VR6 Misfire

[Dutch24V 0]

OK, noted and will mention it when ordering the new one.

Cheers...

[StormyTommy 0]

did the first part of the ecu reset procedure

Hesitation problem has returned, :( i.e. with car warmed up @ steady 60-70mph car 'misses a beat'.

Still need to do 'basic settings' & get error codes.

[Dutch24V 0]

Replaced the TPS yesterday and no difference, except the car doesn't stall now when I unplug the MAF!!

 

It still drops out sometimes at lights though, or when clutching in heavy traffic etc.

 

I'm going to order a new MAF as mine is still the original (190000+ km's now) so geuss it needs replacing anyway? Unfortunately it's the 461 version so must pay 335 Euro plus vat from VW, unless someone know otherwise??

 

I also received my Ross-Tech VAG-COM lead today so will run a diagnostics test on the 60km journey home and see what comes up.

 

I have already replaced the following in the last year to no avail:

ISV

Crank sensor

1 cam sensor (must do the other still - I presume there are 2?)

Coil Pack

Plugs

HT Leads

...and checked intake/all pipe work for air leaks etc.

 

I'm also thinking the frequency valve on my carbon canister could be the culprit if it's stuck open, but guess the VAG scan will tell me for sure.

 

Anyone have any other ideas as I'm running out ?? She drives perfectly apart from the intermittent stalling and has (well, seems to have anyway) full power throughout the rev range. Although I did notice yesterday at low revs she hesitates until the revs get above 2.5 - 3k.

I'm sure a new MAF will solve it but maybe I'm missing something??

 

Cheers...

Dutch

'94 VR

[Kevin Bacon 5]

It's your MAF I'm afraid.....been there and done that, got the T shirt for 2.5 years worth of exactly that kind of behaviour....

 

It just won't stall at all with a working MAF, you'll find that out and is one of the first things you notice. The bucking below 2.5K will reduce but VR6s always had a slight hunt around 2.5K anyway, but it's more noticable in some cars than others. The engine should really start to take off from 3600rpm onwards and be smooth with it.....

 

Is there a Bosch dealer in your neck of the woods? They are £150 exchange direct from Bosch.....don't give the dealer they're mark up unless you have to...

[Dutch24V 0]

Thanks for comfirming that Kev.

 

There is a Bosch dealer almost next door to my local VW dealer as it goes, but..., do I have to take the inards out of my existing MAF first and swap them at the bosch dealer, or send of my complete MAF and wait for them to send it back with new inards??

 

Reason being I can't be without the car for any time as it's my daily driver!

 

BTW: When I ordered the TPS I specifically told VW to order the correct bolts as the new TPS is smaller than the original, as you had warnned me. Guess what, it still arrived with the original, now far to long bolts!!

 

F*#@ing muppets...

[Kevin Bacon 5]

Yep, that's a classic VW sign that they don't give a flying f'ck about their older cars and how customers are to supposed to fit superceded parts to them. But then they're only in it for the money, so can't expect anything else to be honest.....

 

Anyway, rant over..... get yourself down to a hardware store and get some shorter bolts....think they're M5s from memory, they need to be about 2cm long.

 

After you replace the throttle sensor, reset the ECU by pulling the plug on it or disconnecting the battery for 5 mins or so, then check with VAG-COM that the throttle angle is less than 14 degrees.

 

MAF - no you order it from Bosch (they send you a whole new one) and then you give them your old one after you fit the new one, and it's a 10 minute job. Basically, Bosch reuse the plastic body and put new innards in it.....but in reality you'll find it's a brand spanker.....

[Dutch24V 0]

Unfortunately so true!!

 

I have already sourced my own bolts as couldn't be bothered trying to explain again to dim-wit sitting behind the VW desk!!

 

To be honest I didn't actually reset my ECU after replacing as just presumed it was a plug'n'play part. Will it make any difference then to the running then or is the reset just to check the angle is correct?? I lined up the litlle cross hair thingy with the sensor in the correct place so guess it should be fine. What if it isn't??

