Idle issue..Crank..starts..stalls

[roh92cp]

EDS50 [quote][/quote]If I am driving and push in the clutch sometimes it will idle down to set rpm perfect, other times it will just drop really fast and stall.

This is the same crap that happens to me and I'm baffled at how randon it is. Most of the times the idle will slowly decease and settle on the set rpm and other times it drops of fast past set idle and stall or surges up down until it stall.

[cgrey8]

If you push in on the clutch shortly after going to Closed Throttle, then the RPMs should drop steady. However if you are on a long decel while in gear and then hit the clutch, that's probably when the RPMs do a nose-dive. Confirm that THAT is what's happening. If so, it's working as designed, albeit bad design.

[EDS50]

EDS50

If I am driving and push in the clutch sometimes it will idle down to set rpm perfect, other times it will just drop really fast and stall.

This is the same crap that happens to me and I'm baffled at how randon it is. Most of the times the idle will slowly decease and settle on the set rpm and other times it drops of fast past set idle and stall or surges up down until it stall.

I have the exact same problem but only with the a/c on.

[EDS50]

If you push in on the clutch shortly after going to Closed Throttle, then the RPMs should drop steady. However if you are on a long decel while in gear and then hit the clutch, that's probably when the RPMs do a nose-dive. Confirm that THAT is what's happening. If so, it's working as designed, albeit bad design.

Thats whats crazy, it doesnt do it the same way all the time. I could be coming up to stoplight downshifting normally and once I get to about 10mph or so I can push the clutch in and sometimes it will idle down perfect and sometimes it will fall quickly and either recover from 4-500 rpm or just stall. It is random and intermittent. I have even tried dashpot decay rates and everything related. I thought it maybe with how base idle is set with the spout out and iac disconnected but I set it to 700 just so it wont dip that low. Should I try to set base higher to 800? I think I have tried that and i had a wicked hanging idle. I just cant find that happy medium.

[cgrey8]

Have you played with DASMPH? If you are using an X3Z-based tune, it is set to 10 MPH. Since you mention weird behavior around 10 MPH, I just thought I'd bring up that scalar.

[BobCat]

Assume you are running a 75mm throttle body you would then change the Throttle Body Airflow Scalar "ITHBMA" by the ratio of change in size from current to stock.

75mm "aftermarket" / 55mm "stock" = 1.36 multiply the stock value of .5500 lb/min by the 1.36 correction factor and enter this as your new TB Airflow Scalar

This "correction factor" is proportional to diameter... or cross-sectional area??

I'm not sure I follow you, the "correction factor" would remain the same in both instances.

3.14*75mm / 3.14*55mm = 1.36..

[Cougar5.0]

Well, in the example above (55mm vs. 75mm), the ratio of the diameters is 1.36, but the ratio of the cross-sectional areas is 1.86.

Here's a puzzler: if the RPM is stock 672 RPM and you change the throttle body to a 75mm unit, why does the TB airflow change? Doesn't the engine require the same amount of air no matter what size TB you are using?

Doesn't the throttle body airflow actually change from running the idle higher than stock? Isn't the only other significant variable the camshaft?

[BobCat]

Well, in the example above (55mm vs. 75mm), the ratio of the diameters is 1.36, but the ratio of the cross-sectional areas is 1.86.

Here's a puzzler: if the RPM is stock 672 RPM and you change the throttle body to a 75mm unit, why does the TB airflow change? Doesn't the engine require the same amount of air no matter what size TB you are using?

Doesn't the throttle body airflow actually change from running the idle higher than stock? Isn't the only other significant variable the camshaft?

You will find though in a lot of cases you can't get the car to idle or respond correctly without first altering this value. I've went thought the procedure listed below and you'll find the correction method I posted will get you close in most cases.

You are correct, the proper way to calculate this value is as follows:

ITHBMA - This parameter is the air mass flow through the throttle body when the butterfly is closed against the idle stop screw and the ISC dutycycle is 0%. This value is used by the eec to determine the ISC dutycycle required to meet the calculated desired idle air flow. Alter using this method;

With the engine fully warmed up and the idle steady, set the 'Disable ISC' (aka Z_ISCSW) parameter value to "Yes" and hopefully the car will still be idling. Adjust the throttle body stop screw so that the car will just barely idle and set the TPS to ~0.95 volts. Datalog the MAF's flow over a period of 30 seconds and calculate the average. Convert this kg/hr value into lb/min and use this value for this parameter.

