Gramps Posted April 4, 2023 Report Share Posted April 4, 2023 Hi All. Further to one of my recent posts where if I left my my 987.2 Boxster S (2011) for a few days to a week it would crank for a long time then be very lumpy on starting I've tried cleaning the MAF as suggested but I've still got the issue. The car will run fine once started and starts fine the next day, though it still takes quite a few cranks. Having done futher googling I'm wondering if it may be the fuel pump. I was getting error codes saying bank 1 and 2 lean, hence the MAF was suspected, but could they also be due to a low fuel pressure.? It seems early 987.2s had their pumps changed by Porsche, mines a 2011. I looked at the live data using my iCarsoft and it was showing about 660PSI fuel rail pressure and 42% Fuel Level Input. Can't seem to find what they should be. Can anyone here throw any light on it? Any advice more than welcome. TIA Gramps Quote Link to comment Share on other sites More sharing options...
½cwt Posted April 4, 2023 Report Share Posted April 4, 2023 @Richard Hamilton ? Quote Link to comment Share on other sites More sharing options...
John2000 Posted April 4, 2023 Report Share Posted April 4, 2023 (edited) 1 hour ago, ½cwt said: @Richard Hamilton ? I bet Richard loves you? Edited April 4, 2023 by John2000 Quote Link to comment Share on other sites More sharing options...
The Caped Crusader Posted April 4, 2023 Report Share Posted April 4, 2023 Quote Link to comment Share on other sites More sharing options...
½cwt Posted April 4, 2023 Report Share Posted April 4, 2023 2 hours ago, John2000 said: I bet Richard loves you? He is a mine of info and usually very willing to help. I might be wrong but I think he likes the challenge of solving problems. 2 Quote Link to comment Share on other sites More sharing options...
Gramps Posted April 4, 2023 Author Report Share Posted April 4, 2023 4 hours ago, ½cwt said: He is a mine of info and usually very willing to help. I might be wrong but I think he likes the challenge of solving problems. You're right. Richard has been there before for me re my PCM3 🙂 Quote Link to comment Share on other sites More sharing options...
Gramps Posted April 4, 2023 Author Report Share Posted April 4, 2023 5 hours ago, The Caped Crusader said: Sadly mine is a cold start issue after left standing for a few days 👍 Quote Link to comment Share on other sites More sharing options...
Gramps Posted April 4, 2023 Author Report Share Posted April 4, 2023 Thanks to all for inputs so far. Does anyone have any running or ignition on only figures? 🙂 Quote Link to comment Share on other sites More sharing options...
iborguk Posted April 4, 2023 Report Share Posted April 4, 2023 What were the actual error code numbers thrown ? Quote Link to comment Share on other sites More sharing options...
Gramps Posted April 4, 2023 Author Report Share Posted April 4, 2023 2 hours ago, iborguk said: What were the actual error code numbers thrown ? Hi @iborguk, not had any codes that relate directly to the HPFP. From rooting around the forums it seems some don't get any codes at all and some do. I think the codes I've got so far were P0171 & P0174 (banks 1 & 2 lean), and P1094 which refers to the MAF. I've cleaned the MAF (as best I can) a couple of times and it hasn't made a great deal, if any, difference. I also don't see how the MAF would cause it to crank so much before starting, of it being very lumpy once it catches (when cold after standing a few days), whereas fuel pressure seems to make more sense??? Appreciate any advice. Cheers Gramps Quote Link to comment Share on other sites More sharing options...
iborguk Posted April 5, 2023 Report Share Posted April 5, 2023 Hi, OK so nothing logged re fuel pressure too low/high logged although I acknowledge you're saying others have not had anything logged re the HPFP. Your rail value of 660 PSI equates to 45.5 bar. I don't know the expected value ranges there although someone with a working car might be able to compare for you. Given the codes thrown and the engine hesitation to start I'm thinking vacuum leak. I can see in your other MAF thread @Paul P mentioned AOS, which is a common faulting component, which can cause vacuum leaks. One test for a failing AOS is the inability to easily remove the oil cap with the engine running. Quote Link to comment Share on other sites More sharing options...
