Idle - isv, maf, tps, tb cleaned, readings .. what next!

[_Matt_ 32]

Hi,

 

Ugghhh, I've read threads and threads on VR6 idle issues and it feels like I've been hunting down this annoying issue ever since i've had the car.

 

Can't see the tacho move on idle so relatively minor but you feel a vibration pulse through the cabin and when you've got your head in the engine bay you can hear and feel the engine lug and catch itself. It never stalls but it's giving me the sensation it wants to.

 

I've stripped the throttle body, isv and re secured all vaccum hoses. No fault codes displayed via scanning.

 

I cleaned the ISV with carb cleaner and lubed with gt40.

 

On reassembly nothing has changed with the idle issue. When I disconnect the ISV the idle rises slightly and idle is smooth. However that might just be becuase it's not at 640 rpms anymore (it idles between 640-680 on vcds). When being drvien the engine is smooth.

 

How does the ISV work? is it playing a role once the engine is warmed up? Maybe mine is goosed. It is the orignal unit but wasn't particularly dirty.

 

All other parts on the throttle body are original and have the yellow paint markers from factory so I'm fairly confident the idle damper hasn't been messed about with.

 

There are lots of other new parts whilst hunting down this issue and fixing others - coil pack, leads, FPR, fuel pump relay, new PCV, new cam and crank sesnors, new thermostat and sensors.

 

Haven't touched the fuel pump, knock sensors or MAF. Can't think of much else that would affect it. The car drives fine hence why i've not done the pump or MAF...

 

Any ideas... :D

 

Thanks

Matt

Edited February 10, 2019 by pfnsht

[fendervg 32]

How bad is it? All VRs idle a bit erratically, even if everything is ok - the late OBD2 VR engines in the Golf etc don't have an ISV and use a motorised throttle body instead, so tend not to have these idle speed issues.

 

The ISV won't behave any differently when the engine is hot vs cold - it's sole function is to regulate air intake when the throttle is closed at idle by pulsing the valve to allow enough air in to maintain a smooth idle speed. Once the throttle body flap opens again, the ISV won't be doing anything. You could try swapping out with a know good one to see.

 

Have you performed the basic ECU settings procedure again after all the changes (it's in the Wiki on here). Other things to check would be the injectors and the fuel pressure - I've seen a leaky or old injector causing idling problems.

 

The most common cause though is still a vacuum leak somewhere, so I would check again, especially the intake boot and the pipework near the air box and underneath there. Even a small, nearly invisible crack can cause issues.

[_Matt_ 32]

Thanks for the reply :) I haven’t performanced the ecu reset actually. I’ll try this. I normally just let it adapt itself over time, but the battery has been disconnected during the work.

 

The idle isn’t terrible like you see in some of the videos online. You can’t really hear it in the exhaust note but do hear a subtle clatter in the engine bay as it corrects itself and the vibration in the cabin is similar to the one you get when you don’t give it enough gas when releasing the clutch.

 

I’ll pay some more attention to the vacuum lines. Is there a DIY technique to follow to fine these leaks? I’ve tried spraying carb cleaner to no avail. Must admit I haven’t given much attention to the lines running to the carbon canister though.

 

Fuel injectors are a good call. I was suffering from some warm starting issues which could be linked to leaky injectors as well, however since installing a one way valve from the pump outlet it’s been resolved. I don’t think it would hurt investing in a fuel pressure gauge as well.

[robrado974 1]

Let us know how you get on . I’m still finishing the interior as and when I get the time. I have left my dodgy idle for now . I will be checking the hoses again in due course and the oil breather valve which I haven’t checked. Really annoying issue .

[Keyo 47]

After changing the MAS, PCV Valve and hose, FPR , Cam Sensor , ECU and fuel pump relay and Crank sensor my car is starting great and running smooth, it had new leads and sparks last year alongside battery also getting a new starter next week as making an awful squeak sound on start up. However taliking about the ECU my car had a remap in 2003 in conjuction with a BCA air filter and Shrick VGI, not sure wether I need to got to Stealth and have it remapped as I have now fittd a Stock air box which does not suck in as much air also how much they would charge.

 

Reckon an older car would benefit hugley from the injections having a professional clean. Have you had any error codes to do with mixture ?

Edited February 7, 2019 by Keyo

[_Matt_ 32]

No error codes currently, but then OBD1 isn’t that great for error reporting.

 

Before I delve into taking out the injectors (had a quote @ £85 from Mr Injector) I’m going to try:

 

1. Clean the MAF and TPS sensors (I didn’t do this when I cleaned the TB and ISV) with electrical contact cleaner.

2. Vacuum leak check again, especially under the airbox

3. Multimeter 5v testing of the sensor plugs

4. the ECU reset

5. See if I can run a TB recalibration via VCDS although believe what I have read is for OBDII cars.

6. Fuel pressure test at the rail

7. Injectors

8. Chalk it up to experience and pay a professional…. But I am enjoying the troubleshooting at the moment.

 

The issue does smooth itself out and gets worse occasionally. Makes me think it’s a sensor dying. Equally vacuum leak is high on the cards as the problem is only at warmed up idle (and not during the higher cold start idle).

