Strange running issue 997.2 any ideas

Phil 997 · 30 Jul 2018

Myself and my Porsche tech have been struggling with a difficult to diagnose fault , car was running ok then started to missfire at revs over 3800 about where the timing values change , missing on one cylinder only, but kept moving between the cylinders and across both banks , so decided to change the 4 solenoids on the DFI engine the two top and two side ones , this improved it but during a good road test the problem returned after about 4 miles of ok running its now missing on 2,4,6, disconected the maff to see what would happen, no change problem still their so it wasnt the maff playing up. no fault codes just the check engine light on the dash. very strange , have filled up with vmax on the road test to discount a batch of crappy fuel . theres a noticable lack of power on the road test even though the engine initially was running ok until the fault returned. have considered cam solenoids but would have expected a fault code for that.
anyone had similar or can throw some ideas my way :thumb:

jonno_ · 30 Jul 2018

Sorry to hear you've got more grief Phil!

As we discussed in the 'other place' (!) I think I'd check if it needs the HP fuel pump campaign was done first.
Sounds like you've ruled out dodgy fuel, high lift solenoids, maf.

Can't be coil packs - those faults wouldn't 'move', so seems most likely to be FP to me.
Good luck sorting! - where's DeMort?

Phil 997 · 30 Jul 2018

thanks Jon, yes I am leaning very much towards HP fuel pump , it may have been replaced as theres no outstanding campaigns on my car but it may well have gone again as as its a known issue with early gen2 and has symptoms like we discussed I have it ,makes sence to investigate that next and either solve it or rule it out. :thumb: :thumb: thanks for your thought mate its a great help. dam chocolate gen2s I need another reliable gen1 :floor: :floor: :floor:

spongebob squarepants · 31 Jul 2018

Phil 997 said:
thanks Jon, yes I am leaning very much towards HP fuel pump , it may have been replaced as theres no outstanding campaigns on my car but it may well have gone again as as its a known issue with early gen2 and has symptoms like we discussed I have it ,makes sence to investigate that next and either solve it or rule it out. :thumb: :thumb: thanks for your thought mate its a great help. dam chocolate gen2s I need another reliable gen1 :floor: :floor: :floor:

Hang on I'll stop you there! On my 3rd never a single problem! Plus if there were I'd drop it at the OPC tell them to make it right I'll collect it later :grin: :hand:

jonno_ · 31 Jul 2018

How's the investigation looking?

Did you manage to get the injector correction stats?

deMort · 31 Jul 2018

Sorry young man .. im not as active as i was atm .. faults like this and you really should phone me asap :thumb:

You have changed all the solinoids .. vario cam are the top ones with high lift being the ones in the middle of the head.

Im afraid none of these was likely to be the fault .. each one only effects a single bank and each can be seen on a tester on the actual values section... gen 2 only i might add .

I take it you have a misfire on one or more cyls at higher rpm which moves to different cyls .. is that the only fault codes you have .. random misfires ?

Nothing else at all ?

Fuel pressure in this case is the most obvious but normally anything related to the high pressure pump will throw up a code .. ive not yet seen one that didnt .

Low pressure pump is possible .. i would have thought you would see a low injector pressure though .

To check you need to look at the values for the pump on idle .. your looking for about 45 bar but you also check the specified fuel with the actual .. they should be pretty much the same so you would rev the car and watch the figures .

Other things .. DFI engines do suffer from build up on the valves .. this is more a general lack of power not a misfire as such .

Your guy also needs to look at the short and long term fuel trims .. is it rich or weak at low , mid or high rpm ... Rkay , Frau or Frao .

Phone me if you want .. usual times

jonno_ · 31 Jul 2018

Ah, Iain, such a credit to this place!
Hopefully that'll help tie things up!

Phil 997 · 31 Jul 2018

spongebob squarepants said:
Phil 997 said:

thanks Jon, yes I am leaning very much towards HP fuel pump , it may have been replaced as theres no outstanding campaigns on my car but it may well have gone again as as its a known issue with early gen2 and has symptoms like we discussed I have it ,makes sence to investigate that next and either solve it or rule it out. :thumb: :thumb: thanks for your thought mate its a great help. dam chocolate gen2s I need another reliable gen1 :floor: :floor: :floor:

Click to expand...

Hang on I'll stop you there! On my 3rd never a single problem! Plus if there were I'd drop it at the OPC tell them to make it right I'll collect it later :grin: :hand:

:floor: :floor: :floor: :thumb:

Phil 997 · 31 Jul 2018

deMort said:
Sorry young man .. im not as active as i was atm .. faults like this and you really should phone me asap :thumb:

You have changed all the solinoids .. vario cam are the top ones with high lift being the ones in the middle of the head.

Im afraid none of these was likely to be the fault .. each one only effects a single bank and each can be seen on a tester on the actual values section... gen 2 only i might add .

