Ok, I may be over reacting, but I think something is wrong, and I need some expert opinions. I went to the track tonight, and had real crappy times, even if I was consistent. Anyway, you can see from the charts, I was .5 slower tonight than I was on 2/6. There was a huge difference in the DA's, but I do not think that accounts for this much of a difference. Crap, tonight I was running the same times that I was before the tune and DR's. I did have great reaction times, with a 0.000 on my first run, and my worst was a 0.056. I am at least trying to find something to be happy about.

I was not having any traction problems whatsoever, and as you can see, I was off .05 at 60', .2 at 330', .3 at 1/8, .4 at 1000', and .5 at 1/4...... So, I was having a consistent loss of power through the entire range.

The last chart shows my last runs prior to the tune and with no DRs. As you can see, the pre-tune times match almost identically with the runs I had tonight. Could something have happened to cause me to loose the tune? I know how weird that sounds, but I am at a loss to understand how I could go back to pre-tune numbers all of a sudden.

I really wish I had a data logger, as I know it is hard to give any advice without it.

Anyway, from looking at these numbers, anyone have any ideas as to how I could drop this much in time?

Thanks..... Slightly perplexed..... Bob!

Screenshot2010-04-24at125921AM.png

 

Did you do a throttle reset before you went on the track ??

 

I did a throttle reset at the track before I made my first run.

 

The DA really does have a big effect on your times. You went from running in 45* in February to 80* now. Welcome to racing in southern heat and humidity. Although your 1/8 MPH does seem a little low by a couple MPH.

I'd be willing to bet your timing is being pulled, too. Combination of the warmer air and maybe even lower quality gas. You won't know for sure without actually data logging. One thing to try is either put a bunch of 100 Octane race gas in if they sell it at the track (though I'm not sure if the ECU will adjust in time). Or go buy some octane booster and put it in your tank when you fill her up with 93 and drive around for a bit. Lately I've been running about 12.5@110, 12.6@109 (this is what I ran at the track tonight.) I've used octane booster twice now. Tonight I tried the NOS octane booster with nitromethane (12.99 at Autozone). Although it did keep my timing from being pulled, I ran the times listed, which is what I've been running for that past month without any booster. I put almost the full bottle in to a tank that was 2/3 full. Then drove 35 miles to the track. Not impressed with the NOS O.B.

The first time I used octane booster was 2 weeks ago on the 14th. I bought a bottle of Lucas Oil octane booster, the racing formula (9.99 at Autozone). Put the entire bottle into a nearly empty tank while at the gas station, then filled her up to the top with 93 gas. Drove the 35 miles to the track. My timing barely got pulled and I ran a best that night of 12.38@111. Had 3 runs at 12.4 and 2 runs at 12.5 with trap speeds between 111 and 112.

So give your car an octane boost and go back to the track. I recommend the Lucas Oil. You should hopefully see your times improve. I'm not guaranteeing it, but for 10 bucks, why not give it a shot?

 

Thumper, I appreciate your comments, but here is where I am still at a loss. The runs that I made in November was at 71 degrees.... So, 10 degrees cooler. This was prior to my Dyno tune and DRs. I really do not think that 10 degrees, with 600' lower DA would completely negate the benefits of the Tune and DRs. Or, am I totally off base here. Thanks

 

I used to use octane booster alot but I've since read articles and watched a video from 5th gear documenting that most octane boosters actually result in a 2% loss in hp/tq.

The only thing I can put it down to Bob is if you disconnected the battery, because I know the ecu takes a full tank of petrol to adapt again.

I hope you figure it out. Goodluck my friend.

 

I say belt slip. Check your belt. Make sure there is no oil or residue on it or the pulleys. mine went south after the crank pulley was in it. there was just enough oil seeping past the crank seal that it was getting all over everything slower me down about .3.4 tenths. When i cleaned all the pullies off and put a new belt on i was gtg.

If you look at your SC pulley is there any black residue on it or around it? if so thats oil and belt material.

 

+1, I've heard of this problem a lot. Especially since you're losing everything at top end...

 

No boost my friend...look for slippage...and heat does take its toll.....I usually start out good and end bad....but, I usually hit the 12.3 first, then fall off....I vote for the belt slipping and heat soak....good luck

 

I am not sure that heat soak would be my issue. I let her cool for 45 minutes with ice on the SC before I made the first run. I used ice on the SC between runs. And, out of the 4 runs, there was only a .011 difference between my best and worst 1/4. If I were having heat soak issues, I would expect to see a larger gap in my times.

I just checked my pulleys and belt. There is no residue of any sort on or around the pulleys or belt.

Kolevski, said something that was interesting. Would disconnecting the battery have anything to do with this? Here is the deal... Before last night, I have not driven the car for about 6 weeks. During that time, I was working on the illuminated door sill project. While working on that project, I had the battery connected/disconnected many times. I was actually wondering last night if me disconnecting and reconnecting the battery so many times could have affected the ECU.

 

I would say, that if it did, your times would improve the more the ECU adjusted....and I use ice as well between runs...unless you some how blanked your tune...I don't see anything else it could be...

 

This is a good point. I'm not sure if it is true or exactly how it works, but supposedly the ECU will apply any Long Term Fuel Trims even when we go WOT. Disconnecting the battery will clear any LTFTs. This would then change your AFR's, which would affect your times.

I don't remember where I read that, but I think it was somewhere here on the forum, or maybe over at mbworld. I haven't actually tried clearing my LTFTs or even datalog that I have any, but after I put on the NW manis in January, it took a couple of weeks before I saw my AFR's lean out while at the track. (I don't drive my car much day-to-day).

Looks like the only way to really know would be to drive the heck out of your car then go back to the track. I feel your pain, bmorgan! These damn cars bug the crap out of me sometimes!

 

That could be your answer...need to drive the heck out of it for awhile to let adjust back...maybe our tuners will have a better opinion....

 

Thanks guys. I guess I will try to drive her as much as possible this week, as I am racing in the Import Showdown next Sunday with Steve, and possibly XRay. Not feeling too great about things right now, but we will see. The worst part is, Steve will never let me live it down if he beats me next weekend.

 

I'd say there will be some black marks appearing on some unknown back GA roads....soon....LOL

 

And quite possibly some known ones as well. LOL

 

bob you dont have to worry. i dont need you to lose your tune to beat up on ya!! ask goodgenes!!

 

Well, if you are that strong Steve, maybe you just forgot to update your signature. Without a slip, it's just talk.

I am looking forward to you coming down Steve. It will be fun.

 

Well I know for fact that blowers love cool air and hate hot air. More than other cars.a roots supercharged car will feel like two different car on a hot day vs cold day. so I say the answer is the D/A difference.

 

I dont think disconnecting your battery is the issue.... I have had mine on and off multiple times in the last few weeks and not driven the car anywhere.... I drove it the 40 miles to Woodburn this morning and my first run was 11.96sec, second was 12.1sec (operator error) and third was 12.0sec... these runs were one hour between each and the DA was -726' on #1 and -667' on #3.... my worst run of 12.1 was at DA of -743'....but that was my launch.....

It certainly wont hurt to get some time on the ECU..... but I dont think it is going to make a difference...