[Keyo 47]

MAS sensors are not cheap and Im a sucker for BOSCH parts if possible but I just went for JP Group, and by all accounts looks well made very happy with it its Danish and cost £65.

 

Im changing the cat and exhaust soon and have a new Bosch lambada sensor , I reckon this will really finish off the smoothness of the engine.

 

One thing many people over look is the recirculation system in late VR6 which incorporates a breather tube from the petrol fill cap area then onto the carbon canister which releases gasses to a light blue solenoid (connected to ECU has a socket and plug)located by the by the airbox , if the solennoid jams open this can also lead to some of your symptons. Also the PCV vavle, so many possibilties, but the way I see it are most of the parts are very old on the car so any part replacemnt for the car is a huge benefit and not fitted in vain.

 

Be interested to hear what you discover after your investigation.

 

https://www.ebay.co.uk/itm/New-JP-GROUP-Air-Mass-Flow-Sensor-1193902400-Top-Quality/192493486795?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Edited February 7, 2019 by Keyo

[_Matt_ 32]

Thanks for the link! Yes I normally prefer known brand parts but where I’m replacing like this on whim I’m prepared to take a punt. The Bosch MAF’s are too much for me @ ~£200 so the one in the link is more a normal price for MAF imo.

[Keyo 47]

Thanks for the link! Yes I normally prefer known brand parts but where I’m replacing like this on whim I’m prepared to take a punt. The Bosch MAF’s are too much for me @ ~£200 so the one in the link is more a normal price for MAF imo.

 

I did mate I still have the old Bosch one in the garage , it is an absolute rip off the Bosch one for a rado my merc Bosch was only about £105 nippers new. Hope you sus out the issue but in doing so you are really performing a good health service to your motor and reliability.

[fendervg 32]

After changing the MAS, PCV Valve and hose, FPR , Cam Sensor , ECU and fuel pump relay and Crank sensor my car is starting great and running smooth, it had new leads and sparks last year alongside battery also getting a new starter next week as making an awful squeak sound on start up. However taliking about the ECU my car had a remap in 2003 in conjuction with a BCA air filter and Shrick VGI, not sure wether I need to got to Stealth and have it remapped as I have now fittd a Stock air box which does not suck in as much air also how much they would charge.

 

Reckon an older car would benefit hugley from the injections having a professional clean. Have you had any error codes to do with mixture ?

 

I'd say the remap was purely to allow for the Schrick VGI and to do some fettling of the factory code in the ECU. Unless you have a turbo/super charger pushing more air in, the engine will be sucking in exactly the same amount of air with the stock air box as it would with a cone. The only real difference is induction noise on a naturally aspirated engine, so assuming you still have the VGI on, you should be fine.

[Keyo 47]

Thanks for the replt Fend anything that saves the coppers is more then welcome as the VGI is still on .

[_Matt_ 32]

Okay managed to spend some time working through the list.

 

1. MAF cleaned and tested with multi-meter - think it is okay - I'm seeing a reading fluctuating between 0.85v to 0.9v on idle. There is a perm 12v source to the MAF as well.

 

2. Took of TPS and sprayed electrical contact cleaner on it.

 

3. Carried out ECU reset procedure and read the basic settings, after driving it is a little better on idle.

 

4. Took all my vacuum lines off, inc. carbon canister and inspected carefully for cracks. No problems there.

 

5. Plugged in my OBD11 device and monitored the live readouts (there are no engine fault codes):

 

- I found my idle speed sits mostly at 680 rpm but drops to 640 and up to 720 rpm every couple of seconds.

 

- Coolant temp is good - steady 87 degrees

 

- Lambda value fluctuates around 1.0 which I think it normal.

 

Things I am not sure about:

 

- Injector timing is 3.3 to 3.7ms. I've seen references it should be around 1.5ms reading around forums?

 

- The EGR temp jumps between 182 degrees to 217 degrees centigrade every 1 second (I didn't think I had an EGR valve and maybe this is coming from the O2 sensor?)

 

- The timing should be +-1 degree of 6.0. Mine jumps 4.5 to 6.8

 

So I think maybe something is wrong, although it did get better following the ECU reset procedure. Just thinking out aloud

 

- if the temps are coming from the o2 sensor perhaps it is over fuelling due to a bad injector, which probably points to why it's backing off the timing to 4.5 degrees every second too.

 

- Motor mounts are worn and letting too much vibration through. If the numbers above look normally this could be a possibility.

 

Any other ideas :D

 

Thanks,

Matt

Edited February 10, 2019 by pfnsht

[Keyo 47]

Okay managed to spend some time working through the list.

 

1. MAF cleaned and tested with multi-meter - think it is okay - I'm seeing a reading fluctuating between 0.85v to 0.9v on idle. There is a perm 12v source to the MAF as well.

 

2. Took of TPS and sprayed electrical contact cleaner on it.

 

3. Carried out ECU reset procedure and read the basic settings, after driving it is a little better on idle.

 

4. Took all my vacuum lines off, inc. carbon canister and inspected carefully for cracks. No problems there.

 

5. Plugged in my OBD11 device and monitored the live readouts (there are no engine fault codes):

 

- I found my idle speed sits mostly at 680 rpm but drops to 640 and up to 720 rpm every couple of seconds.

