Help! I lost 70 bhp somewhere

[wirestriker]

Hello guys, had a bad surprise yesterday on a rolling road.
My car is a 3R, with all the usual upgrades: full Roush exhaust, bigger intercooler, fuel pump wiring, hard pipe kit, remap, BOV etc etc.

The car seems to run well, no misfires, pulls without hesitation in any gear, no smoke, no oil consumption, starts at 1st time, boost rises promptly and is steady at 0,7 bar.
But in the last months she seemed to be a little lazy at higher RPM, past 5000.

So i decided to have a quick RR session, this is the response(sorry fo the pic size):


Damn!!! 309 BHP, 284 at the wheels at 5500 rpm... she's lazy for sure!

The RR guy (who knows NOTHING about real sportcars like the Nob) told me the fueling (lambda value) is very very rich in his opinion and could cause the lack of power at high rpm. (around 0,950V from 4000 to 6000rpm)


What should I look for?
Faulty lambda sensor? Clogged cats? Spark plugs? (yes, they're little old, around 7k miles)
Thanks!

[JLSELAN]

No doubt that an overly rich mixture at high rpm will sap power. But since the lambda sensors are not "in the loop" at WOT, the culprit is probably the ECU map itself.

[Mike Tuckwood]

It may be worth checking that both Turbo wastegate actuators are working correctly.


Mike.

[D_G]

My 3 had a similar problem but was low on boost, it made 319bhp at 0.45bar. It's now at 0.75bar and makes 380bhp which is similar boost to what you have so it points to a fuelling issue rather than turbos.
You need to run through the basics really, check fuel pressure etc, my car ran progressively badly over a long period but once I had it mapped it's a different car...maybe just needs a session with a laptop.

Cheers

Dave

[burge124]

Mine is a little lazy at the moment, need to take to a rolling road but a few people on here have suggested the spark plug coils/ignition

[JLSELAN]

Ignition/spark plug problems tend to show up at hi rpm combined with hi load (e.g. extracting major power going up a long hill); and the problem will be obvious because you'll have very poor engine performance accompanied by electrical breakdown. IOW, problems like that will show up immediately during a RR "pull". No evidence of that in the posted plots.

Edited by JLSELAN on Sunday 16th January 21:50

[Gadgeroonie]

The transmission losses do NOT look correct, was the car tested in 4th gear ?

if you made 280 hp at the wheels i would have expected your power to be nearer 330 bhp - which is about right for a std 3.0 3r

a good 3.0 makes 340 bhp so you are not far off

(Am i right you are in italy ?)

[mgbond]

Gadgeroonie said:

The transmission losses do NOT look correct, was the car tested in 4th gear ?

if you made 280 hp at the wheels i would have expected your power to be nearer 330 bhp - which is about right for a std 3.0 3r

a good 3.0 makes 340 bhp so you are not far off

(Am i right you are in italy ?)

He has the uprated exhaust and IC, most 3Rs I know with this make 370+?

Bondy

[Gadgeroonie]

i would be suprised to see 375 without more more boost

[mgbond]

Gadgeroonie said:

i would be suprised to see 375 without more more boost

Really, everyone we know that has put the rousch exhaust and Pro ally IC on after a remap on std boost have hit these figures. Tony was about 390 and others were plus 370 on DD RR's

Most 3R's std only made about 330 so after those mods plus 370 would be about right wouldn't it??

Bondy

[Jim O.]

Is this the same dyno that you used before for your baseline?

[funkybmx1]

I made 400 at track and road. With just fuel wire mod, hayward exshaust and standard intercooler. Had .5 actuators

[david.mt]

wirestriker said:

boost rises promptly and is steady at 0,7 bar

Doesn't the boost (pink line) actually drop off before 5kRPM and continue falling which will explain why you are not achieving peak power. The scaling is not great but it does look to fall. Maybe new actuators are required?

[wirestriker]

Thanks for the useful info guys. I'll try to clarify:
- Yes I'm in Italy.
- It's the first time my car goes on a RR. I've no evidence of the previous RR session taken when the car was in UK before I bought it.
- I was told that my 3r was mapped for reliability, not for maximum power, hence the fuelling should be a little rich, but not SO rich.
- I thought that a weak actuator could cause difficulties in building up boost at low RPM, but as you can see 0,7 bar is reached at 3500 rpm which seems to be a good value. Then, past 4500 rpm the boost slowly decrease to 0,6/0,5 bar, which is not bad for a std turbo, or am I wrong? Maybe someone has a RR plot to show how a similar car should perform?
- The car was tested in 4th and in 5th, both giving same peak power results. This plot refers to the 4th gear pull. (188kmh/117mph at 6490rpm)

- This specific RR is a little too "strict", a lot of the car tested the same day (it was a club meeting) reported similar results, around 5%- 7% lower than declared by the factory.

- What about cats? Maybe my car was mapped without them, and then they were added for MOT reasons, leading to a rich mixture?

And finally, maybe someone knows my car better than me, licence plate in uk was KX53CTZ.

[YellowShed]

Blocked cats!

YellowShed

[wirestriker]

Thanks.
What's the most common way to "block" a cat? It's some sort of obstruction caused by the cat itself collapsing, or it's a matter of carbon/dirt accumulating in it? In this case, would it help to use a "cat cleaner" or something else to add to the fuel?

[RobP]

Usually CATs 'collapsing', blocking gas flow. They will need replacing if this is the issue.

[XLRONYX]

On a previous car I had a section of the honeycomb "brick" inside the cat break loose and get itself lodged sideways at the downstream muffler inlet.

Jeff