 » Site Navigation | | | | » Recent Threads | | | |  |  |  |  10-02-2007, 01:55 PM | #1 | | Senior Member Join Date: Mar 2005 Location: NJ Posts: 1,625 |  DASC people! help please...
got a (possible) DASC issue... will apreciate all comments.
I'm experiancing hesitation under hard acceleration...
As I'm accelerating (at any speed), I feel a jerking motion (like having a rope tied around the rear fender and being yanked back repeatedly)... almost as if the belt is slipping - then catching on. It does not feel electrical nor fuel related, but very much so mechanical.
Yesterday I actually heard the blower 'chirp' as it was cutting off...
Also worth mentioning... ASC light is on and the system is still not operational despite having replaced the throtle actuator (with a second hand one, though). My mechanic is lost for clues on ASC issue as he swore it was the TA. Could this be somehow conected to the hesitation??
Further... No CEL (!) - no visualy appearent vacum leaks. Magnecore wires / Denso Iridium plugs / coil pack / MAF - ALL virtually NEW.
Other than under acceleration (and hard one at that) - car idles/drives perfect.
Anyone had this happen before??? |  |  | | 10-02-2007, 01:59 PM | #2 | | doesn't care about you. Join Date: Aug 2004 Location: Denver, CO Posts: 3,925 |
Start by replacing your belt. If you can hear the belt chirp, there is something wrong. Check the tension on the belt and make sure the tensioner is working.
Who many miles on your plugs? Do you have a boost gauge? __________________ 
'99 Dinan M3 | | | | | 10-02-2007, 02:21 PM | #3 | | Senior Member Join Date: Mar 2005 Location: NJ Posts: 1,625 |
No, no boost gauge... @ most 15K on the blower / @ most 15K on the plugs as well / about 10K on the coil pack & the wires... belt originally came with the kit - looked at it yesterday top to bottom & I saw no imperfections whatsoever (not even on the sides where it rubs against pulley flanges)... the belt path (while running) shows no deviations at all - every pulley is perfectly straight & dispalys no vibration - belt rotation is smooth. the 'chirp' I could swear came from the blower.. almost like a internittent / interupted dasc 'whine', only louder & sharper & ONLY as the car was cutting off  it does, however, make more sense that it is the belt vs. the unit itself (unless the blower itself is about to seize - which it shouldnt as it is practucally brand new)... I will check the tensioner today & see if that works properly as I did not do that yet... How tight should the belt be?? when engine off, should it have any play at all?? I do not remember the tension when we installed it... thanks! Quote: Originally Posted by DustenT  Start by replacing your belt. If you can hear the belt chirp, there is something wrong. Check the tension on the belt and make sure the tensioner is working.
Who many miles on your plugs? Do you have a boost gauge? | | | | | | 10-02-2007, 07:04 PM | #4 | | doesn't care about you. Join Date: Aug 2004 Location: Denver, CO Posts: 3,925 |
Quote: Originally Posted by marko No, no boost gauge... @ most 15K on the blower / @ most 15K on the plugs as well / about 10K on the coil pack & the wires... belt originally came with the kit - looked at it yesterday top to bottom & I saw no imperfections whatsoever (not even on the sides where it rubs against pulley flanges)... the belt path (while running) shows no deviations at all - every pulley is perfectly straight & dispalys no vibration - belt rotation is smooth. the 'chirp' I could swear came from the blower.. almost like a internittent / interupted dasc 'whine', only louder & sharper & ONLY as the car was cutting off it does, however, make more sense that it is the belt vs. the unit itself (unless the blower itself is about to seize - which it shouldnt as it is practucally brand new)... I will check the tensioner today & see if that works properly as I did not do that yet... How tight should the belt be?? when engine off, should it have any play at all?? I do not remember the tension when we installed it... thanks! | The belt should have 1/4" to 1/2" of play. Not much at all. It should feel tight. __________________
'99 Dinan M3 | | | | | 10-03-2007, 01:20 PM | #5 | | Senior Member Join Date: Mar 2005 Location: NJ Posts: 1,625 |
belt is tight & healthy... checked it yesterday. the tensioner seems to work Ok (got an ever so slight play/oscillation while spinning on idle, but I think that is acceptable, no?)... something else seems to be disengaging the SC briefly... car is fianally going to a shop this afternoon for the ASC problem (@ the end of my witts with that $hit)... I'm hoping thats whats causing the issue - maybe the malfunctioning ASC is falsely sensing wheels slipping & therefore pulling back @ the throttle (??). Quote: Originally Posted by DustenT The belt should have 1/4" to 1/2" of play. Not much at all. It should feel tight. | | | | | | 10-04-2007, 08:44 AM | #6 | | Member Join Date: Mar 2004 Location: NE Wyoming Posts: 36 |
Quote: Originally Posted by marko got a (possible)
Also worth mentioning... ASC light is on and the system is still not operational despite having replaced the throtle actuator (with a second hand one, though). My mechanic is lost for clues on ASC issue as he swore it was the TA. Could this be somehow conected to the hesitation??