 

- Coolant temp is good - steady 87 degrees

 

 

 

- Lambda value fluctuates around 1.0 which I think it normal.

 

Things I am not sure about:

 

- Injector timing is 3.3 to 3.7ms. I've seen references it should be around 1.5ms reading around forums?

 

- The EGR temp jumps between 182 degrees to 217 degrees centigrade every 1 second (I didn't think I had an EGR valve and maybe this is coming from the O2 sensor?)

 

- The timing should be +-1 degree of 6.0. Mine jumps 4.5 to 6.8

 

So I think maybe something is wrong, although it did get better following the ECU reset procedure. Just thinking out aloud

 

- if the temps are coming from the o2 sensor perhaps it is over fuelling due to a bad injector, which probably points to why it's backing off the timing to 4.5 degrees every second too.

 

- Motor mounts are worn and letting too much vibration through. If the numbers above look normally this could be a possibility.

 

Any other ideas :D

 

Thanks,

Matt

 

Have you tried a good old bit of injector cleaner like redex or something like that and give it a good run between 4.5 and 5 revs for a few minutes , you never know .

 

Also can you get someone to rev the engine have a look under the car at the exhaust where it meeets the catalytic and see if there is any smoke leaks around that area. Just saying that because had those symptons what you have mentioned and today I noticed a smoke leak where the exhaust meets the cat area, and after the last couple of months checking VAG fault codes every other day it finally threw up code 00537 Oxygen sensor regulation sporadic and 00561 mixture which I expected as the cat and O2 sensor have never been changed. The O2 sensor apparently dont show a fault unless they are totally bad.

 

Thankfully I have these ready to fit .

 

EEC Catalatic (British made)with fixing kit

 

https://www.ebay.co.uk/itm/Fits-VW-Corrado-53I-2-9-VR6-Genuine-EEC-Catalytic-Converter-Fitting-Kit/302431565696?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

Bosch O2 sensor for late model VR6

 

https://www.ebay.co.uk/itm/BOSCH-Lambda-Sensor-650mm-0-258-003-604/292799998577?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

 

 

Solennoid charcoal vavle just incase is stcking open (second hand new ones are £120 plus wow !!!)

 

https://www.ebay.co.uk/itm/BOSCH-0280142155-AUDI-VW-SEAT-034133517-VACUUM-VALVE-SOLENOID-VALVE-TESTED/323645249228?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Edited February 10, 2019 by Keyo

[_Matt_ 32]

Thanks for links Keyo :) I believe I do have a very minor exhaust leak up front, notice it once the engine is warmed up. Planning a stainless system for it at some point so quietly ignoring the problem at the mo!

 

I've tried the injector cleaner but I suppose a more concentrated mixture wouldn't hurt.

[Keyo 47]

A leaky exhaust and bad lambada = rough running engine bad mixture.I could see the heat gasses escaping from the cat on mine to today quite prolific so I reckon that could give the sensor a crooked reading could be wrong though.

 

Found these guys really sound and the cheapest for Milltek Catback.

 

https://www.milltekexhaust-roadrunnermotorsport.co.uk/

 

Just to add might aswell do the down pipe if doing the rest of the exhaust system, can get one for £65 with gasket and bolts from BM catalsyt (British Manufacture) it would be rude not to.

 

I had a good look at the EEC Cat earlier and it seems well made also the Bosch sensor screws into the housing spot on.

Edited February 10, 2019 by Keyo

[Jim Bowen 1]

Does it change with any electrics on? Like hazards and full beam? I had an issue not long ago where the revs would pulse with the hazards and change the revs when full beam was on. Was my alternator needed servicing

[_Matt_ 32]

CHeers Jim. Oddly the car seems to be behaving much better most of the time since the work (mostly just cleaning).

 

I did have a go at popping all the electrics on and idle seems fine.

 

I think i am left the characteristic very very very slight lumpy idle.

 

I’ve got some injector cleaner to run through but if it remains as is I’ll be happy.

[_Matt_ 32]

Installed the JP MAF today (cheers Keyo for link) and it continues to idle perfectly. It did after cleaning the Bosch one to be honest but had already purchased a replacement.

 

Also notice no surging while cruising (this was very subtle) and it's less snappy on off throttle. Win!

 

On to the next job.

[Keyo 47]

Glad to here it mate sounds like your motor is in good hands, I put my old Bosch Sensor in the JP box. always good to have a spare with parts getting thin on the ground.

 

Today I tested a used EVAC solenoid purge vavle I purchased off ebay described as tested. Put the inlet end of the solenoid on a manual Vacum pump up to 15 pressure and it held, thought great it works but once connected power it clicked but didnt release the pressure so epic fail as solenoid must be stuck, got a refund thankfully but had to fork out just over a ton for a new one :puppydogeyes: .

Edited February 17, 2019 by Keyo

[_Matt_ 32]

Ouch!

 

Yes i did the same and popped the box on my "spares" shelf!