Jump to content

OBD2 AAA stalling when cold, then running on five?


Recommended Posts

Ok, i have a obd2 aaa vr6 golf with 60k miles, and i've noticed if i boot it when cold, which i know isn't a good idea but anyway, within like the first three minutes of start up it will die at about 4 krpm, the revs will tail off then it'll stall, try and bump start it by bringing out the clutch in 2nd but no go. tried re-starting it on the move with clutch pressed but again won't fire. each time it's happened i've had to switch off then restart and it will run on 5 then after a few revs go to 6 and be fine.

Also if i wait a few minutes after i first start it up it's fine and when warm it's fine, no problems at all.

I've spoke to the last owner who said he noticed this, fitted new plugs but ran it on SUL which cured the problem. i've also spoke to the owner before who said he noticed the same but just drove it sensibly until warm. so the problem has been present and got no worse over 20k miles?

I've chucked in a bottle of texeco injector cleaner but alas still the same, i've checked the MAF senser and thats all clean and dry. next step is to try running some optimax through it to see what happens but i'd like to know if anyone has experienced similar troubles?

Something else possibly connected is the oil temp senser for the MFA is broken, does the ECU take this reading for anything?

Link to post
Share on other sites
  • Replies 63
  • Created
  • Last Reply

Top Posters In This Topic

ok, bttt!!

i've changed the oil today to 10/40 megnetec, came out of work tonight and exactly the same, started fine, waited a bit, revved it got to about 4k and it died, cranked for about 30 seconds nothing, sounds just like no compression. waited about 30 seconds and after about 15 seconds of cranking it fired on 4/5 then after holding it at about 1500rpm it started firing on all six.

whilst cranking it stank of fuel so i'm thinking not fuel pump/relay problems.

there was also a back fire type sound from under the bonnet. [like your ignition timing is out on a older car] once going there was a tappet rattling, which quietened then drove fine.

do vr6's have nikasil blocks? as it all sounds very familiar from when i worked with BMW's :(

It's also the 4 wire o2 senser? ht leads are all on tight aswell.

Link to post
Share on other sites

ok, plugged it in today and i have DTC 00553 - mass air flow senser g70 open circuit/short with ground error occurs intermittant.

fault code cleared and i took it for a test drive and the code didn't come back. so it's possible that code is just there from where someone has discnnected the senser previously?

i checked live data and maf was reading 4.1-4.9 g/s at idle and upto 16.1 g/s @ 3krpm, which for a 2.8 litre engine i'm thinking could be a little low? but have no experience with this engine so am unsure how this should compare?

idle speed was reading 680rpm, coolant temp 76oC, intake air temp 48oC.

O2 senser was switching between open & closed and the voltage was 0.360v at idle and 0.335v at 3krpm.

ambient air temp was 21oC so think intake air temp is rather high?

Link to post
Share on other sites
  • 2 months later...

right, 4k miles later and it's still doing this!

i've been driving sensibly and it's been ok, but ambient temps have started to drop and it's getting noticably worse.

random thought was fuel pump relay playing up not giving enough power to the pump as thats what i think it feels like, fuel starvation.

removed fuel pump and ignition system relays and cleaned contacts inside and it seemed better after being parked up for approx 4 hours, although it just would not rev over 5krpm. but did return to idle and kept running on all six cylinders so i thought i was getting somewhere. only this morning still the same.

foot down as i pulled out infront of someone, through the gears into 3rd and revs started dropping despite full throttle, into second still the same and i had to pull over as it stalled. waited 15-20 seconds restarted, ran on 5 cylinders kept it at 1500rpm and then fired on all six and ran fine.

possible related? is i had a missfire about 2 weeks ago, just comming onto the slipway on the motorway in 3rd gear, about 2000rpm, foot down and i had a missfire, i paniced so eased off, continued my journey, done 1k miles since with no issues at all, just put it down to driver error.

tonight started it up pulled away and thought hang on, i have a missfire here, revved it and it cleared. popped the bonnet and had a look and the front most top ht lead on the coil-pack was arcing out. switched off removed all the leads, sprayed it all in wd40 and noticed about 5 of the six terminals on the top of the coilpack was cracked at the base, as when i pushed the leads back on i could see bubbles in the wd40.

