Tough One

[PalmerWMD]

1994 Q45t:

Has run on previous 94 engine with same mods, low 14's in the quarter.

The current 94 engine (said to be 6x,xxx miles Unable to verify milage at this point) is a take/out.Not very clean internally , recent flush (envirolution), showed no excessive sludge though.Still has some varnish (even tho I am working on that)Gets very good milage, burns no oil, since it burns no oil, I assume compression is good ,as rings seem tight, but will verify soon.(when we assume...:oface)Previous engine ran low 14's w/ following mods.:Level ten performance transmission with quicker shifts and higher stall speed.Borla exhaust (cats deleted)4.08 rear diff (!)JWT TCU, JWT ECU, (custom made by JWT for this car/ with these mods)

All these mods are still in car.rear tires: new Kumho Ecsta 712 traction AA, treadwear 280 rated.Gas tank on ESpare wheel removed.

Problem:

car has always felt very slow compared to my other Q's.Today I went to verify.The car consistenly took 15.9 seconds to quarter!!:eek:"Good" launches with minimal wheelspin ( maybe more due to lack of power, than good launching technique).

The quarter mile slip showed 2.4-2.6 60 foot times and trap speeds at 91/92 mph.The low trap speeds reflect a power problem not a launching problem.My previous Q achieved trap speed of 97 mph w/ lots of wheelspin off the line and 2.6 60 foot times.(only w/ JWT ECU/TCU and w/o quicker transmission. rear diff, less grippy tires on that previosu Q)

temp 68-70 F in the runs I made today.elevation unknown but not unusually high.More info:Engine installation was not done at dealer, or higher end independent like T3, but a personally known tech, said to be "good".

There is so much aftermarket on this car I have a feeling the dealer will just give up or say something like " aww, its an older car thats gonna happen".

Anyone willing to speculate on the casues or suggest the steps to be taken to acertain cause and possible fix?

Fred...

PS: I have some best guesses too. but I just wanna present tha raw data so as not to pre-form any opinions.

[DAEDALUS]

The weather was cool, but had you driven it hard soon before your runs? How was the humidity? Retarded timing is my first guess, from hot motor, bad (unplugged) temp sensors, or possibly bad knock sensors. Have the fuel pressure checked with the tank near empty. Given the mods, I would say I'd be surprised if a Consult analysis doesn't turn up some possible culprits. I've been wondering how well Consult interacts with the JWT units. The same as far as I know...I think all the same input is there.

[PalmerWMD]

More additonal data I just remembered:-idles smoothly-But sometimes idlessmoothly at 650 and sometimes, at 1500. Both rpms occur when car is fully warmed up seemingly at random.

Fred...

[PalmerWMD]

The weather was cool, but had you driven it hard soon before your runs? How was the humidity? Retarded timing is my first guess, from hot motor, bad (unplugged) temp sensors, or possibly bad knock sensors. Have the fuel pressure checked with the tank near empty.

the car had idled woith open hood in cool temps for almost 20 min time before the run.

Humidity unknown but didnt at all feel excessive by seat of pants.

Unplugged temp sensor is a good lead I think, since i had my doubts on the quality of the install.I will have knock sensors checked also (hopefully they arent cracked indicating a previosu over heat)

Fred...

PS: Thanx for the speedy reply

[Q45tech]

Have a dyno test done in each gear [from idle to 150 mph].Set a Consult up to monitor inj time, advance, temp, MAF, rpm [remember the memory is only 3.0 seconds] do 1st gear runs from 4,000-7,000 rpm [it will barely fit timewise in memory].

Get a 5.0 VDC digital voltmeter and continuously sample the MAF output voltage......tell me what you get at WOT 4,000,5500,6000,6500,6900........I can reverse calculate the airflow grams per second to HP with injector data........the problems is errors why a Consult is really needed since it shows every data point on a single line every 3/100 of a second -100 readings in 3 seconds.

Coolant temp above 194.99F or knock sensors or just too advanced timing [above 15 BTDC] not reading 27-28 BTDC at 6,000 rpm.

The other thought is the 4.083 requires a 2nd shift [to 3rd] to complete the quarter vs a 90-93 JWT 3.538 which can do 97-98 in 2nd gear at 7300 rpm.

Netting the 94 second gear plus the 4.083 yields a 820/10 vs 740/10 mph in 2nd so 2nd gear is only good for 87 mph MAXIMUM and the shift probably occurs at 78-80 mph so you lose 0.75 to 1.0 seconds in the 2nd to 3rd shift.

One would need to log the shift points and shift times and ignition advance recovery times to know for sure.

While the 4.083 works well to improve zero to 30, and zero to 60 even zero to 80 [especially 55-80 mph passing] it may not be ideal for Quarter mile??????????????????.

