Miss firing on bank 1.2.3

[Geoffcollyer]

Any got any idea what’s wrong on boxster 986  2.5 thanks 

[Paul P]

Guesswork.  Since I have no 1st hand knowledge of the 2.5 engine. 
 

but something affecting all of one bank seems to point to something cam related so maybe variocam actuator (if the 2.5 has that) or cam chain tensioner. 
 

I am sure someone with more knowledge of that particular engine will be along soon with some more specific info. 

[edc]

Any yellow CEL? What other symptoms or codes are there? Not a lot to go on from what you write. Unlikely that all coilpacks go at the same time. If it's 1 bank then possibly can solenoid? 

[Geoffcollyer]

Engine management light is on as well 

[edc]

If the CEL is on then the best thing is to get the codes read then cleared. 

[Geoffcollyer]

Ok thanks 

[Steve Laming]

36 minutes ago, edc said:

If the CEL is on then the best thing is to get the codes read then cleared. 

Codes P300, P301,  P302, P303.

I'm Geoff's neighbour, I cleared the CEL earlier today and upon restart it was ok...........for 20 seconds, then back on again.

Leaning on the roll hoop and top of windscreen, you can "feel " the missfire.

ePorsch, I think Geoff.

Unless @TROOPER88 is available ?

Cheers,

Steve.

 

 

[TROOPER88]

Thanks Steve but I am super busy.

Those codes are ignition related and in this case related to one bank only and as such it is most likely the variocam solenoid,

 

Paul

[Steve Laming]

A bit more info on this subject.

Leading up to the CEL on the dash, Geoff filled up with petrol from an ASDA fuel station. It was as he was putting the fuel pipe back, he noticed it was the new E10 fuel. Upon start up, the EML appeared. He called me and I suggested calling in on the way home to a Shell station and top off the tank with V Power.

When he got home, I connected my code reader and it came up with multiple misfires. The codes, as mentioned before were P0300, P0301, P0302, P0303. I cleared the codes but the EML came back on 20 seconds or so after re-starting the engine.

A call to a local indy suggested that the fuel was not the fault as these models should run on them and the Porsche website suggests pre 1996 cars ie 993, 968, and 928 would be more affected.

A call to an OPC was greeted with a possible 24 hours labour charge !!!!!!!!!

Geoff took the car to a local garage with an ex OPC technician yesterday and he read and reset the codes. Again same codes, pointing to one bank miss fire. Possible variocam sensor issue (as Trooper88) said.

This time EML stayed off.

Geoff drove home and car is still good.

I have suggested doing about 40-50 miles today and refilling with V Power again to dilute whats in the tank.

So, is it a co-incidence that the EML light came on, or as research on Supermarket fuels shows, they have different additives when compared to BP, Shell etc.

Keep you posted !

PS Geoffs car is a 1999 2.5L model.  Fuel flap, only suggests 98RON be used. 

[½cwt]

If not variocam, O₂ sensor could be another other bank specific misfire cause.

[the baron]

2 hours ago, ½cwt said:

If not variocam, O₂ sensor could be another other bank specific misfire cause.

I had the same issue a couple of years back, immediate thought and diagnosis was variocam which is an expensive fix.

Took it to Lee and CPS to actually do the variocam and he diagnosed it as O2 sensors, an hour later I was back on the road with more cash in the bank than I had expected that day.

[Boxstclever]

I would have thought that if it was related to the fuel it would be showing codes for both banks.  

Another vote for cam solenoid or O2 sensor.

[Steve Laming]

8 hours ago, Boxstclever said:

I would have thought that if it was related to the fuel it would be showing codes for both banks.  

Another vote for cam solenoid or O2 sensor.

Yes, I was thinking the same re fuel issue should affect both banks.

I had an O2 sensor go on mine a couple of months ago. It struggled to run properly and a really bad misfire. Almost stalling at junctions. Geoff's isnt like that, so perhaps it points to the cam sensor afterall.

As an aside, I went to fill the Cayman up at my local Shell station this afternoon. Their normal unleaded now shows E10 on the pumps, with V Power on E5.

[GmanB]

Not sure if it's related but the government website says:

Porsche

E10 petrol is cleared for use in Porsche vehicles with petrol engines since the 1998 model year and all Boxster models with petrol engines since the 1997 model year.

The Carrera GT is not cleared for use with E10 petrol.

https://check-vehicle-compatibility-e10-petrol.service.gov.uk/manufacturer/Porsche

Glad I didn't buy that Carrera GT last year....! 

 

[Natplant]

I had same fault codes on my 2.5, it was the 02 sensor, replaced with a new Bosch one, two months later other side one went same symptoms. Not too expensive to remedy but would advice you do both. 

[CRC]

I have an ongoing occasional issue with those misfire codes coming up every now and again, though for some reason they haven't come on for a few months now, so fingers crossed.

O2 sensors were changed a couple of years ago when I changed the catalytic converters, but made no difference to the frequency of the codes coming up ( which can happen several times in a few days or can go months without coming up - very random).

The codes come up because the ECU times how long the crankshaft sensor takes to get to a certain point, and if it appears slow, it logs that in a cumulative counter and when the values get to certain number, it puts the codes on - always cylinders 1,2 and 3 in my case.

The engine runs sweet as a nut and revs very cleanly with no hint of a misfire throughout the rev range.

One thing I did notice while investigating the electrical wiring diagram, was that the three coil packs on cylinders 1,2 and 3 are all grounded at a single ground point on the engine. Cleaning up that ground point may be all it takes to solve the problem, though to my shame, I've never actually managed to find it, despite looking from the top, bottom and side with a torch. It must be there somewhere!!

 

 

[edc]

Is it the crank sensor itself that may be causing the issue? 

