I've been tuning the FP and timing using my laptop and Craig Moates software. Through many runs and plug reads I've settled in on 51 psi and have no knock. I'm timing 0-60 because my tranny won't make the 2-3 shift at WOT. I do a consistent launch rolling on the throttle each time to minmize wheel spin. I've tried WOT vs. about 3/4 and consistenly run .2 sec. faster with 3/4 throttle. I noticed this through SOTP the last time I was out making runs and decided to purposely not go to the floor a few times tonight. I confirmed my suspicions. Any ideas? I have a new fuel pump and still have the gauge on the window, so I'm okay there. Maybe this is the kind of thing that will force me into programming my own prom.

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'87 Formula WS6 - ZZ4 Crate TPI, ported heads, LT4 hot cam, 1.6RR, Accel runners, Accel lower, ported plenum, Edelbrock 58mm TB, pulleys, SLP cold air, headers and full exhaust, gutted cat, Walbro 255, Koni yellows, aftermarket panhard & LCA's.

 

Maybe your fuel pressure is too high. At WOT, the computer goes into open-loop, which means it does not control the injectors anymore, so basically the fuel pressure controls the amount of fuel entering the cylinders. Since the computer no longer controls the fuel, your car may be drowning, and slowing down. And again, the computer can't correct it. At 3/4 throttle, the computer still controls the fuel, and it may be adjusting it to optimal. Just my opinion.

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1990 Pontiac Formula 350
Rebuilt 355
COMPCAMS 212/212 .440/.440 cam
Flowmasters 80 series.

 

According to my plug reads, it doesn't start getting really rich at WOT until I hit about 53 psi. There doesn't seem to be a huge amount of difference between 49 & 51, but around 48 and below the plugs are snow white.

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'87 Formula WS6 - ZZ4 Crate TPI, ported heads, LT4 hot cam, 1.6RR, Accel runners, Accel lower, ported plenum, Edelbrock 58mm TB, pulleys, SLP cold air, headers and full exhaust, gutted cat, Walbro 255, Koni yellows, aftermarket panhard & LCA's.

 

You really should be testing with a scanner and reading your O2 sensor. You want around .850 at WOT.

Even better and more permanent....go with a air/feul ratio gauge on the a-pillar. It will tell you, in real-time, the actual air/fuel ratio. You can then ajust for optimum performance.



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Mike L.
It ain't pretty.......

1987 IROC Z TPI 350 A4 3.27 Borg-Warner.

Mods: 2300-2500 Stall Converter, Shift Kit(GM parts), TPI Specialties Stage 3 PROM, Modified Airbox w/ K&N's, homemade cold air, Relocated MAT sensor, Gutted MAF, 160* thermostat, MSD 6A, Accel 8mm Wires, bypassed TB coolant, Flowmaster 3 chamber single 3" in/out muffler, 3" MAC mandrel intermediate, custom dual !cat Y-pipe. airfoil, ported plenum. !smog

http://www.MichaelLasiuta.home.att.net

**BOYCOTT LAPEER DRAGWAY**

 

WEll I agree your fuel pressure sounds too HIgh, but here is another thought completely different from everyone elses.
Your shift points. If your a 3/4 throttle you would be shifting sooner and a lot of the tpis run faster times when shifting in the 4200-4500 RPM range versus something in the 5000+ range, but thats on a stock manifold and cam. I woudl try adjusting you Kick down canble a little and seeing what happens. Also that might be the whole thing with your 2-3 shift. YOu ihgt not be building enoug line pressure to make the shift with the WOT and Torque converter engaged.

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89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

 

Reading the plugs is more accurate than the o2 sensor in our cars, beyond 14.7 afr its useless.

 

What a crock of ****!

The ECM ALWAYS controls the injectors. At WOT the ECM has a PRESET variable by which it calculates how many miliseconds the injectors should be open. At WOT you should see about 8-10ms. Messing with the fuel pressure will make the fuel atomize better or worse, and give slightly less or more fuel. The preffered way to do it is trough PROM burning where you can set how many ms the injectors will stay open at WOT. A 3% change in the tables in the PROM will make the car gain or lose 3 tenths. If you can, get a custom burned chip or learn how to make your own. It's REALLY easy.



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92 Z28 5.7
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Trick Flow 23° heads, Comp Cams XR270HR-10 cam, Accel intake base + ported TPI,
TES headers, Flowmaster catback, MSD ignition, #24 SVO injectors, 1LE aluminum driveshaft.

