Acceleration problem...

jojodivo · 08-04-2011, 07:57 PM

Sometimes can be jerky between 2.5k to 3k rpm but not always, seems to pull ok between 3k-4k rpm but as soon as it gets a little above 4k rpm there is a pronounced jerk (dip in rpm) and instead of the engine pulling hard to redline it seems to just sputter along (reduced torque). Crazy thing is car is showing no codes

what is going on here? Anyone have anything like this happen to them?? Car is an 03 Z4 3.0i with an AA tune.

inTgr8r · 08-04-2011, 08:11 PM

did it happen right after the tune?

krnnerdboy · 08-04-2011, 08:24 PM

most likely bad gas and the dme is pulling timing...if you want to quick check it then I recommend
NOS octane booster race formula, the one that raises 60 points<--and no I'm not kidding...the n54/55 guys have been using it to substitute race gas for their tunes...most pepboys have it

wonton180 · 08-04-2011, 09:52 PM

could be spark plugs. how many miles on it since last changed?

azadian2b · 08-04-2011, 10:11 PM

Quote:

Originally Posted by krnnerdboy

most likely bad gas and the dme is pulling timing...if you want to quick check it then I recommend
NOS octane booster race formula, the one that raises 60 points<--and no I'm not kidding...the n54/55 guys have been using it to substitute race gas for their tunes...most pepboys have it

Just FYI, if it says 60 it's stating it with 0.1RON being the unit of measure. Article I briefly read said it was effective to raise Octane rating by 1.8 RON, which might help turn bad gas to reasonable gas, but doesn't even come close to race gas octane levels if you're starting with pump gas.

http://members.rennlist.com/951_race...omparison.html

jojodivo · 08-05-2011, 08:25 AM

@inTgr8r, it didnt happen right after the tune - right after the tune car ran GREAT! (was done in january, better than stock)

@wonton180, it has been about 40k since spark plugs were changed, could it be time for some new ones?

Not sure it could be the gas as the problem has persisted over a coupe tanks from different Shell stations. Thanks for the inputs guys!!!

sho-one · 08-05-2011, 10:11 AM

do you have an AFE intake, mine did the same thing after I installed the intake. I reset the battery and it went away but after a couple hundred miles came back.

ZStig · 08-05-2011, 10:12 AM

could also be a throttle position sensor, but you'd have a check engine light and limp mode.

wonton180 · 08-05-2011, 10:28 AM

I'm not sure how a aftermarket tune (ECU software we are talking about here?) would potentially affect spark plug life. If it's dumping more fuel in, I suppose it could accelerate wear.

the OEM plugs typically last 50-60K. The reason I said spark plugs is that they generally present as a studder during acceleration around the 2-3K RPM range. it's a cheap fix.

jojodivo · 08-05-2011, 11:11 AM

@sho-one, I have a K&N air filter but a stock intake.

@Roffle Waffle, I was thinking it could be a TPS too until it showed no codes and then I was kinda dumfounded as to what could be causing this and why there were no codes.

I was also thinking it could be the vanos related but I had the seals fixed about 40k miles ago so it shouldn't be that. If anyone else has any ideas please feel free to chime in. Hoping to try and fix this without having to take the car in.

txz4 · 08-05-2011, 11:54 AM

sounds like pulling timing to me as well.

08-04-2011, 07:57 PM	#1
jojodivo Private 3 Rep 67 Posts Drives: 2003 Z4 3.0i Join Date: Mar 2009 Location: Chapel Hill NC iTrader: (0)	Acceleration problem... Sometimes can be jerky between 2.5k to 3k rpm but not always, seems to pull ok between 3k-4k rpm but as soon as it gets a little above 4k rpm there is a pronounced jerk (dip in rpm) and instead of the engine pulling hard to redline it seems to just sputter along (reduced torque). Crazy thing is car is showing no codes what is going on here? Anyone have anything like this happen to them?? Car is an 03 Z4 3.0i with an AA tune.
	Appreciate 0 Tweet Quote

08-04-2011, 08:11 PM	#2
inTgr8r Lieutenant General 2432 Rep 11,667 Posts Drives: M2 Comp Join Date: Mar 2006 Location: Toronto iTrader: (10)	did it happen right after the tune? __________________ '21 M2C Hockenheim Silver '18 718 Cayman S Lava Orange (sold) '13 E92 M3 Santorini Blue (sold) '07 Z4 M Coupe Alpine White (sold)
	Appreciate 0 Quote