[EDS50]

I can say this. I took the car out tonight after making what I thought were all the correct changes, and it is acting the same way I described, only this time it is shooting past desired rpm and stalling with the a/c off. I thought I had it perfect in the driveway but I see how smoothly that went. Back to the drawing board.

[EDS50]

Well, in the example above (55mm vs. 75mm), the ratio of the diameters is 1.36, but the ratio of the cross-sectional areas is 1.86.

Here's a puzzler: if the RPM is stock 672 RPM and you change the throttle body to a 75mm unit, why does the TB airflow change? Doesn't the engine require the same amount of air no matter what size TB you are using?

Doesn't the throttle body airflow actually change from running the idle higher than stock? Isn't the only other significant variable the camshaft?

You will find though in a lot of cases you can't get the car to idle or respond correctly without first altering this value. I've went thought the procedure listed below and you'll find the correction method I posted will get you close in most cases.

You are correct, the proper way to calculate this value is as follows:

ITHBMA - This parameter is the air mass flow through the throttle body when the butterfly is closed against the idle stop screw and the ISC dutycycle is 0%. This value is used by the eec to determine the ISC dutycycle required to meet the calculated desired idle air flow. Alter using this method;

With the engine fully warmed up and the idle steady, set the 'Disable ISC' (aka Z_ISCSW) parameter value to "Yes" and hopefully the car will still be idling. Adjust the throttle body stop screw so that the car will just barely idle and set the TPS to ~0.95 volts. Datalog the MAF's flow over a period of 30 seconds and calculate the average. Convert this kg/hr value into lb/min and use this value for this parameter.

I followed this procedure as well and I got a value of 1.31 which I thought was really high for my relatively small 65mm tb.

[EDS50]

Have you played with DASMPH? If you are using an X3Z-based tune, it is set to 10 MPH. Since you mention weird behavior around 10 MPH, I just thought I'd bring up that scalar.

I have messed with it before also by raising it to 20mph and lowering it all the way down to 2mph just to see what would hapen but I really saw no change.

[roh92cp]

I can say this. I took the car out tonight after making what I thought were all the correct changes, and it is acting the same way I described, only this time it is shooting past desired rpm and stalling with the a/c off. I thought I had it perfect in the driveway but I see how smoothly that went. Back to the drawing board.

I have the same frustrating issue where I can work on the transition from idle to part throttle in my driveway and get the transition to work great driving back and forth and free reving. Everything seems to be fine for a little while and then just random it starts to act up again. Its as if everything I've done just gets undone some how.

[roh92cp]

Assume you are running a 75mm throttle body you would then change the Throttle Body Airflow Scalar "ITHBMA" by the ratio of change in size from current to stock.

75mm "aftermarket" / 55mm "stock" = 1.36 multiply the stock value of .5500 lb/min by the 1.36 correction factor and enter this as your new TB Airflow Scalar

This "correction factor" is proportional to diameter... or cross-sectional area??

The math to determin the change from stock 55mm to what ever size throttle body you run for ITHBMA is simple right the number in ITHBMA is the same as your T/B size

65/55 = 1.18 x .5500 = .6499 to put in ITHBMA
75/55 = 1.36 x .5500 = .7499 to put in ITHBMA
90/55 = 1.63 x .5500 = .8999 same as the T/B size

[EDS50]

I can say this. I took the car out tonight after making what I thought were all the correct changes, and it is acting the same way I described, only this time it is shooting past desired rpm and stalling with the a/c off. I thought I had it perfect in the driveway but I see how smoothly that went. Back to the drawing board.

I have the same frustrating issue where I can work on the transition from idle to part throttle in my driveway and get the transition to work great driving back and forth and free reving. Everything seems to be fine for a little while and then just random it starts to act up again. Its as if everything I've done just gets undone some how.

I am wondering if in fn1325 aka adaptive learning we need to make the 2 positive special idle cells in the very top row negative. I noticed that there are two positive cells @900rpm and 1100rpm which are set to 10 which I believe allows learning at these rpms. I am thinking with these set the way they are from the factory that the ecu is learning around our adjustments. Maybe someone with more knowledge can chime in on this. I can give it a shot and see what happens.

[EDS50]

Assume you are running a 75mm throttle body you would then change the Throttle Body Airflow Scalar "ITHBMA" by the ratio of change in size from current to stock.

75mm "aftermarket" / 55mm "stock" = 1.36 multiply the stock value of .5500 lb/min by the 1.36 correction factor and enter this as your new TB Airflow Scalar

This "correction factor" is proportional to diameter... or cross-sectional area??

