I have been searching through posts and reading stickies and I am still unsure of where to go. My engine fires right away when cold. However when first tuning it would try to stall. Since I was using S_AUJP, once I got my lower VE decent at idle I changed the Loop Open % Change AFR Vs. Temp table. I raised the values from -4d all the way to 80d and that seemed to help. In that the car started right away and will somewhat idle on it's own. Then yesterday I changed that table back to stock and it went pig rich on a cold start. It seemed like the commanded AFR was lower then with the values raised. That seems odd, I thought increasing the value would lower the commanded AFR but it seemed like it did the opposite. I've seen post that mention lowering the park IAC counts and possibly adding some spark. Is modifying the Loop Open % Change AFR Vs. Temp table the way to go or am I going about this all wrong?

P.S. After running the stock table on start up my plugs were black. I am changing them today do you think my heated O2 is OK? I'll also change the oil.

I've got the same type problem

That table is for fuel adjustment when you have warming up issues during the time up till closed loop is enabled. I don't think its the best adjustment for not having the VE table or IAC set correctly.
Reducing the settings in the table would reduce the fuel but it is by %, so the VE table being correct will help to keep things in order.

For stalling, You need to determine if your problem is air or fuel related.
If you "seem" to be ok with air and fuel try adding a bit of spark in the closed throttle table. Try to keep that setting inline with your main spark table so you don't have big changes when you do step on the throttle.
If your o2 seems to go lean just before the stall (or starts the stall event) then you may need fuel by using the table during warmup. You would probably have a richer setting in the colder areas and have it tapered out as the temp comes up.
Before messing with the table be sure you have all the mechanical stuff setup correctly.
Get the TPS around 0.45 volts closed at idle with around 30-50 IAC counts. Unless its a radical setup that is just being difficult, those two things alone can make a big difference. Vacuum leaks will also be a big contributor to such stalling at low RPM.
HTH

OK, I do need to reset my IAC. For some reason I am getting really high counts. Looking at what was going on previously I had 5-6d more of spark. When that was present the car seemed to idle OK while warming up. My last run was missing that spark because I lowered my closed throttle SA and my main table around 800 rpm in the 100 KPA column. I did notice returning the Loop Open % Change Table to stock actually did raise the commanded A/F ratio instead of lower (I was looking at the wrong column). So it looks like my engine wants at least 27d SA with coolant temps around 50*. One thing I noticed is that Tunerpro was showing me 1.10 v for the TPS value. Yet when I checked with my multimeter I was seeing .59 v. That was using the correct ads file
My setup isn't radical at all. Just your average 408 with a HSR cam is 219/227@.050. I'll have to play with it some more this weekend.

Let me know what you find. I have 30 degrees timing at cold
temps and still have 160 IAC counts and my tps is set at 5.4. When
I go in to closed loop iac counts drop to 0
730 8d

OK, today I burned a new prom. I added more timing at idle and raised the cold idle timing while warming up. The car started and ran but it wasn't really smooth. It didn't stall out. It still has a strong odor. I am attaching a copy of the data logs and the bin I used. The bin is based on S_aujpV2. There are 2 data logs (small) I stop the engine at one point because the INT and BLM were not changing when the engine should have been in closed loop. When I restarted the engine went into closed loop after a short time and the INT started dropping like a rock. The engine stalled out and I figured I was finished. I haven't reset the IAC yet since the engine is running rough. The TPS is always showing over 1 V at idle yet when I connect my DMM I get .58?? Could there be something wrong with my TPS or is that the math in the ADS file for Tuner Pro? Or could that be my problem if the ECM thinks its seeing over 1 v all the time? The next thing I can do is to restore the Loop Open % Chg vs Temp to the higher values I had but the exhaust is pretty stinky right now so I can't tell if its lean or rich. If anyone has time can they take a look at my bin and see if I have something messed up? Thanks

I was noticing the O2 is not crossing very much. Would this be typical for an over rich A/F ratio or is it telling me my O2 sensor is shot? I've already replaced the plugs because they were fouled out.

can't open zip files

I renamed it to bin but its still FUBAR. You'll have to save the file and upload it again.

