off. I thought it would richen it/retard timing or not do anything but I'm lost at this point. I actually leaned it out a bit where it was having trouble and it helped a little. Still can't give it the throttle I can with the stock O2s without getting a ton of knock though. With stock O2s I get a few counts here and there like you.

I'm using MAF correction and ignition. I don't have the injector stuff hooked up but maybe down the road I will.

However, I'm almost positive it has something to do with the CEL. As soon as the light comes on it starts knocking under high load/low RPM but when the light is off I have no problems, actually less knock than stock. I would love to eliminate this problem without adding more crap to my car but I may have to just buy an O2 simulator.

[RL7]

Probably a dumb question, but did you read the CEL to make sure it was for O2s and not something else?

[HLxDrummer]

Ya I did check :) Was hoping it would tell me specifically what about the O2 threw the code but no luck.. Thanks for all your help by the way!

[mh3kgt]

Yeah, I'm 1g here (92) and I don't get any CEL's from my O2's being unplugged with maftpro. Interested to see what is causing your knock issues tho

[HLxDrummer]

Man, lucky you guys!

What else does the ECU control that could cause this? According to the wideband AFR is constant, according to the logger timing is constant, boost is irrelevant.. IAC? I have a steady AFR though so that shouldn't matter..

[RL7]

Are you logging the wideband with the datalogger? I don't have an accurate gauge, so I have to do this, but I would probably do it regardless. It lets you see a lot of stuff that you may otherwise miss. For instance, with some of this knock, I sometimes see an instant 0.5-0.75 drop in the AFR, this leads me to believe it may be some sort of misfire. It's pretty easy, you just feed your wideband output into the EGRT pin on the ecu and set the software up to log that. If you are doing that, do you see the AFR doing anything even slightly suspicious when it knocks? You may just want to go nuts and kick it down to 10.xx at the knocking point to see if that does anything. It may be worth a shot to hook up the injector stuff and play with the Accel map. I'm not sure if it actually does what it is supposed to do, but it does seem to good a good job of keeping the AFR pretty level. It is extremely baffling that the timing and AFRs stay the same and it knocks only once the CEL comes on. Mabye take an identical drive before and after and post up the logs of that particular point?

[HLxDrummer]

I actually have it feeding into my Scanmaster 3, but haven't logged it. Good thinking though, my AFR does jump around some and it could correspond with the knocking.

I would try making it way rich but I think that may make the problem worse with all that fuel. I've gone down to 13.8 AFR, however, and no big difference. 4* retard doesn't make a big difference either.

I can post logs if you think it will help. I'm pretty sure it corresponds with the CEL, but I guess it would be nice to see what the ECU is doing to cause the knock, huh? Maybe making it overly sensitive? I'm not familiar with what the ECU can/will do..