The math to determin the change from stock 55mm to what ever size throttle body you run for ITHBMA is simple right the number in ITHBMA is the same as your T/B size

65/55 = 1.18 x .5500 = .6499 to put in ITHBMA
75/55 = 1.36 x .5500 = .7499 to put in ITHBMA
85/55 = 1.54 x .5500 = .8499 same as the T/B size

I came to realize this as well after Bobcat provided us with the calculation. I was using the calculation in the help file which recommend logging maf kg/hr with the isc unplugged for 30 seconds. Then taking that average kg/hr and converting it lbm/min and using that as the value for ithbma. So for example, 33.3300 kg/hr = 1.224678lbm/min. Since 1.31 lbm/min is a value I calculated yesterday, it seemed way too high. That would also mean that using 1.31 for ithbma, would also mean I would have to use 1.51 for the desired rpm row in fn875n since the factory set up is 0.5500 ithbma and 0.75 fn875n for rpm 672.

[roh92cp]

I can say this. I took the car out tonight after making what I thought were all the correct changes, and it is acting the same way I described, only this time it is shooting past desired rpm and stalling with the a/c off. I thought I had it perfect in the driveway but I see how smoothly that went. Back to the drawing board.

I have the same frustrating issue where I can work on the transition from idle to part throttle in my driveway and get the transition to work great driving back and forth and free reving. Everything seems to be fine for a little while and then just random it starts to act up again. Its as if everything I've done just gets undone some how.

I am wondering if in fn1325 aka adaptive learning we need to make the 2 positive special idle cells in the very top row negative. I noticed that there are two positive cells @700rpm and 900rpm which are set to 10 which I believe allows learning at these rpms. I am thinking with these set the way they are from the factory that the ecu is learning around our adjustments. Maybe someone with more knowledge can chime in on this. I can give it a shot and see what happens.

Holy crap I'm glad you you had me check FN1325 mine as at all 3's except the last 2 colums are 1's. I don't know why my tune is set this way. I wish I could post a screen shot but I'm at work and can't do from here. All my cells are in positive.

Ive also checked a tune that Clint sent me and fn1325 on his is much different the top row is -47 except for the 900 and 1100 rpm cell.

[EDS50]

I can say this. I took the car out tonight after making what I thought were all the correct changes, and it is acting the same way I described, only this time it is shooting past desired rpm and stalling with the a/c off. I thought I had it perfect in the driveway but I see how smoothly that went. Back to the drawing board.

I have the same frustrating issue where I can work on the transition from idle to part throttle in my driveway and get the transition to work great driving back and forth and free reving. Everything seems to be fine for a little while and then just random it starts to act up again. Its as if everything I've done just gets undone some how.

I am wondering if in fn1325 aka adaptive learning we need to make the 2 positive special idle cells in the very top row negative. I noticed that there are two positive cells @700rpm and 900rpm which are set to 10 which I believe allows learning at these rpms. I am thinking with these set the way they are from the factory that the ecu is learning around our adjustments. Maybe someone with more knowledge can chime in on this. I can give it a shot and see what happens.

Holy crap I'm glad you you had me check FN1325 mine as at all 3's except the last 2 colums are 1's. I don't know why my tune is set this way. I wish I could post a screen shot but I'm at work and can't do from here. All my cells are in positive.

Ive also checked a tune that Clint sent me and fn1325 on his is much different the top row is -47 except for the 900 and 1100 rpm cell.

Maybe we are on to something? I am gonna go mess with the car a little so I will report back with my findings. I edited my post with the rpm cells. It was 900 and 1100 rpm cells that are positive.

[roh92cp]

I hope we are on to something, can you post a screen shot of your fn1325 table. I just sent this question and my fn1325 tables with all 3's to my old tuner for him to look at. I think this is part of my problem, but I'll let you know what he says.

[EDS50]

I hope we are on to something, can you post a screen shot of your fn1325 table. I just sent this question and my fn1325 tables with all 3's to my old tuner for him to look at. I think this is part of my problem, but I'll let you know what he says.

It is currently set to the stock a9l/X3Z settings.

