16v 9a flatspots at low revs

[corradoloon 10]

Hi , i am having bother with my 93 2l 16v 9a.When pulling away it has terrible flat spot,just dies on you.Up the revs it is fine and flies. Very embarasing at it kangarroos away from the lights though. Had it in vw and was told metering head at fault, but at roughly £1000 exchange that not feasable. Got 2nd hand one but that was worse. Back on original but any ideas ,thoughts welcome.Timing ok. Ignition ok.:scratch:

[Jim 2]

Do you find you only really suffer this in 1st gear? I get something similar with mine and have never been able to get to the bottom of it... pulling away from traffic lights or at a junction, the car just feels like it's running about 50HP! Even if you put your foot down it just feels gutless. Had all sorts of stuff changed on mine, had timing checked etc.. never been able to improve it!

[Taufin 0]

Hi,

 

I had a similar problem in a 1990 1.8 16V, turns out the filter/airbox assembly was not secure, when I securedit the problem went away.

 

Good Luck with it.

[davidwort 0]

Hi , i am having bother with my 93 2l 16v 9a.When pulling away it has terrible flat spot,just dies on you.Up the revs it is fine and flies. Very embarasing at it kangarroos away from the lights though. Had it in vw and was told metering head at fault, but at roughly £1000 exchange that not feasable. Got 2nd hand one but that was worse. Back on original but any ideas ,thoughts welcome.Timing ok. Ignition ok.:scratch:

 

What do the plugs look like? this is always a good indicator of engine health and correct fuelling.

Get the lambda value checked by an MOT station, how old is the sensor and is it genuine VAG?

Check the injector o-rings, inlet manifold gaskets, rubber inlet sections and all the vacuum tubes and connectors.

The base timing may be correct, but does it advance correctly as you increase the revs?

Might be worth getting the throttle sensor checked too if it has a throttle position sensor, can't remember on the 9A.

[easypops 8]

Might be worth getting the throttle sensor checked too if it has a throttle position sensor, can't remember on the 9A.

 

It does, clipped onto the throttle body, called a throttle potentiometer when i bought one, bad wiring on this caused my bad idle/poor running for ages until i found 2 of the 3 wires had burst at the plug, the plastic covering was ok though, the wires had burst inside

[corradoloon 10]

Cheers for ideas,i'll check out plugs and all connections tomorrow. Was on gas analyzer at vw, found lean and adjusted. Never cured it though. They also found crank one tooth out on timing. that sorted but still same. Must be something simple/stupid.How easy 1.8 turbo transplant???

[corradoloon 10]

I have disconected electric plug on cold start valve/fifth injector and it has improved it tenfold, no more flatspots.Drivable once more in heavy traffic.Coincidence?????????.

[sexybourbon 0]

If any one else is giving this a go i might as well try it lol i have these flat spots tho not as terrible as yours sounded ! Mines only in first really in a morn sometimes second asweal but only on cold starts if i put my foot down a tad

[stereoflaver 0]

I have the same problem, flat spots at low revs when cold.

[boost monkey 0]

sounds like perhaps the CSI is dead then if unplugging it has helped that much. Or the loom controlling it has a break somewhere.

[sexybourbon 0]

Well if it is yhe cold start valve i wont be buying another i rang for a price about a week ago and a new csi is 105 quid wich is a tad expensive

Thinking about it now does anyone think this could be the reason behind exessive fuel consumption ?? i e the cold start injector being knackerd !!