So obviously i have a problem with the coil-pack and i suspect that would be the main cause for my missfire on both occasions. but could that be the cause of my main problem?

all help appricated as ever!

my next course of action is to get hold of a fuel pressure gauge and see what i am getting when cold. i've spoke to ford technical i know it's not a ford engine but it was used in the galaxy and since it's where i work it's easy to ask people who might know] only they didn't, best suggestion, was oil clogging up lifters and to try a thicker/thinner grade and see what happens next, 5w/30 for example. i haven't tried this as personally i don't think it's that, any clogged tappets would have been cleared simple because the vr6 motor runs so hot there wouldn't be a blockage?

Link to post
Share on other sites
  • 2 weeks later...
  • 2 weeks later...

This is EXACTLY the problem I am having with mine currently. I've changed the spark plugs, HT leads and coilpack and it still does it.

As you say, if it is left to warm slightly from startup, then it's fine, but give it some revs (even just at tickover) and it will more often than not cutout.

I *think* it's some kind of overfuelling problem. My guessest the moment are intake temperature sensor and lambda. Anything that basically controls the flow of fuel into the engine when it is cold. I reckon too much is getting chucked in at higher revs when it comes 'on cam' (when it goes, there is a kick at 3500-4000 rpm) which is flooding the engine, causing it to cut out.

Link to post
Share on other sites

Excellent! somone who has the same problem!

how many miles has yours done?

and when was the fuel filter last changed? - just a random thought?

I wonder if i disconnect the lambda senser if the ecu will go to a basic setting thus try and eliminate a faulty lambda senser?

Link to post
Share on other sites

Mine has done 127k, serviced every year by a VW specialist after the official VW services up to 80k.

I don't know when the fuel filter was changed, I suspect it hasn't been but I very much doubt that this is a cause of the problem as it runs fine when warm.

I'm ordering an air intake temp sensor from Euro Car Parts tomorrow. At £13, it's worth a shot. The next step will be lambda sensor, but I'm going to get a VAGcom lead in the meantime and see what I can glean from that.

It's definitely choke/temperature related as when it has been running for a couple of minutes, it won't do it.

I suspect it is being flooded as the amount of black/greay smoke that comes out of the exhaust when it does it is quite substantial, indicating unburnt fuel.

Link to post
Share on other sites
  • 1 month later...

Interesting thread. Only just found it and it applies to mine as well. I've taken to letting it warm up standing. If it happens on the road it does seem to 'flood' easier which makes it much harder to restart.

No coil pack on mine and I've cleaned throttle body & ISV ( long over due ! ) No codes error codes so will try new sensors.

TG

Link to post
Share on other sites

Today i've replaced the ht leads with genuine vw ones, and checked the plugs, i have NGKR BKR5EKUP plugs which look normal and the same grey colour accross all six,

i've checked all the electrical connectors under the bonnet, for corrosion, all spotless and secure. removed both cam and crank sensors and cleaned the ends, though to be fair they were spotless.

checked continuity of heater circuit of the hego sensor and although i didn't check resistance, i did have continuinty accross the senser so am assuming the heater circuit hasn't failed.

just to recap: new leads, coil pack, 65k miles, 10w/40 oil, throttle body cleaned, standard except 57i K&N,

Link to post
Share on other sites
  • 2 weeks later...

I've just VAG-COM'd mine and got one error, 00533 - Idle Speed Regulation

14-00 - Adaptation Limit (Add) Exceeded

Which I was led to believe to be the throttle body, so I removed it, cleaned it, performed the adaptation procedure and went for a blast.

No more errors for me. I don't expect this to be the cause of the problem, but I'll report back when I start it from cold again tomorrow.

Link to post
Share on other sites

×
×
  • Create New...