-57 -57 10 10 -89 -89 -89 -89 -89 100
-57 -57 -57 -57 -57 -57 -57 -57 -57 -57
-63 -63 -63 10 10 10 10 10 -57 -57
-53 -53 -53 10 10 10 10 10 10 10
-43 -43 -43 10 10 10 10 10 10 10
100 100 10 10 10 10 10 10 10 10
100 100 10 10 10 10 10 10 10 10
-82 -82 -82 -82 -82 -82 -82 -82 -82 -82
-82 -82 -82 -82 -82 -82 -82 -82 -82 -82

[roh92cp]

I just got word from my old tuner and he says the way it was set up with all 3 except 1 in the last 2 colums in fn1325 keeps the PCM from learning at WOT based on short term trims and should not effect idle. He says he has setup thousands of tunes like this without issue, so I don't know I guess back to the drawing board.

[roh92cp]

Are you sure the top row is idle in fn1325.

[cgrey8]

Yes, the top 4 cells are "special idle" cells. Technically it is the top 6 cells. But GUFB only references the top 4. Their special meaning is detailed in the comments section at the very bottom. They have to do with idle in neutral/drive and ac on/off.

Note that just because there are other cells on beyond in this table that can be edited, they should NEVER be tampered with. Those cells are literally exposing other parts of the BIN that technically are not part of this table. For whatever dumb reason, Ford designed this table so that it didn't perfectly consume all possible cells since some of those cells aren't used. They commandeered them for other purposes. So if you go tampering with them in any way, you risk corrupting the tune. It gets even worse. The stock values up there are -89 and 100. The table is setup so that -84 is the largest possible value you can enter into this table. So if you screwed up and typed something else up there, you can't set it back to -89 manually without modifying your def file to allow you to do so. I've screwed with those numbers in the past not knowing better and as I recall they DO mess with things and it's never good.

I've brought this up to Clint before, but it's one of those things that just isn't a high priority. So I make sure to bring it up when it is relevant.

[EDS50]

Yes, the top 4 cells are "special idle" cells. Technically it is the top 6 cells. But GUFB only references the top 4. Their special meaning is detailed in the comments section at the very bottom. They have to do with idle in neutral/drive and ac on/off.

Note that just because there are other cells on beyond in this table that can be edited, they should NEVER be tampered with. Those cells are literally exposing other parts of the BIN that technically are not part of this table. For whatever dumb reason, Ford designed this table so that it didn't perfectly consume all possible cells since some of those cells aren't used. They commandeered them for other purposes. So if you go tampering with them in any way, you risk corrupting the tune. It gets even worse. The stock values up there are -89 and 100. The table is setup so that -84 is the largest possible value you can enter into this table. So if you screwed up and typed something else up there, you can't set it back to -89 manually without modifying your def file to allow you to do so. I've screwed with those numbers in the past not knowing better and as I recall they DO mess with things and it's never good.

I've brought this up to Clint before, but it's one of those things that just isn't a high priority. So I make sure to bring it up when it is relevant.

Is it safe to set cells 2 and 3 to -57 instead of 10 to disable adaptive learning in those cells? Would there be any adverse effect?

[roh92cp]

Yes, the top 4 cells are "special idle" cells. Technically it is the top 6 cells. But GUFB only references the top 4. Their special meaning is detailed in the comments section at the very bottom. They have to do with idle in neutral/drive and ac on/off.

Note that just because there are other cells on beyond in this table that can be edited, they should NEVER be tampered with. Those cells are literally exposing other parts of the BIN that technically are not part of this table. For whatever dumb reason, Ford designed this table so that it didn't perfectly consume all possible cells since some of those cells aren't used. They commandeered them for other purposes. So if you go tampering with them in any way, you risk corrupting the tune. It gets even worse. The stock values up there are -89 and 100. The table is setup so that -84 is the largest possible value you can enter into this table. So if you screwed up and typed something else up there, you can't set it back to -89 manually without modifying your def file to allow you to do so. I've screwed with those numbers in the past not knowing better and as I recall they DO mess with things and it's never good.

I've brought this up to Clint before, but it's one of those things that just isn't a high priority. So I make sure to bring it up when it is relevant.

Not trying to prove you wrong or offend but I'm getting conflicting information on this. I've just talked with my old tuner Don LaSota very reputable SCT software tuner and he claims there is no black magic in changing all the cells in fn1325. As he has set all cells to 3's except the last 2 colums are 1's. He says this table just tells the PCM after how many cycles to apply changes to WOT.

[EDS50]

Setting the cells in adaptive made no difference in the stalling with the a/c on. Its weird how I can step on the brake pedal and push the cutch in @ 40mph and the rpm drops like a rock to 500 rpm or just stalls and other times it happens at 10 or even 5mph. and sometimes it just doesntdo it at all. what the heck could be going on, and this all is happening with teh idle set to 850 and 950 with the a/c on.

