Well, I finally got my burner working and made a few chips. I had been running a basically stock 305 chip with a little timing and the VATS and EGR disabled. Other than that it was stock. Now that I have my burner going I'm trying to tune it. Here's what happened.


1st chip:
NO VATS or EGR
different timing table
24# inj const instead of stock 19#


*I was under the assumption that the injector constant was the first thing I needed to change and go from there. Is that right??

Results:
It ran like complete crap in open loop at initial startup. It would idle ok and stuff, but once you started to give it gas and let out the clutch, the BLMs would rise(135-14? range), the o2 readings would go to almost 0 (~.03 or so), and it would spit/sputter and stumble. When it went into closed loop these readings weren't as drastic, but the BLMs were still high and the o2 readings were still low. It still wasn't running the greatest but way better than in open loop. It almost seemed as if it needed more fuel at partial throttle application. I need more fuel right??

I also noticed while driving down the interstate (6th gear, 80mph, 1800rpms) that sometimes the o2 readings would go down to almost 0v! These low readings seemed to correspond with some low vacuum readings at the MAP. This would usually occur on a coast downhill in gear, off the gas. It would also do it sometimes when I was barely in the gas... again at certain low vacuum readings I believe. I'm assuming I need to add in some fuel in those areas on the VE table at the corresponding Kpa areas?? Is that correct? How do I go about doing this?? I have read traxion's sticky posts up above and they help alot but some of it confuses me too. Are the VE tables for open and/or closed loop or what?? Well, I guess that is it.


*Sorry for the long post. I'm new to this, I've reasearched PROM burning quite a bit and I have a decent understanding, but I definately need all the help I can get. Thanks for any help!!


BTW I'm using tunercat, I'm running a brand new heated o2 sensor, and I'm using a pretty nice Monitor 4000E scanner. Thats it, later

 

While at one time using the injector constant was an answer it was only due to folks not knowing how to dither the MAF tables and scalers. Changing the IC needlessly will cause you more grief then any other error you can make.

If you have 19s use 19.

If you have a lean or rich spot correct the MAF area if it's at parcial throttle, or the WOT stuff to cure WOT.

With the EGR off be sure on getting the cruise timing correct.
Different cars like different amounts of timing in different places.

Please get a note book, and start documenting what changes do what, and you'll start to note tends of what your combo like and dislikes. 3 months from now, it will be easier to look at notes rather then repeat every thing you do today.

 

Damn fine thing he mentioned he had 24lb injectors and a speed density car in the sig or i would have thought grumpy was on to something

As to the very low O2 readings on decel, thats normal, DFCO. When you do under a certain MAP value (in constants table) the ECM basically shuts the injectors down.

Other than that, could be pump shot and / or VE making you go lean as you let the clutch out. Tune VE based on cruise / steady at that RPM, and the transient is more pump shot (AE vs. diff TPS)

 

<sigh>
Yep.

Anywho.

When you make an injector change, all the time based stuff gets trashed. So you *may* have to be in and lessen some of the cranking fuel stuff.

The VE tables are used all the time once the engine is running.
Closed loop just means there are corrections applied to them in the form of BL, and Int..

When you make a huge correction like that, and many times it's just a good idea to clear teh ecm of anything it's learned so that it starts learning in from 0.

 

YES!! Ed and grumpy, 2 of the guys I was hoping would reply


THANKS! Now, I'm new to this and not sure what you guys are saying I should do first?? Change my IC, then adjust what first?? A few questions now....


Ed:
1) DFCO... what is that??
2) AE= what??
3) "more pumpshot?" "AE vs. diff TPS".... what?


Grumpy:
1) "Lessen some of the cranking fuel stuff" what is this referring to and where to adjust it?
2) "Clear the ECM, let it relearn from 0" What? Just unhook the ECM out by the battery for a while and reconnect??? Do this everytime I run a new chip? right?

*Sorry guys, like I said I'm new. I'm willing to learn anything and spend the time to get this right! Thanks for your patience!

