Engine problem getting worse! Puzzled...

Our03z4 · 07-30-2017, 09:17 PM

Can't figure out what is going on with my Z4 2.5 manual. The car has been acting like it wants to stall at take off sometimes, this happens when the car is up to temp. That has been going on for a while but now it's actually stalling, did it three times today after a 5 min idle when I went to take off and also stalled twice at start up. When I was going about 60mph it sputtered twice. I use top tier 93 fuel. Also have already done plugs, wires, vanos, coolant system during this and none have made a difference. Could a bad battery be the cause? It's 6 years old so I am getting a new one any ways. Seems to be worse if the a/c and headlights are on so makes me wonder or it could be just a higher load on the engine. Bad oil level sensor? No dash lights on either other than the air bag light.

Thanks for any thoughts!

pokeybritches · 07-31-2017, 01:27 AM

Fuel / air / spark / timing.

If you run through a tank of gas each month, it's probably not bad gas. A stuck injector is unlikely although still a possibility, but you would have misfire codes and a check engine light. Since your issues are at idle, I doubt it's a fuel pump or clogged filter. When did you last change your air filter?

My troubleshooting recommendations, in order:

1. Try pulling the codes. Sometimes pending codes are stored which don't trigger a check engine light.

2. The intake boot has a tendency to crack. If yours hasn't been replaced, I'd consider it, or at least check for vacuum leaks.

3. An O2 sensor or your MAF sensor may be on its way out. Once the car is warmed up, you can unplug the MAF sensor (which will throw a check engine light), but it may help isolate the problem. If the car runs fine with the MAF sensor unplugged, more than likely you either have a bad MAF sensor or a vacuum leak (see #2).

4. The rubber on our cars is getting old and brittle. Consider checking all vacuum lines, including those to the idle control valve.

Steeler · 07-31-2017, 06:42 AM

similar issue here

http://www.zpost.com/forums/showthread.php?t=1400606

Our03z4 · 07-31-2017, 09:31 AM

Thanks so much everyone! Just checked the intake and the smaller off shoot line after the maf is almost in half it's so bad. Also found cracks in most tubes so I'm amazed it even runs at all. Thanks again!

07-30-2017, 09:17 PM	#1
Our03z4 Captain 1682 Rep 684 Posts Drives: 2008 BMW Z4 3.0si Coupe, Join Date: Nov 2016 Location: USA iTrader: (0)	Engine problem getting worse! Puzzled... Can't figure out what is going on with my Z4 2.5 manual. The car has been acting like it wants to stall at take off sometimes, this happens when the car is up to temp. That has been going on for a while but now it's actually stalling, did it three times today after a 5 min idle when I went to take off and also stalled twice at start up. When I was going about 60mph it sputtered twice. I use top tier 93 fuel. Also have already done plugs, wires, vanos, coolant system during this and none have made a difference. Could a bad battery be the cause? It's 6 years old so I am getting a new one any ways. Seems to be worse if the a/c and headlights are on so makes me wonder or it could be just a higher load on the engine. Bad oil level sensor? No dash lights on either other than the air bag light. Thanks for any thoughts!
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07-31-2017, 01:27 AM	#2
pokeybritches Colonel 479 Rep 2,782 Posts Drives: ESS/G-Power Z4M, VF Z4, 996tt Join Date: Sep 2009 Location: Los Angeles iTrader: (12) Garage List 2006 BMW Z4M [10.00] 2006 BMW Z4M [8.50] 2003 BMW Z4 3.0i [9.00]	Fuel / air / spark / timing. If you run through a tank of gas each month, it's probably not bad gas. A stuck injector is unlikely although still a possibility, but you would have misfire codes and a check engine light. Since your issues are at idle, I doubt it's a fuel pump or clogged filter. When did you last change your air filter? My troubleshooting recommendations, in order: 1. Try pulling the codes. Sometimes pending codes are stored which don't trigger a check engine light. 2. The intake boot has a tendency to crack. If yours hasn't been replaced, I'd consider it, or at least check for vacuum leaks. 3. An O2 sensor or your MAF sensor may be on its way out. Once the car is warmed up, you can unplug the MAF sensor (which will throw a check engine light), but it may help isolate the problem. If the car runs fine with the MAF sensor unplugged, more than likely you either have a bad MAF sensor or a vacuum leak (see #2). 4. The rubber on our cars is getting old and brittle. Consider checking all vacuum lines, including those to the idle control valve. __________________ VF Engineering Z4 3.0i, ESS Z4M, G-Power Z4M, 996 Turbo
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07-31-2017, 06:42 AM	#3
Steeler Colonel 2428 Rep 2,702 Posts Drives: Built not Bought 04 Z4 VF Join Date: Feb 2013 Location: Kitchener Ontario Canada iTrader: (2)	similar issue here http://www.zpost.com/forums/showthread.php?t=1400606 __________________ W2A Intercooled Vortech V3Si, custom ducting, Alpha N, 60# Bosch,2.62 pulley, multi port WMI, Severn Tuning(pokeybritches), Tial, magnaflow,SS race muffler, 42 design,3.91LSD, H&R, Hotchkis,ST coils,Konis, Megan camber arms, AKG SS, Nylon mounts, Poly bushings, Carbon interior, CF Aero.APEX
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07-31-2017, 09:31 AM	#4
Our03z4 Captain 1682 Rep 684 Posts Drives: 2008 BMW Z4 3.0si Coupe, Join Date: Nov 2016 Location: USA iTrader: (0)	Thanks so much everyone! Just checked the intake and the smaller off shoot line after the maf is almost in half it's so bad. Also found cracks in most tubes so I'm amazed it even runs at all. Thanks again!
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