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#1 2016-12-21 16:00:48

Registered: 2015-09-28
User Number: 33488
Posts: 4

Fuel flooding during cold ambient temp starts

Let me lay out the current situation and then give you the background.

My 2005 2.5i floods out and won't start when it's cold outside, pretty much anything below 40 degrees Fahrenheit. Under warm temps, it starts up and runs absolutely fine. No codes, no issues, no nothing. But if it's cold outside (again, ambient temp, not just the engine being cold), it immediately floods out and won't start.
This all started more than a month ago when, on a Monday morning, the car wouldn't start. It eventually started but was missing on two cylinders, which was also confirmed with trouble codes for same. Parts were purchased, replaced, checked, etc. and this issue evolved to the situation you read above. I'm pulling my hair out trying to get to the bottom of this and so is my buddy who owns a shop and has pulled some of his own hair out over it. Another shop also gave me a misdiagnosis at one point that cost me $600, so that has only added to the frustration on this issue.

Today, we know it has proper spark and air, and it obviously gets fuel, though not always the right amount. It has no trouble codes and nothing electronically appears to be wrong with it. The flooding occurs on all four cylinders, so it seems unlikely that a failing injector would do the trick, but I haven't replaced those yet, so...

Here are all the things that have been checked and/or changed:
-New plugs (NGK), wires
-New coil pack
-New battery
-New fuel pump and pressure regulator (after a misdiagnosis from a local shop hmm )
-New coolant temp sensor
-Checked and cleaned mass airflow sensor
-Checked and cleaned MAP sensor
-Verified cam timing was correct
-manually verified spark

So, I'm open to ideas on this one. Any thoughts are much appreciated.

Last edited by demay0592x (2016-12-21 16:37:53)



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#2 2016-12-21 21:59:37

Potato, Patreason...
From: San Antonio, Texas
Registered: 2011-07-31
User Number: 5779
Posts: 2239

Re: Fuel flooding during cold ambient temp starts

Short term, get a block heater installed or carry out a couple large pots of hot water to pore over the block in the morning.  Long term, don't know.  Only time I had issues starting when cold (besides normal cranking reluctance) was when I got my first e85 tune.  It was an issue with the way the tune was done and was never an issue after it was fixed.

2005 Saab 9-2x Aero:  More than you've had done to your car.
2015 Forester XT Touring



#3 2016-12-22 12:58:33

From: Denver. Past: Detroit & NM
Registered: 2005-06-14
User Number: 215
Posts: 4107

Re: Fuel flooding during cold ambient temp starts

This won't help mechanically, but is a trick I've learned. Keep in mind, I don't have my scenarios fully correlated to cold, and mine is on an Aero motor.

The trick:
Next time you have a hard time starting, try pushing the gas pedal to the floor. Most modern cars have ECU programming that recognizes - counter-intuitively - that on startup, a fully depressed pedal should CUT fuel delivery. So if you are turning the key and the car isn't starting, just turning, jam the pedal to the floor and see if it fires up shortly.

I learned this as I have on 2 known, and 1 additional suspected, occasions flooded the car (I suspect a leaky injector, though it was generally in colder months but has done fine on even colder days so who knows). In those events, everything turned, it just wouldn't actually fire.  The first known occasion I didn't actually do anything - it sat for a while as I charged the battery and it fired up later. The second time it happened, I had it towed to a shop where they let it dry out for 2 days before it eventually fired up (but I had tried numerous times, and the tow truck driver, so it was likely really flooded). Lucky for me, because the shop was starting to suspect some major damage. The suspected time would actually have been my first. However, I thought it was my starter, and after towing it either the starter freed up or the fuel had evaporated. I still had the starter replaced and had no issues for a year or two. It's only in retrospect that the symptoms seem quite similar.

Anyway, subsequently researching flooding issues yielded that little gem above. I've successfully used it once when the symptoms seemed to repeat - cranking without firing.

Good luck!

le sigh



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