BTW- I have a ton of mechanical ability with these cars... now I just have to get the "technical" aspect down

 

I'm not Ed, but I think I can answer these. I *THINK* DFCO stands for Deceleration Fuel Cut-off. As explained above, when the vacuum increases (kPa decreases) to a certain point, the injector duty cycle basically goes to zero. I think it's for emissions (and to make sure the car really starts slowing down when you let off the gas).
AE = acceleration enrichment, this is the pump shot mentioned in #3. Cars with wet intake manifolds (i.e. carbs or TBI) need more than port fuel injected cars, but from what I understand, port injected cars still need that bit of extra fuel on transient load increases (like when you snap the gas down off the line). There are tables for adjusting how much pump shot to use, based on the delta TPS value. My ECM also has it vs delta MAP. Yours may, as well. Oh, it's called pump shot, because carbs had an accelerator pump...

I'm also not Grumpy, but I'll try here, too.

There are going to be several tables your ECM uses to fairly precisely tune the startup fuel. On my car, there are 2 tables:

1. Startup AFR decay vs coolant, which is a multiplier table to the next table. This one is used to control how much fuel is sprayed in during a cranking condition.

2. Crank AFR vs coolant - this is used after crank, when RPMs have come up a bit (kicks in during the idle flare).

There are also open loop AFR vs coolant vs MAP tables to deal with. There might also be a table to mess with the *closed loop* AFR. BTW, if you set your injector constant correctly, I don't think you should have to mess with ANY of this stuff, but, YMMV.

As for resetting the ECM every chip burn, no, I don't think that's necessary. But something like an injector constant change, or large changes to VE, you might want to disconnect the negative battery terminal for some time. The amount of BLM data (and whatever else there is) that the ECM stores through an ignition cycle varies by ECM, but reset it to be safe (not that you'd hurt anything, but you could skew the results).

HTH

 

Kevin, thanks. You helped me some! You state that if I set the IC correctly, I shouldn't have all these problems. How could I be setting it incorrectly? I set it to 24 for my 24#'ers. I think my cam is screwing all this up and messing with the vacuum!


*now guys, is he right? Is all that stuff true for our cars as well as his? I'm still not sure exactly where I need to start at then.



THANKS for all the help so far guys!

 

You are right. Cam swap.

You can't do a cam/injector swap on a MAP car without tweaking the VE tables at the very least.
Then if you feel froggy and tweak the spark tables you will have to re-do the VE tables.

 

The basic problem you're fighting is that at low rpm, your big cam is less efficient than your stock cam- ie, it produces lower VE values than stock. This is caused mostly by the camshaft overlap, which can force exhaust out the intake and pull intake air out the exhaust- this is "reversion".

If you do a search on "reversion", you'll find lots of interesting posts, some by people with your exact cam and problem. You've asked a good question. I looked over these because I'm still trying to understand this "big cam issue" myself, so regarding my observations, YMMV.

>>I'm assuming I need to add in some fuel in those areas on the VE table at the corresponding Kpa areas??

You don't directly "add fuel" in the VE tables, you are telling the program there is increased cylinder filling at the particular RPM and load (kPa) points. The ECM calculates the amount of fuel required at those points based on the % efficiency data in the VE tables (amongst lots of other things). Increasing the VE will increase the injector pulse width (add fuel) and vice versa.

The problem you've got is that although you ought to drop your VE values at the lower RPM values (because of the drop in efficiency), you may actually have to increase the amount of fuel required because the exhaust gas is "inerting" the charge (there are some good comments by Grumpy to this effect in one of the posts). Some of the posts I read are complicated by sensors and gaskets that don't work properly, so be careful.

>>"Are the VE tables for open and/or closed loop or what??"

There is a clarification of this in a post by RBob as I recall. As I recall, the open loop stuff all depends on the VE tables for all calculations. However, if your BLM's are correcting for lean, the WOT open loop calcs will use that data, while if your BLM's are correcting for rich, the WOT open loop won't use these to lean out.


John

 

So although Im running rich across the whole spectrum, when I go to WOT it backfires which would indicate I need more pumpshot?

