I just replaced the battery in my 2003 MCS. has 58k miles. on my way back from autozone (with the battery changed) the car has no power at all. it feels as if the SC was removed. and when i rev the car in neutral...its very slow in climbing R's. its not missing or anything like that...no service lights or anything. i replaced it with a duralast gold H5-DLG. which was what they and every other auto parts store had listed as the replacement battery for the car. because it is vented. this shouldn't have any bearing on the car running. but as soon as it was replaced. the car had no power at all. any suggestions? the car is fairly modded and prior to this would spin first and second gear easy....now wont even break a tire in 1st. tried searching forums saw nothing about this issue....any help would be appreciated...

edit...ok...tried to see if maybe the air filter was bad...its fine. car still has no power..double checked the intake hose from the trottle body (disconnected the plug) after that SES came on. ran to autozone....code p0123 and p0222 came up. after leaving ses light went out. still has no power at all under throttle. idles fine...even when revving in neutral slower then normal rev climbing. the 2 codes say throttle position sensor. when he looked up the part is said see throttle body. from how the car is acting it would make sense that the throttle position sensor is off. also i dont recall hearing this before...but when i shut the car off...about 3 seconds after...there is a buzz noise that comes from the throttle body that lasts about 2 seconds. not overly loud...but dont recall ever hearing it before.

 

ok...ty for all the help! lol well after some research it seems the BPV has failed. gonna go do more research. it does seem that the SC is not creating any boost but is making normal sounds. and i do hear a whoosing of air like its escaping somewhere. so im guessing this valve is broken and not closing to allow boost to be created. anyone else have a BPV fail? guess it was pure coincidence that it went when the battery was replaced.

 

nope - not too helpful were we...

sympathy most certainly, but I for one was a bit baffled...

so what to do get when you cross an elephant with a rhinoceros?
(elifino!)

 

I think most folks read about the power loss after a battery install, and kinda smiled....when it rains, it pours!!

Obviously the battery did not have anything to do with the issue...
But the story made it sound like you were implying the battry caused it....and with some posts, folks just move on...trying to trouble shoot an issue online is tough...especially if the person does not have a certain level of mechanical knowlege/experance, and getting the help of a pro is best.
Bypass valve...perhaps...but usually will not throw codes. Sounds like you need the help of a pro unless you have $$ to spend on replacing parts that may/maynot be good....remember the problem could be the part with the sensor...or caused by an issue upstream or downstrem of that sensor....
Good luck.

 

PS
If the bypass valve is stuck, then you would only be able to tell the difference at higher rpm's ....at very low rpm's, the sc is vented to atmosphere....the valve closes at a rpm above idle to allow boost...below that, the air from the sc is vented to reduce the load on the motor, improving fuel economy.
it sound like the car might be running in "limp mode".....usually it means something serious is going on, and the computer is running car using ultra safe preprogrammed numbers, and disregarding the sensors, since it has determined they cannot be trusted...

 

when its under full throttle there is less acceleration then if i give the car half throttle. also at low revs there is more acceleration then high...so im guessing the bypass valve is stuck or broken. i also hear a lot of air whooshing under acceleration and revving. as if the boost is escaping. another thing that makes me thing the BPV is malfunctioning. the SES codes were from unplugging the the TB. clearly this is a rain it pours scenario. and the BPV just decided to stop working. im gonna order a detroit tuned bpv. and see from there. car idles fine....and doesnt not miss. its as if the S/C is not giving any boost to the motor. also i notice the exhaust is popping much more then before...not like back fire..but almost gurggleing. this may have something to do with the issue at hand as well.

and btw was joking about the no help. i figured everyone was as stumped as i was. but the reason i worded the issue as such is thats how it all went down. i didnt know if maybe the ECU was not set up..or if there is something u need to do when installing a new battery. some cars are just funny that way. im usually very good and diag. but this was odd...and im not use to diaging a boosted car....this is my first one...and the newest car ive owned ever.

 

if it was in limp mode wouldnt it throw a SES? and yes at low R's feels like it has a lil power...under full throttle...the higher the rpms...the more it seems to fall on its face...

 

Limp mode would have a code....stuck.bypass valve would feel like you decribe I think....
It is possible to zip tie the bypass shut...then you can drive it and see if there is a change...free test...the dt one is liked by some...hated by others ...it is kinda abrubt...if you drive with finesse, you won't like it....if you are agressive then you might like it.

 

Im a pretty aggressive driver. What do u mean by a 'finesse driver'? I had my gf get in the car and rev the car. I see the bypass valve move when the car is started and sits at idol. It appears to open....But doesn't really move at all...and the revs climb slow and it seems like it takes longer then usual for the revs to go back to idol.

 

Not sure I will be much help but I will chime in. The codes you got from unplugging the throttle body are common... well at least in my world if I were to go do the same thing I will have the same codes just saying. Also a bad TPS would put your car into limp mode I know because I had a bad throttle body with a sweet spot where it would just come out of no where. Restarting the car always seemed to fix the issue (SES still on though).

Also what zippy means about finesse with the DT bpv is that while cruising or light acceleration you may experience yo-yo because the stiffer spring the car has a hard time keeping it partially open. I took mine out and sold it I too drive aggressive and loved the hell out it then but when driving to work trying to cruise in traffic took more care with my foot than I was willing to do and could never get away from the yo-yo feel.

Also back to your problem I kind of got lost in the mix of you unplugging the tps then having codes. But you said you had no SES lights after the battery change? Just no power right? If I am not mistaken I think the bpv being bad will throw a code. You should try zippy's idea and zip tie it shut to see if that helps.

 

ok...just got home...had my dad come out and rev the car....the valve moves...but when u rev the car it closes for a second (prolly less) then opens and stays open the rest of the way through revving...which makes sense how its running...when u first accelerate to about 1500-2k R's it starts to make power...then falls on its face quickly. im guessing the valve is broken and isnt staying shut? so upgrade to the DT BPV? lol

 

check the vac lines running to the valve...one may have fallen off...or have been cut.

 

really? that would be quite odd....check in the am...too dark now...would be AMAZING if thats all it was...LOL

 

checked this morning looks fine...i cant see where the line goes after it leaves the valve. there is only 1 lone going to the valve correct? i see one on the ball side of the actual valve. but thats it.

 

Yup...a vac line....in general, more vac, the faster the valve closes....
there is a mod that re-routes the vac to get more vac to the valve...vacgain mod...some like it....but if the line had gotten pinched/cut...you might get odd operation...
Some folks have taken the spring out of the valve...they sometimes break...and inspected it....then dropped in a new spring...as a temporay/permanant solution...depends on how good you are at finding a spring...could save you $60..

 

ok i guess im tearing the car apart....sux! wish me luck...