Please help with problem with an engine that I supplied recently

[Jon T]

Hey guys, I am hoping that you can save my backside from a possibly expensive problem for me.

 

Long story short, I sold a VQ35DE bare engine to forum member Pedro85 to replace a engine with damaged internals.

 

My engine is now installed but will not run in his car. I will list problem details below, but first some quick details about my engine.

 

Just so that you don't think that I am selling dodgy engines; the engine is a 48k miles from a 2005 UK car. I bought the car from a forum member on here, so we have plenty of history etc if he is willing to get involved.

 

Here is the engine cold start and test video:

 

I can not identify any issues in the video, so I am certain that it is a faultless engine.

 

I also checked the cylinder pressures and they were all tops and nearly identical, as expected.

 

I've offered the customer to return the engine, but neither of us want to do that, so we are really hoping to get it working properly.

 

 

 

The problem - I'll paste in here parts of our private discussion regarding what the problem is:

 

"

Bad news i'm afraid, i've just heard from my mechanic that the engine isn't working

 

According to him there's no oil pressure and one of the cylinders isn't firing. He seems to think it might be timing related

 

The mechanic has worked on my car a few times, but not to this extent. He is a very experienced mechanic though, he often swaps out engines, rebuilds them etc. I went down to see the car for myself and suggested that the coil pack wiring might be the wrong way round but he had already checked that.

 

He said that the engine isn't generating any oil pressure and there is ignition happening in the plenum, suggesting that the inlet vales are open on the compression stroke, he thinks that it might be caused by insufficient oil pressure to the hydraulic lifters. The other cause might be the ignition timing but since these cars are electrically timed he doesn't think that it could be this.

 

He also said that when he tried to turn the engine over it filled the workshop with smoke.

 

My original engine has a hole burnt into one of the exhaust valves causing a miss fire, with pieces of the valve having fallen into the cylinder.

 

Did you check to see if the engine was generating oil pressure when you tested it?

"

 

So we have some good info there.

 

Although I know these cars pretty well, I am not an engine mechanic, so I am hoping to get some of the bigger brains involved in this please?

Edited August 12, 2016 by Jon@Emperor

[Jon T]

So the first thing I have done is to review my records to look for anything I've possibly done wrong or unsual.

 

- the bare engine was supplied complete and drained. I hadn't opened up any of the VVT system, or removed the VVT variators/soleniods at the top.

 

- if we look at my pallet record photos below, we see that I laid the engine on it's side for postage. I don't usually do this. I was in a real hurry for this delivery, so laid it down without thinking. Now, thinking about it, there is a chance that it was orientated just slightly passed plumb level, and hence oil dregs from the block could have seeped into the cylinders. This would explain the smokey engine when the mechanic started it up. From my experience just a few drops of oil can produce a @*!# load of smoke. But could this actualy cause any mechanical issues? Not in my mind. There is never going to be enough fluid in there to hydrolock is there? Even if there was, I couldn't see it produce our results.

 

https://goo.gl/photo...dPTLwRY74zU7hU9

https://goo.gl/photo...rBCSRX36VXjUrMA

 

- I have supplied around 50 VQ's. I have had some non-starters before. In each case it turned out to be the VVT variators in each case that was to blame. They had seized up while out of the car, and were cocking up the timing and producing similar results, just without the smoke. In each case the mechanics invloved removed and cleaned through the variators, and hey presto! Everything worked.

Edited August 12, 2016 by Jon@Emperor

[Pedro85]

That pretty much sums up the problem.

 

I should add that my first comment about one of the cylinders missfiring was incorrect, that was from my conversation with the mechanic this morning not long after i had woken up. I went in to see the car in person and ignition is actually happening in the plenum on all six cylinders.

 

Any help you guys provide would be really appreciated, i'm now over 3 months in to trying to get my car sorted and this may be the final nail in the coffin for my zed....

 

Cheers

[Ricey]

So what are we saying?

 

No oil pressure

Ignition happening in plenum chamber

 

All else is well?

 

How is he reading the oil pressure? Internal gauge? Diagnostic?

 

Has he compression tested again to check for sticky valve?

 

 

Sent from my SM-G925F using Tapatalk

 

 

[Pedro85]

He did his own compression check when the engine arrived yes, everything checked out fine.

 

Im not sure how he is reading the oil pressure.

 

Thanks

[Ricey]

Sorry I misread you there Pedro. Ignition in plenum on all 6 has got to be a timing issue.

 

Sent from my SM-G925F using Tapatalk

 

 

[Pedro85]

Do you have any idea what could have caused the timing issue?

 

If it is related to there being no oil pressure, any idea what could have caused that issue?

 

Also, is the engine a write-off now that it has been turned over while being miss-timed?

 

Thanks

[Ricey]

Do you have any idea what could have caused the timing issue?