 

This is why aiming for BLMs of 125 (or something less than 128) is a good idea. That way, if the BLMs have to increase 1 to correct, you'll be at 126, instead of 129, and your WOT fueling will be the same.

 

Well, I've driven it some more and watched the scanner quite a bit in doing so. It actually seems like the 02 voltage drops in low vaccum areas or when you have a partial throttle application after coasting. What is the conversion for vacuum to Kpa? I increased the VE tables like 3 or 4 across the board just to see what would happen. It was too rich at idle again, but seems ok while going down the highway or when getting into it. The 02's did drop some though when I'd start to get in the throttle though. Is this where that pump shot comes in? I looked at a "pump shot vs. differential TPS" table in tunercat but I don't understand what those adjustments would do. Can anyone help me on this, or is there somewhere else to adjust the pumpshot. How do I know if I need to? I'm just not sure why the 02's are dropping like they are in some spots. I also noticed that even though they drop sometimes, my BLM's are pretty damn close to 128 as well as my integrators. This brings me to my last question. What is the difference between BLMs and INTs? When do you lock the BLMs to tune? Sorry to sound dumb, but this is a lot of info to digest. Sometime I wish I had a MAF car. LOL Thanks for any help guys!

 

I have two questions at this point. When your O2 voltages "drop," what exactly do you mean by that? The O2 is always switching, as long as block learn/closed loop mode is engaged. Also, are you pressing the gas while this happens? Or can it happen when you are stationary on the gas (i.e. keeping a TPS of 32%, all while the O2 voltages "drop").

If it's only while you increase your throttle position, I'd say that means you have a weak pump shot. You should see the integrator go above 128 during this transient (especially if your ECM can talk at 8192 baud). I wouldn't watch the O2s for this type of tuning. A wide band is best. Second to that, watching the integrator.

You would lock your BLMs to 128 when you are around +/- 1 or 2 BLMs away from your goal value. Someone posted a formula on what to do with integrator values.

INT = short term fuel trim, it reacts quickly, and can help cover a weak pump shot.

BLM = INT values integrated over time (long term fuel trim), with 12 or 16 cells on your RPM/MAP table (values can be modified).

The BLM is used to judge a trend, like too low VE in a certain area. I don't think watching the INT is good for much except pump shot (and my 160 baud ALDL comm is way too slow for this).

 

Kevin, first off thanks so much for all the help so far. It means alot. Now to the other stuff. When the o2V drops, I mean it goes down to almost zero. I know it is always switching, but sometimes it goes to near zero and stays there for awhile if I'm stationary on the gas. When I go to give it a little more gas the o2 voltage will come back up and start fluctuating again like it should. The voltage also drops sometimes if I'm off the gas for awhile. Then when I go to get back in the gas (just slightly, remember I have a T56/3.42's that doens't turn much RPM going down the road) it stumbles/stutters unless I hit the gas hard to clear it out. I'm not sure what is causing this! I messed with the pumpshot vs. differential TPS tables and turned the multiplier up. I went for a drive and it didn't make a difference.... still does the same thing. My BLM's are all over the place too, I'm guessing my VE tables need some major work Sometimes they're perfect at 128, other times they suck! I'm also assuming that you're telling me to basically ignore the INTs and the o2 voltage and concentrate on the BLMs?!?! As for a wide-band... I'm making some dyno pulls in 2 weeks and my car will be hooked up to a wideband o2 then!

BTW-whats the difference between vacuum and Kpa? Are they the same thing just measured in different ways? Whats the conversion? I know my scanner shows it in inches of vacuum or whatever, but I'm curious how those numbers correspond with the Kpa values in the VE tables. THANKS!

 

What is your method of examining your BLMs? Hand held scan tool or full blown computer logging? A program like WinALDL will constantly log data as well as sort it. This is a much better option than randomly looking at your BLMs and seeing "random" values. If the data is sorted by RPM and MAP, you can start to see a pattern emerge, and use that info to dial in your VE.

From your first paragraph, though, it sounds like you have a bad/slow O2 sensor, despite its new-ness. Might want to throw another one at it just to see if that was the cause.