[Q45tech]

1.48 x 4.083=6.041.544 x 3.538=5.46271.00 x 4.083 = 4.083

At 90 mph in a 4.083 in 3rd the engine torque [let use 4400 rpm is 280 x 0.787= 220 x 4.083 x 1.00 = 900 lb/ft to tire road interface.

At 90mph in a 3.538 Q in 2nd the engine torque [let use 6200 rpm is about 184 x 3.538 x 1.48 = 960 lb/ft

In 94 transmission they changed 1st and 2nd by 5% to let the engine complete the quarter in 2nd gear to save the shift time of the non JWT ecued so the quarter miles were close vs a stock 90-93 [+-0.4 secs].Proper gearing design says you always want to be near redline when you finish a quarter mile in your set up you are at 4900 rpm............you have a much faster 94 Q to 80 mph just not in quarter probably much faster to 135 mph [3rd to 4th max] than without the 4.083.

Its the transmission gear spread not the diff [multiplier]....you must balance acceleration in each gear [time saved] and hope the 2 gears acceleration improvement is more than the time lost in shifting to 3rd..........this requires a zero to 35 mph [1st gear] and a 35-65 mph [2nd gear] and a 65 to 98 mph [3rd gear]......then the 55-80 pass goes to pot because you cannot optimize both at the same time.

For Nitrous it is probably ideal as Nitrous produces the most torque improvement at the activation and middle rpms [3,000-5,000???]

[PalmerWMD]

Dennis:

Thank you for the information.I will do as you sugges,t except I may have trouble finding a shop that has both a consult and a dyno (only dyno I know here in town is a shadetree mechnic)

On the optimaization:Much superior times have been achieved w/o racegas and NOS (like I was running(, but with same ECU, TCU, Rear Diff, transmission combo .I bwelive I am about one and a half seconds short of what teh car needs to run.Also seat of the pants the car feels weak.

If shift optimization was the main culprit I still would have had a feeling of powerful accel in day to day driving and probably just less (or none) of a gain on the trackThe rear end combined with the higher stall speed and the TCU work real well., in normal driving,i can tell form where I am rev-wise during a given driving situtation.Others experience on the track suggest a great improvement over stock numbers.

I will address the items I can address more readily (knock sensors,timing) in the next few days.If I am unable to fix I may rent a consult and go to the dyno.

Fred...:bowdown

[PalmerWMD]

If I cant get this fixed locally, I will take leave and take it to T3.It certainly runs strongl enough for normal driving.

Fred...

[Q45tech]

By the way a 90Q with 3.538 in 2nd at 6800 rpm would have about 1050 lb/ft at 92 mph vs 900 lb/ft rear wheel torque for your 4.083 in 3rd JWT ecued 94..........that 150 or 17% more can be felt as a 2-2.5% decrease in time from 85-92 mph plus the extra shift time............thus explains the 1.1 second increase in quarter mile time for your 94 at least to me.

If I do a quarter mile in drive 1,2, 3 shifts vs leaving the transmission in 2nd [1>2] and hitting the rev limiter beyond the lights [like 50 feet beyond] the difference is also dramatic....the mph drops from 97 to 93.5 and the whole run takes 0.7 secs longer.

You just cannot make up for shift time [2>3].We gotta measure the shift time and how long the tcu/ecu cuts back ignition advance in prep for shift , during shift , and the slow build up back to normal after shift.

What you need is an accelorometer graph showing the real acceleration per 0.01 sec increments thru the quarter...maybe measurements taken at 1/8 mile or just stop watch numbers zero to 80 [10.25-11.0 seconds].......the dyno can be set to record the zero to 100 mph [in seconds] easily then measure the time on the chart that the loss of power occurs [how long the shift takes] with a ruler.

[Q451990]

If I cant get this fixed locally, I will take leave and take it to T3.

Something tells me that's your best bet... maybe we can coordinate our trips down there if you wait for a few weeks.

Heath

[Q45tech]

We gotta find a safe place to run and record 85-100 mph?

[Q451990]

T3 Needs a track

[Former_240_s14]

I am not as educated on these great machines as you all are....but I was at the track with Fred and this is what I began to think.....so please, just hear me out....

1. You can smell excessive gas, even in the cabin.2. The car has minor vibration, esp on acceleration3. No oil consumption, but still noticable power loss

Wouldn't that lead someone to beleive that their is a (Fuel Related) problem at hand here. I have driven Fred's old Q, and this new one, and the old Q felt faster. Something is def. not working properly on this.

[PalmerWMD]

-Yes, the engine smells like its running rich, but i also have that race gas fuel cell sitting in my trunk making for some gas smell.-There are a couple of mior vibrations in the car. The most noticable one appeared right after my new tires and can be felt most thru seat, I am confident it is a tire balancing issue.-There is another one, and it does occur durring accel, it is kinda minor and I have been unable to pinpoint form where it comes (transmission, driveshaft engine mounts etcetc?)

