Start-up Bang/'Slow Start'/AGM Battery

[Ecto1]

Hi, I'm new to the forum. I purchased a '15 ecoboost PREMIUM ragtop a few days ago & I'm running down some 'issues'. Hope you all can help.

The first is a start-up 'bang' along with a rocking of the car. The bang only happens once and the car only rocks once. The bang & rocking aren't severe but they are discomforting. I had the car checked over by the local Ford Dealer where I bought it BEFORE I bought it. They claim the car checks out OK. I took it to my local Ford Dealer and he claims that he thinks the car suffers from 'slow start'. He claims it's 'normal' for an ecoboost with a few miles on it (just under 60K). I'm not convinced.

Anyway as I was puzzling over things I'm wondering if an AGM battery is necessary for this car. The guy at the Ford parts counter claims that this car came new with an AGM battery. The previous owner replaced the battery 3 months ago with a non-AGM chemistry battery. From the service records I was able to get from the previous owner it looks like the battery was replaced less than a year before. With the same battery mfg/part # as is in the car now. The battery in the car reads '590 CCAs' which is what the Ford OEM battery spec claims.

The AGMs have a lower internal resistance and should be able to provide current more easily than a normal Lead Acid (SLA) battery. Anyone replaced their battery? Any experience/complaints with non-AGMs in this car? Should I REALLY replace the almost new battery with an AGM? Will it solve the 'slow start/start-up bang/rocking?

Thx.

Sponsored

 

[luc]

Car doesn’t care if you have an agm or sla battery, only that the cca are the correct one
Have your battery load tested
If good the issue is not the battery, if bad, replace it
Your dealer is full of sheet
Having so many batteries replaced In such a short span of time, point to a problem other then the battery
Either a drain on it or a starter problem

 

[Ecto1]

Car doesn’t care if you have an agm or sla battery, only that the cca are the correct one
Have your battery load tested
If good the issue is not the battery, if bad, replace it

Both Ford Dealers tested the battery. They claim it's A-OK.

 

[luc]

Both Ford Dealers tested the battery. They claim it's A-OK.

So you have to look elsewhere
Put a voltmeter on the battery and see how much the voltage drop when cranking the engine

 

[luc]

Also can you explain the rock and bang a little better?
There is no reason. For the car to rock if you are in neutral when you crank it

 

[Ecto1]

So you have to look elsewhere
Put a voltmeter on the battery and see how much the voltage drop when cranking the engine

Not sure I can. The car won't let me start it with the hood or doors open (smartkey/pushbutton start). & Probably the trunk open as well. I can try and use the 'gauge' function in the dash but it's not really suitable for tracing voltage during start-up. The display resets during start-up disabling the gauges so I don't think I can see what's happening as the engine turns over.

 

[Ecto1]

Also can you explain the rock and bang a little better?
There is no reason. For the car to rock if you are in neutral when you crank it

Difficult. The car rocks. (& it's an auto so it's in Park instead of neutral - not that it matters). The driver's side lifts a little and the passenger side drops a little. It's only an inch or so but you can feel it when the car starts. There's also a bang from under the car at the same time. The sound seems like its coming from near the firewall on the driver's side, but that's probably because I'm in the driver's seat when I start the car.
The dealer calls it a 'thump'. Not sure it makes a difference. It's a metallic banging sound that only happens once as the engine starts.
I thought it might be an engine mount or a trans support but I crawled around under the car and tried pulling and pushing on the trans mount and trans. Didn't achieve much. I looked over the engine mounts but I can't see anything so it's hard to say. But when I accelerate full throttle from a standing start or at any speed there's no bang or rattles that indicate anything loose in the drive train so I think the mounts are all OK.
It might be an exhaust pipe making the bang. I tried pushing and pulling on the exhaust while I was under the car checking the trans support but I didn't achieve much here either. The exhaust moves a little, it's designed to, but not that I can explain the bang. If the bang is from the exhaust I suspect its due to the rocking motion of the car when it starts. At least that's the only theory I can come up with so far.

Thx.

 

[PoCoBob]

Keep us posted on what you find out about the bang. I have something similar with my GT. I've been under the car looking for signs of anything hitting but have found nothing. A few months ago someone posted it was one of the quirks of the A10 transmission but I really don't know. To me it sounds like it's coming from the rear and almost like the trunk being closed.

 

[Coyote Chase]

Ecoboost...normal....60K....
I'm surprised they didn't tell you about carbon build-up on the valves and then try to sell you a cleaning!?
Which is something your ecoboost mustang motor may need. But, I've heard many pros and cons about this service.
Hopefully a member who has had this service done can give us all some valuable insight!

 

[PRG3k]

Similar to this?

 

[Ecto1]

Ecoboost...normal....60K....
I'm surprised they didn't tell you about carbon build-up on the valves and then try to sell you a cleaning!?
Which is something your ecoboost mustang motor may need. But, I've heard many pros and cons about this service.
Hopefully a member who has had this service done can give us all some valuable insight!

I just had the injector & TB cleaning service done (at the dealer). I'm told this includes the carbon build-up on the intake valves. Hasn't made any difference to the start-up bang.

I don't know if the service is necessary or not but I've read several tech articles that claim it is necessary. I asked if they used walnut shells to blast the valves (the squirrel nut zipper cleaning service) but they said they'd never heard of it. They use a chemical solvent to clean the valves. I just hope the cleaning prevents problems with stuck valves later on.

 

[Ecto1]

Similar to this?

No. Not even close. If I can figure out how to make a video while starting the car I'll post one. I haven't figured out how yet. I'd also like to make the video with the hood open but the smart key nonsense doesn't seem to permit it. #$^&!

 

[Ecto1]

Keep us posted on what you find out about the bang. I have something similar with my GT. I've been under the car looking for signs of anything hitting but have found nothing. A few months ago someone posted it was one of the quirks of the A10 transmission but I really don't know. To me it sounds like it's coming from the rear and almost like the trunk being closed.

The web shows the 6R80E as the trans in the '15 ecoboost. Something that dawns on me now that you mention the trans is the torque converter or front pump in the trans making this noise. Not sure if it would rock the car but it's certainly possible. Sounds like I need to find a trans tech and have them take a look. (I have a 3rd party warranty - aka service contract - on the car until the end of Nov this year. If the problem is internal to the trans I'll want that diagnosed BEFORE the contract expires).

Thx for the idea.

 

[Cobra Jet]

Check engine mounts. The only way you're going to get "lift" upon a start up event is if 1 or both engine mounts are loose, or deteriorated.

Check the trans mount as well and all the bolts securing the driveshaft to the flanges.


If the problem is not those areas, then as mentioned above the issue may be related to the transmission.

 

[Rapid Red]

FWIW, checking voltage is not a way to find excessive battery loads.

Only the AMP reading will show it, for a starter. Most dime store multi-meters will not be capable.

Series wired

I'll assume the dealer would know if the starter was at fault, loose/noise form the pinion gear & flex plate engagement ?

Even if that were the case rocking does not compute. Does it rock before it fires, or at the same time.

Happens cranking, then turn it over again and it fires up ok_Could be timing related, to much advance, wet cylinder, coming up on the combustion stroke.

Sponsored