Dyno results

[PSH]

Well the boost looks normal for a 250bhp car without a DPW, as for AFR well that doesn't look too bad at least it's in the right side of mixture. What are the plugs, rotor arm and distributor cap like not to mention leads, these can all cost you power and since the graph seems to show boost/afr acceptable i would certainly check electrics first. Does the car hesitate under full boost at any time? , this can be a sign of an electrical break down on any one of the items listed above. Pete

 

[PSH]

also on looking at your torque figures , you seem to be loosing torque even though it peaks around the correct amount it tails off far to quickly?

 

[JamesO]

Air flow meter a bit sticky maybe? I know it is a totally different beast but after I fitted a wideband gauge to mine when running the stock ecu, I noticed that in the upper rev range the mixture seemed to lean out quite a lot and it did seem to take an age to get from 80 to 110. Its much better now with a richer mixture at higher revs/load. If I ran a turbo car I would definitely fit a wideband even more so if its modified in any way, just to keep an eye on a 20+ year old management system. Saying that I'm not sure if the ecu ignores the afm over certain revs, maybe the injectors need cleaning.

 

[Flick]

ORIGINAL: PSH Well the boost looks normal for a 250bhp car without a DPW, as for AFR well that doesn't look too bad at least it's in the right of mixture. What are the plugs, rotor arm and distributor cap like not to mention leads, these can all cost you power and since the graph seems to show boost/afr acceptable i would certainly check electrics first. Does the car hesitate under full boost at any time? , this can be a sign of an electrical break down on any one of the items listed above. Pete

It doesn't hesitate or flat spot at all. I shall have the plugs replaced and the dizzy & rotor arm inspected during its service next month. It was the torque and boost tailing off that made me think it was a boost issue. I thought the AFR should be 11.0-something under boost?

 

[Diver944]

Those graphs look just about right for a standard car to me, (shame they couldn't print the bottom part of the AFR) maybe a little richer than ideal but look at these other standard cars to compare, and you'll see its not that much different:: [link=http://www.cannell.co.uk/UKL%20G387RNJ.htm]http://www.cannell.co.uk/UKL%20G387RNJ.htm[/link] [link=http://www.cannell.co.uk/UKL%20F356JNX.htm]http://www.cannell.co.uk/UKL%20F356JNX.htm[/link] [link=http://www.cannell.co.uk/UKL%20CLC944T.htm]http://www.cannell.co.uk/UKL%20CLC944T.htm[/link] The boost dropoff curve is exactly what I would expect to see with a standard wastegate, so I don't see a problem there. How fresh is your air filter? If it's old and dirty then it could be restricting airflow, hence the richness. If everything else checks out then you could safely turn up the boost enhancer a little which will increase airflow and therefore lean it out a little

 

[JamesO]

Isn't it going lean at nearly 15.1air to fuel ratio rather than rich? Or am I miss reading the graph

 

[944Turbo]

The rich running will be robbing you of some power. With a BE it will make more boost in cold weather, I set mine up in the summer and was hitting overboost in the winter. A week AFM spring will also make it run richer in the low revs before iirc 4,500rpm. The BE can only go so far in overcoming a weak wastegate, it removes the opening signal until it opens but if the wastegate is very weak the exhaust pressure will open it early. This can be overcome to a certain extent cheaply by shimming the wastegate. However if the seat is cracked it wont help much, and really a DPW is the way to go. A K26/8 (as fitted to 250BHP cars) will overcome some boost leaks and still obtain 0.9bar and this is a common problem with all those lines running everywhere. Tony

 

[PSH]

well that's what i meant by right side of mixture , it may be a little rich but it's not as rich as mine at full bore ( admittedly I have many mods) so I'm guessing it's not far off normal, it's been a long time...lol The boost looks normal to me for a non DPW car, the boost on a 944 turbo was designed to loose boost as soon as it peaked , IIRC it actually starts to tail off before max boost is reached ( ie it's rate of build) on a standard car. According to Porsche designers back in the 80's this was to make the car easier to drive and more to the point make it marginally slower than the 911 turbo of the day( would upset the 911 boys...lol) As James said it can also be the AFM, this would loose you power but also make the AFR read different as the ECU tries to match what the AFM sensor is telling it thus affecting the mixture... if you get my drift....??[8D] Pete

 

[Flick]

Hello chaps, I had the car tested today at SRR mainly out of curiosity and it brought up some surprsing results. Though the car is down on power what concerns me is that the AFR is through the floor especialy on boost and the boost itself is weak and weakens through the rev range.

