I just had my car dyno'd, made good power but hit some sort of limiter@ 140mph. I lost about 1000 rpms worth of HP because of it. Anyone know if there is a speed limiter on the a4 cars?

Thanks
-Ken

 

Theres not, did you hit the rev-limiter? It cuts out the fuel.

 

There could be some sort of shift point there but it did not hit the rev limiter. I'll have my tuner check it out, just odd that it wouldn't go no more at 140.

-Ken

 

That is one screwed up dyno, never came close to the rev limiter and even the drop to 13.4 a/f ratio is way too lean. doesnt look like a dynajet so I assume its a Mustang dyno. Looks like it dies about 5300 rpm. I'd hold it in 1st or second and see if it still quits at 5300.A decent operator would have done that. In my dictionary , decent operator is defined as one without his head up his ***,,,

 

It was definently the car. We did a pull in second and it ran all the way to 6400. There were other vettes there too, only 6 speeds that I saw though. Didn't see anyone else hook up the o2 sensor but the shop seemed respectable and seems quite surprised at the AFR reading. I was just there for some numbers so we didn't try and diagnose anything.

-Ken

 

The 2004 A4 coupe/vert is electronically limited to 6000 rpm and something like 175mph. You probably know that already. I would try it on another Dyno. Good luck.

 

Did you have traction control turned off? Just a thought, I am sure you already checked that.

 

Hmm, that could be it. I wasn't in the car so is could have been on. It was really starting to make good power so it could have slipped I suppose. We dind't hear anything on the ground and the video doesn't show any sign of slipping, but it was loud as hell and turning 140mph.
-Ken

 

Well that sure would be nice if that is all it is. I hope your luck is better than mine.

 

If it was not off, then because your front wheels arent moving, you will get Active Handling errors. This could activate the AH/TC, therefore cutting the fuel. And it wont happen every time, either. That cam was still pulling like a freight train when it cut off at 5400!!! And you still made 375 at the wheels......wow. Who's your tuner??!

Robert / Gen 3 MS

 

Some joker from Gen III

-Ken

 

Ok, for those of you curious enuf to have looked into this post and noticed the Ken's AFR on the dyno graph. Setting aside the big drop at mid chart, the whole AFR shows to be very lean. Starts off 14.5:1, ends at 13.5:1. One tuning secret revealed: AFR while car sitting static on a dyno will be nearly a full point leaner than out on the road. There you have it. This is why I get more power from my tuning with everything else being the same. I tune out on the road. I can attach my portable wide band unit into a car while on the dyno and read 14.0:1 AFR, just as the dyno's WB will read. I will then take car out on the road with portable still hookd up and get a flat 13.2:1. I have experienced this phenomenom time and again. I will tune my customers with my portable unit out on the road then they go to the dyno and get lean AFRs. Well, if the car truly ran 14:1 or leaner in real life while pulling 29* total timing, the engine would rattle and ping while KR pulled back timing a ton. Ken's car runs about 13.0:1 on average through 2nd and 3rd gear while pulling 29* timing with O KR. He's pulling 115 traps at the strip. Need I say more? Few people realize they are leaving a lot at the table when they have their car exclusively tuned on a dyno. But face it, most tuners dont have time to tune out on the road, plus there is a safety factor.

RJ

 

LEANER on the dyno????

I thought with more load & air actually moving thu etc, it would be leaner on the road & RICHER on the dyno while static...

No??????

Your comments that it is leaner on the dyno is opposite most peoples thinking.. Most guys tune slightly RICH on the dyno because as it is driven on the road it leans out...

 

Not been my experience at all. completely opposite. On several occasions, as a matter of purposely testing this out, I've pulled a car right off the dyno after it showed a lean AFR, say 13.8:1 AFR, with my LM1 still hooked in, drove the car on the street immediately after and WOT run and had 13.0:1. I've duplicated this several times over the last 1.5 years on a couple different cars. And I dont think I am going crazy (Although, many would beg to differ!!). Trust me, if Ken is running 13.5:1 after 5k on the dyno and you're theory was right, then he'd be over 14:1 on the road = ping city, car would rattle to death and power would be TERRIBLE. So, how do we explain the 115 traps the same day? Trust me, this is my experience on this. I am not saying someone has performed the same tests I have and gotten opposite results, I am just telling my own side of the story; I have verified this many times over, and my cars run like scalded ape's on the street and at the track, no KR, ~13:1 AFRs, 28-30* total timing, depending on dynamic CR (e.g.- later intake closing event from bigger cam = lower dynamic CR= more timing dialed in on a high static CR motor). Badda-bing, badda-boom

RJ / Gen 3 MS