7427 $OD MAF - how to reduce cranking fuel?

[babywag]

When I installed this I drove it a little then the truck got parked for a while.

It has a problem w/ cranking fuel being too much, it'll frequently fire then stall when cold.
2nd time it usually fires and stays running, but it's too rich.
It does it when warm too.

Today it stranded me for about 30 minutes w/ my 3yr old, so time to figure this out.
Truck had been sitting for ~15-20 minutes. It initially fired and I made the mistake of trying to rev it a bit.
The engine stalled and after some restart attempts it acted like the engine was flooded.
The battery started to get weak so I stopped trying and called for a tow.
Got a call that it would be ~45min.-1hour wait, so figured I'd try one last time.

I cranked hit the pedal for clear flood mode(it was turning over VERY slow), and it fired, ran really crappy, then cleared up.

So, back to the main question.
I checked some of the $OD MAF fueling stuff compared to a stock $OD bin and they are all the same.
Obviously something is different, but I don't know what/where in the MAF bin that is causing the problem.
Any thoughts or suggestions?

[EagleMark]

I've got the same issue with the $0D MPFI option with cold start and have not figured it out yet.

[babywag]

Bummer....I can't find the cause either.
My normal $OD bin starts just beautiful, however until I can figure out why the $OD MAF does not, I'll have to switch.
Not going to give up, because I like the MAF system.

The 3yr old drove me nuts.

[bags50lx]

Have you tried to compare the files and see what is different?

[babywag]

I checked some of the $OD MAF fueling stuff compared to a stock $OD bin and they are all the same.

I wonder if the MAF is bad/needs cleaning? Classic symptoms;
Hard starting...stalling after starting

[babywag]

I wonder if the MAF is bad/needs cleaning? Classic symptoms;
Hard starting...stalling after starting

Cleaned the MAF, no change. Swapped the MAF w/ another known good one, no change.

Standard $OD bin, starts immediately no issues hot or cold.
$OD MAF bin, starts and stalls 1st try, and sometimes struggles to start when warm.

Frustrating...runs fine, just this pesky starting issue.

[EagleMark]

Are your VE tables dialed in? Or MAF tables in this case? This has to be in ballpark before you go mucking with other stuff. I've never done the MAF in $0D so can only give some ideas...

Other things I've tweaked in modified TBI engines to facilitate good cold starts, but not limited to:
1. Choke AFR vs. Temperature
2. Open Loop AFR vs. Temperature vs. Vacuum
3. Crank to Run AFR vs. Temperature
4. Stuff in the Cranking Fuel Folder.

[babywag]

Are your VE tables dialed in? Or MAF tables in this case? This has to be in ballpark before you go mucking with other stuff. I've never done the MAF in $0D so can only give some ideas...

Other things I've tweaked in modified TBI engines to facilitate good cold starts, but not limited to:
1. Choke AFR vs. Temperature
2. Open Loop AFR vs. Temperature vs. Vacuum
3. Crank to Run AFR vs. Temperature
4. Stuff in the Cranking Fuel Folder.

All the matching fuel parameters/tables in $OD vs. $OD MAF are identical, (@ least the ones I have found/compared/changed).

I can load the 2 bins @ will with my Ostrich, and I also have 2 memcals w/ the different bins.
Both run the engine just fine, everything seems w/in normal ranges etc.

The only real issue is starting the engine, and it isn't just cold starts, the warm/hot restart is what got me, and prompted me to post up.
It is just way too rich on cranking/initial fire, and I don't know what to change to "fix" the issue.

[EagleMark]

It is just way too rich on cranking/initial fire, and I don't know what to change to "fix" the issue.

I just gave you some ideas?

Is the bottom end of the MAF table smooth and sloped like the rest? Look at it in 2D view!

[notime2d8]

All the matching fuel parameters/tables in $OD vs. $OD MAF are identical, (@ least the ones I have found/compared/changed).

I can load the 2 bins @ will with my Ostrich, and I also have 2 memcals w/ the different bins.
Both run the engine just fine, everything seems w/in normal ranges etc.

The only real issue is starting the engine, and it isn't just cold starts, the warm/hot restart is what got me, and prompted me to post up.
It is just way too rich on cranking/initial fire, and I don't know what to change to "fix" the issue.

I found this info on another thread:

"Keep in mind that while MAF makes tuning easy, the MAF table dominates the fueling as the fuel is directly calculated from the MAF sensor and calibration. If there are cells that are reporting too little flow, the engine will go lean whenever it enters those cells. At idle, this manifests itself as the engine surging up and down and then a stall. As an experiment, try increasing all the airflow values from 0-20 grams/sec by 15% and see what that does. if the idle dramatically improves, then you need to redo the MAF table. Your BLMs can be a help, too. Take a look at them at idle. It sounds like closed loop is whats keeping the truck idling. There are limits to how high/low the BLMs can be to be saved. If the BLM is way out, the PCM will not save that value, but a default max instead. Hence, the poor idle on restart."