[roh92cp]

Setting the cells in adaptive made no difference in the stalling with the a/c on. Its weird how I can step on the brake pedal and push the cutch in @ 40mph and the rpm drops like a rock to 500 rpm or just stalls and other times it happens at 10 or even 5mph. and sometimes it just doesntdo it at all. what the heck could be going on, and this all is happening with teh idle set to 850 and 950 with the a/c on.

I'm with you brother, we have the same problem. Its so random how it comes and goes, very frustrating.

[cgrey8]

...Not trying to prove you wrong or offend but I'm getting conflicting information on this. I've just talked with my old tuner Don LaSota very reputable SCT software tuner and he claims there is no black magic in changing all the cells in fn1325. As he has set all cells to 3's except the last 2 colums are 1's. He says this table just tells the PCM after how many cycles to apply changes to WOT.

I could be wrong...

[iamperson347]

So when you guys try to calculate throttle body airflow do you pull the spout (or set timing manually through BE)? only reason i ask is because when i was trying to find the lowest idle the car could maintain with the throttle body i noticed timing was ramping up to attempt to keep the car alive. Thats why i asked if we should try to lock timing at 18* or something in the previous post. Any thoughts?

David

[EDS50]

So when you guys try to calculate throttle body airflow do you pull the spout (or set timing manually through BE)? only reason i ask is because when i was trying to find the lowest idle the car could maintain with the throttle body i noticed timing was ramping up to attempt to keep the car alive. Thats why i asked if we should try to lock timing at 18* or something in the previous post. Any thoughts?

David

When setting ithbma, I am only disconnecting the iac. It is easier to disable the iac in the tune while datalogging the values needed provided your car doesnt stall out when you do so.

[EDS50]

Setting the cells in adaptive made no difference in the stalling with the a/c on. Its weird how I can step on the brake pedal and push the cutch in @ 40mph and the rpm drops like a rock to 500 rpm or just stalls and other times it happens at 10 or even 5mph. and sometimes it just doesntdo it at all. what the heck could be going on, and this all is happening with teh idle set to 850 and 950 with the a/c on.

I'm with you brother, we have the same problem. Its so random how it comes and goes, very frustrating.

I think I may have made some substantial progress today. I kinda went back to the beginning and started over. I started by resetting the base idle and making sure the throttle body set screw was in the correct position and once that was done I reset the tps to 0.95 on the BE digital dashboard. From there back in the car I went and since I am using an a9l ecu but an X3Z tune, I decided to take all of the "idle" related scalers functions and 1 table and set them to the factory a9l specs on the X3Z tune. Then I went back to page 1 of this thread and applied all of cougar5.0's settings as he illustrated them. I did make dasmin slightly larger and set it to 0.3501 just to have some extra cushion. Once I set everything the way cougar5.0 has his I cleared the kamrfs and started the car. It hunted up and down a little bit which a adjusted by setting numpr to 1.2031 for starters since I know the bottom end of my maf curve is a tick rich and that cleared up the idle hunt. Once adaptive started learning the new settings the idle became more and more stable. With about an 1/8" tweak to the tb set screw, I got iscdc down to 36 and ipsibr down to 0.0. I also set fn111 values that were 0 spark to 19.50 to try and better limit spark hunt dipping too low at idle. With those settings the rpm was still dropping too fast for me so I went into fn879 and experimented by adding 0.20 lb/min to all the values between the top and bottom rows on the left side. The dashpot settings are what seemed to cure the fast idle drop. The idle does hang ever so slightly but not enough to be concerned over and even with the a/c on the car will not stall out coming to a stop. I am not saying its fixxed yet but todays test drive proved succesful as I tried to make the car conk out with the a/c on and it did not shoot passed 900 rpm once on a decel. The end result is my car idles steadily at 800 rpm and 860 with the a/c on. When coming to a stop the idle will hang at 1050 rpm and hold steady until I come to a complete stop and then settle down to 860 with the a/c on. so far so good I guess but I want to give the ecu a couple of days to let adaptive fully run its course and see if the settings stay. For some reason or another, my car always idled better with the a9l idle settings vs. the x3z idle settings. Wierd but it is what it is. Once I am done with any final tweaks and give adaptive a chance to do its things, I will post my settings up the same way cougar5.0 was nice enough to do. Just for the record I have used cougar5.0's settings in the past with great success but for some reason I got away from them (brainfart I guess) and that is when I started having my troubles. Hopefully I am back on track now.