Rolling Road test

I can feel the car is not running right, not pulling sometimes, hesitation then power, lethargic power and plain 'just not quite right', so I decided to put it on a rolling road to see what is happening.

Power seems down a bit, 144 at the wheels and 181 at the fly peaking at 4750 and 6000,
Torque measured as 162 at wheels and 204 at flywheel, peaking at 4200.

The AFR plot tells a story, running VERY lean and seems to be an issue at about 3800 (perhaps this is where the ECU is retarding?) and at 4500 (perhaps the injectors are max'd out and unable to cope any more?)

Basically I have a hybrid turbo, have increased the boost to about 14-psi and installed a chargecooler.

http://homepage.ntlworld.com/s.taylor88 ... elsbhp.jpg
http://homepage.ntlworld.com/s.taylor88 ... eelbhp.jpg
http://homepage.ntlworld.com/s.taylor88 ... /boost.jpg
http://homepage.ntlworld.com/s.taylor88 ... cs/AFR.jpg

Firm confirmation that an Adaptronic and bigger injectors are required for my car too. A summer holiday project I think

You shouldnt be that lean though, and so erattic. I could be suspect injectors or fuel pressure related.?

Are you running that upgraded fuel pump with the std reg ? Have you put a gauge on it ?

Yes, I have a Walbro 225 fuel pump fitted, new fuel filter and the standard regulator, and I have not put a gauge on it.
Injectors were cleaned last year, they have 50 k miles and were reported as all good before cleaning.

As for the "erraticness", I'm guessing DG means from 2300 revs, just when the boost starts to come in

So I have to suspect the fuel regulator???
Any recomendations, any one? It looks pretty tight under the V6 plenum, will I get an aftermarket one in there or should I stick with a Renault one?
But if the injectors can't keep up with the demand............

I would think the injectors are capable of handling a bit bigger turbo .
http://www.aa1car.com/library/2003/us60324.htm

cheers lee, great link, i'll read that all in great detail later.
this evening, I checked for air leaks especially around the fuel regulator with a small vacuum pipe held to my ear. no leaks found.
I checked the throttle body micro switches, it seems ok.
I also checked the voltage at the fuel pump. 12.2 at idle and 12.0 when revved. seemed low as the battery has 14.4, so I then took a pair of flyleads from the connector direct onto the pump, bypassing the suppressor and now I have 13.2 and 13.0.
Test drive confirms that the lethargic acceleration still exists, 0-60 was only 6.9, a couple of weeks ago it was 5.9 secs.

Did the RR not give their opinion???

their opinion was "read the logs from the ECU" or injectors.
He has never seen a GTA before, no logs available from the ECU and the injectors were all cleaned last year.
I'm thinking it is fuel pressue, so need to get a gauge onto it.
Any one got one that they can lend to me?

Have you used David's engine analyser to check that your coolant temp and air temp sensors are reading correctly? My sensors were correct but the ecu was interpreting them as strange readings i.e the ECU thought the engine was at 55deg when it was in the 80s. Fitted new ones and the readings were still the same. If you had the opposite i.e the air or coolant temps were reading higher than they should, you'd get lean running.

It 'could' be a sensor fault but its running rich instead of lean, and the coolant and air temp cause enrichments. The fuel pump voltage is a definate problem to be fixed..

[quote="David Gentleman"]It 'could' be a sensor fault but its running rich instead of lean, and the coolant and air temp cause enrichments.[/quote]

Did you just contradict yourself? I'm a bit lost, thought that the mixture gets leaner as the engine temp rises - so if the CTS was telling the ECU that the engine was 130deg when it was actually only 90deg - what effect would that have on the fuelling?

My ECU was interpreting a 90deg signal as 54deg so its not beyond possibility that Simons is doing the opposite. Or is your point that the base map is built for a temp of 90-100 deg and the ECU enrichens for temperatures below that but once you go above that, you are just stuck with the base map - so it should never run too lean by having a higher than design temp?

I think David's point is that the ECU runs the car rich on cold start and warm up and then runs at the proper stoichiometric ratio when at the proper running temp (85-90).

Beyond this (95+) the ECU then richens the mixture again to protect against detonation.

Yes, thats right. If the cars at normal temp, and the sensors are faulty (either reading low or way to high) then they will enrich the fueling, but also likewise retard the ignition if the air temp is reading high....

Simon has used the diagnostic, but something could have happened in the interim...