phazed Posted April 27 Report Share Posted April 27 Just completed the above using parts that I purchased from Nitro V8. Pleased with the install. Car started easily, idled fine so took a test drive. Drives nicely with plenty of 2-3K midrange torque to push along surprisingly rapidly with short shifts. Delivery over 3K induces stuttering which is worse at larger throttle openings and will rev while stuttering. Sounds like one major problem and reading through the, “ fitting 987 airbox” thread I believe Map stated that the silicon pipe work can collapse. I have a silicone elbow attached to the TB and wondered if it is possible that this is collapsing? Any thoughts on this or any other ideas? Quote Link to comment Share on other sites More sharing options...
phazed Posted April 27 Author Report Share Posted April 27 an image of the installation. Anything obvious? Quote Link to comment Share on other sites More sharing options...
phazed Posted April 27 Author Report Share Posted April 27 I did have a gentle rev in the garage while looking at the elbow and taking it up to 4K revs and there wasn’t any deflection on the elbow at all. In fact, there is a little bit of slight hesitation at lower revs which wasn’t there before. I realise that under load there will be more vacuum, but would’ve thought if there was any problem with the elbow, it would have shown some deflection even stationary Just wonder if I should change the MAF which came with the kit of parts for my original one? Quote Link to comment Share on other sites More sharing options...
BBB Posted April 27 Report Share Posted April 27 You could unplug the MAF and see if it runs better. I think it goes onto a default map when you do that (someone will be long soon to add more details I’m sure). That would allow you to check the MAF health. Quote Link to comment Share on other sites More sharing options...
phazed Posted April 27 Author Report Share Posted April 27 Good idea. I have a couple of hours free in the morning so will get onto that and any other suggestions. I might as well and after I have done that change the MAF for the one that I had recently renewed that was in the car with the old 986 airbox. Quote Link to comment Share on other sites More sharing options...
map Posted April 27 Report Share Posted April 27 Looking at the photo I’d be surprised to see the elbow collapsing - it isn’t as long as the one I referenced. Have you had a chance to fully check for any air leaks in the system? You’ve had a lot of that sub-system apart so it’s not inconceivable something’s not quite as it should be. Quote Link to comment Share on other sites More sharing options...
phazed Posted April 27 Author Report Share Posted April 27 I’m pretty certain there aren’t any air leaks. I was extremely careful putting it all back together, and in fact, replacing a few connections which looked old and perished. Doesn’t really feel like an air leak with the continual stuttering when accelerating. Quote Link to comment Share on other sites More sharing options...
bally4563 Posted April 28 Report Share Posted April 28 12 hours ago, phazed said: I’m pretty certain there aren’t any air leaks. I was extremely careful putting it all back together, and in fact, replacing a few connections which looked old and perished. Doesn’t really feel like an air leak with the continual stuttering when accelerating. I wonder if you have damaged one of your injectors ? Quote Link to comment Share on other sites More sharing options...
bally4563 Posted April 28 Report Share Posted April 28 Just now, bally4563 said: I wonder if you have damaged one of your injectors ? If so I have a new one knocking about Quote Link to comment Share on other sites More sharing options...
phazed Posted April 28 Author Report Share Posted April 28 Hi Mick. I would’ve thought it was quite difficult to damage an injector although not impossible. They all stayed in position pretty much apart from one where I removed and replaced an O ring. The engine runs up to approximately 3K very smoothly without any stutter or missing at all. It is only when you push on from 3K that it starts playing up, hesitating and stuttering. just need to walk the dogs and then I will try what has been suggested above and replace the MAF. Quote Link to comment Share on other sites More sharing options...
pacificjuha Posted April 28 Report Share Posted April 28 (edited) Isn't the 3K rpm close to the rpm when Variocam activates? If yes, then this issue could be related to the Variocam operation - are the electric wire pugs to Variocam solenoids well connected on both sides? Edited April 28 by pacificjuha Quote Link to comment Share on other sites More sharing options...
