phazed

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.

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!

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?

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!

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?

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. 

I have an urge to buy a brand new MAF just to tick that box. Not sure where else to go from here.

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.

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?

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. 

👍

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? 

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.

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?

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!

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…
 

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? 

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.

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.

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.

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? 

an image of the installation. Anything obvious?
 

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?

Dampers are dampers. Fitting same height springs won’t change anything. The car will remain at the same height. I haven’t had any firsthand experience of fitting even lower springs with your existing dampers but I would imagine that just a 10 mm additional drop would be fine and the dampers would cope with that. No doubt it will give you a firmer ride. Is that what you want? 

Personally, I can’t see the advantage over standard which I think is great. 

Good luck with your mechanical.

Interested, see your progress with the Cayman Z top.