Faulty injector or something else

ChrisSuich · **Posted:** Mon Aug 31, 2009 5:51 pm

My MINI, after 97000 miles, has decided to become hard to start after it sits overnight or all day at work.

Some symptoms I have noticed (I added commentary on the list items too make sure my observations aren't tainted.)

Today was 1st time after sitting at work in recent weeks is was an overnight thing

more frequently than the past

exhaust vibrates more than usual. Urethane engine mounts amplify this

not

did I forget to clean them

My first thoughts are a bad injector.
How could I determine which one maybe going bad?
I do have access to an AutoEnginuity for any debug work

I'm looking for any ideas on what else could cause these symptoms?
I don't want to assume my first thoughts are the problem before I go spend big bucks buying injectors.

Ash Nelson · **Posted:** Mon Aug 31, 2009 5:54 pm

Perhaps the injectors are dirty? Perhaps you got ahold of some dirty gas and it is causing issues, maybe even dirtied up the fuel filter enough to restrict flow?

ChrisSuich · **Posted:** Mon Aug 31, 2009 6:01 pm

I thought about a fuel pump problem.
There is no WOT performance loss the butt dyno.

The overnight hard start has been going on for more than one tank.
I have had bad gas in a car once. Couldn't make it up a long hill. It doesn't feel like that.
If it were a dirty filter, wouldn't it be worse above idle as well?

Kevin Harvey · **Posted:** Mon Aug 31, 2009 6:18 pm

Hmmm, interesting. I am assuming the Mini's have some sort of open loop for cold starts. I may be mixing terms, but what I am thinking is that the computer does not pay attention to any sensors until the car is of xxx temperature. Since it is a cold start issue, to me, that rules out any sensors, but I could be wrong.

How is your fuel pressure in the rails on a cold startup? Is your fuel system holding pressure over night or leaking down? If you let the fuel pump run for 5-10 seconds, does that help with the cold start?

Of course, that doesn't help explain the rough idle. You may have a faulty injector that is stuck open or something...... I would think that could affect cold start and idle quality, but not sure.

Just throwing out some ideas.

ChrisSuich · **Posted:** Mon Aug 31, 2009 6:58 pm

Kevin Harvey wrote:

How is your fuel pressure in the rails on a cold startup? Is your fuel system holding pressure over night or leaking down? If you let the fuel pump run for 5-10 seconds, does that help with the cold start?
.

I'll have to try that tomorrow morning.
I had thoughts that a leaky injector would flood the cylinder and that would make it hard starting. I assumed the pump would pressurize very quickly.

Chris Halweg · **Posted:** Mon Aug 31, 2009 7:39 pm

Is your temp gauge working properly? When the coolant temp sensor fails on Volvos, it's hard to start cold and can have rough idle. Sometimes the engine surges as well, but WOT is normal.

Steven Carter · **Posted:** Mon Aug 31, 2009 7:56 pm

just did some searchng...not a Mini owner, so I apologize if this is of little help.

http://www.motoringfile.com/2008/07/07/ ... ix-coming/
http://www.motoringfile.com/2008/02/20/ ... #more-6447

Is this issue similar to yours?

Ash Nelson · **Posted:** Mon Aug 31, 2009 8:11 pm

I know vaccum leaks can cause a lot of weird issues, but I'm not familiar with MInis to know if any of the fuel/enviromantal stull is vaccum operated or not.

BriceJohnson · **Joined:** Thu Apr 13, 2006 7:33 am **Posts:** 2230

Steven Carter wrote:

just did some searchng...not a Mini owner, so I apologize if this is of little help.

http://www.motoringfile.com/2008/07/07/ ... ix-coming/
http://www.motoringfile.com/2008/02/20/ ... #more-6447

Is this issue similar to yours?

nah, he's an R53. The R56 is the new turbo.

ChrisSuich · **Posted:** Mon Aug 31, 2009 9:52 pm

I've experienced the "Cold start" problem. The engine starts fine but then stumbles 30 seconds later. A quick restart of the engine and all is well.

As for the other cold engine noise, I never thought of describing the engine sound as a diesel, but that actually is pretty descriptive. I have it , but never too bad.

ChrisSuich · **Posted:** Tue Sep 01, 2009 8:44 am

So this morning I turned the ignition to on for a 10 seconds, then off, then back on again for 10 seconds before trying to start the engine. I definately heard the fuel pump running for those two times.

1st attempt at start failed. It was a definite struggle to start running.
On the 2nd attempt immediately after 1st, the engine cranked right up with no stumble 30 seconds later like I might normally have on a 65 degree morning.

Michael Westerfield · **Posted:** Tue Sep 01, 2009 8:50 am

Could it be something like a IACV or some sort of cold start valve?

MarcusMcRae · **Posted:** Tue Sep 01, 2009 9:31 am

ChrisSuich wrote:

If it were a dirty filter, wouldn't it be worse above idle as well?

If you have not replaced the filter in 30-50k miles start there.

You could also try pulling the plugs to check them and cleaning the MAF.

BriceJohnson · **Joined:** Thu Apr 13, 2006 7:33 am **Posts:** 2230

my wife's mini when its cooler will start up, have a brief "stumble" as you describe it, and then settle into a fine idle, but nothing that ever sounds like its not going to start.

ChrisSuich · **Posted:** Tue Sep 01, 2009 11:06 am

MarcusMcRae wrote:

ChrisSuich wrote:

If it were a dirty filter, wouldn't it be worse above idle as well?

If you have not replaced the filter in 30-50k miles start there.

You could also try pulling the plugs to check them and cleaning the MAF.

I replaced the plugs a few thousand miles ago. This is second set of replacement plugs. I replace the originals around 40-50K.

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Faulty injector or something else

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