For some reasone I have been encountering many "odd" problems with tuning this engine. This latest has put me at a loss. The engine is a 355 with ported TFS heads, hot cam, exhaust, 10:1 CR, Potted and Siamesed TPI with a T-5. I am running the 1227730 with the super AUJP v3 and using TunerProRT.

The problem is that the engine is lean between idle and 1600 RPM, period. In open loop the idle is rich at .850-900, then above idle starting at 1000RPM to 1600RPM the engine is lean no matter the map reading/cell. The afr on the one wire O2 sensor will read rich at idle and then plumet to a reading of between .4 and .150. I have raised the VE table considerable with no change. The oddest part is that as soon as it hits 1600 RPM the AFR will jump to .850-.900! I have tried setting the same value at the cells less than 1600 as the cell that is 1600 (So the whole row after idle is the same value). This does not help.

I am starting to think that it is a problem with the code I am running or table (lower VE table) I am using.

 

Check the injector PW as the NB reported voltage drops. If the PW is dropping off, then something funny is going on.

Otherwise may want to see if there is some sort of strange exhaust leak.

How does the engine run at the 'lean' area?

RBob.

 

BLM cell boundaries are changed in that bin to be 900, 1500, 2000 RPM as opposed to the stock settings of 700, 1200, 2000 RPM.
You may be having the same type of issue I had with one end of the range being lean/rich, the other end being the opposite.
Rich at 1000 RPM but needing fuel at 1500 will cause the learning to chase what your needing at 1500 because it keeps pulling back the fuel for the 1K area you started at. Could be off base but your logs may show this trend.
If you see evidence of that you might want to shift them to have definite "idle", "off idle" and "cruise" areas.
You will have a better idea of where those should be in your setup.
HTH

 

This could be the case. I will have to find out exactly where the lean condition starts. I do believe that it starts at 1000RPM or shortly thereafter.

The engine will surge a tad and be lacking in power, You have to give it some throttle, but to much will almost "freeze" the engine. It won't quite die, but will stall. It is deffinatly acting lean.

 

You usually end up with an area that is funky with a cam that comes in after 1600 RPM. I usually warm up the engine and start out tuning one KPA value for RPMS less than 1600 RPM by setting the idle RPM to 800, start the engine, read the KPA and WBO2 and NBO2. Adjust the bin VE for that KPA and RPM.
Then set the idle 100 rpm higher and repeat, then set the idle rpm for 1000 and repeat. I do it up to 1600 RPM. That gives a small KPA baseline.

Then drive the car in closed loop and record BLMs. Sit down and look through the logs. Adjust VE and try it in the car and record data. Sit down and go through the logs......I do that about 5 times. Then I make a bin that is open loop and drive and record data to fine tune without BLMs messing things up. The open loop tuning can last for days to years. Once it is where I like it, then I make a closed loop bin and tune the closed loop values to match how it ran open loop. The closed loop bin helps for fuel changes from day to day.

 

My answer comes from my own experience with the same issue. My 'Bird with the 305 build has been reading extremely lean in the "cruise" range, which is 1600 - 2000 rpm. No matter how high I pushed the VE settings for that range, it was running lean.

In building the 400 that I'm putting in, I'm using the 305's heads, 'cuz they'll give me the compression I want, plus I've already ported and polished them. When I pulled the heads off of the 305 to move them to the 400, I got a surprise, AND the answer.

The combustion chambers were caked with soot, from running WAY rich. Put that together with the "lean" readings from the O2 sensor at cruise, and the culprit is the sensor! It's not a bad sensor. It's the wrong sensor.

With headers (sensor mounted down at the collector, not up by the outlet ports), a high-flow cat, and 3" cat-back, the ONE-WIRE sensor isn't kept hot enough at low load and low rpm. When the sensor cools off, the voltage drops, and the computer sees "lean." So it starts dumping in more fuel, trying to compensate.

The answer for mine is to install a 3- or 4-wire O2 sensor with the new engine. I bet the answer for your problem is the same.

 

This is the fifth engine taht I have had in the car and tuned, all of them were built engines. The heads are the Trick flows that I ported out and have had on the engine, which has maybe, 7,000 miles. So my problem is not soot. I have been using an unheated O2 sensor for quite a while, and never had a problem like this. I have even tuned 3 of the engines with a set of hooker long tube headers, and had "0" problems. I know all of the sensors are good because I have tested them and replaced what neded replaced.

I believe that the changed BLM cells were part of my culprit. I changed the areas of the VE table to coincide with the area that would change. This showed improvement. I am starting to wonder if I am seeing the odd effects of a larger cam (218/228) mixed with a TPI set-up. One of my previous engines used a combination very similar but with an HSR, I did not have the same VE table. I have started to try the combination of datamaster and VE master on it again to see if my tuning was way off.

