sudden enrichment and stalling

[nitz]

looking through all the threads about stalling there are suggestions covering BOV, ISCV tables, MAF scaling, BISS, ROMs etc etc that all could contribute to stalling issues (very overwhelming). in my case when one does a quickish start from standstill and immediately depress the clutch, the idle will suddenly drop and afr goes rich. it does catch itself sometimes and may peg to 2K rpm after slowly coming down. Most times it just goes rich and stalls or hovers at 10 afr and comes back up. it seems to be happening more and more often. it's almost as if the MAF detects more air than really present and fuel is dumped. below is evoscan log, notice the odd 96 load area and increased airflow once the stumbling starts even though off throttle (14% is off throttle). any pointers would really help. i've done a boost leak test and switched back to stock plastic bov with no changes. the car is a 2.3 with revolvers and an intake.

[l2r99gst]

Typical maf overrun at throttle close, which can be due to many things, such as intake pipe, turbo, cams, filter, etc, etc.

I'm sure some people can give you various pointers to make it better, but I would recommend converting to SD if you could. It will completely eliminate the problem, as the root cause is MAF based.

[nitz]

thanks.. i don't have an iat or map sensor at this time. however i do have an autronic which i came off to get better startup, idle, drivability, and knock control. ironically i now have problems with phantom knock, idle, and startup..lol. well looks like i'll be tossing in a standalone until i've got those sensors and ready for oem ecu SD, cuz these problems are taking the fun out of driving my car.

Originally Posted by l2r99gst

Typical maf overrun at throttle close, which can be due to many things, such as intake pipe, turbo, cams, filter, etc, etc.

I'm sure some people can give you various pointers to make it better, but I would recommend converting to SD if you could. It will completely eliminate the problem, as the root cause is MAF based.

[merlin.oz]

Suggest you borrow or try one of the silicon hi-flow intake pipes, they work well and (usually) dont upset the MAF.

[nitz]

well this intake ran perfectly on a stock motor/turbo setup.. so i think it's more a function of extra flow from the cams, stroker, and fpred turbo + the intake. either way do you have a link to what ur suggesting (it's for an evo VI with the battery relocated).

Originally Posted by merlin.oz

Suggest you borrow or try one of the silicon hi-flow intake pipes, they work well and (usually) dont upset the MAF.

[merlin.oz]

ah, the 6 intake is quite different shape to the 9 I think, probably wont suite.
My intake came from MEEK in Sydney, its a SAMCO copy (supposedly).

[casper980]

Originally Posted by nitz

looking through all the threads about stalling there are suggestions covering BOV, ISCV tables, MAF scaling, BISS, ROMs etc etc that all could contribute to stalling issues (very overwhelming). in my case when one does a quickish start from standstill and immediately depress the clutch, the idle will suddenly drop and afr goes rich. it does catch itself sometimes and may peg to 2K rpm after slowly coming down. Most times it just goes rich and stalls or hovers at 10 afr and comes back up. it seems to be happening more and more often. it's almost as if the MAF detects more air than really present and fuel is dumped. below is evoscan log, notice the odd 96 load area and increased airflow once the stumbling starts even though off throttle (14% is off throttle). any pointers would really help. i've done a boost leak test and switched back to stock plastic bov with no changes. the car is a 2.3 with revolvers and an intake.

Upgrade the CPU Autronic in Nice...as long as you have someone reputable to tune it.

[nitz]

of course i do, myself

Originally Posted by casper980

Upgrade the CPU Autronic in Nice...as long as you have someone reputable to tune it.

[gfng]

can this be the tps ????

[nitz]

how so? i adjusted it to within mitsu spec using a voltmeter. not sure what else can be done to eliminate possible tps issues.

Originally Posted by gfng

can this be the tps ????

[linuxman51]

Screen still in the maf or no? I have a similar issue that wouldn't scale out and apparently won't tune out without causing an issue driving off... but mine didn't do it until I yanked the (mostly failing) screen out of the maf. I let off the gas and I can see the load spike 120 with the throttle closed, so I leaned that spot out at 1000rpms and 120 load, it made it better, but I still get stumbling reasonably frequently.

The problem becomes when you pull off from really low rpms it hits that spot on the map with it actually being in 'load' and goes really lean. I suspect I'm going to have to go to SD to fix it, but I'd really like to get mine tuned out 'normally' first.

[nitz]

i initially had the screen out but felt that was causing it. put the screen back in and the frequency of it happening decreased quite a bit. now without rhyme or reason it has gotten worse even with the screen in. i tried another maf with screen just to make sure i didn't have a failing maf but same result.