I would like to see what your AFR is on the WB during these O2 voltage drops. My money is on the fact that the O2 is reading wrong, rather than your AFR being leaned into oblivion.

100kPa (kilo-pascals) means you have atmospheric pressure in your intake manifold - it pulls no vacuum. 0kPa means you have an absolute vacuum in your intake manifold (good luck). To convert, you'd need to know the current barometric pressure of atmospheric (like 29.8 in-Hg, for example). Not sure what the formula is, but the kPa is independent of atmospheric (so regardless of the current barometric pressure, you'll still have a nice, say, 13-99kPa MAP range during running), that's the basic idea.

 

double post!

 

Well I had this huge reply typed up and the PC locked up!

Anyways, I was saying that I'm using a scanner to monitor my BLMs and other data. Problem is I'm trying to figure out how to use the record feature on it and get the data to my PC for viewing. I don't think its gonna happen though What are my other options for datalogging? Anything cheap?

As for my o2 sensor, I'd change it out but its a heated one and the only other ones I have are OEM 1 wire style. I don't think the o2 sensor is junk though. I didn't have any of these problems b4 I changed the IC to 24#!

As for the WB o2... I'll post the data as soon as I make those dyno pulls in 2 weeks. I'm curious what its going to show! I'll probably take along a few chips too (19# and 24# IC chips) to see the difference it makes!

As for Kpa and vacuum, I understand what they are, but my scanner only shows the MAP readings in vacuum and I need them in Kpa for my VE tables. I don't know what to do now!

 

You need to get yourself a PC data logging device if you want to have any hope of dialing in your VE.

WinALDL might work, though I think you'll be stuck with 160 baud. You'll also need a cable. Try AKM Cables. I have one. Works...

If you use WinALDL, it will populate this RPM vs MAP BLM table for you. Then you export the data as a text file and manipulate it in something like Excel. That's what I do.



You can probably imagine how handy this can be...

 

Kevin, yes I can definately see where a device like that would come in handy. I read Traxion's article months back about tuning the VE tables and I thought it would be relatively easy. I thought my scanner had datalogging capability though. I guess it doesn't or else I'm gonna have to do some work to figure it out Oh well, I guess I know what my next step is now. LOL Just for kicks, I added some fuel in the high Kpa areas of my lower VE table. Took it for drive and it seemed to stop the stuttering and stumbling in those low vacuum spots. I know this isn't the right way and its not optimal, but I'm just playing around and seeing what does what! I also added fuel across the entire upper VE table and it seems to run better with that too. BLMs don't look to bad, only when I'm idling or completely off the gas... then they're a little rich. Thanks again for all the help, I guess I'll go looking for some datalogging devices or programs!


*Do most guys use a laptop with winALDL or what?? That along with some kind of communication cable?? TIA

 

Yes, laptop with WinALDL. Also, for a cable, try here:
http://www.akmcables.com/

You definitely need a data logging program because there are way more BLM values than you will be able to keep track of on your scanner. And it doesn't have to be smooth either. For instance, you could have a 108 BLM at 50kpa 2000rpm, then 135 at 2500rpm, 50kpa or something slightly non-sensical like that. So I don't know how valid a blanket comment like "BLMs don't look to bad, only when I'm idling or completely off the gas... then they're a little rich" is valid...let me know when you've acquired some sort of logger. You will love the simplicity and lack of guesswork.

 

Check out http://www.ttspowersystems.com/dm_dload.htm I am using this on my 94Z.I bought my cable from www.akmcables.com also bought the software from him its $10 cheaper.

 

Yes, I agree I need some kind of data logger! As for my BLMs not looking too bad, I watch them quite a bit when driving. I know I'm not even beginning to see all of them, but I try different throttle applications in different gears at different rpms and speeds too. I mean "they look ok" because they're close to the 128 range and not just bottoming out like they were before. LOL One more question for you. I notice that sometimes my BLMs are really low but my INTs are REALLY high. They might be 40 counts or so apart. Is that normal? Just curious. Well, I'm on the hunt for new equipment now! Later