View Full Version : new cam installed-there a relearn needed for the ecm?


fst100
02-28-2012, 05:24 PM
a friend just got the MS4 cam installed along with a 4K stall converter and a street tune by a shop for his 01 ws6 A4. when he started the car up it stalled and had to crank it over a few times to get it running. when he was leaving to reverse out of the driveway it stalled a few more times. i texted him after he left if it was on stock idle and he replied that the ecu is still relearning. if it was tuned right, shouldnt it not be stalling at all?

my gut tells me its still on stock idle which is causing the stalling. ideas/advice?

Zmg00camaross
02-28-2012, 05:39 PM
Who tuned it? But yeah sounds like the tune is off.

sidewayz28
02-28-2012, 05:43 PM
He needs to take the car to a competent tuner.

I would suggest your friend not get on that thing AT ALL.

Does he have a dyno sheet showing AFR?

What was the car tuned with?

fst100
02-28-2012, 05:46 PM
i dont know all of the facts. i dont remember the tuner shop that did the install however the only things i do know is my friend said the shop didnt do a dyno tune but a street tune. i asked him if i could read the ecm with my hptuners but he had to leave.

edit-so theres no ecm relearn after a cam swap correct?

sidewayz28
02-28-2012, 05:49 PM
dude a custom tune is a "ecm relearn"

sounds like the tuner is a joke.

get your buddy on here.

fst100
02-28-2012, 05:52 PM
i figured as much haha. thanks

NY02ws6
02-29-2012, 11:08 AM
dude a custom tune is a "ecm relearn"

sounds like the tuner is a joke.

get your buddy on here.

No, a custom tune is a custom tune. Fuel trim and idle still have adaptive strategy, meaning they still "learn" after a tune. I picked my tuner's brain pretty well while he was doing mine. The tune is just a corrected point for the ecm to start adjusting from. And obviously the WOT fuel maps are corrected for proper A/F ratio. Even with a good tune if I disconnect the battery my first one or two cold starts will be a little rough until the ecm finds exactly what IAC position works the best. Mine will rev a little higher than normal, then drop just below where it should be and hunt for an rpm for maybe 5 seconds, the first one or two cold starts after ecm power loss.

That being said, it sounds like your buddy's tune is all dicked up, even while its relearning it shouldn't stall. He should def take it easy until he gets the tune fixed, and I would recommend he make sure the IAC, TB and MAF are clean and his plug gaps are correct before trying to fix idle quality, as all of these will effect idle and make it harder to tune.

SweeTbone
02-29-2012, 11:59 AM
Personally, I wouldn't drive it anymore as is until you find a GOOD tuner who knows what he is doing to make it safe so you don't damage your investment.

sidewayz28
02-29-2012, 12:36 PM
no, a custom tune is a custom tune. Fuel trim and idle still have adaptive strategy, meaning they still "learn" after a tune. I picked my tuner's brain pretty well while he was doing mine. The tune is just a corrected point for the ecm to start adjusting from. And obviously the wot fuel maps are corrected for proper a/f ratio. Even with a good tune if i disconnect the battery my first one or two cold starts will be a little rough until the ecm finds exactly what iac position works the best. Mine will rev a little higher than normal, then drop just below where it should be and hunt for an rpm for maybe 5 seconds, the first one or two cold starts after ecm power loss.

That being said, it sounds like your buddy's tune is all dicked up, even while its relearning it shouldn't stall. He should def take it easy until he gets the tune fixed, and i would recommend he make sure the iac, tb and maf are clean and his plug gaps are correct before trying to fix idle quality, as all of these will effect idle and make it harder to tune.
lolok so basically what you are saying is your computer will read all the new parameters entered in the new tune, in which your computer will learn from and run differently than stock?

BTW, what makes the tune "adapt" just curious?

edit: I'm going to guarantee the fixes you listed will not help his idle.

NY02ws6
02-29-2012, 12:44 PM
lolok so basically what you are saying is your computer will read all the new parameters entered in the new tune, in which your computer will learn from and run differently than stock?