08-04-2011, 08:24 PM	#3
krnnerdboy Colonel 190 Rep 2,431 Posts Drives: v10 m6 Join Date: Nov 2008 Location: so cal iTrader: (10)	most likely bad gas and the dme is pulling timing...if you want to quick check it then I recommend NOS octane booster race formula, the one that raises 60 points<--and no I'm not kidding...the n54/55 guys have been using it to substitute race gas for their tunes...most pepboys have it __________________ F80 m3, 997 gt3, 14 ram ctd, f15 x5, drz400sm Gone:z4m, boss 302, c6 z06, m6,z3m
	Appreciate 0 Quote

08-04-2011, 09:52 PM	#4
wonton180 Private First Class 3 Rep 106 Posts Drives: 07 Z4MC Join Date: Mar 2011 Location: Philadelphia iTrader: (0)	could be spark plugs. how many miles on it since last changed?
	Appreciate 0 Quote

08-05-2011, 08:25 AM	#6
jojodivo Private 3 Rep 67 Posts Drives: 2003 Z4 3.0i Join Date: Mar 2009 Location: Chapel Hill NC iTrader: (0)	@inTgr8r, it didnt happen right after the tune - right after the tune car ran GREAT! (was done in january, better than stock) @wonton180, it has been about 40k since spark plugs were changed, could it be time for some new ones? Not sure it could be the gas as the problem has persisted over a coupe tanks from different Shell stations. Thanks for the inputs guys!!!
	Appreciate 0 Quote

08-05-2011, 10:11 AM	#7
sho-one MMA fighter and F1 test driver 18 Rep 362 Posts Drives: Z4///M coupe bulletproof Join Date: Jun 2009 Location: omaha ne iTrader: (4)	do you have an AFE intake, mine did the same thing after I installed the intake. I reset the battery and it went away but after a couple hundred miles came back. __________________ NOW:08 M.Coupe SMB #102/248 #1669/1815 :\|MORRVS8\|APEX8\|SS.X-pipe\|SS.PW.Loop\|AFE.intake\|Matte.grill\|short.ant\|Z HP.knob\|interior.LED\|bulletproof 09 Audi Q5 THEN:96Accord\|98Camry\|04TSX SC\|06 M3\|06A4\|05Civic Si\|05Imprezza\|05S2000\|08FJ
	Appreciate 0 Quote

08-05-2011, 10:12 AM	#8
ZStig instagram 997turbotom 279 Rep 7,377 Posts Drives: Interlagos Z4MR Join Date: Jun 2008 Location: Delray Beach, FL iTrader: (4)	could also be a throttle position sensor, but you'd have a check engine light and limp mode. __________________
	Appreciate 0 Quote

08-05-2011, 10:28 AM	#9
wonton180 Private First Class 3 Rep 106 Posts Drives: 07 Z4MC Join Date: Mar 2011 Location: Philadelphia iTrader: (0)	I'm not sure how a aftermarket tune (ECU software we are talking about here?) would potentially affect spark plug life. If it's dumping more fuel in, I suppose it could accelerate wear. the OEM plugs typically last 50-60K. The reason I said spark plugs is that they generally present as a studder during acceleration around the 2-3K RPM range. it's a cheap fix.
	Appreciate 0 Quote

08-05-2011, 11:11 AM	#10
jojodivo Private 3 Rep 67 Posts Drives: 2003 Z4 3.0i Join Date: Mar 2009 Location: Chapel Hill NC iTrader: (0)	@sho-one, I have a K&N air filter but a stock intake. @Roffle Waffle, I was thinking it could be a TPS too until it showed no codes and then I was kinda dumfounded as to what could be causing this and why there were no codes. I was also thinking it could be the vanos related but I had the seals fixed about 40k miles ago so it shouldn't be that. If anyone else has any ideas please feel free to chime in. Hoping to try and fix this without having to take the car in.
	Appreciate 0 Quote

08-05-2011, 11:54 AM	#11
txz4 Major 59 Rep 1,097 Posts Drives: 2006 M coupe Join Date: Oct 2010 Location: san antonio, texas iTrader: (3)	sounds like pulling timing to me as well.
	Appreciate 0 Quote