What the hell is wrong with my car?

B6/7 S4/RS4
#1

So I was camping 20 minutes from the dragstrip this weekend with some friends so on the way home, I decided to stop at the Test & Tune even running all day for some 1/4 mile times (first since I installed the supercharger).

A couple weeks ago, in 35c temps, I ran neck and neck with sakimano’s stock RS4. Not exactly the kind of power I want but it’s a start and the car’s still being tuned.

However, at the track today, in 25c temps (so considerably lower), and with every piece of non-bolted in part removed to save weight, I ran a whopping near stock 13.7 @ 101mph (60ft time of 1.9). Wtf??

I felt the car wasn’t pulling that hard (as the time shows).

Then, I drove 90 minutes on the highway coming home and at the end, I felt the car was pulling better again (more or less as strong as when I ran with saki’s RS4).

Is it a heat thing? The track was mildly busy and it would take me about 10-15 minutes before the next run of sitting there waiting.

I just don’t get it. Assuming the car is about as powerful as saki’s RS4 in 35c, I should be running a hair better than stock RS4 times in 25c on my current tune.

Thoughts?

#2

How hot was it man? Heat is a huge issue, but I’m not sure it’s a 13.7 issue. I don’t even like to run my car if it’s hotter than 70. Was it one of your first visits to the strip? You could lose a lot of time shifting too slow or going out of your power band and wasting time.

#3

thats weird. our car wasn’t really fast when you want in the fall when it had full catless exhaust and some lightweight parts…I think you were running low 14s @ 98-99 or so, correct? And that was with densit altitude of around 200 feet.

Today you ran 13.7 @ 101 in density altitude that was surely near 2500 feet. So there’s that.

Still, it’s not as fast as it should be, considering. I don’t know why.

Did you see Mistro there in his black RS4? It is bone stock and he was thinking of going today (although I may have convinced him not to since it was so hot and would be busy as fuck).

Basically ou went in perfect conditions to suck. I would go in the fall to get a better idea.

For reference, my RS4 went 12.75 in great density altitude (280 feet) but when I went a few weeks ago for fun it ran 13.30 or so on 91 octane. I basically wanted to see what the worst possible quarter mile time an RS4 could run would be…and I wanted to throw in some race gas to see how much it could help. It shaved 3 tenths and added 2 MPH for reference in case anyone cares. I went on a bitching hot, superbusy night (got 3 passes). I had shitty 91 octane in the car. I launched like a fag and bogged it (1.95 every time). Basically a worst case scenario so that when someone runs 13.50 with an exhaust and lightweight wheels on 93 octane, but their timeslip ‘blows out the window’ I know how much the driver is hurting things. 13.30 @ 104-105. I should find the slip and make a thread. The 110 octane I threw in to create a mix out to around 100 was basicall good for 13.08-13.15 @ 106.6 or thereabouts.

#4

I mentioned the temps in my initial post. 25c isn’t that bad guys. Sure, it’s not great but it’s not awful either.
Also, I was neck and neck with saki’s RS4 in temps that were 10c hotter. Doesn’t make sense.
A 1.9 60ft isn’t great either but it’s not plain awful.
As for when I was stock, I couldn’t get any traction on the launch that day. I think my tires were over-inflated and the launching section was way more slippery than today. I was doing 2.4 60 footers that day with a 14.1

Again, makes no damn sense.

And no, it wasn’t my first time out. Just my first time this season.

#5

still, your MPH is what I was looking at when you were with us last year. It was super low. 98 MPH is like tip Avant MPH, not MT6 catless exhaust Avant MPH in 0 density altitude.

#6

Which leads me to my thread’s title. What could be causing this? I personally feel like the car is running too rich when I start pushing it. But that’s just me…

#7

Maybe there were still a few coolers hiding in that spacious avant you forgot to take out? :stuck_out_tongue:

I didn’t up going. I was originally planning to go with Birdman but he slept in and I ended up having to go shopping with my fiance anyways… can’t argue with her when it comes to shopping lol. Plus as Saki mentioned it was probably going to be more crowded than a Wednesday night anyways.