Click here to see pics of my car !

 

As I said in my original post I'm using a scanner. My O2 readings are ~850-875. I'm using 22lb. injectors and this definitely isn't a stock engine (see sig.), so would 51 psi. still seem too high? My injector BPW is ~11 ms. As far as the shift points, I'm shifting manually so I shift at 5200 regardless of 3/4 or WOT. The car runs great (4.8s 0-60), but I just know it's got a ton more potential.

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'87 Formula WS6 - ZZ4 Crate TPI, ported heads, LT4 hot cam, 1.6RR, Accel runners, Accel lower, ported plenum, Edelbrock 58mm TB, pulleys, SLP cold air, headers and full exhaust, gutted cat, Walbro 255, Koni yellows, aftermarket panhard & LCA's.

[This message has been edited by Steve10 (edited August 10, 2001).]

 

You cant shif an automatic manually, your only holding it past where it wants to shift and the allowing it to shift when you sli p it up into the next gear. This doesn't help, it takes away the speed shift the auto is capable of. Set you detent cable to shift at 5200rpms and you will find some more tenths on you 1/4 mile time.

If its not your fuel pressure or your shift points then you need a bigger fuel pump, because a stock pump will not keep up with your needs.

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89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

 

Kyle, I appreciate your comments, but once again read my mods...I have a Walbro 255 pump installed. So your telling me that people should just leave the tranny in D when drag racing? If you have a ton of torque it's impossible to pedal the car off the line until you get traction with it in D. The wheels will spin up and as soon as you let up it shifts to 2nd, then you bog. I don't think the TV cable (detent) is meant to adjust shift points...is it?

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'87 Formula WS6 - ZZ4 Crate TPI, ported heads, LT4 hot cam, 1.6RR, Accel runners, Accel lower, ported plenum, Edelbrock 58mm TB, pulleys, SLP cold air, headers and full exhaust, gutted cat, Walbro 255, Koni yellows, aftermarket panhard & LCA's.

 

heh it may be too simple.. Traction?

 

I think 51 PSI may be a little too rich, even considering your mods. My car runs too rich with just about the same mods, course I am at 5280 feet, but still. I've heard you're always better a little too lean than a little to rich.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End with 2.77:1 Gears.

Current Mods: LT4 HOT Cam, Comp Cams 1.52:1 Roller Rocker Arms, LPE High Flow TPI Baseplate, Edelbrock TES 1 5/8" Headers, Catco 3" High-Flow Catalytic Converter, Hooker 3" Aerochamber Cat-Back System, Transgo Shift Kit, Performance Resource Chip, Accel Ignition, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET: 14.32 @ 97.7mph
(corrected for elevation)

 

Are you experiencing any Knock retard ? This may be where the problem lies. Just a thought.

 

Well, .450 is a perfect air/fuel mixture with the O2 sensor. I don't remember if .8 is rich or lean though.

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1990 Pontiac Formula 350
Rebuilt 355
COMPCAMS 212/212 .440/.440 cam
Flowmasters 80 series.

 

You mentioned your running 22lb injectors i think you may need bigger injectors with too small of injector the pulse wideth so too much injectors are on too long and you lose control of fuel just something to consider

 

or your chips WOT mode may have too much timing advace for your set up!
I think this was mentioned before in relation to knkock retard, but I dont think they mentioned it was coming from the chip. It will have a differnt timing curve at WOT vs. 3/4 throttle.

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89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

 

This might sound stupid but is your tps adjusted properly?If your minimum air rate was changed the tps could be off.

 

First off-ditto synergy. Next-you can shift "manually" wth an auto; and you can only change the shift points with tv cable adjust a little bit. To really change the WOT shift rpm's you must change the wgts and springs on the gov. Of course this applies to the 700r4- the E's are controlled by the prom program. What rpm are you at when you're hitting 11ms inj pulse width? If it is at 11ms all the way to redline-you're going past 100% duty cycle. The inj. will not be able to meter fuel flow properly then. Time for larger injectors! I'm using the F*** 24lb. injectors and staying below 8ms at 5500rpm WOT. Please run a search on diy-prom board-you'll find a wealth of info there! Also at WOT the O2 sensor is not accurate-a lot of people use those readings but your mv will be temp dependant and not reliable. Your plug reading is the next best bet, but keep in mind if you have too cold or hot heat range plug it can effect it. I have recently been looking into wide band O2 sensors myself-the only sure fire way to tune- and have found the prices coming down to the $500.00 range. Still a chunk of change but if it saves your engine..... And yes-traction also can be a problem. Hope this helps, and please look at the diy-prom board and start burnin' your own chips!

