phazed Posted April 29 Author Report Share Posted April 29 Yes, using the original rubber connectors which fit very well, tightly and snuggly. Have the T piece plenum and throttle body off at the moment as have just been checking all the pipework underneath. All looks sound and I couldn’t find any rubber sleeve that wasn’t seated properly. Will put it all back together again shortly and try again. Quote Link to comment Share on other sites More sharing options...
½cwt Posted April 29 Report Share Posted April 29 Have you run a throttle body reset? Switch ignition on but don't start for a minute and it goes into a calibration routine IIRC. Quote Link to comment Share on other sites More sharing options...
bally4563 Posted April 29 Report Share Posted April 29 Have you used the 986 MAF ? If you have used the 987 MAF apparently can give a world of hurt , I did the same job on my first 986 TB air box etc with no issues but using the 986 MAF Quote Link to comment Share on other sites More sharing options...
phazed Posted April 29 Author Report Share Posted April 29 Update. Spent several hours dismantling everything that I have touched to carry out the 74 mm throttle body upgrade. Didn’t touch the manifolds this time as they are bolted firmly in position. All hoses were connected although I had put the rubber sleeve that takes the vacuum pipe, on the forward rubber joiner with the vacuum operated flap. I assembled very carefully ensuring all clips and rubber sleeves were in position. I’ve put the rubber sleeve with the vacuum take off on the plenum, on the offside. I don’t think it was there before as the pipework did not run so smoothly to that position, but I did notice by doing a bit of googling that seem to be the correct position, Possibly! Also noticed that where the vacuum pick up is on the rubber sleeve, it is only a small hole and is central on the sleeve. Easy to have that section overlapping on the hard plastic and therefore blocking it off. I ensured that this was clear before connecting up the small tube. Assembled everything with the MAF supplied with the kit. Bosch F 00C 262 063. Started her up and it ran absolutely awful. Just as before. Hardly idling and popping back through the manifolds and hardly able to gain revs on a light throttle! Tried the other MAF that I had been running the car with the standard throttle body on which is a Bosch 986 606 125 01 or 0 280 218055, (2 numbers printed on it). This ran exactly the same! Really don’t know where to go from here. Could it be that both MAF’s failed coincidentally, I doubt it. I will just say again that with the larger throttle body first fitted, the car ran fine up to 3K rpm prior to me clearing the fault codes which were up and now there is hardly a chance of it running at all… Just put the fault code reader on and it has come up with The P0102 MAF sensor and it states below limit value whatever that means! I have checked the wiring which comes from the loom adjacent to the fuel rail to the MAF sensor and all looks good. Where do I go from here apart from going to buy a box of matches? Quote Link to comment Share on other sites More sharing options...
phazed Posted April 29 Author Report Share Posted April 29 2 hours ago, ½cwt said: Have you run a throttle body reset? Switch ignition on but don't start for a minute and it goes into a calibration routine IIRC. Yes I did thanks. Quote Link to comment Share on other sites More sharing options...
½cwt Posted April 29 Report Share Posted April 29 8 minutes ago, phazed said: ..... Tried the other MAF that I had been running the car with the standard throttle body on which is a Bosch 986 606 125 01 or 0 280 218055, (2 numbers printed on it). This ran exactly the same! The number starting 986 is the Porsche part number, the 0 280 number is the Bosch number. Even if you buy the Bosch boxed part it come with the Porsche number on it proving it is an identical part and costs somewhat less than the same part in the Porsche box.... (applies to ABS sensors direct from Bosch too) Quote Link to comment Share on other sites More sharing options...
phazed Posted April 29 Author Report Share Posted April 29 I have an urge to buy a brand new MAF just to tick that box. Not sure where else to go from here. Quote Link to comment Share on other sites More sharing options...
phazed Posted April 29 Author Report Share Posted April 29 I just thought, the code reader code that I read a short while ago was probably logged when I disconnected the MAF to see how it would run yesterday I think that was spurious. Maybe I should try and limp it up the road to see if it would log codes and load. It is unlikely that a code or codes will log with me just trying to run it for a while in the garage stationary. Quote Link to comment Share on other sites More sharing options...
Nitro V8 Posted April 29 Report Share Posted April 29 Just a thought @phazed ! You are now running the larger 987 MAF tube, could this be causing the running issues? Quote Link to comment Share on other sites More sharing options...
½cwt Posted April 29 Report Share Posted April 29 1 hour ago, Nitro V8 said: Just a thought @phazed ! You are now running the larger 987 MAF tube, could this be causing the running issues? More air through large pipe even though MAF is set for a smaller pipe just over 18% more area so 18% more air going down a 74mm tube v 68mm tube. But would a MAF for a 74mm tube give readings a 986 ECU can make sense of? Quote Link to comment Share on other sites More sharing options...
phazed Posted April 29 Author Report Share Posted April 29 I don’t think so, what’s a few mm… not to run that poorly. To recap, again… car starts and immediately pops and bangs and doesn’t want to rev. just disconnected the MAF and it runs so much better. Will rev but stutters a little. I guess the default is for the 68mm TB. Order a new MAF? Quote Link to comment Share on other sites More sharing options...