I take it you have a misfire on one or more cyls at higher rpm which moves to different cyls .. is that the only fault codes you have .. random misfires ?

Nothing else at all ?

Fuel pressure in this case is the most obvious but normally anything related to the high pressure pump will throw up a code .. ive not yet seen one that didnt .

Low pressure pump is possible .. i would have thought you would see a low injector pressure though .

To check you need to look at the values for the pump on idle .. your looking for about 45 bar but you also check the specified fuel with the actual .. they should be pretty much the same so you would rev the car and watch the figures .

Other things .. DFI engines do suffer from build up on the valves .. this is more a general lack of power not a misfire as such .

Your guy also needs to look at the short and long term fuel trims .. is it rich or weak at low , mid or high rpm ... Rkay , Frau or Frao .

Phone me if you want .. usual times

Hi Iain, mate I was hoping you would see this , thanks for all the info I will pass it all along to my guy , they are round thurs even with PIWIS to look at fuel pressures , mixtures and all the other fuelling linked areas etc etc ,I have ordered a crankshaft sensor to try that no idea if it would help , having no codes is a pain just the missfires showing , when I get it running right what can I use to clear any build up on the valves . I will see how I get on Thursday and failing that I will give you a call mate at the usual times :thumb: :thumb:

Phil 997 · 31 Jul 2018

jonno_ said:
Ah, Iain, such a credit to this place!
Hopefully that'll help tie things up!

100% agree Jon. :thumb: :thumb: :thumb:

deMort · 1 Aug 2018

Bless you both ..

Ok .. ill do my best to remember to bring home a manual i have .. it explains a lot of the terms that your guy will be looking at on the tester .. trust me i did a similar job today on a gen 2 and i had to reference a lot of the readings as to what they actually mean ..

Your guy will know what i mean !!

That way you can phone me if needed .

Tell him to run the short test section .. its only fuel load at partial load he cant do unless the car is driven .. all the others can though .

Theres one reading but i cant dam well remember atm that needs checking .. H20 or H 30 i think .. its about how the engine is adapting over all .. ill have to look it up tomorrow .

Unfortunatly there is an awfull lot of things the car tells us with a tester .. but understanding them all and knowing what the proper base setting should be confuses me and i guess many of us Mechs .. hence i need my manual

btw .. i got a new phone .. one of these smart phone things .. video calling .. would that work to show me pictures of the tester and readings on it ?

Yup .. im not into phones that much .. i just thought they made phone calls !

Phil 997 · 1 Aug 2018

Thanks Iain hes round after work tommorow , I will show him everything you have suggested and if hes stuck I will call mate :thumb: thanks again for all the info and suggestions :thumb:

Phil 997 · 3 Aug 2018

update,
Today changed the crankshaft sensor as it was the last of the easy things to try, still no luck running lumpy even on low revs , the guy with the piwis was a no show so decided to take it to the OPC for two hours of diagnostics to try and fathom the issue , drove the car to the OPC only a couple of miles and stayed in low revs it ran lumpy but go there ok. OPC have phoned they have checked the oilfilter and see shiney metalic film in the filter , the oil and filter were only changed monday and it has a magnetic sump plug . so it seems the issue may be mechanical they want to open it up and check the tappets, valves etc as they suspect one may be breaking up. they are going to have to open it up to find what the metalic bits are. logically the sort of sticky tappet noise it makes from time to time may be the culprit.
Its very difficult to diagnose a missfire when its random across both banks and there are no fault codes and also frustrating as I feel like I keep spending money without a definitive diagnosis .Even the OPC are saying they cannot be sure it tappets but they do need to find whats happening and the only way seems to be to open it up . Three engine drops since the new year is starting to take the piss though, but if I am to regain confidence in this car I need to get to the bottom of it. :nooo: updates to follow :thumb:

FRZ 911 · 3 Aug 2018

Phil, you're definitely having no luck at all. Hopefully this will be the last issue for a while and you can get back to enjoying the car. All the best fella.

Phil 997 · 3 Aug 2018

FRZ 911 said:
Phil, you're definitely having no luck at all. Hopefully this will be the last issue for a while and you can get back to enjoying the car. All the best fella.

Thanks Frank , me too . I can see the bill for this year another few grand taking to over 10k this year which is a bit dishartening after all the singing of how good these cars are lol. but on a positive note if they can sort it without to much extra cost my ave during 911 ownership excluding mods will still only under £2500 pa as an ave. its just one of those ave where there was not much in the first few years with the gen1 and a big hit all together with the gen2 so fingers crossed after this episode it will be trouble free for a couple of years bringing my ave back down to 2k pa. which to be honest isnt bad for driving a car like the 911 . if you count the 3k profit I made selling the gen1 actually my ave is still around 2k PA .thats my man maths equation but doesnt stop my bank manager frowning at me this year :grin: :grin: :grin:

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