Vanos Rebuild Start Hesitation

[sapote]

Parasitic draw test didn't seem to clear much up, after waiting the 16 minutes for everything to sleep I was still seeing 50mA, with it occasionally jumping to 90mA. Apparently this should be around 40mA or less to be "normal".

Pulled every fuse individually and none of them made a difference to the draw on the battery. Occasionally it'd drop to 10mA but returns to 50mA or 90mA.

Only thing I managed to achieve was setting my alarm off which was nice.

Battery was testing at 11.7v but cranked and started the car fine other than the slight hesitation before catching.

I start to think the low batt affects the hesitation.

50 to 90ma is higher than normal sleeep current.

[jamesfoley]

Parasitic draw test didn't seem to clear much up, after waiting the 16 minutes for everything to sleep I was still seeing 50mA, with it occasionally jumping to 90mA. Apparently this should be around 40mA or less to be "normal".

Pulled every fuse individually and none of them made a difference to the draw on the battery. Occasionally it'd drop to 10mA but returns to 50mA or 90mA.

Only thing I managed to achieve was setting my alarm off which was nice.

Battery was testing at 11.7v but cranked and started the car fine other than the slight hesitation before catching.

[jamesfoley]

Sat 2 days and down to 12v is kind of low, even at 14C.

Charge the batt overnight set at 5A or higher. Crank next day to see it's better. Drive 5 miles or more, park overnight and measure batt posts next day.

Hmm I see your point, 12v is pretty flat. Though with 14v+ when running it should be charging, right?

I've never had the car not start because it's been too flat, or had any lights on the dash to suggest low voltage, but I'm assuming thats because when its running its seeing the 14v+ it needs.

Other than an issue with the battery itself. would there be any other reasons why the battery isn't accepting a full charge?

I have another multimeter I'll try also just to rule out the multimeter being wrong.

Edit: Just to add to the confusion, battery is at 11.8v this morning after another day of sitting. Obviously have a parasitic draw somewhere...

[sapote]

Sat 2 days and down to 12v is kind of low, even at 14C.

Charge the batt overnight set at 5A or higher. Crank next day to see it's better. Drive 5 miles or more, park overnight and measure batt posts next day.

[jamesfoley]

`12.02v is low for a battery. What was the ambient temperature and when it was last driven and how far?

14.01 and 14.03v shows that the big cables have good connection.

Battery is a 6 month old Bosch S5 which I fitted as part of troubleshooting this issue. The battery it replaced was also a Bosch S5 and there wasn't a change in behaviour when I fitted the new one.

Car was sat for two days before I took those readings, averaging around 14°C ambient at a guess. I can drive the car for 2 hours, turn the car off and then try and start it again and it would still hesitate. But it will also happen first thing in the morning sometimes after being sat overnight. It's completely random.

[sapote]

12.02v across battery terminals.
12.00v from positive jump post to block.

14.01v across battery terminals with engine running.
14.30v from positive jump post to block with engine running.

No accessories running.

`12.02v is low for a battery. What was the ambient temperature and when it was last driven and how far?

14.01 and 14.03v shows that the big cables have good connection.

[jamesfoley]

Yes

12.02v across battery terminals.
12.00v from positive jump post to block.

14.01v across battery terminals with engine running.
14.30v from positive jump post to block with engine running.

No accessories running.

[sapote]

Yes

[jamesfoley]

Maybe the starter is weak due to cable resistance or weak batt.
Do this: first thing in early morning, measure batt voltage with engine off. Then run car at idle, measure voltage at batt posts directly (not on cable clamps), then measure from the fender jump post to engine body and see the difference.

I'm 95% sure the starter is okay, the car has never had an issue cranking, even way back when I had long cranking issues.

Can certainly check voltages though, battery neg to battery pos, and then jump post pos to engine block right? Both with engine off and then engine running?

[sapote]

Intermittent start hesitation is my main issue really. Sometimes it doesn’t just crank and fire, it sort of stumbles into life. 60% of the time it starts normally, and there are a handful of times where it feels like it starts too fast with barely any engine rotation before it fires up.

Maybe the starter is weak due to cable resistance or weak batt.
Do this: first thing in early morning, measure batt voltage with engine off. Then run car at idle, measure voltage at batt posts directly (not on cable clamps), then measure from the fender jump post to engine body and see the difference.

[jamesfoley]

Is your main concern about the status 8, or other problems? Mine also has fuel status 8 ocationally but I think my engine is normal.

Intermittent start hesitation is my main issue really. Sometimes it doesn’t just crank and fire, it sort of stumbles into life. 60% of the time it starts normally, and there are a handful of times where it feels like it starts too fast with barely any engine rotation before it fires up.

[sapote]

I kind of guessed that would be the case, but figured a new TPS wouldn’t hurt even if it was just an experiment.

Just can’t understand what’s going on with this to be honest, the car thinks everything is fine but clearly something isn’t happy…

Is your main concern about the status 8, or other problems? Mine also has fuel status 8 ocationally but I think my engine is normal.

[jamesfoley]

If no codes related to TPS then they are working fine.

I kind of guessed that would be the case, but figured a new TPS wouldn’t hurt even if it was just an experiment.

Just can’t understand what’s going on with this to be honest, the car thinks everything is fine but clearly something isn’t happy…

[sapote]

New sensor gives me 0.53v closed, and 4.07v open on the DIS diag page. BMW technical documents kind of suggest both the throttle and actuator sensors should be opposite, so the throttle TPS when open should match the actuator TPS when closed, but mine don't seem to. I don't know if that suggests the throttle isn't opening as much as the DME thinks it is?
.

If no codes related to TPS then they are working fine.

[jamesfoley]

Replaced the front TPS with a Hella 6PX 008 476-271, part seems identical to the original other than the BMW logo has been removed.

New sensor gives me 0.53v closed, and 4.07v open on the DIS diag page. BMW technical documents kind of suggest both the throttle and actuator sensors should be opposite, so the throttle TPS when open should match the actuator TPS when closed, but mine don't seem to. I don't know if that suggests the throttle isn't opening as much as the DME thinks it is?

I do realise the MSS54 adapts both the closed and open points, so chances are this wouldn't change anything. Either way, new sensor is in and all adaptations cleared in DIS. Throttle position adaptations were still present after an adaptation reset in DIS though, so unsure if its just reset fuel, ignition, and VANOS adaptations, and it leaves the throttle to continue to adapt on the pre and post drive checks.

First drive made no changes to how it reports a fuel system status of 8 when off throttle, but not sure I care about this anymore as it seems to be normal: https://datazap.me/u/jamesfoley/e46-...g=0&data=1-2-3

Will just see what the starting characteristics are like over the next couple of days I guess.