Gramps Posted April 5, 2023 Author Report Share Posted April 5, 2023 6 hours ago, iborguk said: Hi, OK so nothing logged re fuel pressure too low/high logged although I acknowledge you're saying others have not had anything logged re the HPFP. Your rail value of 660 PSI equates to 45.5 bar. I don't know the expected value ranges there although someone with a working car might be able to compare for you. Given the codes thrown and the engine hesitation to start I'm thinking vacuum leak. I can see in your other MAF thread @Paul P mentioned AOS, which is a common faulting component, which can cause vacuum leaks. One test for a failing AOS is the inability to easily remove the oil cap with the engine running. 👍thanks for your input. Not looked into AOS much yet but do they cause some smoking when they are failing? Not got any smoke, thankfully. I'll try the oil cap removal in the meantime. Re vacuum leak, I only get the issue starting from cold when the engine has rested for a few days. Could it be a case there should be some residual vacuum somewhere that loses over time? Cheers...Gramps Quote Link to comment Share on other sites More sharing options...
iborguk Posted April 5, 2023 Report Share Posted April 5, 2023 6 minutes ago, Gramps said: 👍thanks for your input. Not looked into AOS much yet but do they cause some smoking when they are failing? Not got any smoke, thankfully. I'll try the oil cap removal in the meantime. Re vacuum leak, I only get the issue starting from cold when the engine has rested for a few days. Could it be a case there should be some residual vacuum somewhere that loses over time? Cheers...Gramps They don’t always smoke. I had one fail on my 987.2 and it caused the MAF /ECU to have a fight and caused my PDK to drop into emergency transmission mode (took a little while to figure that one out). Quote Link to comment Share on other sites More sharing options...
gillbe Posted April 5, 2023 Report Share Posted April 5, 2023 How about - Damp getting into cracked coil packs, causing long start then lumpiness until dried out. Then ok until left long enough for damp to get in again? No idea really, but having just bought a new set of packs for my 2.9, I’m hoping they will cure a slight lumpiness I feel initially on using the car after being left a few days… Quote Link to comment Share on other sites More sharing options...
iborguk Posted April 5, 2023 Report Share Posted April 5, 2023 (edited) Wouldn’t hurt (other than the wallet) to refresh them if old although those codes seem to say fuel mix to me (and happy to be schooled otherwise.) Edited April 5, 2023 by iborguk 1 Quote Link to comment Share on other sites More sharing options...
Gramps Posted April 5, 2023 Author Report Share Posted April 5, 2023 9 hours ago, gillbe said: How about - Damp getting into cracked coil packs, causing long start then lumpiness until dried out. Then ok until left long enough for damp to get in again? No idea really, but having just bought a new set of packs for my 2.9, I’m hoping they will cure a slight lumpiness I feel initially on using the car after being left a few days… Thanks for your input. My initial thought was maybe plugs/coil packs. Plugs were replaced just before got the car so done about 12k, not sure if the coil packs have been changed at any stage. If the issue is still ongoing come some decent dry weather it may eliminate that possibility. But error codes seem to poin to a common problem affecting both banks (P0104 & P0107, banks 1 & 2 too lean) so fault would appear to be common to both sides, ie in the input side. But possiblity not rulled out 👍 Quote Link to comment Share on other sites More sharing options...
iborguk Posted April 5, 2023 Report Share Posted April 5, 2023 How'd the oil cap test go ? Quote Link to comment Share on other sites More sharing options...
Gramps Posted April 5, 2023 Author Report Share Posted April 5, 2023 Anyone out there got any figures for fuel pressure when cold prior to start, ie just ignition on then same figure once it's fired up? Be interesting to see how they compare with mine. went to start it from cold tonight and my fuel rail pressure was about 150psi with ignition on, when statrted it rose to about 1100psi at fast idle, about 1100 rpm, then dropped down to 660psi or so when the tickover dropped. I also had all 3 error codes appear again, banks 1 & 2 too lean and P1094 ( Implausible Mass Air Flow Ahead Of Throttle Valve) Quote Link to comment Share on other sites More sharing options...