Originally Posted by linuxman51

Screen still in the maf or no? I have a similar issue that wouldn't scale out and apparently won't tune out without causing an issue driving off... but mine didn't do it until I yanked the (mostly failing) screen out of the maf. I let off the gas and I can see the load spike 120 with the throttle closed, so I leaned that spot out at 1000rpms and 120 load, it made it better, but I still get stumbling reasonably frequently.

The problem becomes when you pull off from really low rpms it hits that spot on the map with it actually being in 'load' and goes really lean. I suspect I'm going to have to go to SD to fix it, but I'd really like to get mine tuned out 'normally' first.

[Appauldd]

Looking at your airflow you can see that it hardly goes low enough to allow the LTFT low to adjust and stay consistant. You need to get the idle Hz to be lower.

Your base idle RPM is a bit low for Revolvers. Anything below 1K and it will have issues. Mine are set at 1070 and idle great.

your wide band is showing that it is running rather rich for idle.

your timing is a bit low for the revolvers as well.

SOOOO....

To get the MAF Hz down......on the bottom of the MAF there is a small rubber plug. Remove the rubber and turn out the ecrew until the hole it cloeses into is flush and wide open. This should lower the Hz enough to get the LTFT low to read.

Set your idle to about 1025 to 1070

In the fuel table in the 1000 rpm and below and 60 hz and below cells, set them to stock values

In the timing table same 1000 rpm and below and 60Hz and below cells raise the timing to about 8 degrees

Increase the idle stability timing control to 146 from the stock 128 value


These should help. Give them a shot and get back to us.

Paul

[Fast_Freddie]

^ Freaking Idle/maf based problems guru right there....

[nitz]

the LTFT do adjust and eventually settle just didn't show there cuz i had recently disconnected the battery. However I agree that it is higher than should be (usually hovers at 43hz and sometimes 50hz), but doesn't seem to be outside the cutover for low mid LT as shown below. i see a bunch of silicone and not a rubber plug, so i'll just scrape it out and adjust the screw. for reference here are the Closed Loop - LT Trim Control Values
low->mid 75
mid->low 62.5
mid->high 1587.5
high->mid 1581.25


forgive my ignorance; i am a bit confused by the reference to Hz in the fuel and timing tables you made below. did you mean load instead?
for what it's worth my fuel and timing load axes are scaled as follows.. so if you mean't 60 load and below I would have to do 80 load and below for fuel.

fuel: 10 30 50 80 100....
time: 0 20 40 60 80 100...

i am also not sure what table you mean by idle stability timing control as I do not have a table by this name just the usual idle stepper look-up table which is rpm vs tps and has values below (i am on ROM 96260009):

0 0 0 0 0 0 0 0
10 10 10 10 10 10 10 10
20 20 20 20 20 20 20 20
30 30 30 30 30 30 30 30
40 40 40 40 40 40 40 40
51 51 51 51 51 51 51 51
58 58 58 58 58 58 58 58
62 62 62 62 62 62 62 62
65 65 65 65 65 65 65 65
67 68 68 68 68 68 68 69
70 70 70 70 70 70 71 72
72 72 73 73 73 73 74 76
74 75 75 75 75 76 77 79
76 77 77 77 77 78 79 82
78 79 79 79 79 81 85 89
81 81 81 82 83 86 92 104
83 83 84 85 86 90 99 140
85 86 87 88 90 95 115 160
87 88 90 91 93 102 140 160
89 90 92 94 97 111 160 160
92 93 95 97 101 133 160 160
94 95 98 103 111 146 160 160
96 98 101 110 120 160 160 160
98 100 108 120 120 160 160 160
100 105 115 133 140 160 160 160
104 110 120 160 160 160 160 160
136 130 160 160 160 160 160 160

Originally Posted by Appauldd

Looking at your airflow you can see that it hardly goes low enough to allow the LTFT low to adjust and stay consistant. You need to get the idle Hz to be lower.

Your base idle RPM is a bit low for Revolvers. Anything below 1K and it will have issues. Mine are set at 1070 and idle great.

your wide band is showing that it is running rather rich for idle.

your timing is a bit low for the revolvers as well.

SOOOO....

To get the MAF Hz down......on the bottom of the MAF there is a small rubber plug. Remove the rubber and turn out the ecrew until the hole it cloeses into is flush and wide open. This should lower the Hz enough to get the LTFT low to read.

Set your idle to about 1025 to 1070

In the fuel table in the 1000 rpm and below and 60 hz and below cells, set them to stock values

In the timing table same 1000 rpm and below and 60Hz and below cells raise the timing to about 8 degrees

Increase the idle stability timing control to 146 from the stock 128 value


These should help. Give them a shot and get back to us.

Paul