 

Will order a new MAF tonight then, from Bosch!!

Again, thanks for all the advice Kev...

[RW1 0]

Unfortunately so true!!

To be honest I didn't actually reset my ECU after replacing as just presumed it was a plug'n'play part. Will it make any difference then to the running then or is the reset just to check the angle is correct??

 

Not a "plug 'n' play" part. But check the ECU can see the throttle angle changing about 10 to 12 degrees idle to about 90 degrees full throttle. VAG-COM Measuring Blocks Group 003 field 3. Can be done with ignition ON and engine not started.

 

No need to do the actual disconnect and drive bit if the Corrado is running correctly and the ECU has been set up previously. Just do the second bit of the procedure, ie. put the ECU into basic settings, rev the engine to 3,000 rpm for about 3 seconds and then allow to idle for a further 2 minutes but exit BS when the radiator fan isn't running. You will need to select the right group though for the ECU, 000 or 001.

 

Same for when you change the MAF.

 

Effect of not doing is possible stalling on the overrun and slightly "off" fuelling.

[Dutch24V 0]

OK, thanks for the tip.

 

One question though, stupid maybe but..., what do you mean by 'on the overrun'? Heard this phrase several times just not sure exactly what it's refering to!?

[Kevin Bacon 5]

It's when the fuel is shut off when the engine is deaccelerating. The engine is not making power in this state and therefore only needs enough fuel to keep it idling.

[Dutch24V 0]

That's what I was thinking but nice to have it confirmed.

 

I did a VAG-COM scan and it came back with zero erros. Also checked the throttle angle and it was moving up in nice small, smooth steps. Initial angle with no acceleration is 11.6? Haven't done the basic settings bit yet but might try it later this evening for a laugh.

 

...one other thing leading on from the overrun Q.

I have low compression on 2 (+/- 7 psi) and 6 (+/- 9 psi) and know the HG is on it's way out. Sometimes she emits a little puff of white smoke when cold too, but only when on throttle, not it would seem on overrun. Does this vaguelly point to possible valve stem and/or piston ring wear also?? The head is coming of possibly next month but need to make sure I have enough cash in the bank before braving such a job!!

[h100vw 0]

10PSI is a quite acceptable difference between cylinders IMO. I wouldn't pull the head off for that reason alone.

Gavin

[Dutch24V 0]

Sorry, I didn't mean PSI then!

The other 4 cylinders read between 11.9 - 12.6, so 2 and 6 are very low compared to them. Not sure what unit it was then - BAR maybe??

 

When I do the basic settings bit I presume the water temp should be something like 70 or above??

 

Dutch

[h100vw 0]

Dutch, you have 4 cylinders reading 11.9-12.6 the other 2 are roughly 7 and 9 the units are probably BAR as you say.

 

A BAR is approx 14 PSI. Std motors(not VRs but the cylinders are about the same capacity as an 1800) I have checked in the past usually have about 180 PSI which is getting on for 13 BAR. a 10% spread would be acceptable.

 

2 and 6 on yours are well down. You need to find out why. With the engine warm you should squirt some oil into each cylinder. This will help seal the rings briefly. Then do the check again. If the pressure comes up then the bore/rings are at fault. If the readings are the same then it is the valves not sealing well.

 

The other test you can do which is very similar is a cylinder leakdown. You pressurise each cylinder and see how long they hold the pressure. With this method listening for air escaping from the oil filler cap or dip stick means the rings are gone.

 

Air coming from the inlet or exhaust manifolds is the valves.

 

Any decent garage should have the ability to do that for you.

 

Unfortunately the VR engine has previous form for wearing the rear cylinders. Which is costly to sort out.

 

gavin

[dr_mat 0]

ISTR Dutch mentioning his low compression on a couple of cylinders as long as a year or more ago on the yahoo list, no?

Lasts a long time when iffy, don't it! :)

[Dutch24V 0]

That is correct. Have had these compression readings for over a year now, but haven't checked them recently to be honest.