Precisely, so my guess is that this guys tune is screwed up, but at least the tuner offered a "valid" excuse LMAO

NY02ws6
02-29-2012, 12:48 PM
The tune "adapts" pretty much by trial and error. Ecm knows what values itis supposed to see, and tries values right around the ones that are programmed into the tune until it finds exactly what produces the correct result.

sidewayz28
02-29-2012, 12:56 PM
The tune "adapts" pretty much by trial and error. Ecm knows what values itis supposed to see, and tries values right around the ones that are programmed into the tune until it finds exactly what produces the correct result.

What do you think your MAF does?

fst100
02-29-2012, 01:03 PM
the ecm adapts to a certain extent to what is already set up in the tables. the maf table is set at whatever values it is set either from factory or by editing them but that number wont change if it sense more/less air, it merely goes off the other values dependant on the amount of air it sense. example-factory tune at 3500 set at 110mg/s where when adding a lid more air enters into the tb and increases causing the range in the maf table to move on to the next range 3600 which is set at say, 112ms/g but the value at 3500 stays the same.

however there are other tables that tie in and effect the overall airflow such as iat, spark, LTFT/STFT, and etc. so the ecm 'adapts' but only to the extent to what is already set in the ecm unless otherwise changed.

redtan
02-29-2012, 02:57 PM
The tune "adapts" pretty much by trial and error. Ecm knows what values itis supposed to see, and tries values right around the ones that are programmed into the tune until it finds exactly what produces the correct result.

Wut?

What tables exactly is the ECM using 'trial and error' on?

You're saying that if I command 28* of timing, the computer will first try 27* then 29*? If I command the fans to turn on at 192* the computer will first try turning them on at 190* and then 194*?

86lxnotch
03-01-2012, 07:58 AM
redtan i assume you have heard of open loop and closed loop on a computer controlled car? open loope is considered warmup or enrichment mode were its pretty much based off the tune. when the motor gets to temp and goes into closed loop it feeds off the sensors information. you have the "base" tune and the computer can vary it +/- a % from the base. this accomodates variations such as temp or altitude. these are basic reasons why all the info from the sensors is so important. on your timing reference no because the timing table is based off either load/rpm or tps as well as air temp
example
air temp is 60* and you have 28* timing on the dyno
you leave and drive on a summer day and the air is 90* the computer reads the iat so it knows this and will pull timing accordingly to prevent detonation

this is just a little of the basic crap though

NY02ws6
03-01-2012, 09:30 AM
Wut?

What tables exactly is the ECM using 'trial and error' on?

You're saying that if I command 28* of timing, the computer will first try 27* then 29*? If I command the fans to turn on at 192* the computer will first try turning them on at 190* and then 194*?

well,since the thread was about idle issues, one would assume i was talking about idle airflow...obviously timing is set based on temp, load etc

never said i was an expert, just explaining what I did learn from my tuner to try and answer someone's question.

RPM WS6
03-01-2012, 10:22 AM
Certain parameters in the PCM will most certainly "adapt/learn" to conditions, such as fuel trims (unless you lock them at zero) and WOT timing (if there is KR, etc.). This is true for a stock OR custom tuned PCM.

Idle relearn usually takes a few minutes of steady idle time to complete. This is also true even for a stock PCM/stock engine.

J-Train
03-14-2012, 02:10 PM
No, a custom tune is a custom tune. Fuel trim and idle still have adaptive strategy, meaning they still "learn" after a tune. I picked my tuner's brain pretty well while he was doing mine. The tune is just a corrected point for the ecm to start adjusting from. And obviously the WOT fuel maps are corrected for proper A/F ratio. Even with a good tune if I disconnect the battery my first one or two cold starts will be a little rough until the ecm finds exactly what IAC position works the best. Mine will rev a little higher than normal, then drop just below where it should be and hunt for an rpm for maybe 5 seconds, the first one or two cold starts after ecm power loss.

That being said, it sounds like your buddy's tune is all dicked up, even while its relearning it shouldn't stall. He should def take it easy until he gets the tune fixed, and I would recommend he make sure the IAC, TB and MAF are clean and his plug gaps are correct before trying to fix idle quality, as all of these will effect idle and make it harder to tune.

This is right on. Even on totally stock tuning, when I leave my battery disconected for a few days, upon hooking it back up my car barely will run and idle. After a few minutes or upon driving around the block, idle will imporve and drivabilty becomes fine. The ECU's in these cars are fairly adaptive. Hence why you can cruise around and get away with installing a giant cam on stock ECU tuning temporarily until you get it tuned.