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Put my 2000 GS400 Platinum Edition on the dyno this am with the newly installed OBX headers and Megan Racing SC430 Y-pipe to see the gains. Very disappointing!
Run 5- bone stock car with 60k miles
Run 6- SRT intake and their black-box ECU
Run 13- Added OBX headers and Megan Y-pipe
Sorry for the black in the photos... my iPhone did not want to take pictures of the crappy old computer monitor.
All runs were performed in 3rd gear. It is too difficult to use 4th because the car fights you wanting to downshift. Even using 3rd, I cannot go WOT until about 3200 rpm so we cannot evaluate the bottom end.
Comapring all three configurations:
Gains everywhere from the SRT intake/ECU. This is a great modification to make to an otherwise stock car.
Before and after headers and Y-pipe:
It looks as though these are back to back runs on a car that was untouched. I expected to gain SOMETHING from the headers. Slight loss in power and torque in the ~4200 rpm range that is brief. No gains whatsoever. Very frustrating considering the fitment issues with adding the headers in addition to the cost.
Had him pull up the A/F to compare, thinking "I am surprised that adding these headers didn't lean it out a little and gain a few hp." Here is a comparison between headers+ and stock manifold runs:
It is running VERY rich as compared with the SRT intake/ECU alone. Interesting that it made the same power and torque but at a much richer A/F ratio.
Here is comparing stock A/F to SRT-only A/F, to headers+ A/F:
So the car is now running even richer than it was in OEM configuration. Perhaps the solution is to lean it back out to unlock the gains from the headers, so to speak. Do other people have similar results to share?
I asked about maybe the change being his wideband at the dyno, but he calibrated before each session and seemed very confident that this was not the issue.
1. Has anyone added a S-AFC or similar device to tune A/F?
2. Did you add it on top of the SRT black-box or replace the SRT unit?
3. Any issues with the factory ECU fighting your aftermarket unit or overriding the settings?
4. Anyone running their own wideband for comparison? Thinking of installing an extra AEM I have.
5. Has anyone monitored fuel trims with a scan tool before/after with similar modifications?
6. Is there anyway to monitor the ignition timing or even see what the car is doing? I know it requires a standalone to control the timing, but if I could just see what is happening it might be helpful.
if i'm not mistaken, the SRT ECU is only meant to 'mod' for the intake you have on there. by adding the headers and midpipe, the SRT ECU can't pick up/adjust for the additional bolt ons you have beside the intake... you will need a S-AFC to run and adjust for everything you have... the S-AFC would replace the SRT ECU...
also what do you have after the midpipe? still the OEM cat-back? that might be choking your flow off too...
OEM catalytic converters in place and OEM cat-back. Looking into a S-AFC type device now to replace the SRT unit. I do not think the cat-back is a restriction since the factory Y-pipe is smaller by comparison.
too many people gained 20-30 wheel horsepower from doing the header swap. I didn't dyno mine after install of my obx headers but I know for a fact it made a huge difference. I clearly remember that before I had my headers when I would go wot my aem wideband showed 12.5 flat. putting the headers on would have leaned it out at wot since the factory fuel map in open loop wouldn't have changed. due to more air flow going thru it. maybe ditch the srt stuff and try again.
09-17-15, 10:09 AM
Dyno inside: Stock +SRT intake/ecu +OBX headers - need tuning advice!