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86 406

[This message has been edited by drive it (edited August 13, 2001).]

 

I have drag radials and a 700r4. I leave it in drive and do a burnout, then pull to the line, brake torque at 1000 rpm and take off with little if any spin and 1.90 60 foot times. The tranny shifts 1st to 2nd at about 4800 then 2nd to 3rd at about 5000 rpm. I feel it would probably do a little better if it would shift around 4600rpm on both shifts under full throttle.The car ran 15.01 it is totally stock formula 350 with drag radials.

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1990 formula 350 tpi dual cat auto 9 bolt posi 3.27 ratio

 

OK those of you who think that you can shift an auto manually... Start off in 2nd gear, or just try to do a shift from 1st to 3rd. Oh wait you cant do that. That requires you have a "manual Transmission"
Like I said before you are only holding the shift past where the Tranny wants to shift at and we all know that it has been proven that this does not yield better times with a basically stock motor because they do not make good power in the upper rpms.

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89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

 

Thanks for all the comments. After more analysis of my scan data, I think I found something. I graphed % throttle vs. injector BPW on a 0-60 run at 3/4 and WOT. I found that there is a very sharp transition from ~60%= 8ms then 65%= 10ms and quickly rises from there. So maybe I do need bigger injectors to stay away from the max duty cycle. To you "pro tuners"...would I be able to manage this without buying new injectors if I were programming my prom? I know the LV8 variable plays a role in this also, and I'm still figuring out how it all works together. Is there something I can do now to address this or test it further to verify what's going on?

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'87 Formula WS6 - ZZ4 Crate TPI, ported heads, LT4 hot cam, 1.6RR, Accel runners, Accel lower, ported plenum, Edelbrock 58mm TB, pulleys, SLP cold air, headers and full exhaust, gutted cat, Walbro 255, Koni yellows, aftermarket panhard & LCA's.

 

I'm far from a "pro tuner" but I'll try to answer as much as I can. Prom tuning will not replace the need for larger injectors; and again a wide band O2 sensor is the only sure way to tune WOT. Grumpy on diy prom site has talked about max duty cycle- if you do a search there you will pull it all up. BTW- are you using an 87 chip? Check out using an 89 (6E code) bin. A lot of folk have had good luck using an ARAP bin. Good luck and have fun-that's what it's all about!



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86 406

 

Drive it, the car had a JET chip installed when I bought it, so who knows what's going on in there. When I get inot DIY proms, are you saying I should immediately go with the '89? I wonder what would happen if I plugged in a stock prom from an '89 5.7. Might be interesting.


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'87 Formula WS6 - ZZ4 Crate TPI, ported heads, LT4 hot cam, 1.6RR, Accel runners, Accel lower, ported plenum, Edelbrock 58mm TB, pulleys, SLP cold air, headers and full exhaust, gutted cat, Walbro 255, Koni yellows, aftermarket panhard & LCA's.

 

Yes, I'd go with the 89 prom as it has quite a few refinements and additional info in it-eg, it has a "hwy mode" that you can adjust the engagement points on. It leans out the car at cruise for improved mileage. An 89 stock bin might just suprise you with an immed. improvement.


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86 406

 

Adjusted the kickdown cable and got it to shift at 4000rpm 1-2 shift and 4400rpm 2-3 shift instead of 4500 and 5000. I expect to drop my 1/4 mile et 2 or 3 tenths, we will see.

 

.800 mv is rich. Less than .450 mv is lean.....

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1987 GTA L98 MD8 GH3
355 '97 Vortec 4-bolt block, TRW(suck) forged pistons 10:1 CR, TFS 23*, LT4 Hot Cam, Ported plenum and intake, SLP Siam Runners, BBK 52mm TB, Edelbrock TES, gutted Cat, Flowmaster, CAI w/K+N cone, AFPR, TB bypass, !AIR, !A/C, !EVAP, ARAP, 2300 stall, Alum. Driveshaft, Hotchkis STB, '99 Camaro seats.

Coming Soon!!: Fourth gen 3.42:1 rear, Spohn LCAs and Panhard.