Cold start issues

[Amp34]

We bought a new (used) car a couple of weeks ago and it was running fine up until Sunday. Since then it still runs fine except the startup from cold.

Last week it was fine, starting up within a second or so of turning the ignition. Since Sunday however it takes a couple of seconds for all the cylinders to fire. The first couple still start up almost instantly but then it sounds like it takes a few rotations for the other cylinders to start. After that it runs fine, and restarting the engine straight after all cylinders are firing gets it starting instantly.

One thing I wonder is whether it is fuel related. We let the tank drain almost completely (5l left) and refilled it on Saturday which leads me to wonder if it may be a contaminated fuel issue (or even some kind of gunk from the tank)? Other things I'm wondering is whether it may be a starter motor issue (battery voltage is fine), or even not turning the key long enough, but the latter would be odd as there are two of us driving and it's started happening to both of us at the same time.

The vehicle is a 2010 Ford F150 5.4l V8 - yes I know it's unlikely anyone has any specific knowledge with the engine but I it doesn't seem like it's an issue specific to that engine. And besides, all the F150 forums are full of rednecks and scare me.

 

[Amp34]

It's a fuel injected engine, like pretty much all modern engines as far as I'm aware.

EDIT: But that said it is a similar sort of noise you get when starting a lawn mower from cold, with each cylinder firing until they all fire up properly. Would clogged fuel injectors cause this perhaps, so it's not quite getting enough fuel on startup?

 

[Amp34]

I guess you could test if it was a fuel pressure issue by cycling the ignition from off to run a few times (not start), then cranking it.

Gave that a go but it made no difference unfortunately.

Plugs? HT leads? Coils?

Start by changing the plugs I would.

Sorted my cold start issue where the engine would run lumpily for a few seconds after starting. It is decidedly not a 5.4L V8 though.

Seems it's a bit of a nightmare getting the plugs out of this engine (locations) - they were replaced just over two years and 20,000 miles ago though, but I guess a bad plug is a bad plug...!

I'm going to see if one of the injectors is leaking as that came up on some searches and that seems an easy oil check/smell. Also going to do a quick inspection of the fuel filter to see if it looks new or older - if the latter I'll replace (can't remember if it was replace just before we bought).

I'll look a little more into the plugs to see if I can do them myself, if not I'll probably have to get a mechanic to check it over.

Thanks for the suggestions.

As you can probably tell I'm not particularly car literate - this is my "first" car so never needed to do any work on any others, just hand them back and let someone else deal with any issues.

 

[Amp34]

Battery is a good brand and less than a year old - current voltage is around 13.5v (previous owner installed a voltage readout in the cab...)

Also by cold I mean the engine hasn't been run, it's currently fairly warm here, +15 - I assume battery performance would be more an issue below freezing rather than spring/summer weather?

Air filter was changed two weeks ago as well. I presume there is nothing else I can really look at regarding that easily?

Couldn't see the fuel filter yesterday so I'm going to move the car into the garage so I have a flatter floor to lay on. Need to get a decent jack and stands at some point!* I'll probably just get a replacement as that appears an easy fix and it's cheap anyway.

I'm sure I'll end up taking it to a mechanic but it's nice to have a bit of an idea before hand and go through the motions for the easy stuff - need to start somewhere.

Im also going to try and replace the front wiper motor on our other car today (VW), which seems to have decided to go pop! Hopefully that should be fairly easy, as long as I can get the plastic between the wind screen and bonnet off without breaking it...

*currently just laying under the car, not jacking it up!

 

[Amp34]

Battery is at around 12.34v, using a digital multimeter. That does sound like it may be a bit low then? It shoots up to around 14v when the engine is started so i assume that means the alternator is fine.

I guess it may be worth taking it somewhere and getting a proper test done on it?

 

[Amp34]

It's a pickup truck V8, I assumed it would be a detroit leftover from the sixties.

The engines aren't that old. They do update them every now and then as they are bought as family cars.

That said from 2011 they did have a whole new engine range, with a 3.5 V6 and 5L V8 replacing this engine, which was initially designed a while ago - one of the old "how do you get so little horsepower out of such a big engine jobs" - although 310HP is not too much to slouch about, better acceleration than the VW jetta we also have.

will this have coil packs? ( not familiar with the engine ) if so it could be a bad coil pack causing an issue. do you have access to an OBD reader?

I believe it does, and no I don't have access to an OBD reader unfortunately

 

[Amp34]

So after this thread I went looking at OBD readers. Ended up picking up a wireless one up for e£15 off amazon. Nifty little thing. I may see if I can connect it to the in car screen as well so I can get real time readings for things like fuel consumption.

Anyway, it came up with an error code of "P0150" which on this car is a malfunctioning oxygen sensor circuit, which can also cause rough starting. It's something the guy that sold it to us actually mentioned. Apparently the garage looked at it and couldn't find anything wrong so just reset the engine warning light (which finally came on yesterday).

At least I now know where the problem lies - from what I gather it'll just mean the engine may run a bit rich/lean on startup, so not the end of the world? Now to do some research and see if there is anything else I can do, otherwise I'll probably send it into the garage at some point to see if they can sort anything.

 

[Amp34]

Interesting. I think the coolant sensor is also on the same circuit. I know from aforementioned previous conversation with the owner that the issue was intermittent, and it appears to have gone again, which I guess is why the mechanic couldn't sort it. It could well be a related to a dodgy connection somewhere. I'll be keeping an eye on it and next time I get to the garage will get them to check it out. It starts up fine again now...

 

[Amp34]

So just started the truck up this afternoon and the got the same rough start. The first time since I started the thread in May (and ~5,000 miles).

Interestingly it's the same scenario as last time, not much fuel left in the tank and then fill up to the brim, then the next cold start (filled up yesterday) it starts rough. That said looking at past refill history the fuel left wasn't significantly lower than a few other times I've refuelled.

To me that does seem to imply it's some form of fuel issue. I'm wondering if perhaps there's some gunk in the tank, or if the fuel filter may need changing?

EDIT: Searching online it looks like it could be a dodgy Canister Purge Valve, which is supposed to equalise the pressure in the fuel tank. It appears to also be connected in some way to the O2 sensor system, so those errors can come up. Anyone else has this issue with a vehicle? I'm assuming on mine it's more an intermittent issue, as it appears to work most of the time, but occasionally get dodgy, like now.