Intermittent loss of power - I'm at my witts end and really need help!!!!!!!!!!

[T.C]

Hi everyone, I have previously posted this topic before but am hoping for further assistance as I am losing the will to live and really really don't want to get rid of her.

I have a 1998 vw mk4 20v GTi with only 75,000miles on the clock with a full and comprehensive service history (it took me ages to find the right vag) but I am now encountering a problem no-one seems to be able to help with.

THE PROBLEM - when driving, the car will intermittently lose power and eventually cut out, it doesn't matter on the length/type of journey, and will normally do this at least once a day. I have taken it to my local garage and they plugged in their computer and told me there was one fault code showing and it was a fault with the Coolant Sensor, had this replaced the same day to no effect. I then took it to a VAG specialist and he told me i had a split in my Senzo hose and possibly Breather hose.......replaced both of thee parts and again the problem exists. I have now been told that the only way I will work out what is wrong is by booking it into VW main dealer and they will carry out a full diagnostics on the car, and I'm sure you all know how expensive this could be!!!!

I would normally persist with the problem until I had enough money to put in into VW but unfortunately it is the only car we have and my partner uses it to transport my kids to nursery and back and I fear one day it will cause a serious accident, potentially with my family in the car.

I am not an expert on cars so any assistance really would be appreciated, but please keep it simple, that way I will understand.

If all else fails I'm going to have to bite the bullet and sell it on as is.........and I know I will lose money on it in the end but my family's safety come first.

Cheers guys.

[GTi_James]

sounds silly but are all plugs, fuses and wires connected and is there any smoke or smell of burning?

[T.C]

Hi GTi_James, thank you for taking the time to reply. Yes all plugs and fuses are as they should be, also confirmed by the VAG specialist I went to see.

There is no smoke or any smell whatsoever. The car doesn't even give you any indication when it's going to cut out, it just does it.

Have you ever come across the same problem?

[dan2252]

id say you could do with it puting on a computer again re scanning and seeing what faults there are. coolant temp sensor could be dodgy even more so if it was a non genuine one. with any type of sensor you should always use genuine parts as they are alot better quality. throttle body could be mucky?

[GTi_James]

i know when mine cut out it was due to faulty wiring with my head unit. the car shuddered, rev needle was all over the show and it would slow right down with foot to the floor and then give out. have you added anything to the car? and also see if you can get a rolling road done might solve some issues, on saturday just take it about and see what symptoms there are before it cuts out and check your battery connections etc.

i'll have a check about with my mech i take mine to as hes helped with a lot and saved me a tidy sum, yours a 1.8t?

[T.C]

Dan2252 - cheers for responding mate, I did use a non gen part when replacing the old coolant temp sensor.

GTi_James - some good suggestions there mate. Recently had the fuel pump changed over because the old on was leaking badly under rear seats. I've had the coolant sensor changed over with a non gen part and I had a friend change head unit over a short time ago, all done before the power problem kicked in.

Think i'll spend this weekend under the hood looking at all the points that have been raised this evening.

I'd appreciate it if you would speak with your mech and see if he has any ideas, no-one down this way has a clue, let alone offer me a sensible advice. It's a standard 1998 1.8 20v .

Tom

[GTi_James]

and i have also heard about the engine speed sensor giving out, may look fine but it could cause these issues apparantly without any splutters or codes, maybe something to either save up for as a last resort or if theres no history of it being replace, replace it? 

[sam1990]

i had these symptoms minus the cutting out, turned out to be the boost control solenoid, if you have this plus a leaking diverter valve it could possibly be your issue

[Nino]

TC, i rently had this problem but i cannot tell you exactly what is was, what i can tell you is what i did and how i fixed it.

I was basically driving and then when i dip the clutch it would cut out from time to time.
Also have you noticed if you pish your car hard e.g 5k revs does your car then seem to hunt or idel abit strange while at the lights?

I changed my..
*coolent temp sensor.
*thermo.
*oem dv.
*MAF.
*coil packs.
*did a full service.

And i was still having the issue. Then i did two last things before i was going to bite the bullet and book it in. I went to halfird and tool station and got some carb cleaner and electronic contact cleaner 

I then used these to clean my MAF and TB my maf had a supprizing ammount of black grit/sand like stuff coming out of it. And my TB was full of black crap.

Since doing this my car has performed as it should yesterday i also scanned her and so far that horriable 17705 fault code isnt showing.

Btw incase u didnt know a good way to check if u gt a faulty DV take it off the car, and place your finger on the top of the nipple (block it) then usinf your little finger push the valve frm the bottom and IF the valve basically stays where you pushed it then your dv is fine but if it dont work e.g no vacume and falls back then u got a faulty dv

Hope this helps mate, keep us updated.

[T.C]

Well having now replaced the fuel pump, coolant temp sensor, crankcase breather hose and a few fuses I am still nowhere nearer to sorting the problem out.

I have decided to stop messing about and diagnosing it myself and booked it into a local garage for them to run a full diagnostics test on the car, I'm just hoping they find it in the first few hours and whatever the problem is isn't too major.

Hopefully update you all a little later in the week

Cheers
Tom