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Turbo Engine Rebuild

TBH the MBC is the first thing I'd have isolated. Not trying to be a smartarse, but it's the easiest part to get at.
 
Yes, correct. I'll have a go at that soon as well as an inspection of the banjo bolt set-up.
 
Before you get rinsed for a Lindsey (Or worse 9XX) MBC - be aware it’s just a cheap air compressor adjustment valve similar to this one (adjustment ranges vary - I think the 944 used ones are 0-100 psi hence you need safecrackers fingers to go from 15-18psi):

Pardon our interruption...

www.ebay.co.uk
 
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Eldavo said:
Before you get rinsed for a Lindsey (Or worse 9XX) MBC - be aware it’s just a cheap air compressor adjustment valve similar to this one (adjustment ranges vary - I think the 944 used ones are 0-100 psi hence you need safecraclears fingers to go from 15-18psi):

Pardon our interruption...

www.ebay.co.uk
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Thanks. Got one alleged "UK stock", £7.49 delivered. Will do for the purposes of eliminating a faulty MBC.
 
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The issue I've found with a MBC is they are very agricultural, you don't seem get even max boost from say 3k to 6.5 k. And variations in air temp seem to cause spikes.
 
MBC arrived, went to fit it today, air hose connectors on mine a smaller diameter thread, so I've had to order a couple the right size. Took the banjo bolt off, all is well there. Also tested the air lines from banjo to MBC, all good. Although I haven't been able to test all the blue silicone lines I really can't see there being a problem with them (unless see last sentence).

I turned the original MBC fully down and still no boost control. I'll replace the MBC when the new connectors arrive, if that doesn't resolve it then I have mystery wastegate problem which makes no sense as we opened it up and checked, cleaned everything, put in a new diaphragm, and all looked good, no cracks, valve was perfect. Hope the MBC is to blame, if not I am puzzled.

I will pull apart the old MBC when it is off, if it has disintigrated possibly some debris in the MBC to side port line? Fook knows..........getting quite used to using my right foot as the wastegate now.
 
Good luck sorting the problem out, I'm considering an EBC for my car when it is up and running again. But even a second hand one is around £200, then you start wondering if it is worth saving the money and purchasing a full aftermarket engine management system.
 
dlknight said:
Good luck sorting the problem out, I'm considering an EBC for my car when it is up and running again. But even a second hand one is around £200, then you start wondering if it is worth saving the money and purchasing a full aftermarket engine management system.
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When you consider what it costs to repair a KLR or DME, or buy a new TPS, if any of them start playing up, something like VEMS plug and play makes sense.
 
Well, we have boost control again. Took the old controller off and was able to test the remaining silicon boost lines, as expected all were good. Plumbed in the new controller and turned it fully down. I was very pleased to see 8psi of boost which instantly told me that the wastegate is good and so was the new controller. Pulled into a lay-by and cranked it up 2 full turns. Was then also delighted to see I was then running 17psi with a total stab in the dark of knob twisting! So 17psi it will be, a nice safe level for my set-up. Can also report low 11's AFR at WOT. All is well again for the time being!

£7.50 for the controller, £6 for 2 brass fittings and £1 for PTFE tape. Mustn't grumble at that.

Cheers to Eldavo for the heads up on the boost controller. I'm going to buy half a dozen and get some 9xx stickers put on them and sell them for £199 each........

Edit to add - the controller I bought is an AR 2000 and I had to buy 2 x 1/4 BSP 6mm male elbows to fit it.
 
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Wait until you see that 944Online charge $24.95 for a new reference sensor plug, it’s just a 3 pin Tyco AMP Junior Power Connector plug and you can get them for £3 delivered on eBay.
 
After a further bit of road testing I'm getting to 18psi peak in 5th today and 17psi peak in 3rd and 4th. Just in the right sweet spot I think for power and keeping on the safe side with my set-up. AFR's all good. The rear coilovers along with the geo set-up have also made a big difference. Nudged the rears up to half way stiff and left the fronts at a third stiff and the balance seems really good (obviously they are different brands with Spax rear, GAZ front), not crashy at all at the rear, which it was a bit before with the (past their best and one leaky) GAZ dampers with no springs. Together with the new brakes, gearbox, shifter, ride height adjusted, rubber and CV's all round the car is driving the best it ever has done in my 15 years of ownership. All in good time for my road trip which is pencilled in for 14th September. Can't wait!
 
Done the handbrake shoes today, a job I had never done before believe it or not in 15 years of ownership. Took me about 2 and a half hours in total at a leisurely pace. The little springy twisty shoe retainers are a pest but other than that easy enough. I did learn that the self-adjusters don't self adjust very much! Fitted 2 new ones and wound them right back with the new shoes. It was only after i done the 2nd side I worked out I had to strip the other side back down and adjust for a snug fit. Schoolboy error but it was a nice night and my boy was helping for the first time so all good. Handbrake fab now ready for MOT next week.

The boy now knows lefty loosey and righty tighty! Small steps............

Edit to add: they are handbrake adjusters, not self-adjusters, doh! Couldn't quite fathom how they would "self-adjust" anyway.......... :ROFLMAO:
 
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MOT passed, no advisories, always good! 4 more to go before exemption. 2.5% CO and 50 HC, happy with that, engine seems happy.

All sorted for road trip now, leaving next Saturday! :)
 
scam75 said:
MOT passed, no advisories, always good! 4 more to go before exemption. 2.5% CO and 50 HC, happy with that, engine seems happy.

All sorted for road trip now, leaving next Saturday! :)
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CO is quite high?

I documented my readings from previous MOTs as my last MOT only just scraped through the limit.

I bought a Gunsons gas analyzer to test it once it is back together.

Most of my readings were around 0.50 % CO apart from 3 readings above 1 (1.746, 2.43, and 3.104), HC around 50 apart from the two high CO readings where it was 140 and 165).

High Co Emissions - Rennlist - Porsche Discussion Forums

944 Turbo and Turbo-S Forum - High Co Emissions - I've already posted a thread on this topic but it was getting a bit confusing so I've pulled it together here. Any further advice would be much appriciated. My car has just failed her emissions test on 7.5% CO. I've been trying to track down the...
rennlist.com
 
Noticed it was 0.9% last year. Maybe machine calibration or something, not concerned. You are allowed 3.5% for MOT.
 
scam75 said:
Noticed it was 0.9% last year. Maybe machine calibration or something, not concerned. You are allowed 3.5% for MOT.
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Yes - possibly running a little rich at idle, are you still using the scivision MAF or have you swapped it out to a standard AFM now?
 
The SciVision is up and running again with the loom sorted and a brand new Bosch MAF unit. I've got an almost brand new AFM tucked away for the next rainy day!

I can only go on AFR's however it idles at mid 14's now so it doesn't seem rich, and the AFR's across the range are spot on.

One small issue I have, and haven't been able to sort so far, is that warm idle is nearly 1.1k revs, cold idle is normal around 850/900 rpm. TPS possibly but it seems to be working and clicking when it should as you can see fueling stops off throttle (AFR gauge shows this) and recommences for idling purposes.

It's been like that since the engine build 2 years ago.

Edit to add - with the aircon switched on, warm idle is pretty much back in spec, so it's a head scratcher!!
 
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