Hi guys, I just got TunerPro RT and my homemade 2 transistor cable to link at 8192 baud to my 6E masked '165. Once the transmission had started, I took the 10k resistor out and the datalogging kept going just fine. I was thrilled to not need the high idle ALDL mode 10k resistor installed all the time.

Ok here's one thing I saw immediately that was not good. I started the car cold and ran it up to 165 degrees (Idling, I didn't drive it with the ALDL yet). My O2 sensor reads 0.00 mv idling!! But, as soon as you rev to above idle, it immediately jumps up in the 0.700-0.800 range. The 02 sensor ranges decently at higher rpms, but at idle and just above idle it is at zero or 0.100-0.200 mv. Here's the thing -- I have a 4 wire heated O2 sensor, in the collector of one long tube header on my 327 (which has a choppy idle from the long duration cam). Is it normal for this zero reading with O2 not warmed up at all from driving (I only ran the car for maybe 3-5 minutes, its so cold out I didn't want to stay outside).? I am suspecting that my heater circuit on the O2 sensor is not working, I'll check the wiring tomorrow. If the heater isn't working, would you still really see zero millivolts idling?? Should I be looking for a huge exhaust leak? It is almost impossible with crappy long tube headers to have absolutely perfect seals at the flanges, but the gaskets at the heads and the exhaust ends are both brand new. The weld around the o2 bung is disgusting because I was running the mig on a ****ty outlet with very low line voltage, so it may have pinholes in it, but for the most part I think it seals.

At least I have high speed datalogging now to tune and trouble shoot. Hopefully this crappy cold weather gets out of here quickly.

 

It's hardly more then a piece of nichrome wire, like in a toaster. There's no real curcuit in there.

Yes, cold enough and far enough back, and you could just not have enough heat. Don't forget those headers act to radiate heat.

 

In my opinion, I think the O2 is probably ok. When the O2 is too cold, it acts like an open circuit, causing the O2 volts to stick around .450 volts and it gets real sluggish. I have headers as well, and my motor runs funky for a little while because the sensor is too cold. In closed loop, the computer has to really push the fueling around to get what it wants to see out of the O2. The low volts could be O2 getting into the exaust stream from a leak, the cam, too little fuel... I was messing around awhile ago and I accidentally made the engine run so lean at idle that the O2 volts where .004mV. The motor ran, but just barely, and it was popping like hell.

 

Grumpy, even if the O2 was cold and not up to operating temp yet, why would the O2 shoot from 0.00 to 0.700-0.800 revving the car? Is that typical behavior of a cold sensor? I don't know much about what to expect from the O2, I figured if it were below operating range it would not reach the normal numbers I'm seeing revving.

 

Yeah dimented, I literally had 0.000 volts at idle. The car wasn't idling bad at all. I'll have to get the laptop on the road with me and see what its doing warmed up. The O2 sensor is new, Genuine AC Delco 4 wire, and has less than 500 miles on it.

 

faulty ECM OR the O2 sensor is bad(or wired up wrong). First check the sensor. Next would be to check the ECM, disconnect the O2 and see what the mv's are. With the sensor disconnected the value should be .445 or .455 MV on your scan tool, I forgot but it's one or the other. THat value should not change or fluctuate. Now ground out the wire going from O2 to ECM. ***don't ground the 02 sensor, just the harness wire*** It should read 0.00 volts.

 

All it takes is a 5dF temp change at the threshold *alive* temperature for them to go from off, to on.

It's designed to be on/ off, and rich/ lean. They put alot of time into making just that way. If it's reading, it's awake and well, there's no almost warm enough, or almost rich, with them.

 

I hate to state the obvious, but what's the Integrator and BLM at?
If the calibration is off, it may take a few seconds for them to catch up, and if it's really far off, it'll never get rich enough to read anything. The pinholes can cause problems, but a steady 0 doesn't seem quite right if the tune is close and closed loop active. Do you have a wideband (and if not, darn it, save up for one, they have magical powers, hehe). Maybe there's something in the calibration that is turning off closed loop for you. What is the commanded A/F? If it isn't saying that it is trying to get 14.7, then it's in open loop.

