legacycentral bbs

So here are the numbers that I got running on a DynoJet dyno.


Specs:
1992 SS w/ 240k on the clock
TD05-16g running 9psi (wastegate boost)
'06 TMIC
Helix Turbo back exhaust


Its obvious something is haywire.

Here is my first run:



And my second:



And my 4th run:




Judging by the A/F Ratio it looks like I'm running super lean down low. My theory is that the ECU is basing it's fueling off of a malfunctioning sensor but after around 4500 rpm it is ignoring the sensor and going into closed loop mode.

Any other thoughts?

I should also add that the AFR's transition from Lean to Rich was smoothed out by easing on to the throttle more. As you can see, the AFR transition in dyno run #2 is quite abrupt. This is a run in which I pretty much stomped on the gas. dyno run 4 is different however because I eased on to the gas more. So the change in throttle position was not so abrupt.

Also note the rapid increase in both torque and hp as soon as the AF ration begins leaning out.

Imprezive wrote:Also note the rapid increase in both torque and hp as soon as the AF ration begins leaning out.

I think you mean enriching?

That's not good having that lean of combustion down low for sure.

A fuel delivery issue, perhaps? What do have for EM?

Imprezive wrote:Judging by the A/F Ratio it looks like I'm running super lean down low. My theory is that the ECU is basing it's fueling off of a malfunctioning sensor but after around 4500 rpm it is ignoring the sensor and going into closed loop mode.

Any other thoughts?

I'm assuming you mean open loop.

Imprezive wrote:Any other thoughts?

Yeah....it's the stock ECU, and how it was tuned from the factory..... The fact John saw such large increases in HP/TQ just from a different tune should be an indicator.

Additionally, here is my dyno run. The curves for the AFR mimic yours. Mine don't stay as close to stoch as yours, but they do plummit around 4-4.5k rpm range to 10-10.5 : 1 range. This is also why our fuel mileage sucks so bad.

http://www.main.experiencetherave.com/s ... gdyno1.jpg
http://www.main.experiencetherave.com/s ... gdyno2.jpg

Josh,
~12.9 isn't a bad 'high' AFR. Better than the alternative. That 'shift' in AFR would explain why my (and others, from what I've heard) car feels stronger from a roll-on than from an instant WOT.

+1 for good EM.

beatersubi wrote: +1 for good EM.

Or +1 for getting a different car :O

Get some tuning..... And then turn up the boost. I made 200 whp on NA block and heads, you should at least do this on stock turbo bits, with EM.

Like everyone else stated, install EM and tune to get your AFR under control. That porridge is too hot then too cold, time to get it just right.

haha, EM is costly. Thats my only gripe.

I hate to say it but I think my legacy might be going by by soon...