2.0 Sport cuts out when off throttle

[fpm]

Hi,
I have a 2001 2.0 Sport, with 108,000 miles. Car has previously run faultlessly, until now...

It normally returns 35mpg, but on the last fill it had only done 29mpg. Driving home from work this evening, with tank nearly empty, I'd say it was
going to return something similar, or maybe slightly worse. Then stopped at junction, and car cut out. Started again, and it drove OK short distance to next junction,
which luckily was the turn into my estate. Again, as soon as I took my foot off the throttle to turn in, it cut out. Started car, and kept it in 1st gear with plenty of
throttle to get to my house. Parked up, it will start and run, but only if I have my foot on the throttle. As soon as I take my foot off, it dies. No engine warning lights,
and it sounds and feels OK when its running, if a little strained - feel like I'm applying too much throttle for the revs I'm getting.

Is there a chance the cat converter is dead? When the fuel economy dropped I was hoping that it wasn't that. but now that the car won't idle at all, I'm wondering if
the Cat is blocked somehow?

Any help gratefully received..pleaase!!

Thanks,
FP

[psbarham]

lambda, or maf, try disconnecting the maf and see if it runs ok.

[gallvr4]

throttle body butterfly full of crap......remove the air inlet pipe and open the butterfly flap,clean in behind the butterfly with a drop of fuel as best you can....

had the same issues and this was my cure

hopefully this will work for you aswell

reguards

[foxdie]

Have you disconnected your battery recently or had a flat battery? Chances are the ECU could have lost its idle adjust settings.

Try this: On a cold engine, disconnect your battery again for 10 minutes, reconnect it and start the car, don't rev it or pull away, turn the aircon on maximum cold setting so the aircon keeps coming on and off. Leave it like this for about 15-20 mins.

As the engine warms up, the chance of stalling gets greater and greater, a freshly reset ECU learns over time how to "catch" falling revs (ie. when you take your foot off the accelerator).

If it stalls and continues to do so, it could either be what Paul has suggested (start with disconnecting the MAF aka airbox like he says) or it could be the idle adjust stepper motor.

[fpm]

Wow...I thought if I was lucky I'd get one reply...thanks for the suggestions guys.

Update...disconnected Throttle position sensor....no difference.
Reconnected TPS and disconnected MAF...no difference.
reconnected MAF, cleaned in behind the butterfly best I could..no difference.

Car is in daily use, no flat or disconnected battery.

On further study, car will run fine with just even the tiniest bit of throttle, even right down to very low revs...but as soon as I take my foot off, it dies.
That's why I suspected the TPS...any thoughts?

[foxdie]

Fair play for getting right in there and cleaning the butterfly valve

I don't think a faulty TPS would cause the car to stall, I still think somethings reset the idle adjust, try turning the aircon on and seeing if it stalls with the aircon pump on with your foot off the accelerator.

If it doesn't stall, try what I said about resetting the ECU, you can probably do it on a warm engine if you start with the aircon on and just repeatedly turn it on / off (I do that sometimes after flashing an ECU to quickly teach it how to catch falling revs).

[psbarham]

or the idle stepper motor has died. or is gummed up, somewhere on here there is a post about cleaning it.

[fpm]

OK...having the aircon pump on or not doesn't make any difference.

Where is the idler stepper motor, what does it do, and anyone have the link to the post about it - I did a search, but can't seem to find it.

Thanks again.

[elnevio]

Not sure where the idle stepper motor is on the 2.0, or even if it has one in the Galant!

Given that it is a four cylinder, the plugs and leads would be very easy to remove and check for condition and wear.

Have you had a look at the air filter?

[fpm]

Will look tomorrow to see if my car has one, but there seems to be stepper motors listed on ebay for the Galant.

Air Filter is clean as a whistle. Didn't pull the plugs, but I think it has to be something sensor-ish, or the idle stepper. Car runs fine, no misfires or anything,
provided I keep even the smallest throttle opening. Soon as I close the throttle, it dies.

[MarkSanne]

Stepper motors are on all Galants and are my first guess. It's probably be located very near (under) the throttle body. Either in brown-ish or black and cilinder-shaped, only 4x2 inch large. It regulates the rpm's at idle running.

[Eurospec]

I would be suspecting the idle control valve, but you can get a little work around to stop it stalling all the time. On the bottom of the throttle body is a little screw- its the throttle stop. Crack the 8mm lock nut and screw the little screw in. This will hold the throttlebody open (essentially like you having your foot on the gas a little bit. It will still stall out when its cold, but when its warm it will at least hold an idle.

Cheers,

Ben.

[Eurospec]

Be careful not to open it up to much or it will be revving like a crazy horse! Do the set up when the engine is warm.

Also check the wiring plug on the icv, the wires sometimes snap.

Cheers,

Ben.

[fpm]

Hi again....just had a few minutes to look at the car this morning. Tried to take the ICV off, but one of the flippin screws rounded out on me, so that'll take a bit longer to get off than I thought.
Instead of that, I tested the voltages coming back from the TPS with the ignition on. I have a 4-pin unit, and here's what I got:
Pin 1: grn/yel: +5v
Pin 2: blk/yel: 0.67v when throttle shut, to 4.84 at full open
Pin 3: yell/red: 0.04V when throttle shut, to 4.50 at full open
Pin 4: blk, ground.

Now I've seen a few different wiring diagrams/user manuals on the net for these, some seem to be 4-pin, and others 3:
One user manual I saw had a 4-pin setup, and it called pin 2 the 'Idle position switch', and pin 3 the 'throttle position sensot output'.
This '4-pin' manual I found said I should have continuity across 1 and 2 when shut, but when I check for continuity across pin 1 and 2, I don't get any - in fact I have no continuity anywhere on the TPS with the throttle shut!

Another user manual I saw had a 3-pin setup, and only had pin 3 as 'sensor output', there was no pin 2. It stated that TPS output voltage at shutoff should 535 to 735mV, which corresponds to what I'm getting on pin 2, not pin 3.

Anyone any idea if these readings look right?

Just have to get the screw out of that ICV now....

[fpm]

OK, this morning I removed the ICV. It was pretty clean, not really any dirt on it, definitely not anything sticky anyway. Still, cleaned it up, and cleaned the housing where it sits into too. (Question - should I be able to take the whole motor apart? The reason I ask is that the whole centre of the motor just drops in and out of the armature, is that normal? I couldn't see anything broken.)
When I turn the ignition to the 'on' position, I can see the little plunger move, and when I switch off it moves again.
Put the ICV back, but only just loosely held with one screw...and the car will idle (just about) with no throttle. I suspect this is bacause at this point its drawing air past the ICV, because if I press the ICV tight up to the housing, as it would be when fully tightened, she cuts out again.

So...the ICV doesn't 'look' stuck/dirty, and it does move, but when I let the car artificially draw some air in past it, it will just about idle. Worth buying another ICV at this point to try?

Thanks in advance for any suggestions!