If it's reading 0 v, and if that is real sensor voltage, then it is warmed up. When cold, it'll read between 400-530 mV, and then go up or down when warm enough. Heated O2's should stay warm pretty easily. If it is somehow accidentally grounded, well, there you go, but since revving the engine gets a response, it sounds like the sensor is fine.

I'm going to assume you don't have air injection.

Your choppy cam could be misfiring a bit, which won't help. Do you have a way to measure the temperature of the header pipes?

Ooh, great, another fight at the bar outside my window (I'm in China - near Dong Guan). These guys are terrible fighters, and they hit like girls apparently. I feel like a giant (only 5' 10", but can bench about 380). That'll be a good video for the friends back home.

 

Commanded AFR was 14.73, so the car was still in open loop (it was so cold out running it for a few minutes hadn't warmed it up yet). Is it normal to see 0.00 from the O2 sensor idling in open loop? I'm going to go drive around datalogging today and see what happens.

 

It is very possible for a sensor to read that low if it at temp and the calibration is off far enough. As stated see what the INT and BLM are at idle in closed loop.

 

(multiple post)

 

Ok guys, I drove the car around and got it into closed loop. I am still reading 0.00 mv idling, 100-300 mv just off idle,and 700-850 mv with significant throttle. The exhaust always had a very strong smell idling with this engine, even when it was carbed. It's a smell that will stay on your clothes. Is it possible that this is LEAN and not rich exhaust idling? It has good idle quality and great response. How should I start tackling richening up the closed loop idle and off idle, mess with the MAF tables? I am idling around 10 g/sec. The BLM and INT max out at 160 idling and at very light cruise, and are normal at all rpms and loads above that.

 

run the test I described..

 

11s or bust, when I first linked to the ECU, everything was cold, and with the engine not running, the cold O2 read 0.452 mV. I haven't had a chance to get under the car and unplug the sensor, but it looks like it's my tune/camshaft wreaking havoc with the readings.

 

my camshaft specs are 242/250* of duration and closed loop works fine. I really think 0.000mv means something is wrong...

 

This is a good situation to stick a gas analyzer (if you can) in the exhaust and see what the CO levels are doing. It could very well be a lean idle or even a lean misfire at idle. See what it smells / idles like with the O2 reading something and the BLM's closer to 128.

 

You guys are all giving me excellent suggestions, and I appreciate it. I don't have access to a wideband/exhaust anaylzer. I will try unplugging the sensor tomorrow to see what readings I'm getting on the ALDL. If that checks out okay I'll add a ton of fuel in at lower rpms and see if I can't get the car idling in range on the O2 sensor.

 

Well, with $6E, you can't add fuel at lower RPMs directly, but you can go to MAF table 1 and try to blend in some fuel from the bottom up. What is your airflow in grams/second at idle? It's possible that you have a vacuum leak somewhere, and that the air at idle is coming from behind the MAF, and it's not reading it, thus requiring closed loop to climb so far. I'm assuming you have an EGR block off somewhere, and (depending on your manifold), a properly blocked off cold start injector.

Ahh, you're having an idle creep problem when warm, aren't you? This is definitely related. When warm, idle block starts out as lean. Then as fuel is added by closed loop, it comes up because it's running closer and closer to ideal, but it's still so far off. I bet there's a combination of things awry here, like TB too far open, something causing the lean fueling (like bad MAF, vacuum leak, something), and maybe some other things. Get the fuel problem fixed first, then redo the idle speed adjustment.

 

run the test yet? before making fuel adjustments and such, make sure the hardware is OK.....

BTW, I love your car. Where can I see some more pics?!?!?

 

Thanks 11s, no I have not run the test yet. I am concurrently working on my modified 1997 Buick LeSabre (3800 Series II, aftermarket PCM, KYB struts, aftermarket sway bars and exhaust) and had to get it aligned today after more suspension work. I don't have that many pictures of the Camaro, I'll have to take some more. I have a much larger, more detailed version of the same picture in my sig. It was taken on an overcast day, so it's not the best, but I'll get some more soon.

The big pic is located here

 

Just checking to see if you have any results from adding fuel in the idle area.