[CRC]

I wouldn't have thought it was the crank sensor as the fault always comes on 1,2 and 3 and never on 4,5 and 6.

Also, I would have thought that if it was intermittently failing, the engine timing would be all over the place.

[cdm]

I had the same problem with my 2.7. I tried replacing coilpacks, plugs, and O2 sensors without success. It was - and still is - the cam solenoid, but it can be managed.

The codes are generated on start-up after a fixed delay (maybe 30 sec) at that point the cam solenoid should be switched to 'low rev' mode and if it doesn't, the ECU begins to count the misfires until it reaches a set point and then the CEL light comes on. The engine will run great in the upper rev ranges since that is where the solenoid is stuck. It seems that the solenoid is actually fine, the problem is with the oil valve that it drives in the head to move the cam timing. Clearing the CEL will work only until the next start-up.

Three things have helped to address this for me. The first was an oil change using the mega expensive Porsche classic oil (perhaps this was important I'm not entirely sure). The second is to let the car run at idle for a little longer when parking up after a run. This seems to let the oil valve settle back into the low rev mode when the oil is hot. The third was to hold it on fast idle with the accelerator on the next start up, drive off immediately and don't let the revs drop too low until the engine has warmed through.

Worth a try before considering spending £££££ in labour charges to replace it. I think the newer generation of engines have a much more accessible solenoid but not this type.

[CRC]

That's interesting.

So does that mean that if the solenoid is stuck, that both banks of cylinders will be in "upper rev range mode", or are there two solenoids, one for each bank of three. On mine, when the CEL light does come on (which is rarely now thankfully) it does tend to be soon after starting the car to return from somewhere so it has been in true "upper rev range mode" for at least part of the journey to that place.

Strange that everyone seems to mention misfires on 1,2 and 3, never misfires on 4,5 and 6?

 

[Paul P]

8 minutes ago, CRC said:

That's interesting.

So does that mean that if the solenoid is stuck, that both banks of cylinders will be in "upper rev range mode", or are there two solenoids, one for each bank of three. On mine, when the CEL light does come on (which is rarely now thankfully) it does tend to be soon after starting the car to return from somewhere so it has been in true "upper rev range mode" for at least part of the journey to that place.

Strange that everyone seems to mention misfires on 1,2 and 3, never misfires on 4,5 and 6?

 

One solenoid per side as far as I know.  and if there is an issue it could be the Solenoid or the thing. The solenoid operates ( the actuator ) I think you can separate the two components. 
 

One of the diagnostic approaches I read once was to swap them side to side to see if the problem remains.  
 

[CRC]

Yes, you're right, there is one solenoid and one actuator per side, so a sticky actuator could be the issue, and a "detergent oil" might just solve the problem.

When I bought the car, the CEL wasn't on and the old boy I bought it from wouldn't have had the know how to clear fault codes, but it was running on 0W-40 synthetic oil. I changed the oil to 5W-40 synthetic, so maybe the slightly more viscous oil had some effect

 

Edited September 8, 2021 by CRC

[Boxstclever]

On 9/8/2021 at 11:05 AM, Paul P said:

One solenoid per side as far as I know.  and if there is an issue it could be the Solenoid or the thing. The solenoid operates ( the actuator ) I think you can separate the two components. 
 

One of the diagnostic approaches I read once was to swap them side to side to see if the problem remains.  
 

Unfortunately, I don't think they are interchangeable, and it certainly wouldn't be an easy job if they were.  You need to remove the Cam cover to get them off.  The only way to "swap" them over would be to swap the loom over, but as they don't reach, it would require making up adapter harness'.

 

They can be read and scoped by a competent technician with the right scan tools and oscilloscope.  This should show if it's the solenoid or the actuator.

 

[CRC]

I checked the old invoices for my car as I seemed to remember something about a variocam fault, and sure enough, back in 2011 when the car had done 74,000, a main Porsche dealer identified Bank 1 vario cam faults present along with the words

"On starting, loud bang from O/S/R wing and smoke coming from O/S/R wheel arch area. Vario cam has been disconnected and blows fuse when reconnected. Requires new unit".

The unit was then changed by a Porsche specialist a couple of weeks later and £1250 + VAT - 11 hrs labour and £600 for the adjuster and solenoid.

I was aware of how the V-tech system works on a Honda, but had no idea how the Porsche system worked, so looked it up and found the following.

On each  bank of three cylinders, there is one exhaust cam shaft and one inlet cam shaft.

The exhaust cam shaft is driven by a chain from the intermediate main shaft, which is in turn driven by the crank shaft.

The inlet cam shaft is driven by a chain from the exhaust cam shaft, and all the vario cam system does is to actuate a solenoid valve that allows oil pressure to enter a piston that effectively alters the tension of the inlet to exhaust chain, ie, it presses the chain guide upwards or allows it to fall backwards, which apparently has the effect of advancing or retarding the opening of the inlet valves.

I find this a little difficult to understand as the number of chain links between the two sprockets must remain a constant, but apparently it does, and I can certainly feel when it cuts in on when as there is a "step change" in performance at around 4-4.2k rpm.    

[Paul P]

5 minutes ago, Boxstclever said:

Unfortunately, I don't think they are interchangeable, and it certainly wouldn't be an easy job if they were.  You need to remove the Cam cover to get them off.  The only way to "swap" them over would be to swap the loom over, but as they don't reach, it would require making up adapter harness'.

 

They can be read and scoped by a competent technician with the right scan tools and oscilloscope.  This should show if it's the solenoid or the actuator.

 

OK - must have been a different model - it's described here and looks like it's accessible without removing cam covers. But that is a 987.

 https://aldousvoice.com/2017/03/10/porsche-987-variocam-solenoid/

Wonder how many workshops have an oscilloscope.