OK, I'll try to upload the files again. Here is the bin file. I changed the file extension to "txt" so once downloaded change it to "bin". I'll post the logs in the next post.

OK, here is the CSV file from the Tuner Pro RT. Unfortunately it is not from the first start I forgot to hit record so you'll see the start temp is about 12*C and the recording started at 50*C. But the car didn't stall. I added more timing and a higher desired idle for colder coolant temps. But if you open this in excel you;ll notice at line item 3180 in excel that I stopped the engine and restarted because the INT and BLM were not changing. At this point I am thinking my O2 sensor is not working or maybe I have other mechanical issues? The engine threw a code 45.

The best thing I can suggest after looking at the bin is to flatten out the "hole" in the SA vs Temp table and then use the main SA table and the closed throttle table to get it to operate the way it likes.
Then go back and remove some spark from the main table and have it added back in by the temp table if needed.
Looks like you have corrections in too many places that you are fighting.
The temp table has a bunch removed and you have added it back into the main SA table.

The major issue is the 100 Kpa values in the main SA table.
The program uses those values until temperture comes up.
You have almost 10* loss between 1000 and 1200 rpm.
I'm betting that is your stalling issue.
Try to check that the closed throttle table value is kind of close to the main SA value so you don't get large changes during transitions from one table to the next. Trying to cover up those kinds of big changes can make you think its an AE problem.

There is a bit of a low spot in the lower VE at 700 and 55 kpa that you may want to bring up to be closer to the values around it.
I'm assuming you idle around 850 rpm at 55 KPa when at operating temp.
HTH

Do an Advanced Search for "730 cold spark advance issues" (from 3-8-07) Z69' explains it that the MAP is not used until 44.5C is reached.
The SA is taken from the 100 Kpa column on the main SA table.

The best thing I can suggest after looking at the bin is to flatten out the "hole" in the SA vs Temp table and then use the main SA table and the closed throttle table to get it to operate the way it likes.

That's good advice. I wasn't sure why the original bin had the SA taken out right there. I did shift the values slightly since my MAP kpa values at idle are higher then a stock TPI. If I can get the engine running good enough then I can figure out what the best cold idle spark advance the engine wants.

I will check out the thread you referenced and fix the VE table. Up until this recent issue the engine normally idles around 850@45kpa.

It is interesting to see what GM did with in the ARAP bin vs. AUJP as far as cold spark and the correction tables and start up SA.

Some good news. I changed my coolant temp correction table to give about 4* more SA below 50* coolant temp, zero'd out all startup spark advance, and changed the 100kpa column in the main spark table to be 26.02 up to about 1600 rpm. The strange thing is when I wen to start the engine it did not start right away. It always has in the past even with the tune off. So once it started I had to help it for a little bit but it idled on it owns after 20 seconds or so. Still smelled rich but the engine was a lot smoother as it was getting about 31* SA until about 44*C. My O2 was over 800 mv after it kicked into closed loop so I threw a code 45. Which shouldn't happen because the VE table was decent before winter. Also it seems to idle high compared to what I have commande plus the IAC counts are always high even though I set it and it should be a lot lower. So I sprayed some carb cleaner around and the idle raised when spraying near the map sensor. I didn't have time to check it out but I plan to replace the map hard line and elbow connections I used. So maybe I am fighting vac. leaks also. I wonder why the engine didn't starting right away until I cracked the throttle? Thanks for your help so far it gives me hope.

If your IAC is reset properly, the IAC Park Position can help to get that initial start if you are lacking air.
Sounds like things are moving along.

I was able to inspect things further and the map hard line is OK as is the elbow connections. So I started looking more at the TPS since I keep getting code 45 and an incorrect TPS signal can cause that. I connected Moates software up and that show the TPS value at idle as 1.18V. So I am going to replace it. This will make the second TPS that I've had to replace within 500 miles. I'll have to search around to see what's going on. If that is the culprit then things should be good again. At least the cold warm up is much much smoother then it has ever been.

OK, after looking in the archive it seems like TunerPro shows the TPS% is the percentage of max voltage. Which is correct because max is about 4.3 and my idle voltage is .54. So Tunerpro seems to be correct there. Now about the TPS voltage shown in Tunerpro is that suppose to be real TPS voltage? Is the factor of 0.019608 correct for the ADS file?