 

Eric and 11s, I really appreciate your continued concern and help. I am a full time senior engineering student, and have not had time to further troubleshoot the O2 sensor and datalogs. I have no classes tomorrow and, weather permitting, will be spending as much time as necessary to get some on-the-chart idle readings. The car runs so excellent as-is with the TPI, I can't imagine how well it's going to run when these little issues are corrected.

 

I know how it is, I have a good friend that is studying electrical engineering. Time is at a premium on class days.

 

UPDATE -- I added a lot of fuel in the 1st MAF table (25-30% around the idle cells) and also richened the open loop enrichment. I have not datalogged yet (or else I wouldn't be on this computer typing right now!) but the car fired up and idled instantly, cold. Usually you have to peddle it until the IAC catches it. ALSO the warmup was finally run at target high idle rpms! When the car would idle cold before it was always ~400 rpms below target. I know why now - way lean. The exhaust smells a lot better now. I'll start datalogging and continue modifying the MAF tables.

 

ALL FIXED!!!!!!!!!!! I am now idling around 128 BLM and 750 mv. The only problem was that my tune was too lean. Nothing was wrong with the O2 sensor or ECU (as suspected, I was extremely careful wiring everything and I used a Painless harness). I bumped up 10 g/s (my idle mass flowrate) from 0.55v to around 0.91v on the #1 mass air flow table and bumped everything else up accordingly in #1. I also made my afr % vs coolant temp much richer down low (10% richer). The car starts easily, idles immediately, and reaches the target high idle, does its warmup routine with no hunting or surging, and FINALLY gets down to target hot closed loop idle. Once I had the car rich enough, my minimum air setting quickly became ~1100 rpms and I had to close the throttle blades way down. The car has no problem coming down to its 750 rpm target hot idle now. I left a few counts showing on the IAC at target idle just for the hell of it (6-7 counts). This isn't causing any surging and I figure this gives the IAC a little room to trim things if it wants to. Whoever says MAF systems aren't easy to tune probably hasn't spent any time with them. This is fun!

The bottom line is, you can easily show 0.000 mV at idle if the tune is too lean. And I wasn't so lean that the car wasn't driveable -- it did idle ok and drive great. Like Grumpy said, the narrow band O2, by design, has a very tight tolerance for what it considers "in range" AFR. 0.4 V on the mass air made the difference between 0.000mv idle and 0.750-0.800 mv idle.

 

Glad to hear you got progress on it. The narrow band sensors like Grumpy said have a very small window when it is working correctly. Sometimes it is hard to distinguish the smell between a rich idle and a lean miss idle. Is the O2 swinging in closed loop at idle?

One more question, what is the highest O2 Mv that you have seen with your painless harness? I can only get mine to read 650-750 Mv while the wideband is showing below 14:1 and that was with 3 diffrent sensors (2 heated and 1 unheated) it will read down to double digits without a problem though.

 

The O2 swings nicely at idle, setting up lots of cross counts. I have had the reading swing as high as 0.820 with this AFS73 4 wire O2 sensor and the Painless harness.

 

Congrats on fixing it.
Well, I was on the right track! And I could still be right on! I don't know why your MAF is sooo far off. I haven't tuned any big cam MAF cars though, so maybe it's normal?!? Another thing that it could be is the Injectors themselves - What flowrate are you using? Most saturation injectors have problems when the PW gets near 2 milliseconds (usually don't fire a full shot, and is usually inconsistent). In your bin, do you have the Injector flowrate correct for both single fire and double fire mode?

 

I'm using 24 lb/hr Multec II injectors. Yes, I have the single and double fire constants set correctly. This car has 2.02/1.7 valves and a choppy single pattern old-fashioned hydraulic flat tappet cam with around 310 degrees advertised duration. This sure as heck was not originally set up for fuel injection. The BLM's are very good above idle, so it looks like the choppy long duration/lots of overlap just need a rich idle to make the motor happy.

RednGold86, you were absolutely 100% dead nuts on relating my idle creep up problem with being too lean (and guess what? because the idle was so lean, I had the throttle body cranked way open to get the minimum air speed up high enough). Your diagnostic intuition is excellent! I am idling with the injectors around a 1.65-1.7 ms pulsewidth now with the BLM and INT around the magical 128 mark.