phazed Posted April 28 Author Report Share Posted April 28 I will check. Without sounding too much like an idiot, whereabouts are they connected? Things have moved on. Changed the MAF for another I had and test drove to my son’s garage/workshop. Car went that much better but not absolutely perfectly in my opinion. Put his code reader on and it came up with oxygen sensing adaptation, lower load range, bank two and the same for bank one. Cleared faults. Started car up and I could hardly get it to idle as it was popping and banging all over the place. Removed the plug to the MAF which made it run slightly better but still badly, good enough to drive a few miles home. Consoling myself with a cup of coffee and a couple of crumpets and I will put the original/original MAF back in and see what happens. If those fault codes were from the new O2 sensors that I have fitted, all four. Does that mean I have to go to someone, with more in-depth code reader to reset parameters? Quote Link to comment Share on other sites More sharing options...
BBB Posted April 28 Report Share Posted April 28 I haven’t been following your build thread, but I have read that some lambda sensors need extensions or 90 degree elbows fitted once you start messing with exhausts and also perhaps throttle bodies? Quote Link to comment Share on other sites More sharing options...
phazed Posted April 28 Author Report Share Posted April 28 It has four new O2 sensors. They fit and connect fine. Just to recap. Car was running fine with a recently replaced MAF and the 4 x 02 sensors. Fitted the 74 mm throttle body, pipework, larger plenum and 987 airbox. Car ran well up to about 3K with what seemed more torque in that area. After 3K it started stuttering but you could drive through it to the red line. Fitted the previous Bosch MAF and car seemed to run better but not completely perfectly. Drove to son’s workshop, connected his code reader and the car threw up the codes listed in the original post. I think this is spurious as they may well have been logged from before I renewed the O2 sensors with the new exhaust. Cleared the codes and then the car ran absolutely terribly, so bad, popping, missing and not revving that you couldn’t drive it. Had to disconnect the MAF and drove it home with a car still running rough as I guess that the default setting was for the original smaller throttle body et cetera and with the 74 mm throttle body it didn’t run well. Changed the MAF, disconnected battery to reset and car runs so badly that you couldn’t drive it. No codes logged up at the moment as I believe that you have to drive it for a while for them to register. So it isn’t the MAF and certainly shouldn’t be the O2 sensors. Strange that deleting the codes instantly made the car run terribly… I am at a bit of a loss at the moment… Quote Link to comment Share on other sites More sharing options...
½cwt Posted April 28 Report Share Posted April 28 (edited) The bad running sounds like when my MAF had failed and when teh codes were cleared. seems like it was only running on 3, 4 or 6 cylinders never all 6 when it would run. Replacement (2nd hand) MAF solved, ending 986 606 125 01 or Bosch 0 280 218 055. That said no fancy changes to the induction system like on yours. I'd be amazed if it was lambda related as they are new and if affects both banks which means at least 50% of the new ones are defective. You have also fitted new pipework that they tread into I believe. Some people have said they fitted a 90° spacer to move the sensor back from the exhaust flow a bit more. Are the lambdas OE (up to '02 MY, 986 606 126 01 or 986 606 226 00 '03 onwards) or or Bosch (0 258 003 806 to '02 or 0 258 006 506 '03 onwards)* or another brand? * Bosch also do two other compatible 'universal' versions with a loom adapter kits 0 258 986 505 up to '02 and 0 258 986 602 for '03 onwards. Edited April 28 by ½cwt Quote Link to comment Share on other sites More sharing options...
phazed Posted April 28 Author Report Share Posted April 28 Thanks for your insight. lambda sensors are pattern ones but good quality that were sourced through my sons parts supplier. He is very much on the ball and doesn’t supply rubbish. That said, it is running so rough you couldn’t even pull away from the curb! It must be something simple. It runs better with the MAF disconnected, but still not good but I think that is because it now has a different throttle body on it and the default setting is for the 68 mm throttle body, well that is my theory! Just spent some time checking all breather hose connections, jubilee bands, around the rubber sleeves and anything else that is visible. It is just so strange that it ran perfectly okay on the 68 mm throttle body and then ran OK but with the stuttering above 3K and now after the faults were cleared, it hardly will run at all! Quote Link to comment Share on other sites More sharing options...
bally4563 Posted April 28 Report Share Posted April 28 You have a air leak check the bellows to the Plenum,it can be difficult to ensure they are fastened correctly, certainly under neath where you can’t see , I had similar symptoms some years ago 1 Quote Link to comment Share on other sites More sharing options...
