NZPPCC - The NZ Primera & Pulsar Car Club

General Forums => General Car Discussion => Topic started by: Vet88 on 10 October, 2015, 11:33:10 PM

Title: P12 QR20DE 2l engine problem
Post by: Vet88 on 10 October, 2015, 11:33:10 PM
First of - my apologies for the long post but I have a really odd problem that requires a bit of background.

Having read thru the last 6 years of threads in this forum (and others) and not found anything like this problem, I have a question for those good folk that have seen and worked on engines that have a stretched timing chain. Can you tell me what symptoms the car had?
Reason I ask is my 2007 Primera 2l QR20DE engine cvt is playing up. One mechanic said stretched timing chain, another said coil pack issue, another said “possible” fuel pump problems. So here are the symptoms my car shows:
It starts perfectly with no rattle or odd noises. Sometimes it revs at 1500 at idle on starting and then drops down to 700 after moving off. For the first 10 – 15 minutes it drives fine and then as you drive along and try to accelerate gently, it develops a flat spot between 1500 to 3000 rpm. Gently touch the accelerator, engine revs, no power. It will even slow down even though the engine is revving higher until after about 5 – 10 seconds or so and then the car will surge away as the power comes back on. If you put your foot flat to the floor it will accelerate fine, try to accelerate away gently or at a medium speed and the flat spot is there. Pump the accelerator rapidly 3 or 4 times and it will accelerate okish with a slight miss on its way up to 3000+ revs and then run fine above this rev range. When it has this problem and you come to an idle, the engine is really rough with the rev counter flicking up and down (mechanic who said timing chaining based his comment on this). As you move away from a stop, the engine revs to 1500 – 3000 range (depending on how much accelerator you give it) and there is no power, it will crawl along until after about 10 seconds or so and then power returns and the car takes off with the revs staying constant. Again, foot to the floor and it powers away fine. The problem is worse (really lumpy idle) if you use the engine to decelerate for a distance, especially going downhill. Often after running really bad for 10 - 20 minutes or so the problem then goes away and the engine runs fine.
It has thrown a couple of errors for the O2 sensor on bank 1, sensor 1 or sensor 2. I have never had a cam or crank sensor error or any other error which I find odd if the timing chain is stretched. Problem is getting progressively worse, at the start it only occurred during motorway driving now it occurs when driving anywhere.
I did ask a Nissan dealer in Auckland (won’t name them here as I’m not sure about the rules for this) the cost of looking at it, $195 for a scanner to be plugged in and around $500 to “check” the timing chain and see if it is stretched! Given I can buy a 2nd hand motor for around this price, I have not gone down this path yet as it just seems to be a deep financial hole with no definite answer at the end of it.
Car has been serviced regularly but it does have high kms, 300k. Other than this flat spot issue, it runs perfectly well and I’d happily drive it for another 300k.

I am considering an engine swap, can I ask those that have removed a QR20DE engine from a primera, can you detach the transmission whilst the engine is in the car and lift the engine out or is the only way to get the engine out is to drop the engine / trans and remove it from under the car?
Title: Re: P12 QR20DE 2l engine problem
Post by: grim_reaper on 11 October, 2015, 01:13:33 AM
Sounds like more like spark, maybe fuel.
With the stretched chain, they throw codes related to a miss match between cam & crank sensor.
Title: Re: P12 QR20DE 2l engine problem
Post by: more_fasterer on 11 October, 2015, 10:01:53 AM
Can you please confirm whether it's a QR20DE or a QR20DD?  The DD's are the ones with direct (read: high pressure) injection and suffer from issues with the pump and timing chain as a result.  I don't think anyone has posted up on this forum before with a stretched timing chain on a QR20DE.

When you say the rev counter is flicking up and down, can you go into a bit more detail?  i.e. does it bounce wildly with no reference to actual RPM, or does it flutter by a couple of hundred RPM while the engine is running rough?

These engines are really reliant on a good o2 sensor reading under normal operation, so if the o2 sensor is giving some really odd readings it may cause the engine to lean out and run like you've described.  Tellingly, the engine computer ignores the o2 sensors when you're flooring it.  I suggest starting by fixing what you know is wrong (the o2 sensor) and going from there.
Title: Re: P12 QR20DE 2l engine problem
Post by: Vet88 on 11 October, 2015, 11:43:42 AM
It is a QR20DE engine. This car is one from the UK, not a jap import.

The rev counter flutters by a couple of hundred RPM at idle when the engine is running rough and in tune to the engine running rough (if that makes sense). When the engine is running normally it is steady.

The O2 sensor fault only occurs when the engine is running really badly and only intermittently. For example: engine doing it's bad thing for the last 5 minutes, I pulled into a car park that had a slight uphill to it, the engine had no power as I tried to gently accelerate into the car park, I held the throttle steady revs around 1800, the car slowed right down and almost came to a stop then there was a backfire, the O2 sensor fault activated and then I pumped the accelerator quickly 4 times and the engine gained power again.

