Loaded

Lower then I expected But power went up then took a dive!
Tip in?

I tested my vacuum system HVAC doesnt hold.

The rest does.

Plugs look great 60psi + of fuel pressure.........

This looks like I have described before the thing runs like a scalded dog 3/4 throttle but when floored it takes a dive.....

WTF gives!



BTW thank you ROB and your lovely spouse for cooking out and sharing your beautiful Villa with us at the track!

hacker-pschorr

Wow, that is low. Last stock S4 I saw on a Dynojet pulled 260rwhp (automatic).

Loaded

Yes there is something wrong at 4300 RPM it takes a dive!

ROG100

Don't want to hijack the thread but my GTS dynoed at 270RWH.
Last time I dynoed on another machine it was 282RWH.
Since then I added the X pipe and no cats.
I expected better - maybe 300RWH.
The car is running slightly rich at the top end.
Roger

Loaded

Roger, I checked every under hood dash pot vaccum line etc. all held vacuum perfectly I feel it has something to do with the throttle somehow it is going rich and i just dont know why.

Jim R.

Might be time to look into the hall sender and/or knock sensors being faulty and pulling the timing way back.
Is the WOT switch functional?
Also, dirty fuel injectors with poor flow and spray patterns will kill some power.

Long shots: aftermarket (ebay) chips or stock?

partially clogged cats?

Definitely down on power, I would try to find out why.

Jim

wildguy

How hot did you water temp get? When your water temp gets upto a point on the dyno, ECM adds much fuel. It's a safety feature. Otherwise there is something else.

hacker-pschorr

Doesn't the flappy kick in around 4k? Us 16 valvers don't have to worry about these things.

Loaded

well remember this lays down at pure 100% throttle. If you pull back it snaps in to power instantly its the craziest thing to feel

ErnestSw

The chart shows that the flappy kicked in around 3800rpm like it should. If the chart is accurate you should have heard your car take a crap at about 4500rpm. The engine sound should have fallen off noticeably. Roger, post your dyno run and let's see whether you're showing the same "problem" at 4500rpm. Looks to me like the dyno may have taken a crap, not the car. The two meaningful air fuel curves look normal to me.

ROG100

One concensus - is something wrong with the dyno??

wildguy

Looks like the flappy flapped all three runs. Looking at the previous A/F ratios, it seems that they were real rich anyway. The third run got a bad reading but if the previous two were in the low 12s then I'm sure the third got hot and the ECM dumped fuel which in turn dumped your power. Get an adjustable Air Fuel regulator and bring your A/F ratios up to 13:1 on that same Dynojet Dyno, but make sure your cars is cool with fans or a cool down between runs. I bet with the raise in A/F ratio you'd be were regular S4 cars should be. Hopefully your is more than regular

Just ideas, I've spent too much time on dynos.
Guy

wildguy

It's rare that the dyno took a ...
Low 12s in AFR is too low for naturaly aspirated cars but good for boosted ones.

wildguy

Also, remember that your reading the ridges and valleys of the dyno chart. Some could read a diiference of 10 horses. Have the dyno operator play with the smoothing in the dyno software. This will tell you how close the pulls really were. But still too rich.

ErnestSw

My 91GT ended up with an AFR of 10.5:1 at the top end of a 310HP run with an X pipe. It's NOT an AFR problem.