Forum » General Tuning Discussion » Odd Dyno Issues

Odd Dyno Issues

General Tuning Discussion

Forum Posts

Courses

Blog

Tech Articles

Discuss all things tuning in this section. News, products, problems and results. 

= Resolved threads

Page 1
Author
88 Views

Hopefully you guys can help on this random issue. Not sure if it’s an issue with the Dyno (I used someone else’s due to location) We also ran a high powered 2J and numbers seemed a bit lower than the owner had claimed it to be (not familiar with the car or owner so can’t really determine claims)

Engine/Setup

RB25NEO Swapped into an E36 BMW

EMU Black with Wiring Specialties Harness

Precision 6262 (.63 rear) with Tial 44mm gate(22 lb spring)

1050cc Injectors with a walbro 450 lph in tank on 93 Octane

PRP Cam and Crank Trigger kit

Issue: Engine is up and running very well, all controls functional and AFR’s match the target within a few percent at worst. When power run was performed on wastegate pressure car made 390 HP & 307 TQ and was very smooth. After all tables verified it was time to add some boost and see how it would respond. While adding boost the car made NO Additional power however when I advance timing it would gain HP until knock was detected. Just a bit confusing that it will not respond to a boost increase but will a timing increase. I’m not super familiar with the EMU Black ecu. Is it possible for a setting to not allow wastegate to function above spring pressure?

Josh @R-Tuned Media

It's possible (and common) for the wastegate to be plumbed wrong for boost control. What boost pressure did you measure (either with the dyno, or with the sensors on the car? Does the manifold pressure increase as expected (just in case you have a sensor with the wrong range, and are not increasing the fuel with increased MAP). Any boost leaks?

Other issues could be a restricted intake path, poor charge cooling so the pressure build up is partly due to increased temperature, restrictive exhaust, blocked catalysts (if used), etc. It is absolutely possible to increase boost and actually lose torque/power if things like timing, mixture, charge cooling, restrictions aren't addressed.

I'd also suggest going back to the original 'boost' level and optimising the ignition, it sounds like it was running a little retarded if you could gain from advancing it, which would just be throwing away potential torque/power. Then you can check for leaks, collapsing hoses, confirming actual boost and charge temp's, etc. as you would have a base point to work from.

Different people have different ways of doing things, though, so that may not work for your methods.

[edit] 22lb wastegate spring? Not familiar with the engine, but that seems to be rather a low power figure for that spring - the original builder didn't forget the wastegate seat by any chance, it's caught a lot of people out before.

So we took a look at the basics again tonight. Base timing checked good, leak down and compression all great. Boost leak test seemed to be ok, but only left it to sit for about 15 mins with minimal loss. Found what looked to be a damaged vacuum line on both the wastegate and the boost control solenoid. Once we got it back on the dyno I noticed the VCT was not functioning and it would fall on its face. After getting that sorted we noticed the dyno was running out much faster than it’s set parameters. Slapped a shop car on there that had been tuned on the same dyno under similar weather conditions and it seemed down on power as well! So now to get the dyno troubleshot and give it another go. Thanks for the assist! Car absolutely rips on the street, so I think we’re gonna blame the Dyno for this one!