 

I had a TBI motor with a weird lean condition once so much so after the cat till almost the muffler inlet were lit up bright orange at say 2000rpm after maybe 3 minutes running motor like this. the culprit turned out to be that rubber line that connects the fuel pump to the sending unit in the tank.

this rubber line had a hairline cut in it and enough to drop fuel pressure abour 6psi. while not a massive drop for you TPI guys on a TBI this cuts pressure in 1/2 .... probably not your problem but a thought

 

I do not think that it is my problem, as I have a constant psi at all times. I even checked it while I was driving. I am still tunning it. I got a good recomendation from VE master, that helped. VE master helped to illustrate your point between on and off idle and the differing BLM cells.

 

If you're smart, you'll pay attention to what others have told you concerning the O2 sensor. It may work okay occasionally, especially if the timing is off and it's still burning in the exhaust, but if you have headers on a closely tuned motor, you pretty much HAVE to run a heated O2 sensor to be sure it is reading correctly. Not only that, but it really needs to be an AC-DELCO if you really want it to run right. Far too many folks have ignored this advice and wasted lots of time, fuel, and money. The whole point of asking for advice is to listen to it. I suggest you go back and re-read the responses to your initial post. Or ignore it and keep stumbling around chasing ghosts. The choice is yours, I'm just trying to help you out.

 

What is the genesis of these comments? I do not remember being rude or implying negative ideas about you or any one else in this thread. I do not think that I have treated you rudly, ever. I would be obliged if you would offer me the same courtesey.

I thought about and gave a response to every suggestion, and reason on why I believe it could or could not be it. I was not blothiating.

The header vs O2 sensor has been covered in detail in many different debates from many people for many years. My reasoning is that I have tuned many other engines, one very similar to this one with great results without the use of a heated O2 sensor. I also remember that Ceramic coated headers hold in more heat, which will help the O2 sensor. This engine also uses shorty headers, so the sensor is not too much further back from the original location. So those two things are working in my favor.

I do not believe that I am stumbling around if I am attaining real progress. Meaning that the lean condition is going away, and drivability is increasing. I think that I had demonstrated a problem and was being helped to find a solution. Which would mean I am not chaising ghosts.

 

Sorry, I didn't mean to be insulting or rude. And no, as far as I know you've never been rude to me, either. I was just trying to get you to look again at what has also been proven many times over. So I'll just go back to minding my own business and STFU. Sorry for butting in.

 

At your strong suggestion I will finally try the heated O2 sensor. Heck they are only $20, so if it does nothing I am not out much. I could probably run it off of the key on or ecm on.

 

Well, let us know if that helps any or not. If it doesn't, I'll buy the sensor back from you for $20. How's that sound?

 

What is the part number and manufacturer for the $20 heated O2 sensor? I'd like to try one.

 

Kind of an odd question, but is SNG available in the US yet? We use them (yep, in Chiner), and I now know the guy that designed them (made in Singapore). They seem to be up to snuff at least.

Anyone care to measure the resistance (or impedance if you want to get technical) of the heater on an AC-Delco? We were using 4 Ohm (lightning fast warm-up - so fast that it burns itself out with continuous on-time), and now 6 Ohm without fault. Just curious how fast an average off-the-shelf heater would work.

That's all, hope I don't interrupt, enjoy your regularly scheduled programming.

 

AFS-75 is the model number that I am using that I was able to find.

 

Well, did the heated O2 help out any? Inquiring minds want to know.....

 

LOL! It will unfortunatly be a little while before I know for sure what the effect was. When I went to change the O2 sensor I found something very elementary. The vacuum refernce line going to the AFPR was unhooked. So I was running a 46 psi all of the time. I had left it unhooked since I was checking the fp during idle and driving. I plugged the line back in and it dropped the idle a hair and lowered the map reading, and raised the BLM's.

 

I've about had it now though. Did some more datalogging and changing and I am getting nowhere again. Nothing is seeming to really help. I am getting readings of 148-155 BLM now. So the ecm is adding a ton of fuel. I am adding a ton of fuel according to the VE table as well. I am in the upper 75% of my VE table now. Reconnecting the AFPR only worsened the problem. The problem on average is still starting at 1600 RPM and showing a dramatic increase in BLM. Idle is great as well as anything below 1500 rpm.

What is further confusing is that I can burn the same .bin with open loop only and it will read pig rich at nothing lower than .9 volts! So why is the ecm adding fuel?
I am about ready to go back to msefi.

