vr6 intermittent performance ?!?

[paulob]

hey vask'ers.. i got a 94 vr6 golf a couple of months back.. manual NZ new so lots of fun.. when i got it, it went really well.. few little things to fix up but all good..

it had a miss at idle and sometimes when driving, so i have changed the plugs, and leads.. miss still there so i got a new coilpack on there and after that it ran like a rocket, way better than when i even got it so i was happy as larry...

but now.. i am getting intermittent performance, some days it will go like a bat out of hell and other days it will be 'flat' in reposnse for lack of a better word.. when giving it slight acceleration you can kind of feel it pulsing like it wants to go but somethings holding it back...

becuase i know how it can go, its quite a dissapointment when you put your foot down and it feels more like a 1600 honda civic than a hatchback with a v6 in it.. ive read up on the internet and theres a lot of talk about ignition related issues but ive pretty much replaced everything ignition .. people are talking about MAF sensors and O2 sensors but im reluctant to keep replacing things until the problem goes away... i thought maybe vacuum leak or something but its almost too intermittent for that.. literally within 10 minutes of driving it can go from running like a slug, back to normal, and then jo average again...

ive had the computer in it scanned and no errors came up.. can someone help me get my vr6 back??

anyones opinion or personal experience would be welcomed!!

cheers
paul

[SteveC]

it seems vag-com can be a bit iffy on intermittent problems, it didn't pick up on the faulty hall effect sensor in the wife's Polo until the problem occured while it was plugged in

[mockey666]

I'm in the same predicament.

I have a 94/95 vr6 with the same intermittent surging/missfire/Holding back. Some days fine some days not. Worse when wet or hot I think.
On a good day It still fly's.

I have new leads,plugs,coilpack. Each time I replaced something it went a bit better.Although it could just be my brain tricking me as the car usually goes better at high revs anyway, And I usually would give it a good thrash after replacing the part.

The plugs were the first thing I replaced. I should have done the coil pack and the leads first. I think my plugs might now be fouled up because they ran with the original faulty leads and coil. I am going to replace the plugs one more time(I'm going round in circles) Also I suppose a MAF is possibly the next thing to try. I've just got vag-com sorted on my mac and have some instructions on there website how to do a MAF test. Which I'm gonna do this weekend.

Also recently clutch, mounts and timing chains.

Clean Throttle body, Clean ISV, Clean air filter( I have a sponge filter in the factory box what do you use?)

We should stay in touch until we get to the bottom of it!!!!!!!

[GLIDN]

it's a bit of the ball park but it could be the Blue Temp sensor, it's located on the Thermo stat housing, looking into the car just to the right bottom there will be a blue white and yellowy/beige from memory sensor.

I did experience similar issues with my vr6 once i replace that sensor it was all ok.

[paulob]

hmmm,.. well i guess i have some solice in that im not alone 

today prime example, i could literally hold my foot just on the accelarator and it would surge and fart about.. by the time it had warmed up and i got to work it was running ok.. i have to keep it outside so i have been wondering if all this crap weather and damp is responsbile.. when i say ok though, it wasnt fantastic.. last night on my way home from the time i turned the key on till the time i got home (20 min drive) it was a rocketship.. its messing with my mind!!!

well if you ve done the same as me (replaced everything ignition) then i wonder where to next.. have you replaced fuel filters and things?  ive had mixed reports saying that it couldnt possibly be the fuel filter or pump but who knows.. after that i suppose its going through all the sensors and finding out if they are doing their job.. does anyone know where to get a service manual for this engine?? then at least i can sus what sensors are on a vr6 motor...

where abouts are you? im in auckland.. how did you get on with your vag-com.. ive contemplated buying one too just to keep it plugged in and see if i can get something to show.. im a pc engineer so happy to give it a go on a pc if that helps out..

cheers
paul

[VR6]

Faulty Ignition switch
Faulty Temp sensor
Faulty Air flow meter
Faulty ecu relay.
Most are really easy to find with a Vag Com.  The airflow meter may not show due to the fact that it is still supplying information but just the wrong amount, Same with the temp sensor. It may be telling the engine that it is at 90 degrees when it is actually at 30.

[SteveC]

does vag com identify faulty ignition switches?  the wife's polo refuses to start from time to time (getting more frequent) the ignition lights etc light up, then when you trun to start, nothing

it seems to me like a faulty switch, would the software record a fault like that?

the car's only done 80,000 kms, seems a bit early for the switch to crap out!

[VR6]

Does it turn over and not start or just nothing?. In Vag com you can definitely see the ECU voltage 

[paulob]

thanks 'Vr6'

i have my suspicion it prob is a sensor reporting the wrong info.. in this case, because the ecu is still getting info from the sensors (although it could be wrong), is there a process you recommend or should a vag-com (plugged in while the car is running) report back these numbers so I can see if they are within the acceptable values, or if they are out, ie: engine hot as but temp sensor reporting 30 degrees for example..

if theres a process here, then i'll hunt down someone with a vagcom and try and ascertain what sensor is at fault (not reporting acceptable info) .. i'll look in to that relay as well and test...

thanks for your suggestions..

paul

[SteveC]

Does it turn over and not start or just nothing?. In Vag com you can definitely see the ECU voltage 

nothing at all, no click such as you might hear from the starter solenoid

[VR6]

Look bring it into Platinum VW Spares where I work, and I,ll scan your car for you and let you know if there is anything that looks wrong. I had a GTi last week that had me going. It had been to many places including VW for intermittent rough running and stopping over the last 5-6 months. Turns out that the air flow meter was the problem and this was killing the engine dead. I had never seen or heard of this before and would not of believed it myself if I hadn,t changed the meter while it was playing up. The customer was so happy she dropped off beer tonight. Cheers

[VR6]

nothing at all, no click such as you might hear from the starter solenoid

Most likely to be the inhibitor switch for the starter if it is an auto or loose battery cables. Always check the easiest first and never take anything for granted. Next time, place the car in neutral or into park and try it.

[SteveC]

Most likely to be the inhibitor switch for the starter if it is an auto or loose battery cables. Always check the easiest first and never take anything for granted. Next time, place the car in neutral or into park and try it.

nope, it's manual, but I will try the battery terminals although the car cranks over well when it connects

[jjustice]

I have a similar problem with my 2.0L 16V GTi manual 1998 Mk3.  When it is cold it seems to miss slightly at low rev's.  High rev's it feels OK.  Once it warms up it drives much better.  I've already replaced the coil pack and the plugs.   I was going to get some new leads, but I don't want to keep replacing parts when they may be OK, especially when the leads are $160 from Platinum.

Any ideas?

[VR6]

temp switch