 

If it is related to there being no oil pressure, any idea what could have caused that issue?

 

Also, is the engine a write-off now that it has been turned over while being miss-timed?

 

Thanks

I've asked my mech and he's not got any ideas but unlikely it's a sticky valve situation.

 

For all 6 to go it must be timing related.

 

Could of clacked a valve or 2 but hopefully nothing too drastic.

 

Does anyone know if the VVT system is electronic or oil pressure fed?

 

Sent from my SM-G925F using Tapatalk

 

 

[ZMANALEX]

If the engine was running okay before, then it has got to be a fitment issue.

 

Sounds like the technician has messed up some where along the line.

 

Pm received and replied to Pedro.

[Jon T]

Hey guys - soz I had to go out to collect yet another crashed Zed - lol

 

I just realised that I completely missed the part about there being no oil pressure.

 

 

So let's look at the logic:

 

- timing problems can not causing oil pressure problems

- oil pressure problems we think can cause timing issue due to lifter malfunction.

 

 

So if the mech is correct about the oil pressure being low, doesn't that mean that the route cause MUST be oil pressure?

 

And the only cause of pressure problem is oil pump right?

 

Does everyone agree with that rationale?

 

 

I forgot to answer Pedro earlier. Yes the oil pressure was looking fine during my test. I'm really pee'd off that I didn't show the pressure gauge in the video. I must start doing this. If required we can talk to Shresh who I bought the car from to confirm no previous pressure issues.

Edited August 12, 2016 by Jon@Emperor

[ZMANALEX]

The lifters are not hydraulic, they are mechanical.

 

Oil pump failure, I don't think so.

 

The issue will not be oil pressure related.

 

See my previous post.

[Pedro85]

Any idea of what could have gone wrong during fitment to cause these problems?

 

Cheers

[ZMANALEX]

Any idea of what could have gone wrong during fitment to cause these problems?

 

Cheers

 

Something hooked up wrong or not hooked up at all.

 

Or lack of fuel perhaps.

 

Flywheel fitted in wrong position and not registering with CPS.

 

etc,etc,etc.

[Jon T]

The lifters are not hydraulic, they are mechanical.

 

Oil pump failure, I don't think so.

 

The issue will not be oil pressure related.

 

See my previous post.

 

Duh! Sorry yeh - I have actually dismantled about 5 of these engines believe it or not, completely forgot they where solid lifter on valve.

 

OK that's good news.

 

We are now happy that oil pressure can not be the cause of a timing issue.

 

Like Alex says, it sounds more like a "traditional" timing problem.

 

So this leads us to question; is there actually a lack of oil pressure? Pedro I wonder if you could question the mechanic as to how he is measuring the oil pressure? Or is he just assuming that the pressure is down due to his own thinking.

Edited August 12, 2016 by Jon@Emperor

[Keyser]

If it was me I'd be looking at timing with the symptoms you have - if he did a compression test before firing then there should be no oil in the bores to cause a lock, it sounds like either the coil packs are hooked up wrong rear 2 on right hand bank as you look into engine bay usually get crossed - just the way that looks correct is not. if it's not coil packs then I would go with Alex on flywheel 180 degrees out which will give you that sort ignition of timing reverse or CPS is not working / faulty,

 

Oil pressure if it's the gauge it is not reliable you need to remove the sender and put an oil pressure meter on to prove there is no pressure, unless this has already been done?

 

More info = more help

Edited August 12, 2016 by Keyser

[Jon T]

If it was me I'd be looking at timing with the symptoms you have - if he did a compression test before firing then there should be no oil in the bores to cause a lock, it sounds like either the coil packs are hooked up wrong rear 2 on right hand bank as you look into engine bay usually get crossed - just the way that looks correct is not. if it's not coil packs then I would go with Alex on flywheel 180 degrees out which will give you that sort ignition of timing reverse or CPS is not working / faulty,

 

Oil pressure if it's the gauge it is not reliable you need to remove the sender and put an oil pressure meter on to prove there is no pressure, unless this has already been done?

 

More info = more help

 

Some good info there:

 

- rear coil packs mixed up: yes, I have done this myself several times and it gave all kinds of weird symptoms, took me ages to figure it out. Invariably the white numbers have worn off the looms I find, so really easy to get them mixed up. Strangely, they are SUPPOSED to look the wrong way round at the rear NS. If they look right, then they are wrong. Do you know what I mean? I guess this could fool our man if he is not used to VQ's.

 

- Flywheel out of alignment: I didn't realise it was possible, but yes needs checking if all else fails.

 

- Bottom CPS: yes these often get "smacked" when changing engines due to their position. From my experience when the CPS is gone, then it won't run at all.

 

- Oil pressure gauge: That is exactly what I was thinking. We need to ask him if he has measured the oil pressure with a proper gauge as the in-car one is just a toy and often doesn't work any way.