Are you suggesting I start with replacing the O2 sensor to see if that fixes things?
.
Title: Re: P12 QR20DE 2l engine problem
Post by: pTen on 11 October, 2015, 08:29:26 PM
Unplug the o2 sensor, it will throw a code but ecu will run basic fuel maps (I did this with my p12 trying to find a fault). If the problem is still there it will be something else.
Title: Re: P12 QR20DE 2l engine problem
Post by: more_fasterer on 11 October, 2015, 09:04:01 PM
Are you suggesting I start with replacing the O2 sensor to see if that fixes things?
.

Yes. pTen's suggestion is a good one too.
Title: Re: P12 QR20DE 2l engine problem
Post by: Vet88 on 12 October, 2015, 12:13:37 AM
Thanks, I will try this tomorrow or Tuesday when I get some time and let you know the result.
Title: Re: P12 QR20DE 2l engine problem
Post by: pandap10 on 12 October, 2015, 07:02:37 PM
Check for air leaks also.
Title: Re: P12 QR20DE 2l engine problem
Post by: Vet88 on 13 October, 2015, 12:35:30 AM
OMG pTen, you are godsend. Unplugged both O2 sensors and drove a regular route where I could previously draw on the road where the problems would start. There and back, around 20 minutes each way, and not a fault. Will drive it tomorrow for another 2 hours in a start stop environment but at this stage it looks like an o2 sensor. Can anyone recommend which brand to get for this car and from where? I've read lots of different opinions as to what to buy and lots of it conflicts.

I've found an engine with 100k on it for a good price so I'm most likely going to buy it and hold it in reserve given the km's the current engine has. I have the manual and it says to drop the engine / trans to get it out. I don't have that capability at home so can anyone say if the trans can be disconnected whilst it is in the car and the engine removed upwards?
Title: Re: P12 QR20DE 2l engine problem
Post by: My real name is Lance on 13 October, 2015, 12:18:41 PM
If it says drop it out the bottom, that's probably the easiest way. Just drop it onto a garage creeper or something. Then jack the car up really high and slide it out the way.

On p11s you can lift it out the top I think. Not sure about P12s.
Title: Re: P12 QR20DE 2l engine problem
Post by: Vet88 on 13 October, 2015, 04:58:09 PM
Ok, I'll give some thought as to how I can lift the front of the car high enough. Not keen on using a jack, might have to rent a lifter from hire pool for a morning.

For those in the know about the O2 sensors, until I get one is there any chance of damaging the engine whilst they are unplugged? I assume gas might be slightly heavier in use, any other side effects? Does anyone remove them permanently? I assume you must do something with them if you remove the cat?
Title: Re: P12 QR20DE 2l engine problem
Post by: My real name is Lance on 13 October, 2015, 11:13:08 PM
I admit I haven't had a lot of experience with the QR engines, but most of us here haven't.

In the SRs, you can remove the O2 sensor no problem, and the engine goes into open-loop mode 24/7 (as opposed to closed-loop). It runs slightly richer in order to be on the safe side of stoichiometric. It might wear out your cat converter 0.0000000001% faster, but who cares about that anyway.

They are only narrowband sensors anyway. Just a "rich" or "lean" signal. In open-loop the computer makes it so it is most likely "rich" most of the time.

I can recommend that you don't do the following ;D

(https://primeracarclub.co.nz/forum/proxy.php?request=http%3A%2F%2Fi100.photobucket.com%2Falbums%2Fm15%2Fafroboltski%2FCar%252015-12-14%2FJacked_2_zps89dc9ee4.jpg&hash=a408ea19d957a7cffdc4e24489f24fe0)
Title: Re: P12 QR20DE 2l engine problem
Post by: jevans on 14 October, 2015, 12:06:09 AM
I admit I haven't had a lot of experience with the QR engines, but most of us here haven't.

In the SRs, you can remove the O2 sensor no problem, and the engine goes into open-loop mode 24/7 (as opposed to closed-loop). It runs slightly richer in order to be on the safe side of stoichiometric. It might wear out your cat converter 0.0000000001% faster, but who cares about that anyway.

They are only narrowband sensors anyway. Just a "rich" or "lean" signal. In open-loop the computer makes it so it is most likely "rich" most of the time.

I can recommend that you don't do the following ;D

(https://primeracarclub.co.nz/forum/proxy.php?request=http%3A%2F%2Fi100.photobucket.com%2Falbums%2Fm15%2Fafroboltski%2FCar%252015-12-14%2FJacked_2_zps89dc9ee4.jpg&hash=a408ea19d957a7cffdc4e24489f24fe0)

That is literally the most dangerous but most artistic jacking I've ever seen ;D
Title: Re: P12 QR20DE 2l engine problem
Post by: jonathanhogdahl on 26 August, 2019, 07:20:11 PM
Sorry this late but:
I had the same problem last week after cleaning the throttle body.
After hours of frustration I decided to check all the intake areas including manifold for leaks by spraying WD Throttle Body Cleaner with engine idling at 2000-2500 rpm.
Last resort - I sprayed into the oval intake behind the nearside head lamp.
The engine slowed down to 700 and then more, until it stalled.
I restarted and it idled at 650rpm!!!!!!!!