½cwt Posted April 29 Report Share Posted April 29 Just now, phazed said: I don’t think so, what’s a few mm… not to run that poorly. It is a few mm extra on a diameter and it is a square law. Quote Link to comment Share on other sites More sharing options...
phazed Posted April 29 Author Report Share Posted April 29 43 minutes ago, ½cwt said: It is a few mm extra on a diameter and it is a square law. I understand, but it is running exceptionally poorly. Literally, just popping and banging back through the manifolds and hardly at all being able to raise the revs. Out of desperation, I disconnected the rear pair of O2 sensors and it ran absolutely terribly. Reconnected them and disconnected the front pair of O2 sensors. Same again. Don’t know what I was expecting, but that’s what I did! Quote Link to comment Share on other sites More sharing options...
phazed Posted April 29 Author Report Share Posted April 29 51 minutes ago, ½cwt said: More air through large pipe even though MAF is set for a smaller pipe just over 18% more area so 18% more air going down a 74mm tube v 68mm tube. But would a MAF for a 74mm tube give readings a 986 ECU can make sense of? Missed this. There is quite a difference I agree. From memory, people who have done this upgrade, (if that is the correct word) have not had the engine remapped but there again I believe some have for very small gains. Is that correct? If the above is true then can the standard ECU learn to deal with more air and add the correct amount of fuel given that it is more than just a few percentage change? Quote Link to comment Share on other sites More sharing options...
phazed Posted April 29 Author Report Share Posted April 29 At this point, I will order the MAF tomorrow. Just to confirm, I will quote this number. Bosch, 0 280 218 055 Open to any other bright ideas! yours desperately! Quote Link to comment Share on other sites More sharing options...
iborguk Posted April 29 Report Share Posted April 29 (edited) http://986forum.com/forums/performance-technical-chat/32074-987-v-986-air-box-15.html#post608234 Edited April 29 by iborguk Quote Link to comment Share on other sites More sharing options...
bally4563 Posted April 29 Report Share Posted April 29 If no air leaks I believe your issue is the 987 maf housing, previous post re world of hurt 1 Quote Link to comment Share on other sites More sharing options...
iborguk Posted April 29 Report Share Posted April 29 (edited) As per previous posts if the larger 987 MAF housing is in play then it could be the ECU is getting confused by airflow results due to the larger diameter tube. A code reader and review of the MAF live values could confirm that. The link two posts back has references to keeping the 987 MAF housing and reducing it (pvc pipe basically). See posts 299 and 303. Or reuse the 986 MAF housing. Or keep the 987 MAF housing and flash the 986 ECU with a revised MAF table, I've seen some references to using a 996 mapping. Edited April 29 by iborguk Quote Link to comment Share on other sites More sharing options...
phazed Posted April 29 Author Report Share Posted April 29 Thanks for that. Looks like I overlooked the MAF tube reduction! Not in the garage atm so just asking what is the internal dia required? I assume the same as the 986 MAF tube? Is it ok to use the 986 MAF tube and then step up immediately to the larger tube before the TB? Not in the garage now till Wednesday so will continue then. Quote Link to comment Share on other sites More sharing options...
bally4563 Posted April 30 Report Share Posted April 30 7 hours ago, phazed said: Thanks for that. Looks like I overlooked the MAF tube reduction! Not in the garage atm so just asking what is the internal dia required? I assume the same as the 986 MAF tube? Is it ok to use the 986 MAF tube and then step up immediately to the larger tube before the TB? Not in the garage now till Wednesday so will continue then. That’s is what I did ,reducers either side of the 986 MAF housing Quote Link to comment Share on other sites More sharing options...
phazed Posted April 30 Author Report Share Posted April 30 Now why didn’t anyone tell me! 🤔😁 Quote Link to comment Share on other sites More sharing options...
½cwt Posted April 30 Report Share Posted April 30 I do hope this turns out to be worth the pain! The search for a few extra ponies on an already fairly well tuned modern n/a motor ain't easy. Quote Link to comment Share on other sites More sharing options...
Randeep Posted April 30 Report Share Posted April 30 13 hours ago, phazed said: Thanks for that. Looks like I overlooked the MAF tube reduction! Not in the garage atm so just asking what is the internal dia required? I assume the same as the 986 MAF tube? Is it ok to use the 986 MAF tube and then step up immediately to the larger tube before the TB? Not in the garage now till Wednesday so will continue then. Ahh, I didn't realise you were using the 987 MAF tube, the 986 and 987 sensors are the same (I believe), the tube however is bigger and pushes readings out of tolerances. This is why I needed to get a remap to deal with the difference or you can use a reducer inside the tube. The car will run ok without a map, however I think it will run rich and will create lambda sensor errors. A new MAF sensor might be worth getting to rule that out as well... Quote Link to comment Share on other sites More sharing options...
phazed Posted April 30 Author Report Share Posted April 30 Thanks. Just to recap. Use the 986 tube and car should run okay and hopefully should give a small hike in performance. Use the 987 tube and a remap is required and would that give a performance upgrade over the 986 tube as above? If so, who would remap considering I’m situated in Surrey. Also, what would be the approximate cost? Quote Link to comment Share on other sites More sharing options...
phazed Posted April 30 Author Report Share Posted April 30 986 MAF holder is 74mm int dia. 987 MAF holder is 80 mm in dia. So if I sleeve the 987 MAF holder with say, a 20mm wide collar, is that all that is required? Air flow will go through the 80mm MAF holder, be reduced through the 74mm collar, spill out into the larger 80mm tubing and go on into 74mm plenum. Is that it? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.