Edited August 14, 2016 by Jon@Emperor

[Keyser]

Ref Flywheel - they have a pin on OEM but anything is possible especially if the pin is missing aftermarkets - most have the pin hole but I have come across some that will fit out of line even with the pin fitted.

 

I know exactly what you mean about the coil pack wires they just look backwards and the numbers never seem to last. The oil gauge sender can be damaged and so can the CPS so they need checking.

 

Good luck

[Jon T]

Are you up to date Pedro? Do you understand my points from post #16?

[Jon T]

Can a mod please move this thread into the proper technical section please? Not sure why I created it here. Thanks

[Pedro85]

Yeah got it cheers,

 

Ill give him a ring tomorrow and see if he's in to ask about the oil pressure.

 

I did ask him about the coil packs being mixed up and he said he had tried it both ways, either way though that wouldn't account for all six cylinders being miss timed.

 

Ill see what he says about the flywheel/CPS too.

 

Thanks for all the help guys.

Edited August 12, 2016 by Pedro85

[Pedro85]

No answer today, looks like they might have the weekend off.

 

Will try again on Monday.

 

Cheers

[Jon T]

Gotcha

 

I have been discussing it with friends today.

 

The oil pressure problem and timing problem we do not think can be linked to each other.

 

For the engine to have developed a separate oil pressure problem AND timing problem we think is pretty much impossible.

 

Hence I don't think they could have measured the oil pressure at all.

 

Let's see what happens Mon.

 

Thanks

 

 

 

PS - it may be worth investigating where the nearest 350z specialist is to you? I've sold so many of these VQ's, and my spider senses are telling me that these guys, as good as they are, may simply not have the experience to fit this engine VQ properly.

[Jon T]

I have been emailing a chap that fits VQ's. Unfortunately he is down south, so is no use to you, but has some more info to add:

 

"

Hey john looked at the post.

 

Ive done a lot with these engines and they are bomb proof.

 

The hydraulic lifters are mechanical.

 

There should be no firing in the manifold or plenum and on 6 cylinders. For this to happen the ecu would be reading engine position, and controling the firing as it normally would.

 

The flywheel i believe can fit many positions, there is a mark on flywheel to say where it should go. If its wrong it can give a too early firing, symptom, then what happens is all the other sensors are trying to correct everything, so you got fuel mixtures going wrong, timing being retarded, etc. So its a knock on effect.

 

My experience of diagnostics john is always solve the basics. And look at the facts. If it was working before fine, then theres no reason it shouldnt now. Always check basics:

- Has he put oil in it?

- Has he put flywheel on properly?

- are they correct spark plugs?

- did he turn the engine over by hand to build some pressure and settle the chain?

- do a code read post codes?

- is it correct engine ie revup or non revup. (we did check this didn't we Pedro?)

 

Logically, if it worked before, then i would say its fitment fault.

"

 

 

 

So to update our list:

 

1) Rear coil packs mixed up. We think that this has been checked.

 

2) Flywheel out of alignment.

 

3) Bottom CPS: yes these often get "smacked" when changing engines due to their position. From my experience when the CPS is gone, then it won't run at all.

 

4) Oil pressure gauge used to check oil pressure.

 

5) Has he put oil in it?

 

6) are they correct spark plugs?

 

7) did he turn the engine over by hand to build some pressure and settle the chain?

 

8) do a code read post codes?

 

9) is it correct engine ie revup or non revup. (we did check this didn't we Pedro?)

[Tricky-Ricky]

First off as all the others have said, the oil pressure is in no way related to the misfire timing problem, has the mechanic used a mechanical oil pressure gauge to verify there is a real problem with the oil pressure, and not just the sender or gauge?

 

To me the diagnosis is a bit daft for a experienced mechanic as he hasn't verified that his theory of the imaginary hydrolic followers are keeping the valves open etc by at least running a leak down test!

 

Now the VVTI system not working would not cause the issues, but IF the coil packs are wired wrong it still wouldn't cause the reported issue of ALL six cylinders causing pre ignition in the the intake runners, apart form not being able to tell with a common plenum, which is why he is saying that

It would only take one coil or two coil packs to be firing incorrectly for it to look like this is happening, but he should know that anyway!

 

So has all the coil pack wiring etc been checked? as this to me sounds the likely reason, once this and the oil pressure has been double checked properly then it time to start delving deeper.

 

Now there may be good reason for your mechanics diagnosis, but so far i am not impressed.

[Tricky-Ricky]

On the flywheel alignment, i wasn't actually aware that it had a position sensor on the flywheel, just the crank sensor one on the front of the engine, i would guess that if the two cam position sensors where switched it could cause a problem, but i suspect it just wouldn't run as the system relies on correlating the crank, and cam sensors to be able to fire and fuel in the correct sequence, my first checks would be as i mentioned above.