Cold idle and acceleration promblems

[flexiblefish98]

Hi there.....please help! 
Just bought myself a '95 Golf Gti 8valve and am having problems with idle from cold and acceleration at low rev range.
When starting from cold car needs to be held at 1500rpm or above until warm or it stalls. Also when approaching junctions etc car stalls at low revs. When accelerating from low revs cars hesitates before finally pulling.
Car smells strongly of petrol from exhaust and is poor on mpg.
Car has had new cat, lambda sensor and vacuum pipes and leads, plugs etc all seem fine. Local garage appear a bit stumped, car doesn't seem to accept the computer diagnostics either (always been very reliable garage, very trustworthy).
Would really appreciate some advice and help so I can get my new pride and joy going properly! Cheers, Stewart

[Christo77]

Hi there..
Well from what you say it could be something in the cold start/Idle system..what's the running like when it's up to temperature?
Other than that it could still be a multitude of things..I'm assuming the distributor cap and rotor have been looked at or replaced..
The ignition coil is known to breakdown..
Onother good one is the ole throttle body, they need a nice clean internal where the butterfly valve is otherwise can cause running problems..plenty of posts on this if you do a search..
That'll give you something to go on with anyway  

I'm sure other good chaps here will give you more pointers too

Christo

[christomk3gti]

+1

Also check your MAF sensor. if this is knackerd it will cause you to run tooo rich hense mpg issues. Unplug it, go for a spin, see if there is any difference. If there isnt then its goosed. If there is, then itl be fine.

[flexiblefish98]

Thanks Christo.

When it's warmed up it will idle but its seems only just. On acceleration from standing when warm car appears bogged down as if flooded by too much fuel. Car cuts out easily at junctions and roundabouts if you dont make sure you keep revs up.
Distrib cap and coil have not been changed, but there appears to be no missing when running.
Do you know what the score is with cold start-simple to fix?

Cheers, Stewart

[flexiblefish98]

Excellent, what does the MAF stand for/do? If car runs better when unplugged will that mean it needs replacing?

[Christo77]

Welcome, You have an idle stabilisation valve mounted around the rear of the cam cover although i've never dealt with one of these so i can't comment on how to check..
I have a feeling yours is a more general running problem.. Another couple of things to think about are the water temp sensor.. and the fuel filter, if the filter hasn't been replaced in some years then you could have restricted fuel supply..It might not make sense seeing your getting plenty of fuel smells but you need to rule out certain things before you start spending..

Christo

[javalin]

>On acceleration from standing when warm car appears bogged down as if flooded by too much fuel
change the coolant temp sensor first - its £30 from VW.  Does the temp gauge work (just an indication as these are dual sensors in a single unit)?  Do you know if the thermostat is opening?

Fuel filters are spec'd for the life of the vehicle - running improves a bit after changing but not huge.  Not the OP's problem in my view.

Rotor cap and arm are a must-change item on these.

I think if you unplug the MAF the engine won't run or will run very badly.

James

[flexiblefish98]

Thanks for all the info Christo

[flexiblefish98]

Hi James,

Temp appears to come up to normal (middle) and stays there whilst idling. Fan kicks in ok.
Whilst driving temp needle does drop though. Will check out suggestions.
Still not certain about MAF sensor though. Could this be causing both the idling when cold and acceleration issues?
Cheers, Stewart

[javalin]

It could do - but most likely cuprit is coolant temp sensor (CTS), Oil temp sensor or ignition (plugs, wires, arm, cap, coil) IMHO

CTS will cause the engine typically to run rich (i.e too much injected fuel).  I bet it's ok when driven hard?

Interesting the fuel smell - lack of good ignition?  But parts changed...

Has the ignition timing and compression been checked?

James