[Kempy 0]

It does, clipped onto the throttle body, called a throttle potentiometer when i bought one, bad wiring on this caused my bad idle/poor running for ages until i found 2 of the 3 wires had burst at the plug, the plastic covering was ok though, the wires had burst inside

 

This is a issue with mine after plugging it into Vagcom, I can work out exactly which the potentiometer is? etka isnt very clear

[will 2 0]

mine is doing this also, what is a csi :/

[easypops 8]

This is a issue with mine after plugging it into Vagcom, I can work out exactly which the potentiometer is? etka isnt very clear

 

Its on the throttle body, its the electrical part.......here(i hope) is a pic of where the plug is:thumbleft:

[sexybourbon 0]

mine is doing this also, what is a csi :/

 

It stands for cold start injector

Its the fith injector for if its bloody freezing but from what iv read on here its not needed that often even if its freezing

 

Can anyone tell if a knackard cold start injector would be the cause of exessive fuel guzzling lol

[Kempy 0]

might do till the car reaches proper operating temps? My was giving poor mpg before it broke down on the side of the road. It wont start now, garage want me to get another metering head for it

[easypops 8]

My old valver had a faulty csi........constantly fuelling(so i was told by a vw specialist garage)........unplugged it and it stayed like that for years with no adverse effects :)

[sexybourbon 0]

Cool i think mine may well be past its day tbh iv replace the other four injectors ill have a go at unplugging the sensor and see how it runs without it and is there not anyway of salvaging or fixing the metering head u have kempy ?? Is it this thread that stated they are about 700 quid to replace or something like that or silly money anyway ??

[Kempy 0]

Its a bit of a job to fix one apparently, I dont know how much a new one is, a lot id imagine.

[easypops 8]

I replaced mine on the old valver and it was less than £200........not sure the exact cost and that was 5+ years ago...........thinking about it i might have a spare one in the garage in my box of valver spares(not the old removed one) , one i bought as part of a job lot of spares iirc..........i'll dig it out if you like and take a couple of pics.............i know you have one arranged so you can let me know :)

[sexybourbon 0]

Just popped in to vw as i was passing ! 998.90 for a new metering head mate and thats on an exchange basis asweall haha so yes silly money

The guy did mention tho that they can supply a valve and gasket repair kit for the metering head for 78.00 squid wich is better inless u can find and guarrentee a second hand unit with low miles on otherwise it could be just as bad as the one you are replacing

Also the new blue sensor for the csi is 40 quid and a new throttle sensor with loom is 78.00 lol

[easypops 8]

£998 !!!............i do remember having to take the old one off......but i didn't pay anything like that!.........i'm saying it was less than £200 when i got one as i know for sure i wouldn't have paid more lol............£998!!!!!!!!!:bonk::epicfail::shock::shocked!::cuckoo:

[davidwort 0]

Metering heads rarely go wrong unless they have been physically damaged, or in some cases adjusted to try to compensate for other running problems (tamper proof adjustment screw cover removed on top of unit) or have water in the fuel rusting the plunger inside the unit.

Move the air flap gently by hand, should be smooth progressive movement with a bit of resistance.

The electronic fuel enrichment module on the side of the 9a metering unit is essentially an ECU controlled version of the bi-metallic strip Warm Up Regulator on the 1.8 KR engine. These seem pretty reliable.

Your best first steps are to check the resistance of the throttle potentiometer (TPS) with a digital multi-meter, check out you-tube for some good guides e.g.

http://www.youtube.com/watch?v=IsX5q3jBeBQ

 

also check the temp sensor on the metering head housing, remove and check resistance changes uniformly in warming water, cold tap water in a pan over a low hob will do.

 

Check for any open circuits or erratic changes in resistances.

[pumbaa 0]

Some folks will have 2 switches rather than a potentiometer. So it knows when its on idle and when its at full throttle. Worth bearing in mind if you can't seem to find it!

 

And they are interchangable and it makes no difference which one you have.

[Kempy 0]

I do trust the guys working on the car, they keep telling me theyve work on golfs for years etc. But they are sure they metering unit needs swapping even after giving them one from my other valver. I need to go check they fitted right I think lol

 

ALso Mr Wort, i will test the TPS once I get the car back, it had very eratic low revs, now where near as smooth as it could be

Edited April 6, 2011 by Kempy