Sorry for the large pictures:

I haven't compared the afr & boost to other runs yet but neither look right to me. I don't think it's a boost leak as I'd have thought it wouldn't have reached 0.9bar in the first place but I am wondering if the actuator or wastegate could be faulty? It has a JMG boost enhancer but I don't know if it's adjustable - I'm sure it was boosting fine (on the guage) when I bought the car so I've ruled out the idea that the BE may have adjusted itself.

What do you think guys?

Btw it's going in for a service next month.

Thanks in advance!

 

[PSH]

Isn't it going lean at nearly 15.1air to fuel ratio rather than rich? Or am I miss reading the graph

James the AFR reading is the dotted line that dissappears of the bottom of the chart and then back up to around 10.3 [8D]

 

[JamesO]

My laptop screen is crap didn't see the dotted line that is the afr, In my defence I may have been drinking officer.

 

[Flick]

Thanks chaps.

 

[awattam]

Can I ask how much it cost for a run like this? It's something I'd like to do to check up on my S2.

 

[PSH]

Can I ask how much it cost for a run like this? It's something I'd like to do to check up on my S2.

check the rolling road thread.. it's this saturday and there are still places...[] Pete

 

[awattam]

ORIGINAL: PSH

Can I ask how much it cost for a run like this? It's something I'd like to do to check up on my S2.

check the rolling road thread.. it's this saturday and there are still places...[] Pete

That would have been great but I've got plans on sat [] I guess I'd be looking at more £ if I go on my own?

 

[PSH]

I think an average may be around £70 but you may find somewhere cheaper, look for a Dynamics dyno though and perhaps have a word with Rick Canell as to baro settings... many dyno's give you inflated readings due to settings being tweeked to give a false high reading or just inaccurate calibration ...[][] Pete

 

[rcsalmons]

ORIGINAL: Diver944 Those graphs look just about right for a standard car to me, (shame they couldn't print the bottom part of the AFR) maybe a little richer than ideal but look at these other standard cars to compare, and you'll see its not that much different:: [link=http://www.cannell.co.uk/UKL%20G387RNJ.htm]http://www.cannell.co.uk/UKL%20G387RNJ.htm[/link] [link=http://www.cannell.co.uk/UKL%20F356JNX.htm]http://www.cannell.co.uk/UKL%20F356JNX.htm[/link] [link=http://www.cannell.co.uk/UKL%20CLC944T.htm]http://www.cannell.co.uk/UKL%20CLC944T.htm[/link] The boost dropoff curve is exactly what I would expect to see with a standard wastegate, so I don't see a problem there. How fresh is your air filter? If it's old and dirty then it could be restricting airflow, hence the richness. If everything else checks out then you could safely turn up the boost enhancer a little which will increase airflow and therefore lean it out a little

Paul F356JNX was running v.rich if you remember and it turned out to be a faulty ECU. Rich

 

[Alexw]

Sorry to derail but how does that work? Calibration and such, I've never understood why it makes such a difference?

 

[Diver944]

ORIGINAL: rcsalmons F356JNX was running v.rich if you remember and it turned out to be a faulty ECU.

Yes but wasn't that at part throttle and normal driving? At full wde open throttle (like on the Dyno) it was just about where it should be. I've been wondering if Flicks car maybe has a faulty fuel pressure regulator and its running at slightly too high a fuel pressure so it is rich everywhere? Does it drink petrol normally, do you get circa 350 miles per tank?

 

[Flick]

ORIGINAL: rcsalmons

ORIGINAL: Diver944 Those graphs look just about right for a standard car to me, (shame they couldn't print the bottom part of the AFR) maybe a little richer than ideal but look at these other standard cars to compare, and you'll see its not that much different:: [link=http://www.cannell.co.uk/UKL%20G387RNJ.htm]http://www.cannell.co.uk/UKL%20G387RNJ.htm[/link] [link=http://www.cannell.co.uk/UKL%20F356JNX.htm]http://www.cannell.co.uk/UKL%20F356JNX.htm[/link] [link=http://www.cannell.co.uk/UKL%20CLC944T.htm]http://www.cannell.co.uk/UKL%20CLC944T.htm[/link] The boost dropoff curve is exactly what I would expect to see with a standard wastegate, so I don't see a problem there. How fresh is your air filter? If it's old and dirty then it could be restricting airflow, hence the richness. If everything else checks out then you could safely turn up the boost enhancer a little which will increase airflow and therefore lean it out a little

Paul F356JNX was running v.rich if you remember and it turned out to be a faulty ECU. Rich

That's interesting to know as yours is the closest to mine on that link. I hope it's not that. After its service and investigation & remedy I'll go back to SRR and see if it made a difference and go from there as I'm convinced the AFR is too rich.