TROOPER88 Posted April 28 Report Share Posted April 28 I do not get involved in the mods whatso ever but what I will say is that the 02 sensors should be Bosch. I had a 986 in the workshop on Wednesday and the issue was the heating element in one of the 02 sensors; I found a break in the wiring harness; it was not a quality part. You could smoke test it as Bally maybe on the right lines with air or vacuum leak. Quote Link to comment Share on other sites More sharing options...
phazed Posted April 28 Author Report Share Posted April 28 That’s what I thought Mick. I have just been around all 8 clamps making slight adjustments and ensuring that they are properly clamped down on the plastic tube. All seem to be good. It certainly does sound like a large air leak. Again, it may be just a coincidence but why has it suddenly decided to run so badly when I cleared the codes? Out of frustration, I just changed the MAF sensor again to unknown good one and it is exactly the same. Do I need someone with a proper Porsche capable code reader? Quote Link to comment Share on other sites More sharing options...
phazed Posted April 28 Author Report Share Posted April 28 2 minutes ago, TROOPER88 said: I do not get involved in the mods whatso ever but what I will say is that the 02 sensors should be Bosch. I had a 986 in the workshop on Wednesday and the issue was the heating element in one of the 02 sensors; I found a break in the wiring harness; it was not a quality part. You could smoke test it as Bally maybe on the right lines with air or vacuum leak. I hear what you are saying and it wouldn’t be the first time that an electronic/electric part has failed. Would it really upset the running that much if one of the O2 sensors failed? It really is undrivable. Quote Link to comment Share on other sites More sharing options...
bally4563 Posted April 28 Report Share Posted April 28 7 minutes ago, phazed said: I hear what you are saying and it wouldn’t be the first time that an electronic/electric part has failed. Would it really upset the running that much if one of the O2 sensors failed? It really is undrivable. My Money Peter still is a big air leak, I remember when I had the your RS 60 and tried a IPD plenum which was SO ! Unsuccessful, put the original Plenum back on and it ran with the symptoms you are describing, as I had a air leak , but it was the bellows , re Lamba sensors , you generally just get a CEL warning, never found when its happened car ran like a bag of shyatee Quote Link to comment Share on other sites More sharing options...
phazed Posted April 28 Author Report Share Posted April 28 Thanks for that Mick. I tend to agree with you that it sounds like a large air leak. I think I will remove them tomorrow and reset them even though I’m not that optimistic but worth a try. As for the joining tube with the flap inbetween the manifolds. It has only the small vacuum tube that goes to the underside, doesn’t it? Quote Link to comment Share on other sites More sharing options...
bally4563 Posted April 28 Report Share Posted April 28 1 hour ago, phazed said: Thanks for that Mick. I tend to agree with you that it sounds like a large air leak. I think I will remove them tomorrow and reset them even though I’m not that optimistic but worth a try. As for the joining tube with the flap inbetween the manifolds. It has only the small vacuum tube that goes to the underside, doesn’t it? Yes , but I have run with disconnected didn’t make any difference, I reckon that one of the Plenum tubes is on but folded under , but underneath where you can’t see , I do hope I’m right, as said previously mine ran terrible, and I couldn’t see anything wrong, just revisited work I had done Quote Link to comment Share on other sites More sharing options...
phazed Posted April 28 Author Report Share Posted April 28 👍 Quote Link to comment Share on other sites More sharing options...
Randeep Posted April 29 Report Share Posted April 29 Mine ran like a bag of spanners when one of the silicone connectors fell off due to a plastic tube between the elbow and MAF rubber, changed this to aluminium that was the correct size and it worked well. I also have silicone reducers for the plenum to make sure the fit is tight, are you using the original rubber connectors? Quote Link to comment Share on other sites More sharing options...
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