VR6 running 'lumpy' when warm.

[VR-Sixy 0]

Pretty sure i've seen a thread covering this but can't seem to find it.

 

Started on saturday, The engine was already warm from around a 20 minute drive, and i stopped off at the shops on the way home. Went to start up again, cranked it over, and there was this kind of 'pfhht' noise which i had heard before so didn't think too much of it. Engine started perfectly on turning over the second time of asking.

 

Yesterday, started first time, smooth as you like, but after around 15 minutes, it started to get a bit lumpy and was (what i call) kangaroo'ing like it wasn't firing propertly, then, it would be fine for a while and then revert to lumpy running again.

 

Just been out to the car now (yes, at 6.19am!!) and again, started perfectly, smooth idle, revved up OK and sounded exactly like it usually does. Will run it into work later, and report in again if the 'kangaroo'ing / lumpyness' returns.

 

Anyone got any ideas??

 

Cheers.

[dr_mat 0]

Almost certainly a sensor problem. Could be one of the many engine temperature sensors, or a degrading crank sensor. Get vag-com or equivalent and scan for codes.

 

 

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

[VR-Sixy 0]

Hi dr_mat - thanks for the input. Got 1 massive jolt just as i was arriving into work - felt like the enigine totally missed!! Going to get it booked in anyway for later this week as i need the car for the weekend.

Edited February 19, 2018 by VR-Sixy

[VR-Sixy 0]

Just spoken to the garage - it's going in thursday. If anyone has any other ideas what might be causing this, would appreciate any more input you may have.

 

Thanks.

[dr_mat 0]

Could also be the coil pack or leads. Check for arcing around the casing of the coil pack.

 

 

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

[VR-Sixy 0]

Wouldn't that put the kaibosh on the car running OK until it gets warmed up? It's fine when the engine has only just been started.....

[dr_mat 0]

No, the resistance in the lead casings reduces as it gets hotter.

 

 

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

[VR-Sixy 0]

Ah, OK. I'll wait until the garage have looked at it. Might be something silly - but there again, knowing the Corrado.......... :eek:

[_Matt_ 32]

My mechanic remarked my car felt a little lumpy when warm after he gave it a once over last week (I’ve only had it for a few weeks and hadn’t really noticed). We did spot the PCV pipe was split (Part No: 7M0 128 101) and I’ve ordered a replacement but yet to receive and fit. This is our first line of investigation as the car is showing no fault codes. An air leak would give symptoms of rough running though so maybe you have something similar.

 

I find my car can be a little snatchy on the throttle – i.e when coming off or on of the throttle while cruising it doesn’t feel smooth but then at other times it’s fine. I don’t get exactly the same symptoms as yours but thought it was similar enough to post my experiences so far.

[Jim Bowen 1]

 

I find my car can be a little snatchy on the throttle – i.e when coming off or on of the throttle while cruising it doesn’t feel smooth but then at other times it’s fine.

 

I find that too, i seem to notice it more after driving a modern car so just assumed its what things were like in the 90's :lol:

[Kevin Bacon 5]

My MK5 does that as well, and also a friend's MK7. Nothing changes I'm afraid.

[_Matt_ 32]

That’s good to hear Jim! You’re probably right and I used to more modern (and less interesting!) cars these days.

[starsky 10]

Might be time for some new leads

[volksworld13 0]

Check your engine mounts that can cause looseness upon throttle on and off at low speed.

[VR-Sixy 0]

Just checked with the garage and they're awaiting a new crank sensor!! So, kudos to Dr_Mat for the disgnosis!!

Will be picked 'Senor' up in the morning!!

 

Thanks Guys.

[dr_mat 0]

Much as I'd like to be right, please ask, quickly, if they have scanned for error codes while the engine was stationary and seen "engine speed sensor: no signal"?

 

This needs to be verified when the engine is *running* and in fact should be diagnosed with an oscilloscope, otherwise the above error always comes up. If the crank sensor suffers a hard failure then the car won't start at all; but the sensor signal can start to degrade when the engine is very hot if the sensor is borderline.

 

An expensive mistake, from VW they are about £140 iirc.

 

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

[VR-Sixy 0]

I'm not sure what they did Dr_Mat to be honest. But, a new crank sensor and new set of plugs and VR 6 is purring nicely. I'm sure if something else was

amiss, they would have told me. I've been taking my cars (not just the Corrado) to these guys since i first started driving, and they not into ripping poeple off....

not that i'm implying that's what you are inferring......

 

Cheers!

[dr_mat 0]

No not implying they are dishonest, just it's a common mistake and a very specific Corrado/golf VR6 issue.

 

Well, either way you're fixed now so all good. Plugs will make a difference likely too, did you take a look at the old ones?

 

 

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

[VR-Sixy 0]

No, i didn't get to see them Dr_Mat, but by all accounts, they were well rodgered!!

[skid 1]

Much as I'd like to be right, please ask, quickly, if they have scanned for error codes while the engine was stationary and seen "engine speed sensor: no signal"?

 

This needs to be verified when the engine is *running* and in fact should be diagnosed with an oscilloscope, otherwise the above error always comes up. If the crank sensor suffers a hard failure then the car won't start at all; but the sensor signal can start to degrade when the engine is very hot if the sensor is borderline.

 

An expensive mistake, from VW they are about £140 iirc.

 

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

Very interesting point! But would the VaG com pick it up if it was boarderline?

[a_riot 0]

Very interesting point! But would the VaG com pick it up if it was borderline?

 

I doubt it. I had my crank sensor intermittently failing which resulted in a nonstart. I think it was the wire not the sensor though. No codes thrown. It only did this rarely and only after its been running on a hot day. I could wiggle the wires sitting on the front motor mount bracket and it would start up after doing so, so I assumed it was the crank sensor wire. Replaced the crank sensor and never seen it again, but there were never any codes that I saw, temporary or otherwise. When I used to take the car to garages, they would always tell me the crank sensor failed, due to scanning the car with the ignition off...lol. That's a good indicator that they'd don't know what they are talking about.

[dr_mat 0]

I *have* caught a borderline crank sensor issue with vag-com, but you have to keep the engine running, dash in the house and get vag-com and plug it in. The moment you stop the engine the code gets wiped because of the "no signal" code.

 

 

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

[dr_mat 0]

No, i didn't get to see them Dr_Mat, but by all accounts, they were well rodgered!!

To be fair this is most likely the reason for the bad running. At least you have a shiny new crank sensor.

 

 

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

[VR-Sixy 0]

No not implying they are dishonest, just it's a common mistake and a very specific Corrado/golf VR6 issue.

 

Well, either way you're fixed now so all good. Plugs will make a difference likely too, did you take a look at the old ones?

 

 

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

 

Took Senor Corrado off out for a trip to Kent on Saturday, (Weybridge to Maidstone - about 55/60 miles). 80-90mph for most of the way

and he didn't miss a beat. That was a pleasure to drive...... same for the way home on Sunday morning.