Yes, 5 volts divided by 255 steps = 0.0196078 (bit of rounding)

So if the calculation in TunerPro is accurate then the ECM is seeing over 1 V TPS signal all the time. When I checked the TPS still connected to the engine I got 5.5V on the gray wire, .54 on the blue, and the black had connectivity to ground. Yet the ECM is seeing over 1V according to TunerPro and the Moates software.

Here is the log I recorded yesterday. You can see the TPS values. I cut a lot out to make the file size smaller.

Check the connectivity of the Black to ground.
If the connection is not clean it could raise the volts (but you should see that in your reading of the blue wire too)
Not sure why you show 1 V all the time. Check ADS is indicating byte #10 and the calc is set to multiply.
If that is all OK, Check the schematics on Ludis's site to see where the signal ground wire for that input is. I just reloaded and can't get the pic to open or I'd tell ya. You might have a ground problem there that is raising the voltage at the ECM reading point.
B5 is the pin that the black wire goes to the ECM, track the ground backwards from there.
Could be A12, E15, or D1. Should all have very low resistance to the neg battery terminal.

I think your right. I probably have a ground issue. Not sure why other sensors aren't showing erratic behavior. I bought a pre-made harness and there were two ground connections to make at the back of the engine. I attached the two ring connectors with a capscrew to the back of the pass. cylinder head but the wires were tight. I actually put the car up on jack stands last night to try to lengthen the wires some in an attempt to make a better connection. Would it be better to connect the grounds to one of the bolts for the transmission instead of the aluminum heads? I think I am going to attach a few more ground straps to the engine. I have one from the firewall to the passenger side cylinder head and the neg. battery terminaly connects to the front of the engine block. I am going to add one from the pass. frame to the engine or trans., whereever I locate the new ground position for the harness.

How are things going, fix your TPS prob yet?

No it's not fixed yet. I improved the grounds and added 2 more straps. I installed the new TPS and set it at .58V. I then checked for continuity on the grounds for the ECM and sensors at the ECM connectors and all seemed fine. I verified a 5V ref signal at the ECM and the terminal C of the TPS. I also verified I had a good ground at terminal A of the TPS. Since the TPS was set for .58 I checked pin F13 at the ECM and found .58V. Yet with the key on and engine not running I connected with Tunerpro and it was showing 1.18V. I checked the ADS file and it is using Byte 10 and is set to multiply.

Anything new happening, following along
because your engine is somewhat like mine

Not yet, I see you have been battling this a while running searches on the archives. Seems like redngold86z really knows his cold start stuff. There are several good threads he has contributed on with cold start. When did your cold start issues first happen?

I just have to figure out why TunerPro is reporting 1.2V at idle. If I can figure that out then things should be back to normal. It doesn't make sense that the wire leading into the ECM shows .58V yet TunerPro reports 1.2V. Unless my ECM is Fubar. But then why wouldn't other sensors show off values?

Yes redngold86z, sure does. In one thread he talks about
afterstart fueling in 6e What would that be named in 8d
would that be the 2 open loop tables

It depends on your XDF, since I am using the Super_8D.xdf file in TunerPro the two tables are Crank Pulse Mult. Vs. Ref Pulses 1-24 and the other is Crank Pulse Width Vs. Temp.

My Crank Pulse Mult. Vs. Ref table looks totally different then the one in the thread. But I didn't have a start problem until I tried giving the engine almost 33* on startup. So I am going to scale that back for sure. In another thread he says mid 20s is good for a mild build. I think that's the thread you said you had almost 40* or so.


RednGold86z,
Startup IS afterstart enrichment, just named differently by different people making XDFs.
Startup is NOT used during cranking. Only used when RPMs are above 400.

Having a failed start and then re-starting will ALWAYs make it much richer than a 'dry' or 'true' cold start. The fuel is already built up on the walls, and if it fired at all, the piston/chamber is already starting to warm up which richens the mixture quite readily, which is why reducing the fuel by 25% is needed for each cycle.

