Starts And Runs, But Wont Idle!

[Guest mike b]

Hi all,

 

Strange one for me this one. And weirdly this happened after changing the fuel filter under the bonnet, although im pretty sure this hasnt effected anything, surely!

 

After changing the fuel filter, my car chugged a few times, while the fuel filter was filling up and draining through i guess, then fired into life as normal, revved it, then took my foot off and the revs just dropped and then died. Ok, i thought, leave it over night to let the fuel filter through etc. Went to start it last night, and the same thing. Started fine, revved it and it revved, but as the revs dropped to around idle, it died again.

 

One thing to note, is that at constant revs held by me (as it wouldnt idle), eg 3k rpm it sounded like it was popping from the exhaust too?

 

I then took the top pipe off the fuel filter, and it was full of fuel. Checked the spark plugs, 'normal' colour on all 4 according to the haynes. Checked each HT lead sparked using a spare plug when turning over, which it did and now im stuck!

 

It was fine up untill now!

 

Help!

 

Thanks,

Mike

[Guest Mad4tar]

Hi,

 

This is usually caused by a vacuum hose off the inlet manifold.

 

Will

[Guest mike b]

Hi,

 

This is usually caused by a vacuum hose off the inlet manifold.

 

Will

 

Being disconnected you mean?? I suppose one could have been knocked off, but i doubt it. Will have to check.

 

Any thing else to check anyone, as im planning on trying to fix it tonight

[ccgoose 0]

was going to say some sort of an air leak, everything tightened properly etc? I know when i was troubleshooting my misfire on my 205, i missed off the vacuum pipe off the dizzy

[Guest mike b]

was going to say some sort of an air leak, everything tightened properly etc? I know when i was troubleshooting my misfire on my 205, i missed off the vacuum pipe off the dizzy

 

A vacuum pipe on the dizzy?..the orange thing in the engine bay?! I cant remember seeing a pipe on there?

[nick 3]

To me it sounds that the filter was blocked so the idle mixture has been set richer to compensate. Now it has the full flow of fuel through the filter it is running too rich (hence the popping) just reset the idle mixture (hex key on top of the AFM) a bit weaker.

The reason the plugs look ok is that you haven't done enough miles on them to change the colour from when the mixture was ok.

 

Nick

[Guest mike b]

UPDATE:

 

Had a look again last night. Changed the fuel filter back to the old one to rule out any mixture problems and to return it to as it was before and running fine at the time. And the problem still is there.

 

So the symptoms:

Starts fine, no problem there.

Revs fine.

Let go of accelerator and the engine dies and wont settle to an idle.

Popping after revving.

 

Took it for a drive to see if it just needed clearing through etc, (was entertaining braking and keeping foot on revs to stop it dying!) and it didnt change anything. It accelerates fine. But try to go at a constant RPM/speed and it chugs along. There is defanately popping as the revs decend after revving it too.

 

Help me please, im getting very annoyed with it!

 

Thanks,

Mike

Edited October 11, 2007 by mike b

[brianthemagical 1]

afm plug or any wiring around the fuel filter. mixture, getit set at a garage to rule it out.

[Daxed 7]

Definitely rule out an induction air-leak somewhere.

 

Don’t forget the hose tucked away at the bottom of the inlet manifold to the SAD. Mine just let go there and had exactly the same symptoms as yours.

[Rob_the_Sparky 9]

Are you missing the bolt that holds the oil filler on?

 

If yes then this is your air leak...it goes straight through into the manifold and often causes a very hard to find air leak.

[Guest mike b]

Well, youll be pleased (or not!) to know that its now running!

 

I traced every single breather pipe and disconnected and reconnected making sure all werent damaged. I then got to the SAD (i believe!...above the gearbox?) and noticed the 2 parts, eg front (inlet pipe) and back (outlet pipe to inlet manifold and multiplug) were moving from eachother? is this right?! I just fiddled with it and then turned the engine over and its now perfect...infact almost better than before!

 

I now have a slight water leak!...on the exhaust manifold where its bolted on at the bottom ( 4 bolts) one is missing!...not cheared off, so i need to source one bolt to fit!...and it seems i have water seaping here somewhere?? its hard to tell, so im looking for ideas please!

 

Thanks once again for all the help.

 

Mike