Vanos Rebuild Start Hesitation

[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]

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...

[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.

[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.

[Shonky]

Yeah spec is <40mA. Typical is more like 20mA. I'd definitely be looking into that.

You are stalking about a start hesitation. During crank and for a small time initially it's essentially all battery though which is your problem isn't it? What happened with starting after leaving battery on charge over night i.e. fully charged and ready to go?

There are very few things that are unfused at least at some level. You really pulled every single fuse? The only things not going through a fuse is starter and alternator.

Note, you can measure voltage across the fuse to look where curernt is going. Down at that 50-100mA level it's quite small voltages but measurable and sometimes more helpful than pulling fuses since that can wake up a lot of things.

[jamesfoley]

You are stalking about a start hesitation. During crank and for a small time initially it's essentially all battery though which is your problem isn't it?

Kind of, the car has a healthy first and partially second rotation, then as it catches it sort of stumbles into life. Doesn’t do it every time.

Battery obviously has enough cranking amps to turn the car over fine, but wondering if the low voltage as the engine starts is upsetting something.

You really pulled every single fuse?

Yea. Initially I was going through some common known systems like the radio, air conditioning, and central locking, but after seeing none of those made a difference I just pulled each fuse one by one and checked the current draw each time.

No idea how I managed to set the alarm off doing that though.

I’ll check the voltages at each fuse today to see if I can spot anything.

[jamesfoley]

The battery voltage is still low, but I'm not sure its the cause as it did still start on 11.7v without any hesitation at all this morning on a stone cold engine. A 20 minute drive bought the battery up to 12.7v and coming back to the car 10 or so minutes later it had come down to 12.2v which I'm assuming is it loosing some form of surface charge, but it hesitated to start this time.

11.7v engine off, 8.6v cranking, between 13.9v and 14.1v idle and driving, cold engine, perfect start
12.2v engine off, 9.2v cranking, warm engine, hesitated to start.

Pattern does look like its warm engine related, but sometimes its the other way around, hesitates when cold and perfect when warm.

Unsure if voltage fluctuations are causing something to be upset, like an injector or a coil, but would have thought they'd be classed as misfires and would increase the misfire counter, which it doesn't.

I had kind of thought that my OBDLink MX+ dongle that I leave plugged in all the time would be causing the battery drain, but it is supposed to go to sleep after a short period of no connectivity. Also kind of confused why I didn't see a drop in draw when pulling fuses when I should have pulled the fused for the OBD port somewhere along the line.

[sapote]

“I had kind of thought that my OBDLink MX+ dongle that I leave plugged in all the time would be causing the battery drain, but it is supposed to go to sleep after a short period of no connectivity. Also kind of confused why I didn't see a drop in draw when pulling fuses when I should have pulled the fused for the OBD port somewhere along the line.”
Remove the dongle and see if drainage lower.

[jamesfoley]

Not a very interesting update, but swapped out my 6 month old Bosch S5 008 with an Exide EK950, hoping that an AGM battery might last longer with the short trips it does. Bigger battery is a tight squeeze but it does fit without any issues. Back in the phase where it seems to start without any issues, the starter turns noticeably faster now though.

Whats also interesting is my wing mirrors which used to fold at the speed of a asthmatic snail and get stuck, now fold normally...

[sapote]

Very interesting as I was thinking about a weak battery was to blame for the hesitation

[jamesfoley]

Very interesting as I was thinking about a weak battery was to blame for the hesitation

I get the feeling its not going to be the magical fix I'm hoping for, but it would be nice if it was.

Assuming it could still potentially be power related, is there a chance that although I see 14v+ from the alternator, its amp output is low? Or my starter is becoming lazy?

Will of course keep an eye on the battery voltage though as parasitic drain could still be an issue.

[sapote]

Assuming it could still potentially be power related, is there a chance that although I see 14v+ from the alternator, its amp output is low? Or my starter is becoming lazy?

Will of course keep an eye on the battery voltage though as parasitic drain could still be an issue.

If you measured 14v+ at the batt posts, then it is a proof that the alternator is doing fine; if it somehow has less amp output then the measured volt at batt should be lower due to batt internal loading.

As about your starter became lazy weak, since both old and new batteries have about the same voltage of 12.6v before cranking, then faster running starter is solely due to batt cranking amperage.

[jamesfoley]

Well, it was great while it lasted. Solid week of it running fine, only for it to hesitate again today. 12.7v from the battery with the engine off, so I guess that wasn't the problem.

One way to describe it would be that it feels like the starter motor stops before the engine starts correctly, but the engine catches it self and manages to splutter into life.

[sapote]

Well, it was great while it lasted. Solid week of it running fine, only for it to hesitate again today. 12.7v from the battery with the engine off, so I guess that wasn't the problem.

One way to describe it would be that it feels like the starter motor stops before the engine starts correctly, but the engine catches it self and manages to splutter into life.

This is the new batt?
I would also remove and clean up the cable terminals under the jumper post big nut, the gnd short cable from engine to frame, and the batt cable terminals, just to be sure. And at the starter big cable terminal too.

[jamesfoley]

This is the new batt?
I would also remove and clean up the cable terminals under the jumper post big nut, the gnd short cable from engine to frame, and the batt cable terminals, just to be sure. And at the starter big cable terminal too.

Yea, it still has the new Exide EK950 I fitted a week ago, voltages all look good.

Will check the grounds, getting to the starter to just check the cables is a bit of a pain. Really need to figure out how to reliably reproduce the issue, I have no idea why its completely random and its annoying the shit out of me now.