 

As you say, the VR is a pretty resiliant lump when iffy. I drive +/- 100 km per day with a fairly heavy right foot and she still keeps going!!

 

...Using about 5 ltrs of oil (15w 40) every 3000km's or so though but coolant remains good with no leaks so far.

[dr_mat 0]

Ouch, that's some oil thirst though. 2.5 litres every 1000 miles!

[StormyTommy 0]

Got codes read last week (thanks kev) and it showed up intermittent fault with the Camshaft Position sensor. Got one, fitted it yesterday, did ecu reset. Took it for a drive, what a difference! :D I'd forgotten the acceleration it was capiable of. Don't know if it's fixed my steady 60-70mph misfire problem yet because I did'nt want to drive the car at any steady speed. :evil: I'm hoping this has cracked it.

[Dutch24V 0]

Mat: It is but cheaper than the alternative at present. Most of it is leaking down the outside left hand side and back of the block though and not burning in the combustion chamber.

 

Tommy: I had the same when I replaced mine. Huge difference and so much smoother!!

 

Kev/RW1: Friday evening I put the ECU into basic settings and did what was mentioned above. That evening she drove like a b*tch - stalling everytime I clutched and at every set of lights. Yesterday she was a little better and today she hasn't stalled once. Also, acceleration seems a lot smoother than before and she picks up a lot sharper.

 

Anyhow, I have ordered a new MAF today from Bosch. 229 euro excl.. which is just a tad better than the 335 euro excl. VW want.

It's also a swap job as you mentioned. Should get it Wednesday. Can't wait to feel full power again!!

 

Dutch

[Dutch24V 0]

Just installing the new MAF and decided to clean the air filter (K&N panel with standard air box) too.

 

Question: As it's a new MAF I don't want to flood it with oil when I first drive with it, so how much of of the K&N air filter oil I should I use and on what side(s) (only the outside-air exposed side I presume?) to spray??

(the instuctions are in Dutch and unfortunately mine isn't that good!)

 

Cheers,

Ducth

[Dutch24V 0]

Just installing the new MAF and decided to clean the air filter (K&N panel with standard air box) too.

 

Question: As it's a new MAF I don't want to flood it with oil when I first drive with it, so how much of of the K&N air filter oil I should I use and on what side(s) (only the outside-air exposed side I presume?) to spray??

(the instuctions are in Dutch and unfortunately mine isn't that good!)

 

Cheers,

Ducth

[GIXXERUK 0]

27. How much oil should I use to re-oil my filter after it is cleaned?

 

To determine the amount of oil needed for your filter, enter your filter's K&N part number in the Search by Part box on our Application Search Page. If you don't know the part number you can look it up on the same page. Be careful not to over oil your filter.

 

http://www.knfilters.com/faq.htm#16

 

right at the bottom of the page :-)

[Dutch24V 0]

Nice one. Didn't think of looking there for some reason!

 

Cheers...

[Dutch24V 0]

...New MAF fitted, cleaned the air filter and reset the ECU and what a transformation!!

 

Along with the new TPS, acceleration is now so effortless and smooth compared to before and she pulls harder and smoother lower down too. Between 3-4000 rpm is sooo sweet now I don't have to change down to boot it on the highway either.

 

Also, not one hint of even coming close to stalling, she starts and runs smoothly and at 680 rpm from start, without any hunting, hesitation or complaints.

 

My MAF was the original from March '94 and even though the ECU reported no problems with it I highly recommend changing yours if as old as this, you won't regret it!!

 

A very chuffed Dutch,

'94 smoooooth VR

[RW1 0]

Excellent.

 

Just be wary with the K&N filter and it's oiling. Particularly if it's a MAF ending in part number "462". They are sensitive to oil comination. I found with a K&N panel fitted (straight out of the box) that the engine gradually ran rougher over a period of a few weeks. Gone back to VW origianl filters every 10,000 miles as there is no difference according to magazine test review upto that point.

 

You might examine the old one in that light considering it wasn't showing any ECU fault code.