Was this the run from last time? (14.0 @ 99 mph)
http://youtu.be/vuXShGfjT0c?t=1m42s

The temps today weren’t all that bad either. Yesterday’s rain took out a bunch of the humidity too.

Did you happen to get the runs on your dash cam?

Edit: I should mention that I have H-pipes in there now, but I doubt they’d make much of a difference anyways since the cats are all still in place; I’m assuming my driving would probably affect the result more.

Edit 2: What gas and how much in your tank?

#8

Looks like you’ve got some logging to do Axel. :-\

#9

I took everything out, including the rear Avant trunk cover

It wasn’t too bad. Just those damn 8/9 second cars taking 5 minutes to stage really slows things down. That and they had a motorcycle lapping event which meant a lot of bikes were having fun doing 1/4 miles as well.

That was my benchmark.

Exactly, any hotter and I would have skipped it.

I did, haven’t looked at the footage though.

A little less than half a tank of 94 (high octane tune, can’t use 91). Not optimal but my benchmark was fully loaded with the same amount of gas so probably about 120 lbs of extra weight overall compared to today.

Even if my driving wasn’t far from optimal (I don’t go enough to get some good practice in), I wasn’t bogging the car and it can’t explain a 1 to 1.5 second slower times.

#10

It seems like after a longish highway drive, the car has a little more juice. The more I push it, the slower it gets.
Last time I logged it (a month ago), I was in the 6xx RPMs per second in warmer temps but after some long easy driving.

Back in February (colder temps), I had logged 800 RPMs per second. That said, back in February, I was neck and neck with saki’s RS4 as well just like 3 weeks ago (both times, easy highway driving before hand).

However, after a bunch of hard pulls with saki a month ago, my CEL came on because my fuel trims exceeded the acceptable range. It went beyond -10% adaptation (i.e. pulling too much fuel back).

My long term fuel trims are all on the rich side but obviously, I don’t race the car all the time so the only time I did get a CEL was when I did a lot of hard driving in a short period of time.

Of course, as the car gets hotter and hotter, the system will go richer and richer for safety purposes but I’m wondering if it’s going too far.

Then again, I’m no mechanic or tuner so I really have no idea. I’m pretty much confused at this point.

#11

Neck to Neck with a 12.7 Rs4 and today you ran 13.7. Seriously something to look at. From the sound of it. You said the car was running better on the way home. This to me would say that the blower and the car had some time to cool the oil temps down and to get the car out of what sounds like safe mode.

If you drove all that way and then let the car sit. You basically just let the car heat soak. When you go to the track its good to do a few back to back passes. This allows the car to get air past the oil coolers and obviously help cool the car down

Tell us more on this. What leads you to say this. Is there black smoke coming from the back of the car? Most supercharged apps are going to run MUCH more fuel then your standard NA cars.

#12

Unfortunately, back to back passes aren’t really an option. What would you recommend? Simply not shutting the car down while waiting to go back on? That very well might be a big chunk of today’s problem. The reality is that there’s going to be a wait before the next run. For the future, what is the recommended method?

When I punch it, there is smoke coming out the back. How much? Hard to tell as that’s all relative. Let’s just say there’s enough to see from my rearview mirror but not so much that would cause someone to say “holy crap, that’s a lot of smoke”. So a “mild” amount of black smoke? I’m also catless if that changes anything.

And as I mentioned above, my long term fuel trims are on the richer side and when I pushed the car hard for a while, I got a CEL for an adaptation number going beyond -10%.

Oh, and I did a quick pull against a JHM tune 4.2L manual converted A6 last week (evening, cooler temps) from about 50 kph to 130 kph and I was only slightly distancing myself from him. Both myself and the A6 driver were surprised. We both expected that I would leave him behind quite a bit.