 

I have exhausted all of my and your ideas. I am 100% stumped. The heated O2 sensor has not helped. The blm's have sky rocketed. I am getting blms up to 160 and have almost maxed out the VE table. I raised the entire VE table 10%, then 20%, than 32% and saw almost no improvement. I have played with injector constant, fuel pressure, read codes (which are not there), checked for exhaust leaks, checked my wiring, checked injectors, checked for bad gaskets, etc. I can not get the pulsewidth to change at all. It is always between 0.3 and 0.8. I am getting very worried about causing serious damage to this engine because of a lean condition! I guess I am going to have to go back to msefi and try the new V3 I have lying around.

 

Idle and lean do not equal damage. Don't be afraid of a lean idle fearing damage.

I'm sure the "siamesed" intake isn't making anything easier.

Your displayed PW of 0.3 and 0.8 is insanely small.

When the going gets tough, start with a virgin bin (insert dirty virgin joke here).

 

This morning in my last desperate datalog I might have found the problem, the main one at least. The TPS sensor is not reading above 0.8%, even at full throttle! I will have to change TPS and check the leads. Odd thing is the BLM cells are changing as they should. I was under the impression that if the TPS was always bottomed the BLM cell would not change out of the idle cell.
I was always looking at everything except TPS % and TPS signal, which was probably the root of my troubles.

Vern, I imagine after this embarrasment is taken care of I might see an improvement.

 

Ah, that nasty TPS. Has bit me in the butt many times. I have a tendency not to look at that often enough.

The BLM cell changes with RPM and load, as I understand it.

You may be on the right track. Good luck!

 

BLM changes for MAP and RPM. It sounds like you have an SES light problem too. It should have illuminated due to the TPS stuck low. Always make sure the mechanical stuff is good before trying to tune a PROM.

 

I found out that the pblem was not a bad TPS sensor, but rather a slowly dieing ecm. I back probed the TPS sensor and got a perfect 0.55 Volts, checked for WOT and got a perfect 4.50 volts and eveerything else in between was perfect. I then backprobed the wires at the ecm and got perfect readings there.

I turned TunerPro RT back on and was getting horrid readings from the tps. It would read 1.26 Volts at idle! From there it would increase to 1/2 throttle at 4.5 Volts and then back down to 0 volts for WOT. Guess I will be getting a new ecm. It turns out all of my sensors and wireing were good afterall. I will change the ecm and continue on.

 

Hope that solves your problem! Sounds like it has been a really confusing/frustrating road getting to this point. IF THIS SOLVES IT, THEN i'LL BUY THAT HEATED O2 SENSOR from you, just like I said, if it doesn't show any improvement over the one-wire version. I'm a man of My Word....

 

I changed the ecm and was still suffering from the same problem. Though drivability increased slightly, the problem was still there.

I own TunerPro RT v 3 and V4 and Datamaster. I decided to log in all of those programs at seperate times on the same day with the same conditions. I did and found different values going on!

In tunerPro v4 I got the messed up TPS signal and TPS % I described earlier, I logged in V3 and got the correct TPS signal (volts) but a bad TPS %. Than in datamaster I recieved all 100% correct info. I used the same cord for all three times too! Has anybody ever witnessed this?

I then changed to a different .bin and used the same settings, this seemed to cure almost everything! Blms were down to 113-123. Much better than where I was. Strange thing is, everything looks to be identical in the .bin files! So I am tuning again hoping for improvements.

 

I've not seen that particular problem, but stranger things have happened. My guess is something in your definition file is different/messed up, not the BIN since DM shows the correct values. Try a datalog with all three while just sitting in the driveway at idle with a warmed up engine. That should be a decent apples to apples comparison to verify any differences in the TPS stuff.

 

I will see if I can do that. I did not think I was able to run all three programs at the same time.

 

You can't. But running them one after another with no other changes should still give you a decent idea of how they compare.....

 

What mask did you have before, and what mask did you switch to?

using a hex editor to compare the "bad" BIN with the "good" BIN will show you where they differ, and you can compare that to a HAC to see where things went wrong / what changed.

 

You've built a *hot* engine and at low RPM where it's breathing is bad, it's lean.
Not to mention being a 5 spd., and one's ability to really lug the engine.

Comes a time when you have to tune to what the engine wants. BTW, when tuning the fuel doesn't work, try working with the timing. It takes the right combination of both for an engine to behave right.

 

I am runnng 21* of timing right now at idle, what direction would you suggest doing with it first? More or less?
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I will try that, I am not 100% sure of how to use those yet. I can use them, just not well.
Will look what aldl file I am using. I thought it was the same for both.