VR6 Poor Idle and stuttering/missing.

[edition 0]

Hi,

 

I’ve put a ODB1 Vr6 into my MK2 golf and have the a poor idle and a none clean pickup of revs.

 

I haven’t driven the car on the road yet just in and out of the garage but it doesn’t seem to clear up. The car smokes pretty bad if rev’d, like a dark grey smoke.

 

I have done the chains prior to putting the engine in, it’s had new plugs, new leads. Having taken the plugs back out they are all dry but very dark (this rubs off easy enough).

 

I have a few things that I think are possible causes but I wanted to get some other opinions.

 

The knock sensor has abit of damage to the plastic casing, I.e half of the plastic is missing.

 

I have removed the carbon canister and blocked both the little pipe from the little pipe from the pcv and then also blocked the pipe coming out of the side of the head. The pipe was damaged so I took this approach.

 

Also the ISV / damper is noisy, it hisses.

 

 

Any help would be much appreciated!

[markcunningham 10]

Check your MAF and 02 sensor.

Pull MAF connector and it runs better it’s your MAF. I’m running the same engine in my daily 95 Passat! Google 02 test

 

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Edited February 11, 2018 by markcunningham

[edition 0]

Hi,

 

I’ve unplugged my MAF but it didn’t seem to make it any better or worse.

 

O2 sensor, what’s the best way to check it other than replace it.

[markcunningham 10]

Check for vacuum leaks. Let me look into procedure for 02.

 

 

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[markcunningham 10]

Check your MAF first because if the 02 is sensing low oxygen which is a rich condition hence the reason you have grey ish smoke then you want to check other issues first. MAF first. Pull MAF connector and no change your MAF is on the fritz.

 

 

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Edited February 11, 2018 by markcunningham

[markcunningham 10]

Had this issue for a while and thought it was something else. New MAF fixed my hesitation and erratic idle. If your idle stays low but idles good you have to adjust the idle stop on the TB. My guess is vacuum leak somewhere and or ISV. You can take the ISV off and clean it out with carb cleaner.

 

 

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[markcunningham 10]

As far as the 02 goes if all else is good then your checking for voltage reference which is 0.10 0.90v or 1.0v

 

 

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[edition 0]

Thanks Mark. I take it if I unplugged the MAF and it made it no better then I should ignore that as being the issue?

 

What’s the best way to check for vacuum leaks? I think I’ve done wrong with blocking the pcv?

 

The Idle is fairly irratic but at roughly the right rpm.

[markcunningham 10]

Reconnect PCV! Important part! If no change after unplugging MAF or It runs better it’s the MAF. The MAF tells the ECU about your air intake, then the TPS tells the ECU what your rpms are.

 

 

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Edited February 11, 2018 by markcunningham

[edition 0]

I have a pipe coming off the rocker cover going through a valve into the main inlet pipe. I have a pipe that comes off the diaphragm or whatever it is on that pipe that is blocked off.

 

I have a pipe that’s blanked off coming off throttle body..

 

Is that workable?

[dr_mat 0]

This unplugging the MAF at idle business is a potential red herring. My MAF works fine, but the engine never even hiccups at idle if you unplug it while it's running. I believe the opposite is only true of earlier hot-wire MAFs.

 

Crank position sensor tells the engine what the RPMs are, cam position sensor confirms top dead centre position for it exactly, but the TPS only tells it the throttle butterfly opening amount. This is just used to select which fuel/ignition map to use. The knock sensors are only used to control ignition retard, and I think it will fully retard (15 degrees rings a bell?) If one of them is not working at all. MAF and lambda are critical for fuelling, the MAF reading is calibrated using the lambda reading.

 

Trouble is, all the sensors need to be working for the engine to run right.. quickest way to find out what's up is a code reader.

 

A Corrado is for life, not just for the MOT.

Edited February 11, 2018 by dr_mat

[markcunningham 10]

So be it! But at least check that it’s working properly because it’s like chasing a ghost!

 

 

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[edition 0]

Hi sorry, to add I have plugged in vagcom and it doesn’t have any errors listed.

[markcunningham 10]

Mine didn’t show any MAF issues in vagcom either however it ended up being the MAF in my case. On these older OBD1 ECUs rosstech doesn’t. Pick up a lot.

 

 

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[dr_mat 0]

The other thing is you might need to run it for a while for fuelling errors to be picked up by the ECU. It will attempt to adapt for a while before declaring a fault. If you can read the live values out yourself you might shortcut.

E.g. the lambda value needs to be fluctuating between about 0.9 and 1.1 every few seconds, the MAF needs to show realistic values (i.e. they need to change..) and the TPS needs to smoothly increment from about -5 degrees to just over 90 degrees.

 

 

A Corrado is for life, not just for the MOT.

[edition 0]

Ah ok. Maybe that’s why it isn’t showing up errors. I’ve only really ran it for 5 mins at a time.

 

I guess I will insure it and book an Mot and see if it makes it!

 

Thanks for the help it’s much appreciated. Can anyone give me a definitive on what I can do with the pipes I have blanked off.

[Dox 23]

 

Worth checking plug leads are correctly routed, presuming you’re coil pack?

 

 

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[1xshaunx1 27]

Are you running all the loom from the VR6. If so when you turn the ignition on you should here only the auxiliary water pump running after the fuel pump prime. If you can here more stuff making noises as well there is more likely something connected to the white and blue, speed sensing circuit for the spoiler, that can make the car rough, it throws a lot of things out.

[markcunningham 10]

Wow, amazing how vw’s are so sensitive.

 

 

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[dr_mat 0]

Bosch engine management, don't you know..

 

You should see modern cars with two/three lanbdas, those things go limp home mode on a half misfire.

 

 

A Corrado is for life, not just for the MOT.

[markcunningham 10]

Over engineered! Lol!

 

 

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[fendervg 32]

Are you running all the loom from the VR6. If so when you turn the ignition on you should here only the auxiliary water pump running after the fuel pump prime. If you can here more stuff making noises as well there is more likely something connected to the white and blue, speed sensing circuit for the spoiler, that can make the car rough, it throws a lot of things out.

 

The only thing that should ever really be connected to that wire is the GALA feed from the radio for speed-sensitive volume control if you have a head unit that supports it - I've seen problems when this wire is left bare in the radio loom if it's not connected and shorts on the dash metal.

[markcunningham 10]

Ouch!

 

 

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