The initial failed start might be from the Crank Fuel PW Mult vs Ref Pulse table. I would try .75 x8, then .5 x8, then .35 x8. There's also a multiplier available for Ref Pulses greater than 17, but you weren't getting that far before it stalled I think.

-30F starts are VERY difficult to get reliable. I use a wideband powered by a spare battery to get them dialed in. Otherwise, it's shooting in the dark.

Vrump vrump vrump vrump usually means it's rich (and may have some brown exhaust). Vrump vrump poop stall, is usually lean.

[QUOTE=84KYSS;3705677]
My Crank Pulse Mult. Vs. Ref table looks totally different then the one in the thread. But I didn't have a start problem until I tried giving the engine almost 33* on startup. So I am going to scale that back for sure. In another thread he says mid 20s is good for a mild build. I think that's the thread you said you had almost 40* or so.


Yes, that's the thread, I have about 32 degrees now, I will drop it down into
the 20's my main problem now is getting it to idle at the proper rpm
when cold and in open loop, with out iac steps of 160. I have to turn
the idle screw way out and that works, but then after it warms up
the iac shows 0 steps and the idle is high, I'm trying to idle at 1000
rpm when cold and 800 when warm.

Then have you tried changing the values in the Loop Open % Change AFR? Mine was quite lean when I first started tuning my engine. Even though this thread is label the stock table is rich looking back through my bin changes the first start of the day cold loop idle wasn't smooth and stable until I raised the numbers in the 20 through 56 cells. Once I did that after a few burns I could get a nice clean start and idle when cold. It's just that since reinstalling my transmission I've been having this richness problem. But I have to get some new eproms because I was down to one and that one failed last night while trying to burn a new bin.

I have 160 iac steps would that mean it's rich and the iac is trying to lean it out. or doesn't it work like that

In a post by RednGold86Z

IAC doesn't do quite what you think it does, in regards to rich/lean. Sure it can add air, but, that air changes either the RPM or the MAP, both of which are in the VE. It adds to RPM if the load doesn't change (like headlights, AC, transmission, OIL!!). It adds to MAP if the load does change (which is usually seen by the RPMs dropping and MAP increasing, then IAC opens to bring RPMs up, end result is a MAP change). It's almost the EXACT same thing as opening the throttle. Opening the throttle slowly doesn't make it rich or lean, it just lets in more air, which is sensed by MAP which immediately adds the required fuel.

Think of IAC as a way to get JUST the idle RPM correct. Not A/F.

Here's from another reply post by redngold86z

The reason is you're lean, though, probably. IAC shouldn't need to be 160 to hold a 1200 RPM cool idle. Increase the Open Loop % Change vs Coolant Temp, and maybe add some Afterstart Fuel (but only after you're satisfied with the warmup mixture, and if the startup is losing RPMs for a few seconds).
Since it's surging (from your logs) it's safe to add 5-10%.

One thing you can do is wire up your wideband to a spare battery, like a lawnmower or motorcycle battery, and record the A/F during cranking, startup, and warmup without having to wait for the unit to warm up.

I have a heated 02 sensor it reads in the 700 mv range
any thoughts where it should read, don't have a wide band yet
and I don't have any surging

I think I found the problem. I was checking over all the wires at the ECM connector making sure they were getting the proper voltage and ground. When I was checking the resistance of the grounds for B5, B6, and A12, they showed anywhere from 13-15 ohms. While all the other grounds showed 1.6. So it looks like I might have a problem with the wiring harness between where the ground leads hook up to the cylinder head and the connector that goes through the firewall. I am going to start a new thread about the ground.

1tpi,
Before I had this problem my heated O2 (using a mustang one because it's cheaper then the GM heated O2) would first read about 800mv and then gradually fall to a lower value as the engine warmed. If you have the ability to burn eproms or emulate then I would just try making the Loop Open % CHange AFR vs Temp just a little richer say by 10% and see how the engine reacts. Although I don't know if that would affect your situation where the engine won't fire unless you adjust timing or spray ether.

Thanks for all your help, I wish I could help
with your problem. keep working on it and
you will get it. Thanks again, the starting
is improving