Further... No CEL (!) - no visualy appearent vacum leaks. Magnecore wires / Denso Iridium plugs / coil pack / MAF - ALL virtually NEW.
Other than under acceleration (and hard one at that) - car idles/drives perfect.
Anyone had this happen before??? | I had a similar problem a year ago with the ASC light on and the car cutting out. Mine was actually the secondary throttle position sensor (opposite the throttle acutator). What was happening was the ASC/ABS computer was sending bogus signals to the ECU and causing the motor to cut out. Mine was anything from what felt like bucking a headwind to falling flat on it's face wondering if it could even go up a hill. To test this theory disconnect your ASC/ABS computer (found under the glove box closest to the fender...silver I think). If your car runs great replace the secondary throttle position sensor ($50 part). I hope this helps, Sheridan __________________
98 supercharged 318ti Sport
"It's better to be blown than stroked" | | | | | 10-04-2007, 03:59 PM | #7 | | Senior Member Join Date: Mar 2005 Location: NJ Posts: 1,625 |
thank you... sounds similar to my problem. wish I thought of the the 'secondary throttle position sensor' before... all I replaced was the actuator & it yielded no results. unfortunatelly, an overpiced mechanic is taking apart my car as we speak (dropped it off yesterday) to try and fix the ASC. I wonder if that will be the issue? Quote: Originally Posted by adrnln I had a similar problem a year ago with the ASC light on and the car cutting out. Mine was actually the secondary throttle position sensor (opposite the throttle acutator). What was happening was the ASC/ABS computer was sending bogus signals to the ECU and causing the motor to cut out. Mine was anything from what felt like bucking a headwind to falling flat on it's face wondering if it could even go up a hill. To test this theory disconnect your ASC/ABS computer (found under the glove box closest to the fender...silver I think). If your car runs great replace the secondary throttle position sensor ($50 part).
I hope this helps,
Sheridan | | | | | | 10-17-2007, 10:37 PM | #8 | | Senior Member Join Date: Mar 2005 Location: NJ Posts: 1,625 |
thank you for the suggestion regarding the sensor. they checked (upon my request) and it was indeed bad. one thing my mechanic is perplexed about is that he STILL can not get the ASC+T to perform a 'self test'. this self test should theoretically occur as you turn the key half way over (right before the engine starts) & the throttle actuator should pull on the cable ONCE, thus closing & opening the secondary throtle body unit one time. again, this should happen only once, BUT it should happen EVERY time you are about to start the car, I'm told. Sheridan/Dusten (or anyone else willing to offer an opinion)... can you guys tell me if your cars perform these self tests, or is this maybe a function that NOT every ASC+T BMW has?? Anyway, long story short - the light is off (for now), the system is operational & the car does NOT cut out anymore (!) so the two issues were definatelly conected - but I'm told the problem may come back. Quote: Originally Posted by adrnln I had a similar problem a year ago with the ASC light on and the car cutting out. Mine was actually the secondary throttle position sensor (opposite the throttle acutator). What was happening was the ASC/ABS computer was sending bogus signals to the ECU and causing the motor to cut out. Mine was anything from what felt like bucking a headwind to falling flat on it's face wondering if it could even go up a hill. To test this theory disconnect your ASC/ABS computer (found under the glove box closest to the fender...silver I think). If your car runs great replace the secondary throttle position sensor ($50 part).