Fred..

[Q45tech]

Fred ask JWT about the ecu, I am under the impression that when Nitrous is not armed [switch in off position] that the ecu is the same as a non nitrous JWT ecu at WOT...........could the ecu be thinking you are still supplying nitrous [but nitrous valve is off [super rich [+25-30-35%] and the timing reduced ]????????..........find a Consult and measure the injector open time at WOT 4,000 10-11 millisecs tapering down to 9.8-10 at 6500.

[PalmerWMD]

Fred ask JWT about the ecu, I am under the impression that when Nitrous is not armed [switch in off position] that the ecu is the same as a non nitrous JWT ecu at WOT...........could the ecu be thinking you are still supplying nitrous [but nitrous valve is off [super rich [+25-30-35%] and the timing reduced ]????????..........find a Consult and measure the injector open time at WOT 4,000 10-11 millisecs tapering down to 9.8-10 at 6500.

Thats exactly what i have been wondering about all morning.though w/ less technical detail.:dunceI tried to call their # an hour ago but no answer.I also inspected th arming switches a half hour ago, they all appear in the off positon as far as I can tell(which isnt saying much)

Fred..

[PalmerWMD]

The powerloss is big enough to lose 1.5 sec on the track but teh 4.11 and performance transmission mask this loss enough to many people the car appears powerful.

As most of you said (Dennis, I guess I will have to break down and visit dealer to have access to his consult), it appears that the vehicle is runnign either in safe mode. for some reason.Or the NOS switches are in wrong position, arming the vehicle to "think" its getting ready to receive NOS.

I will relook those switches and and talk to rex about what tehir exact positon is supposed to be.

As many of you will realize my frustration knows no limits, last nite after the disapointing quarter mile runs, I started entertaining thoughts of torching the car.

Fred..:eyecrazy:

[Former_240_s14]

[quote=" palmerwmd [B}As many of you will realize my frustration knows no limits, last nite after the disapointing quarter mile runs, I started entertaining thoughts of torching the car.

Fred..:eyecrazy: [/quote]

Thats when I had to calm his arse down and make him think sensibly, lol (jk Fred!) :pface

[PalmerWMD]

Thats when I had to calm his arse down and make him think sensibly, lol (jk Fred!)

Yes it was quite a scene at the track: Rubin laying himself on top of the Q yelling "Don't do it Fred!":eek:, while I with gas can and torch in hand was laughing maniacally:evilhaha

Fred...:firedevil

[PalmerWMD]

YES! YES!

The Q is uncorked!I fumbled around with teh different switches in the car and discovered one that had been lit ever since I got it.I pushed it over until it was unlit.It was blueish, maybe a reference to the NOS?

Anyway, after I pushed that lever the Q was uncorked!I hope it isn't just my imagination ,but the car seems seriosuly fast now.

And I spent the last half hour terrorizing the Preston Ricers with 4000 lbs of angry 32 valve V8 sedan!

MUAHHAHAH

Fred..:evilhaha

[Former_240_s14]

God, that figures!!!!!! Of course we didn't look for that last night Fred!!!!!!! Well, now you need to come up next friday again to run, who knows....if Daunt returns my call I may have my new clutch in by then! Congrats and glad you are now happy, go take it on the highway and see what she'll do!

[UncleBen]

congrats Fred!! i figured it was something simple. i dont' know anything about Q's, but it just didn't seem right that the car was running that slow. i'm sure it is insane fast now! i want a ride!

[AZhitman]

Damn - I was all set to take you up on that race challenge...

Glad you found what was wrong - Go get some new times!!!

[diamondj30]

good going.tear um up.

[Qcentric]

Fred, have you had a chance to take your '94 to the track after you found the right NOS settings?

[PalmerWMD]

Actually teh plot thickens.

Teh new settijng improved response seat of pants but ultimate power did improve only marginally ( My seat-of - pants meter is more accuarte than most)..

In the end the engine was replaced with a low mile take-out at T3 (Courtesy of previous owner).

This new(er) engine is stronger and m,ore responsive.

I now run 15.4 in the quarter a good tiem and exactly stock for a 94 but there is still room for improvement.

My ECU is the wrong one it truns out and I still shift at 6500 when I should shift at 7300, so I lose 10% of my powerband adding a shift.

The car feel strong enough I ajm confident I could drop into the 14's with teh proper redline.

But JWT's service is known to be bad even when you are just trying to give them money.

Imagine trying to arrange for a complacted exchange..

And I may not have time+ energy to solve this anytime soon.

My 91 ran 15.1 with 17 inch wheels.

I will update members as as needed.

Fred..