Thottle hang issues . . .
Jun 19, 2008, 08:53 AM
#47
I will do some logging tomorrow with a wideband and try to confirm whether or not fuel is being delivered during the hang.
It's definitely load/rpm related. I can go higher than 3500rpm under light load and it doesn't hang. It will hang (on stock table) anytime I go over 3500ish whenever I'm right around positive pressure or above (I don't know actual load numbers). Below that it doesn't hang at all.
Another thing I noticed yesterday; I advanced the idle mivec cells to get a little lope and I adjusted the idle stepper table as described above, and now after I drive for a while I get some weird hanging/idling. It will hang/idle at anywhere from 1500-2000rpm and will pull the car along at that rpm even in gear and seems to last indefinitely. When I pull it out of gear it just sits there at that rpm. It seems to only happen in 1st and 2nd gears, basically slowly coming up to a stoplight or driving through the parking lot of my apartment complex. I've tried forcing rpm back down to where they should be with the clutch while in gear and when I pull it back out of gear it will jump back up. The only thing I changed besides the stepper table was the mivec table. I advanced 0-50 load and 0-1250 cells to I think 1.8 degrees. I didn't adjust ign timing cells. They're currently at 7 degrees. I don't know if changing the mivec table would affect this. I don't think it should anyways. Could there possibly be something wrong with my car that's causing this? I've done boost leak checks and can't find any. I don't have any vacuum leaks as far as I can tell by my truboost. I pulled my IAC valve last week and cleaned it with maf cleaner and it seemed to be fine. There wasn't anything obviously wrong with it anyway. It does idle perfectly on the stock stepper table though.
It's definitely load/rpm related. I can go higher than 3500rpm under light load and it doesn't hang. It will hang (on stock table) anytime I go over 3500ish whenever I'm right around positive pressure or above (I don't know actual load numbers). Below that it doesn't hang at all.
Another thing I noticed yesterday; I advanced the idle mivec cells to get a little lope and I adjusted the idle stepper table as described above, and now after I drive for a while I get some weird hanging/idling. It will hang/idle at anywhere from 1500-2000rpm and will pull the car along at that rpm even in gear and seems to last indefinitely. When I pull it out of gear it just sits there at that rpm. It seems to only happen in 1st and 2nd gears, basically slowly coming up to a stoplight or driving through the parking lot of my apartment complex. I've tried forcing rpm back down to where they should be with the clutch while in gear and when I pull it back out of gear it will jump back up. The only thing I changed besides the stepper table was the mivec table. I advanced 0-50 load and 0-1250 cells to I think 1.8 degrees. I didn't adjust ign timing cells. They're currently at 7 degrees. I don't know if changing the mivec table would affect this. I don't think it should anyways. Could there possibly be something wrong with my car that's causing this? I've done boost leak checks and can't find any. I don't have any vacuum leaks as far as I can tell by my truboost. I pulled my IAC valve last week and cleaned it with maf cleaner and it seemed to be fine. There wasn't anything obviously wrong with it anyway. It does idle perfectly on the stock stepper table though.
Jun 19, 2008, 09:47 AM
#48
i dont think anything wrong with your car. my idle is perfect on the stock tables. I have S1 cams in the car. its just the hang issue. fighting the brakes into a corner or dowshifting and then getting on the brakes. the car feels like it has another set of imaginary brakes working since it starts engine braking instead of pulling me in more. quite annoying 
Jun 19, 2008, 10:04 AM
#50
It sounds feasible. Unfortunately, I'm one of those that rests their foot on the clutch while driving. I have kinda tried the pushing the clutch in to see if it drops the rpms afterwards, but I don't have any conclusive evidence of it having an effect, but I'm probably not doing it right.
I was thinking about the purpose of why it would hang from the factory. I'm wondering if it's maybe something like an anti-lag feature. When it hangs, on the stock stepper table, boost seems to recover a little bit quicker than it does with a modified table and no hanging. I haven't done any "testing" so it may be just a result of different variables that normally determine boost response. My turbo also has a foot in the grave, so anything that's boost/turbo related I generally take with a grain of salt.
I was thinking about the purpose of why it would hang from the factory. I'm wondering if it's maybe something like an anti-lag feature. When it hangs, on the stock stepper table, boost seems to recover a little bit quicker than it does with a modified table and no hanging. I haven't done any "testing" so it may be just a result of different variables that normally determine boost response. My turbo also has a foot in the grave, so anything that's boost/turbo related I generally take with a grain of salt.
Last edited by biggie5252; Jun 19, 2008 at 10:07 AM.
Jun 19, 2008, 10:53 AM
#51
well I am guessing that it was designed for emmisions and fuel efficency since alot of other new model cars have similar "features" think about highway driving. let off the throttle at high way speeds and its still coasting. no dumping unburned fuel between on off throttle. as far as testing. have your foot off the clutch and while its hanging just tap it but hold it. obviously not enough to disengage the clutch. just push it lightly and hold it. you shoudl feel it cut fuel or start engine braking. I have however noticed that while it will engine brake, if you rest your foot there trying to trick it it reverts and continues to hang a bit. test that with the wideband and see what happens
Jun 20, 2008, 04:52 PM
#52
On mine I changed the stepper table in the same fashion and it was working great until I took it to the dealer to get the AC recharged, now it has the same symptoms yours does. I really hate the throttle hang, but I might hate the crappy idle more. Maybe when I took it to the dealer they reset my ECU, and it "relearned" the idle. I am going to try setting the stepper table back to it's original form and see if that corrects the idling problem.
i dont think anything wrong with your car. my idle is perfect on the stock tables. I have S1 cams in the car. its just the hang issue. fighting the brakes into a corner or dowshifting and then getting on the brakes. the car feels like it has another set of imaginary brakes working since it starts engine braking instead of pulling me in more. quite annoying
Maybe that has something to do with it? j/k
Jul 10, 2008, 07:08 PM
#55
well I hooked up my wideband this weekend and confirmed my suspisions. when its hanging the car is getting fuel. mine reads about 14.6 when you lightly press the clutch pedal or it stops hanging, it cuts fuel and goes back to read 22.XX. not sure what all that means, other then its getting fuel while its hanging. I am going to post this in the other thread as well
Thread
Thread Starter
Forum
Replies
Last Post