I hope this helps,
Sheridan | | | | | | 10-18-2007, 01:44 AM | #9 | | doesn't care about you. Join Date: Aug 2004 Location: Denver, CO Posts: 3,925 |
Quote: Originally Posted by marko Sheridan/Dusten (or anyone else willing to offer an opinion)... can you guys tell me if your cars perform these self tests, or is this maybe a function that NOT every ASC+T BMW has??
| Mine does not self test. The DISA valve might do this, but with the stock DASC kit it's unmounted and ziptied out of the way. __________________
'99 Dinan M3 | | | | | 10-18-2007, 01:58 AM | #10 | | Senior Member Join Date: Mar 2005 Location: NJ Posts: 1,625 |
aaahhh! I see... nice. that actually explains a lot. I dont think he was familiar with the dasc set up at all, & I completely forgot about that thing (nor did I know it affects the ASC+T system anyway)! so, despite not self testing after dasc installation, your ASC+T system has been & is fully operational all along, right? ever had any issues with the ASC+T otherwise? Also, once you did the Nick G thing & did away with the valve all together (I read somewhere you can just remove it once you get the software), did you notice any issues with the ASC+T, or did it remain fully operational and trouble free?? Ps- Thanks Man! That $hit was driving me crazy & it worried the crap out me that 2 consecutive mechanics could NOT figure this out to save their lives! Damn, I feel stupid now...  Quote: Originally Posted by DustenT Mine does not self test. The DISA valve might do this, but with the stock DASC kit it's unmounted and ziptied out of the way. | | | | | | 10-18-2007, 04:57 AM | #11 | | doesn't care about you. Join Date: Aug 2004 Location: Denver, CO Posts: 3,925 |
Quote: Originally Posted by marko aaahhh! I see... nice. that actually explains a lot. I dont think he was familiar with the dasc set up at all, & I completely forgot about that thing (nor did I know it affects the ASC+T system anyway)! so, despite not self testing after dasc installation, your ASC+T system has been & is fully operational all along, right? ever had any issues with the ASC+T otherwise? Also, once you did the Nick G thing & did away with the valve all together (I read somewhere you can just remove it once you get the software), did you notice any issues with the ASC+T, or did it remain fully operational and trouble free?? Ps- Thanks Man! That $hit was driving me crazy & it worried the crap out me that 2 consecutive mechanics could NOT figure this out to save their lives! Damn, I feel stupid now... | I have never had a problem with the ASC+T. One time it got stuck closed, but that was because I had it mounted stupid. I don't have the NickG software, it was in the plans but I never actually got to the point where I felt I NEEDED it. His software writes out the CEL check for the DISA valve, so you can remove it. __________________
'99 Dinan M3 | | | | | 10-18-2007, 07:26 PM | #12 | | Member Join Date: Mar 2004 Location: NE Wyoming Posts: 36 |
Quote: Originally Posted by DustenT I don't have the NickG software, it was in the plans but I never actually got to the point where I felt I NEEDED it. His software writes out the CEL check for the DISA valve, so you can remove it. | I noticed a big difference with the Stage III. I haven't dyno' it since I installed it but I do have a dyno run with just the stock ECU program and a 10psi pully. I don't think my ASC does a seft test either (other than a electrical test, no moving of parts....that would stall the motor upon start up, duh). S __________________
98 supercharged 318ti Sport
"It's better to be blown than stroked" | | | | |
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