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Need help fixing a fueling problem

R

rickware

New member
Hope someone might be able to help me, I have recently installed a new AET hybrid turbo on my porsche 944 which before the install was making about 275hp. I sent it for a dyno to get the boost set to a safe limit but they have only managed to get it to 214hp @.04 bar as after this it is running dangerously low fueling. The guy at the place thinks it might be either the turbo fitting, ecu breaking down or the air flow meter but he didn't know which one it was. I think the turbo was all installed correctly and I also installed a lindsey racing dual port wastegate at the time and I will recheck all the vacumes etc this weekend. I was wondering if anyone knows an easy way of testing whether the air flow meter is breaking down, or ecu or any other reason why the car would fuel incorrectly. The dyno guy checked all the fuel pressures and it this is all fine, so they have eliminated pump, regulators and filters. My setup is as follows.

Lindsey Dual port wastegate
AET hybrid uprated turbo
Greddy electronic variable boost
Green injectors
BBR Starchip ecu remap chip set (fuel and main ecu)
It also has had an new lindsey racing ported and polished head with new valves and wide fire gasket so hopefully it isn't anything related to the head.

Any guidance would be great or if anyone knows a specialist in my area that can help (fetcham, surrey)

Thanks


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Is it low on fuelling on or off boost? If i'm right the fuel pressure in the fuel rail should increase on boost, is this the case? I think this is how the 944's injection system injects more fuel on boost as the ECU doesnt know what the boost pressure is.
 
gets low on boost, the report shows masses of fuel on idle and low revs and then it starts trailing off as it gets above 3000 rpm. almost the reverse of what you would expect should happen
 
The fuel pressure regulator is the key here I think. Its not got a vacuum line rather than a boost line connected to it by any chance? Or maybe a blocked or pinched hose?
 
when i installed the wastegate, i put a 't' piece into the vacume line that goes from the manifold to the fuel reg. i then came off the 't' piece down to the top of the wastegate. (this is how i was told to set it up by the guys who sold it to me) does this sound wrong based on your comment?
 
Nope thats sound right too me. I'd check that theres no restriction in the line too the FPR. Do you have a boost controller on the same line as that might be reducing the pressure in the boost line to control the wastegate.
 
It depends which port of the DPW the line is hooking into. If I remember correctly the banjo bolt pressure offtake goes to the top port of a Lindsay DPW and the FPR off take goes to the side port via a boost control device (MBC or EBC solenoid for example). In anycase I don't think this is the cause of your fuelling problem.

You might need to hook up an fuel pressure gauge to see if your fuel pressures are right.
 
no, the boost controler goes from the intercooler intake through the boost controller and then down to the side connector of the wastegate. i don't think there are restrictions either as i blew through it before fitting. i'll check in a minute though. in reply to scott, i think mine is setup in reverse as the top goes to the fpr and the side goes to the intake. also the garage check the pressures for fueling under load and it was all fine
 
Scott that would explain it even better I think. Think that when the EBC is regulating boost it is feeding some random pressure into the spring side of the wastegate to control how it boosts. This pressure is less than boost pressure. If this pressure was also feeding into the FPR then it would be seeing less boost than it should and thus the fuel pressure would be too low?
 
do you think that i have set mine up the wrong way round then? i am sure i went top of wastegate to fpr t piece and side into solenoid then to intercooler bango?
 
I wouldn't have the FPR on the same line as the EBC for sure. I would have the FPR on its own boost line or share with the top port of the wastegate assuming that the EBC feeds into the spring side of the wastegate.
 
electronic boost controller specifically, I wouldnt put the FPR on any line with any boost control on or even a boost enhancer.
 
Below is the instruction I got from the people I bought the wastegate from and this is how I think I have set it up

Hi Rick,

Sorry about the delayed reply.

Top port of Dual port wastegate - Manifold pressure
Sideport of dual port wastegate - Controled pressure side

Your Vaccum layout to the wastegate should be as follow's ;


Intercooler Pipe ------------------------> NO port on Greddy.
COM port on greddy ----------> Side port on Dual port waste gate.
T-peice fitted between intake manifold and Fuel pressure regulator ---------------------> Top port of dual port wastegate.

Using the T peice allows a more direct feed to the wastegate and reduces the ammount of vaccum pipes having to run above the exhaust manifold (Dependant on where you have placed the actuator in the engine bay).

Greddy Profec b spec 2 install manual (page 10)- http://photos.imageevent.com/kadepunk/hybridinstallationguides/PROFEC_B_SPEC2.pdf

Hope this helps

Mark
Jon Mitchell's Garage (JMG)
JMG - Independent Porsche specialists
 
sorry, i think i might of confused things, on previous post by side i meant side of wastegate not the side of 't' piece. the 't' peice connects from manifold to fpr and top of wastegate
 
Yep that's how I would set it up. The greddy boost controller should be on its own line feeding into the side port of the wastegate. The FPR and top port of the wategate should be seeing true manifold (boost) pressure. I think this confirms my thinking that the fuel pressure in the fuel rail increases with boost.
 
Sounds like you have it setup correctly. I would double check and also check that fuel pressure is actually increasing with boost.
 
thanks and according to the dyno people it was as they said they checked this. i have seen a youtube video on air flow meter refurbishing that doesn't look all that hard so i might try this tomorrow. (http://www.youtube.com/watch?v=-11J8XawQtc)
 
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