I went to the track last night and got my speed up 2MPH more. What I don't understand is the SLOWER I took off, the faster I went. The only difference in the car from this time and the other times I went to the track was I put weld draglites on and I was running on street tires. On street tires, much to my surprize, I pulled a 1.7 60' But, the better the 60' the slower I went. If I loaded it up (power braked it) and spun or got a good 60' it went slow (81-83MPH's) If I came off the line not power braking it and slowly getting in the gas it went faster. I think my torque converter is bad..........could that cause an issue like this?


The way I even found this out was I let a friend run my car a few times and the last time he ran he ran a 10.01 (1/8) he said it had NO power on that run. So I got in it and drove to see what it was doing. When I pulled up to the line I heard the rear pop so I babbied it off the line, here were the times.


BEFORE the problems (hard off the line)

60' 1.745
330' 5.22
594' 7.58
1/8 8.11
MPH 83.92

60' 1.818
330' 5.466
594' 7.981
1/8 8.538
MPH 80.78


Now with getting off the line EASY

60' 2.120
330' 5.691
594' 8.049
1/8 8.574
MPH 85.69


Here's the one I thought something was broke

60' 2.467
330' 6.007
594' 8.357
1/8 8.882
MPH 85.71


Now, the 1.74 and 1.81 60's were with my OBDII PCM. I CAN NOT run those 60's on the OBDI PCM because of the stall wall. And before anyone thinks, well there's the difference, you changed PCM's that's not it. The better the 60's with the OBDI still the slower I went. And I was NOT spinning on at all on the good mph's. Any thoughts appreciated. On a side note I think I should still be in the 88-90MPH range so I'm still not happy.


*edit* I ran 14 times last night so there were alot to campare to. I just didn't think anyone would want to see 14 time slips. LOL

 

There is definately something wrong..... If you are hearing a pop from the drivetrain you could have more than converter problems.... it could be the gears too. I'd pull the rear cover and inspect the ring for cracks or broken teeth. Possible that the differential is going too. It's not entirely out of the questions that the transmission may be causing the noise.

 

Compare the 330' to 660' times. Your higher trap speed runs were .19 to .20 quicker over the last half of the track than the slow run. I assume you are completely hooked up by the 330 ft mark.

That says more power, perhaps from better air. Look at the air temps or DA for all your runs. See if there is a correlation to mph.

 

Thanks for the quick replies. As far as the rear goes.......(not being sarcastic) I've broke 3 rears, I KNOW it's not a ring or pinion problem. I do have a broke worm gear though. That's probably what it was.

As far as air goes, it was later at night and it did get cooler. But I have ran when it was ~40* out and my best before was around 83MPH. That is WAAAAAAAY low in my opinion for the mods I have. That's the main reason I'm trying to figure out what's going on. It sucks to have spent sooo much and be so slow.

 

Also, that's why I was thinking it "may" be a converter issue. Could it be ballooning out and cause it to be slipping? That's the ONLY thing I can think. It takes off VERY good, I think I could get 1.5 60's with better suspenion and traction. It's always the last half of the track that kills me. I races a guy with a 230 236 a couple of weeks ago, he had a M6 and not as many "supporting" mods as I have and I was raping him off the line but he was catching up by the end of the track. His speeds were 88-89 MPH and mine was 83. I thought he was hitting the juice right about the halfway mark. I know him personally though so I KNOW he was not.

 

I think my opti may be dying.......I just installed new spark plugs and it's stumbling when I first hit the gas. I noticed it a couple of days ago but thought it was probly the plugs. Oh well, guess I better order one before it goes completly out.

 

I would kill for 60ft's like yours. Then again, I should just stop using street tires and that problem would go away.

Sorry I can't help you tho, my car is way lighter than your and runs the same time. My trap however, is pretty high for our E.T.

 

Have you checked all the normal stuff like fuel pressure? Let's get that gremlin and get that thing around 89-90mph like it should be.

 

Yeah, I have a fuel pressure gauge. I check it every once in a while. Last time I checked it was about 2 weeks ago, it was 43psi at idle and at WOT going down the road it actually went up a little.

 

Double check the fuel pressure and see if you are getting any knock retard. Do you have a data scanner?

 

I have a friend that has LT1 edit......we've done some tuning. I'll get him to come by soon and we'll take a look.


I just put the FP gauge on and drove down the road. FP was 43PSI @ idle and dropped to 41 PSI @WOT driving in 2nd & 3RD. It only stumbles under load when I first hit the gas. If I'm parked it don't do it. Once it gets going it feels like it has all the power it ever had. Maybe the button is loose in the opti..........I don't know.

 

Where are you from?

 

What is your A/F ratio looking like?