Did you or someone you know mess with the screws on the TB? Some people think that's an idle screw- but it's not. Just wondering since you made the Scangauge comment.

Yes we've had it before and it was a TPS. You should double check and perform all regular routine maintenance that might've been overlooked before replacing the TPS. It's difficult to completely test a TPS because all you can really test is WOT and CT position resistances. I'd think the PCM would give you a code if the CT resistance was off. You can test this theory by unplugging the TPS after starting it.

Routine maintenance to check/perform.
1) Plugs: pull and check gap at least, check deposits, clean, put back in.
2) Plug wires: Replace if lifetime warranty wires, if not check by spraying wires with household cleaner, and watching at night with engine idling
3) PCV valve: often overlooked, and it's vacuum line is the cause of many low idle/stumbling issues. You should look closely at the rubber elbows, folding them to expose cracks.
4) Fuel filter: should be changed every 25k miles.
5) Air filter: check
6) MAF clean: you're already on that.

At least pull and check the plugs. Yes I know that's not your whole problem, but any one of these could be a contributing factor- the straw that broke the camel's back.

 

Nope- I haven't messed with the screws on the TB and no one else has to the best of my knowledge. I know better than to dick with the screws on the throttle body! [8D]

I'll see about checking the resistance on the TPS and see if my scan tool has the ability to read the TPS signal.
-Any idea what the closed throttle resistance is supposed to be on the TPS?

When I've diagnosed a bad TPS before on another vehicle, I would watch the scan tool readout while S-L-O-W-L-Y pushing the pedal down with the key in the ON position (engine not running). You could tell it was bad because all of a sudden the TPS signal went crazy in one spot and as soon you moved the pedal up or down it came back to normal.

Might as well check everything else too- pretty standard stuff.

Thanks for the input!

 

It's been a while but I just wanted to let everyone know what the problem ended up being since it was somewhat obscure.

Turns out the intermittent dying out right after start was a symptom of a VERY intermittent battery. The battery had one cell which would short itself, but only sometimes. The other cells were very strong. There was quite an unusual voltage pattern through the start/running sequence but the dead giveaway was when the voltage across the terminals fell to 10.5 Volts at rest while I happened to be watching it. When the cell would short, it would drop to about 6.5V while cranking.

As it turns out, the alternator charging only engages a couple seconds after the engine is running so during that couple of seconds, the voltage to the electronics is too low to properly run everything since the starting current would cause the cell to short itself. When the engine did stay running, the idle would drop considerably because of the big load on the alternator as it engaged. After charging was engaged for about 5 seconds, the cell would un-short itself and the battery voltage looked normal.

Anyway, hope this helps someone out.

 

cool thanks!

cool thanks!

 

Hi, thanks for this, old post I know,

but I seem to be having the same problems, Am I right in thinking changing the battery would solve this?

 

Testing the battery is the first thing. Not sure what an '09 Mondeo is, but see if your local parts place will test it free, or at least low cost. Failing that, any garage can load-test it and shouldn't charge too much.

Batteries are too expensive to replace without knowing for sure that's at least part of the problem, unless yours has known problems (boiled, drained multiple times, over 7 years old, etc.).

 

I've been having similar problems for around a year.

Battery diedone weekend,failed to start. Got excited thinking this might have been the culprit all along. Replaced battery and still exactly the same -_-

Car starts (sometimes cranks for a few seconds) and fires up then dies/stalls immediately.

Turn the key straight back on and it starts up and runs fine.

Spark plugs are fairly new irridium, air filter replaced recently.

 

A dirty aircrack at the TB butterfly can do it, clogged enough the engine doesn't stay running for the second it takes to establish a hard pulling vacuum past the deposits to get air flowing. Clean the TB and mainly at the butterfly edges and the bore right where they come closest.

 

Yeah it was dirty and thought that was another culprit so cleaned it up really nice...same deal

 

Clogged PCV can do the same, it subtracts idle air that then has to be pulled harder elsewhere. It's about providing the idle air for a fractional second while the IAC moves to where needed.

 

Thanks!! I'll pull it out this arvo and have a look

 

Dangit. I did it a while ago and posted the reply but it didnt go up. I was wondering why no one replied to me haha XD

I couldn't see anything obvious, looked like a hollow tube. Twisted the connection back on and then 4 days later got the check engine light.

I have an OBD2 scanner on the way. Really hoping that will reveal something!

Where is the air flow metre located on these cars? I've seen videos of similar models that have them located between the airbox and throttle body, but mine has nothing there...

 

A pic or engine type needed, we have no engine like that listed here. Airflow meter = MAF (mass air flow) here.

 

It's a 2009 CL LV Focus. Duratec engine I believe.

I just read that it doesn't actually have a maf (can't insert link, post count too low)

I unscrewed what I thought it was the other day, but it was the TPS.

Couldn't see any other electrical connector on the air intake

 

Ok YouTube had a good vid. I'm gonna go do that now and report back.

 

Wow that was the hardest screw I've had to undo!!

Took out the map and sprayed off some oil and a bit of dirt, didn't make a shred of difference -_-

 

Code that came up last week (after almost a year of the same issue)was p0171 - fuel lean.

 

Vacuum leak.................

 

I've had a look at all the lines I could see. Any culprits that usually hard to notice?

I cleared the fault and it hasn't come back yet (problem still persists though)

 

Any fixes? A friend who is a mechanic has done the works on my car and still no fix for me. Ford focus 2014 Sport TDCI Diesel

 

I have a 2012 Ford focus that has trouble starting and then dies immediately I can't seem to figure out what the problem issue anyone solve their issue that can help?