It seems like you can adjust the MAF table where there is little air flow at the start and decrease either decrease the fuel or report a lower air flow rate....? I still haven't gotten my TBI MAF setup running so i'm guessing on this.

[babywag]

I found this info on another thread:

"Keep in mind that while MAF makes tuning easy, the MAF table dominates the fueling as the fuel is directly calculated from the MAF sensor and calibration. If there are cells that are reporting too little flow, the engine will go lean whenever it enters those cells. At idle, this manifests itself as the engine surging up and down and then a stall. As an experiment, try increasing all the airflow values from 0-20 grams/sec by 15% and see what that does. if the idle dramatically improves, then you need to redo the MAF table. Your BLMs can be a help, too. Take a look at them at idle. It sounds like closed loop is whats keeping the truck idling. There are limits to how high/low the BLMs can be to be saved. If the BLM is way out, the PCM will not save that value, but a default max instead. Hence, the poor idle on restart."

It seems like you can adjust the MAF table where there is little air flow at the start and decrease either decrease the fuel or report a lower air flow rate....? I still haven't gotten my TBI MAF setup running so i'm guessing on this.

I will try adjusting the MAF table from idle/down and see what happens. I didn't think that the MAF table was in use while cranking.

EDIT:
No change after checking/adjusting the MAF table it was very close according to datalog.
Also found a table cranking fuel transition AFR or something to that effect.
Comments state that it enriches the mixture during the transition from cranking fuel to mass airflow fuel.
So the MAF table isn't in play during cranking it seems.
I'll have to check the VE tables, but they were copied from my $OD .bin and that cranks/starts just beautifully.
I did another compare of my $OD and the $OD MAF, and the cranking fuel parameters were all the same.
I tried adjusting a few things dealing with cranking fuel, but nothing really seemed to change.

I think just going to have to get drastic?
Make MAJOR changes to cranking fuel to see if I can get it to not start due to a lack of fuel vs. it not starting due to flooding/excessive rich condition.

[bybyc5]

Hello,


Wondering if you found a resolution to this MAF start/run issue?


I have been searching threads looking for information on installing a MAF sensor for the $0D, 16197427.



Currently running $E6 16168625 on a TPI system, and am swapping in a 16197427 to run IAT and MAF and more tuning options. I am in the beginning stages of this, and would appreciate any information.


If I may ask what MAF sensor you are using?
Any suggestions?



Thank you,


Keith
NE Tennessee

[babywag]

I tried several things, but still had the cranking/flooding issue when starting. Got frustrated and reverted back to normal $OD.
Then converted to E85 when gas spiked to $4+/gal.
Ran that for a while, then dropped my insurance and put the Jeep on non-op when the tags came up for renewal.
(Have too many cars, can't keep them all insured/registered all the time).
When gas dropped so drastically in price E85 became a moot point, so ~month ago I burned off the E85, and switched back to E10.
While doing this is started acting funny, starting issues, and it threw a fit one day, it wouldn't idle/kept stalling.
Through process of elimination (due to no codes) I found the MAP sensor was bad.

Logic tells me the MAP sensor was bad and the cause of the flooding/no start issue running the $OD MAF code???
I have yet to test this theory since I'm not currently driving it.
All I've done is move it in/out of the driveway, and a trip around the block.
Once I get the time, and tags/insurance on it again I'd bet the issue may be gone now.

MAF/IAT sensor I'm using is PN# 25168491

[bybyc5]

Thank you for the quick reply!

I do believe I read somewhere on this site in the hours of piling through threads about maf conversion (have yet to find what I am looking for) that the map sensor is looked at during crank to run. I think that was on the 165 ecm for an MPFI 91 3rd gen Camaro. Found here.. http://www.gearhead-efi.com/Fuel-Inj...light=mass+aif

It's a long thread, 17 pages...yea I read the whole thing..some good stuff in there, but not what I was looking for. Some good tuning tips and processes, and I believe that's where I read the crank to run swap from map to maf.

So if this is true, yes the bad map sensor would mess up the crank to run. Rich or lean depending on how it failed.

If your a 3rd gen Camaro fan ( I am ) this guy has a sweet really clean one! Pictures buried in some of the pages.

I appreciate the part# for the maf.

Thank you,

Keith
NE Tennessee