Problems at the track... need help analyzing

[speedemn]

I was out at the track yesterday - first time with the JWT ECU. Generally, every time I go to the track I do well... but yesterday I had nothing but problems! Problem after problem... if it wasn't one thing it was another... I had about 13-15 runs and MAYBE 2-3 runs where everything worked! However it seems like the JWT ECU has me running no faster than last year without it.

Here is a list of my problems...

(1) Harlan RPM switch kept flaking out
(2) I kept losing ALL pressure in my front passenger tire (I deflated fronts to 18psi but the front passenger tire kept losing it all)
(3) Intake popped right out on one run
(4) I had a hose or two pop out on a couple of runs
(5) Even though the outside temp. was only supposed to be about 50 degrees outside, the lineups were so long that by the time I staged, my coolant was at about 185 degrees and my air intake temp was about 90 degrees (30-40 degrees hotter than it should be)!!!
(6) My Firestones are down to 1mm tread... but despite that, I was able to pull decent (for our tracks) 60' times of around 2.25 however my trap speeds were really low! I'm talkin' 94.xx mph area on average!!! My best ET of the day was only 14.41 - basically I am no faster overall, with the JWT ECU. Unfortunately I didn't take my stock ECU with me to compare, but I was sure that even if my ETs were not good, my traps would be nice and high at at least 97-99 mph.

Overall I was not at all pleased yesterday even though my ET was a tad better than my old PB. My best trap of the day was 95.31 - but other than that they were all 94.xx when the butterfly valves DID open (at least they opened before the run and after the run so I assume they were okay during the run).

Here's my slip with all the same mods, but no JWT ECU, PB from last year (@ St. Thomas):
RT:
60': 2.241
330': 6.160
1/8: 9.421
MPH:
1000:
1/4: 14.496
MPH: 95.62

Here's my slip from yesterday, with JWT ECU (@ Cayuga):
RT: 0.502 (0.500 tree)
60': 2.211
330': 6.102
1/8: 9.320
MPH: 76.25
1000: 12.107
1/4: 14.411
MPH: 94.80

Now I know that I ran at a different track, but I have ran at Cayuga before in the summer heat, with night-time humidity and my traps were 93.x - 94.x then too. This track tends to trap lower. But the ECU should have given me at least a couple more mph... but it doesn't seem like I am any faster from last year at all!

Now trying to analyze the causes, here are some of my thoughts:

(a) JWT ECU was not tweaked/tweaked enough (I do have a 7200RPM rev cut but I wonder if they forgot to program the rest in?! lol)
(b) Vacuum leak?
(c) Losing compression? (I am burning oil and have been since April 2003 or so, but when I checked my compression in October 2003 it was normal 175-180 across all cylinders... could it have deteriorated since then?) If I was in fact losing compression, would I still be running 14.4 (consistent 14.5-14.6)?
(d) Intake air temperature? (when I staged, it was as high as 90 degrees, but at the end of the run it was about 60 degrees, so is it safe to say that it gets cooled instantly once I start moving, so this is not a factor?) I still need to find a better setup than the JWT pop charger... gets too hot too quick.
(coolant temp. is always at about 170-185 - I need to use Jime's thermostat fan mod to control it manually)

I would really appreciate some help analyzing this... or any other things that I might not have considered...?

I will dyno next weekend to try and get an exact comparison of before and after ECU.

[Ceasars Chariot]

speed, I wont be able to help as much as (daveb, mike, and neal) but it appears you are very close to being .1 faster. looking at that and if you could get a few 2.1 60 foots. i think this setup is good for a high 14.2.

I dont understand the MEVI at all, which is one of the main reasons I dont have one yet. Maybe some tweaking is in order here as well.

Im also wondering about shift points here. If you have the new rev limit extended, maybe (guessing here) you might still be driving the old way out of habit. I know I would have to adjust and make myself remember that I can run the car up to higher rpms.

[speedemn]

Originally Posted by Ceasars Chariot

speed, I wont be able to help as much as (daveb, mike, and neal) but it appears you are very close to being .1 faster. looking at that and if you could get a few 2.1 60 foots. i think this setup is good for a high 14.2.

Well, Cayuga is a faster track than St. Thomas... it just traps lower... so overall I am no faster, no slower than without the JWT ECU. St. Thomas doesn't have its timers working which is why I went to Cayuga.

Originally Posted by Ceasars Chariot

Im also wondering about shift points here. If you have the new rev limit extended, maybe (guessing here) you might still be driving the old way out of habit. I know I would have to adjust and make myself remember that I can run the car up to higher rpms.

Nah its not a problem shifting at redline everytime (7200RPM)... it blows by 6500RPM with the MEVI. Maybe I need to shift sooner 2-3? The first thing I need to do is get a Harlan switch that is NOT flaking out half the time... for all I know it isn't working in 2nd or 3rd gear even though it works before and after the runs... Harlan sent me a new switch, along with a letter in it that said that there is a mathematical error in the switch... grrr... so I need him to send me ANOTHER one!!! He said that he would, but he is so hard to get a hold of!!!