Gramps Posted April 5, 2023 Author Report Share Posted April 5, 2023 28 minutes ago, iborguk said: How'd the oil cap test go ? Ah. got wrapped up in checking the "from cold" figures, videoing start up and the like. Meant to do the oil cap test, will go back out and try now 🙃 Quote Link to comment Share on other sites More sharing options...
Gramps Posted April 5, 2023 Author Report Share Posted April 5, 2023 36 minutes ago, iborguk said: How'd the oil cap test go ? @iborguk Well, what do uo know?? started the engine and ticking over lumpy. Went to the boot to check the oil filler cap and could hear a hissing (vacuum leak). The oil cap was not fully tightened. Tightened it up, hissing went and engine no longer lumpy YAY! Came back inside feeling happy then realised I hadn't actually tested the cap removal, did so and it was easy to remove so presumeably the AOS is ok and the loose cap may at least be a cause of the lumpiness. Not sure about the prolonged cranking still. Will try again tomorrow when the engine is cold again. But a step in the right direction 🙂 1 Quote Link to comment Share on other sites More sharing options...
iborguk Posted April 5, 2023 Report Share Posted April 5, 2023 Nice. Clear any active stored codes and see if they come back. Quote Link to comment Share on other sites More sharing options...
Gramps Posted April 5, 2023 Author Report Share Posted April 5, 2023 1 minute ago, iborguk said: Nice. Clear any active stored codes and see if they come back. I did clear them earlier but will go out and double check all clear and give it a go tomorrow. Will be weird if a "not fully tightened oil cap" was the cause of those starting issues as not something I'd ever have considered, but grateful if it was 🤣 Will post results tomorrow Quote Link to comment Share on other sites More sharing options...
iborguk Posted April 5, 2023 Report Share Posted April 5, 2023 6 minutes ago, Gramps said: I did clear them earlier but will go out and double check all clear and give it a go tomorrow. Will be weird if a "not fully tightened oil cap" was the cause of those starting issues as not something I'd ever have considered, but grateful if it was 🤣 Will post results tomorrow Let's see but again a vacuum leak will not help the fuel mix. 🤞 1 Quote Link to comment Share on other sites More sharing options...
iborguk Posted April 6, 2023 Report Share Posted April 6, 2023 How’d you get on ? Quote Link to comment Share on other sites More sharing options...
Gramps Posted April 6, 2023 Author Report Share Posted April 6, 2023 3 hours ago, iborguk said: How’d you get on ? @iborguk @Paul P I tried it an hour or so ago with the engine cold having sat overnight. Checked fuel rail pressure with just ignition on and it was 66psi. Videoed the start and it seems to crank over about 4 times but once it fired it was no longer lumpy, having a cough and a splutter like it was, so that's good. Still cranked over a little more than i'd like but I don't know what the average number of cranks for others on the same car might be but some say once the HPFP was changed theirs was starting on the button. I videoed the screen of my iCarsoft during the start and you see the pressure rise to approx 1100psi on fast idle, about 1100rpm. Paul kindly sent me over some test material for the fuel pump (thanks Paul) but having gone through it it only seems to relate to the low pressure pump in the tank, not the HPFP, but one item of note was that with ignition on but not running it quotes the pressure for the LPFP as 4 bar, which equates to 58psi, so close to what the HPFP reading is with ignition on. So there may be some relationship there in those pressures. Hopefully someone will come up with some good figures for their car so I can see where mine lies. But I'm a lot happier to be rid of that lumpy starting so thanks for the help from all. I can live with the longer cranking time, but would be nice to see if I can get it starting on the button, although if that means changing the HPFP at what seems to be nudging a grand I can live with it, for now anyway . 🙂 ps, I was going to "@" 1/2cwt but I can't seem to get the system to recognise him? 1 Quote Link to comment Share on other sites More sharing options...
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