#13

I’m not sure that back to back runs to “cool” the car down is optimal?? When I go to the track…to run a serious time that I care about…I arrive early before T&T starts (if your lucky and your gates open early) I park, open my hood, and throw a bag of ice on my IM with a towel wrapped around it so water doesn’t run down around the injectors and IM. I only have a 20 minute drive to the strip, but I still think cooling down is a serious factor. After about 30min I’ll go get a pass in to get my adrenaline down…lol Usually at our track if you get there early you can get passes in without sitting in the staging lanes for 10-15 min.

I would just wait until it cools down Axel, a lot of people stop going when it gets cooler too, which is even another positive. Good luck though, I hope you figure this crap out.

#14

73-77F temps is not going to cause my car to go from 12.5-12.7 to 13.7.

#15

This is exactly true. When I had my SRT-4 I ran 13.65 @ 103, in 85F temps.

My random thought of the day would lead me to ask how your MAF is looking.

#16

A few months ago it triggered some errors (sensor error). Every time I cleared it it came back 2 weeks later. However, it stopped coming back 6 weeks ago and hasn’t come back yet.
Not sure what to do about that one.

#17

I never said it would, but if you want to see good ass times your car being cool is pretty damn important. I think a heat soaked engine and horrible DA could cause a pretty shitty time. Saki just noted that he picked up almost 6 tenths because of shitty conditions. If you think something is wrong you should get JHM on the phone and do some logs, have them look into it from a technical standpoint instead of a thread full of “ifs” and “possible” causes.

#18

yeah, 12.75 @ 108.36 to 13.33 @ 105.5 was the good weather/shit weather gap for me…however I also had 91 octane in the second time.

That’s pretty huge. 6 tenths and 3 MPH.

Now, axel’s car in my mind should have run the following

last fall, great DA, no tune, catless 2.25" exhaust + a couple of LW parts = 13.8 @ 101 (basically stock time…going catless with no tune isn’t good for much)
it ran 14.1 @ 98-99 so was off a few tenths and a couple of MPH. His launches weren’t great so that’s part of it. Still a bit slow but not drastically.

this week, shit DA, JHM supercharged and lots of bolt ons = 12.80 @ 110

this fall, great DA, same mods = 12.40 @ 113-114

Just my guesses of course on what a car with those modlists should run in those conditions on our track. I think next Detroit meet when jaybquick and count vohn are there, he should bring the car down for them to check out with their own eyes.

AXEL - post your timeslip up so we can get a look at the various times etc. and so I can see exactly when you ran to determine DA.

#19

I think the heat soak played a large part as Carlos mentioned. Will have to go back on a cooler and more importantly, less busy evening. The 14.1 were really crappy launched and not a good indication. I think a 13.9 would have been easily achievable with better traction at launch. Still, I was surprised at the bad times.
I still think there’s some other smaller issues but not completely sure.
I’ll post the timeslip when I get home later.

As for the JHM guys in Detroit, I’ll be there for sure. Is that usually in the fall?
JHM has my next tune available with LA so we’ll see how that works out once I get it.

#20

I’m trying to explain that the 14.1 even if you launched it terrible still had a trap speed that was around 98 MPH. Your trap speed isn’t going to change 4 MPH becuase of a poor launch. The distance of the track and your accelerating power will determine your trap speed, not how well you launch the car (well…it won’t move the needle 4 mph or something on these cars). Provided you shifted gears reasonably well, the trap speed will be within 1.0 MPH of itself 95% of the time for the same car at these power levels.

Look at my runs from April…I made like 13 passes, including 8 where I wasn’t taking it easy or screwing up gear changes. The variance in trap speed was tiny on these runs. Only one of those was more than 1% off the best of the day…and that was 1.7% off.
12.75 @ 108.3, 1.83 60’
12.77 @ 108.2, 1.85 60’
12.79 @ 108.2, 1.85 60’
12.81 @ 107.7, 1.84 60’
12.82 @ 108.0, 1.83 60’ (vs. the C63 AMG 13.7 @ 110.6)
12.90 @ 107.2, 1.88 60’ (vs. B8 S4 GIAC 91 TUNE…he ran 12.92 @ 109.
12.90 @ 107.4, 1.86 60’
12.97 @ 106.4, 1.87 60’