[I30tMikeD]

Get rid of the harlan, get the summit switch and use some race gas.

[speedemn]

Originally Posted by I30tMikeD

Get rid of the harlan, get the summit switch and use some race gas.

Do you guys all use race gas (the ones running in the 14.2 neighbourhood that is)?

You are right about the Harlan. I had placed an order for a Summit switch and thought I'd e-mail Harlan just to let him know that his switch did not work for me. He then offered to send me a new switch, admitting that there were issues with his previous ones. But the problem is, when I received his new switch, there was a note along with it that said that this switch was flakey as well - in that the LED will flash randomly! I don't understand why he still sent a batch of these switches out!! Now I cannot get a hold of him to send me a proper switch! Is it just me or is he impossible to get a hold of? Even on his LS1 forums, his PM box is always full and people are always trying to find him!

I figure, that if I can get a working Harlan switch, why spend another $50+ for another switch? I had cancelled my Summit order.

But what I don't understand is that I am running the same times now that I did before getting the JWT ECU! I don't know if my Harlan is necessarily the only culprit here.

[96sleeper]

definately get rid of the harlan switch. I bet it doesn't work all the time. You can look at my home page of my dyno as an auto and see where the crappy harlan switch opened fine at then closed prematurely at 6500 rpm. I bet that is part of the problem. Also, a heat soaked engine kills mph, sounds like you engine got heat soaked waiting in line. Also, what is the condition of your knock sensor? If the engine was heat soaked then the knock sensor could have been pulling timing pretty badly. I don't think it is the burning oil. My car has been burning oil for about a year now, hasn't seemed to hurt me yet. It could have possibly been bad gas as well. A little high octane fuel helps out by keeping timing retard at a minimum.

[Dave B]

It's hard to say what the problem is. Jime seemed to have no trouble running and his NA traps were in the 101-102mph range so I would have figured you would have been at least 98mph.

One of your problems could very well be the Harlan. I too have experience the Harlan unit flaking out and it seems to flake out when you really need it to work....at the damn track!!! This is why my Harlan unit is mounted to the lower portion of my dash and I can see the indicator light. If I see the light flashing (means it's flaked out), then I switch to manual operation of my MEVI via a toggle switch. 1st gear seems to flake out the Harlan more than any other gear. I think it has something to with the fact that the butterflies open and then nearly 1.5 seconds later you've shifted and the butterflies close. I think this rapid on/off operation is more than the Harlan can handle. My best runs, oddly, have come with me hitting the toggle switch at 5400rpms in 2nd and leaving the butterflies open the rest of the race. I plan on dumping the Harlan soon because I plan on getting the SAFC-V assuming the wiring doesn't look too hard.

Your car could also be experiencing the same problems my car does with inconsistentcy. I've noted wild ET/MPH swings ever since adding my JWT ECU. If the motor is hot then I'm in the consistent high 14.5s-14.6s@95mph. If I let the motor cool for 30-45 minutes then it's easy 14.4s@98mph. Not until I added my JWT ECU did my car really become influenced by heat. I'm sure it has something to do with the advanced timing and extremely lean A/F JWT chooses to run above 5000rpms. JWT programs the A/F to right around 14:1 across the whole rpm band which is stupid, IMO. Any car guru will tell you that you want to richen the mixer as rpms rise in the upper rpms. Nissan programs in about 12:1 which is a little rich. 13:1 from 5000-7000rpms would be ideal, especially with all the extra air the MEVI crams in.


As for race gas, I've run 14.4s@98+ with 92 octane and 96 octane. Since the ECU runs things so tight in the upper rpms, I'd recommend higher octanes for consistentcy.


Dave

[I30tMikeD]

I have ran 4 or 5 times now since I started running 96-97 octane at the track. For me it makes all the difference in the world. I am not sure why my car responds to the higher octane so much more than the other JWT ECU guys but it does. Without the race gas I am 14.5-14.6 @ 95mph-96mph. With the gas I am 14.2-14.3 @ 98mph-99mph. I have now ran enough with and without the race gas to be sure of this.

I get the 104 unleaded at the track and i can actually see my trap speeds increase as the race gas gets mixed in. Usually by the 4th run my car is running like it should.

I feel for you about not getting the results you expected. Don't know if you remember or not, but I went through a whole race season not knowing why I was not seeing the times I should have been. Once I got my VI activation squared away (got rid of the harlan and went with the summit switch) and started using race gas things changed.

I don't know how you are checking the activation of your VI, but I always just used to rev to the activation point while in neutral to see if the opend. It always activated using that method so I thought there was nothing wrong. It was not until I wired my harlan inside my car and watched for activation via the green light did I find out that it only opend 1/3 of the time at best. Then other times it would flake out and start blinking and it would not work until the car was shut off and started back up.

I may also get the SAFC-V in the future to better control my deactivation points.