Passat 1.8 20v turbo, hunting on idle & poor acceleration

[vwpassat1.8juic]

1998 R-reg Passat 1.8 20 valve turbo 100k.
Sounds like its hunting on idle, revs stay at about 700=750rpm and when i accelerate it has loss of power....
1: oil change and oil/petrol filter changed.
2: redex in tank.
3: sprayed carb cleaner in idle throttle control valve.
4: plugged in me sealey VS8650 hand held diagnostic only code (after a few readings and clearings) coolant temperature sensor - which will be replaced soon.
I had a friend look at it and he said 99% sure its coil pack....?
But wouldnt my diagnostic had picked up if it was coil or spark plug...?
Any help much appriciated....

[corkycat]

hi ive been tuning vag cars for a few years now and have had this problem on a few...
when you accelerate hard do you hear a noise coming from the engine bay like leaking air??
if so this is a common fault with this engine and setup.. take the engine cover off.. standing in front of the engine (standing at front of car directly between headlights leaning over the grille) look at the back of the engine on the right hand side..... you should see a breather pipe coming off the air intake (its a breather return pipe roughly 4 inches long in the shape of an L)
if you check the bend this will probably be split
either replace or cut where split and use a right angles hose conecter to repair...
as for temp sensor just remove from can and use a brillo pad and clean it so its shinny,, replace and job done this will cause you no more problems.

[Crasher]

After the coolant temp sender has been replaced, remove and clean the throttle body but it will need readapting to the ECU in Basic Settings 04, Main Group 098 which you won’t be able to do with your scanner. Also it is possible you have an air leak and even a failed lambda sensor due to the coolant temperature sender giving the ECU the wrong information which can cause the engine to run rich.

[vwpassat1.8juic]

changed all 4 spark plugs today, and noticed when i pulled off coil 2 with engine running no diference but when i pulled off 1,3 & 4 coil you could hear the differnce in running.... so i changed number 3 coil still no different so took coil back for refund.... when took coil out of chamber there was no clicking....there is supply going to the coil plug 14.6 v i think....
so will try to source another coil

[j.johnson23]

You might find the ignition amplifier is faulty.It can fail causing one coilpack to not work.It`s mounted on inlet by the MAF.Dead easy to change.Not cheap though.

[vwpassat1.8juic]

Could it be the cable/connector from ignition module - coil....?
£15.77 from local VW or is it likely to be ignition amp £142 from local Vw ouch....

[Crasher]

A failed module normally causes all the coil packs to play up in random fashion, not just on one cylinder up but unfortunately the only way to tell is by fitting a new amp and four new coil packs. I have never seen a wiring fault there but there is always a first time. One thing though, pulling up a coil pack to do a spark test as we used to do in the old days, with plug leads overloads the coil pack and the amp, often causing failure of both.

[j.johnson23]

I`m only going on my own experience on this.The amplifier stopped cyl 2 from firing.I tried a new coilpack but misfire continued.An elecrician friend check amp outputs and found no feed to cyl 2 coilpack.A new amp cured problem.I got mine from local factors for around £70.Still ok after 18 months.

[vwpassat1.8juic]

wheres the best place to read amp outputs from the ht plug or from the actual amp itself and what sort of reading shall i'll be getting...?

[j.johnson23]

The best place will be on output side of amp.You will need a wiring diagram and know how to read it though.