Anyone with an adjustable TPS should pay attention. This is something I have learned from the Turbo Buick crowd, and it is important to max power. When setting the TPS, the wot reading is just as important as the idle setting. GM computers require a TPS signal above 4.60 volts to enable wot fuel and spark tables. Following is the steps required.

1. Warm engine to operating temperature.
2. With engine off, and key on ground ALDL connectors A&B.
3. Wait 30 seconds, then disconnect IAC connector (with key still on).
4. Set minimum air rate to spec. (those with modified engines will obviously have to pick a base idle).
5. Adjust the trans TV cable (push the tab in and retract the cable into the sheath, then press the gas pedal to the floor.
6. Extend the TV cable one more notch by hand (to ensure the throttle opens all the way).
7. Loosen the TPS screws and set the base idle reading. (0.54 is spec)
8. Have a friend floor the throttle and watch for the TPS to reach a minimum of 4.60 VDC. If it doesn't, or it goes over 5.0 VDC, (yes i know the signal is only 5.0, you can get better than that though) move the sensor backwards (most likely) or forwards to achieve between 4.80- 4.88 VDC.
9. Be sure whoever is running the pedal isn't pushing it to the absolute firewall. Just the normal amount of pressure you would use to get WFO.

10. Enjoy.

Da Problem Child

------------------
Torque is KING!
All pray to the god of grunt! When ye thinkth ye has been whupped than shall ye meet the mighty Buick! For none can surpass her majestic power, and all will yet try. All pray to the god of grunt. For the King of torque has arrived!
1. 82 Camaro+ 1. 455" Buick+ 1. N2O plate = YOUR WORST FRIGGIN NIGHTMARE!!!
Da Problem Child
ProbChldR@aol.com

 

Thanks for that info. I've been getting slightly less that 4.6 volts based on my Diacom WOT readings.

I'm going to give your procedure a try and I'll post on how it works out for me

Jake - Not to be confused with my namesake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

 

ProblemChild, thanks! I adjusted the TPS a few times on my multiport v6 (yes, it's the same exact procedure), and could never get the TPS above 4.28 volts WOT. So basically you're saying the TV cable interferes? Glad to know about the 4.60 value.

I suppose I could unhook the TV cable from the linkage to get the same result. Oh hey if I take the TV cable out of the picture, if the voltage won't get past 4.28, could that mean I need a new TPS sensor?


------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards

 

Just thought I'd give an update.

I reset my TPS voltage yesterday as I said I would and my Fluke digital voltmeter reported that I got 4.82 volts at WOT.

Tested the TPS too by slowing opeing the throttle by hand and watching the smooth voltage increase. No problem found since voltage increase without any skips or jumps.

I wanted to do a few WOT blasts on my favorite back road using Diacom to record everything but my laptop's screen died. Guess that'll have to wait 'til another day.

I did the blasts without being able to record them though and I noticed that my digital tach has lost it's mind. It showed me 6800 RPMs just prior to the 1st to 2nd shift (700R4) and I KNOW the engine wasn't that high.

Maybe it's the tach filter, but I've read that GM discontinued them.

I'll post when I'm able to get some recorded results.

Thanks again for the info.

Jake -Not to be confused with my namesake.

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

 

Well, here's the latest and it isn't good news.

Used a friend's laptop and Diacom to record several WOT blasts with the higher TPS voltage settings.

Went to my favorite deserted road, which is about 10 miles from my home, and the car drove normally all the way.

Pulled to a stop, started Diacom recording and nailed the throttle. Nothing.

Car just sat there just like it was experiencing a giagantic bog.

So I lifted and then gradually pressed the throttle to the floor. Car took off and continued on without a hitch.

Made severl more WOT blasts but the bogging never recurred.

When I got home I played back the recordings and here's what I found.

One a few of the WOT blasts from a standing position and from a rolling position, the ECM would not go into PE (Power Enrichment) mode and remained in closed loop.

TPS voltage was at 4.82/4.84 but my A/F Commanded ratio remained at 14.7:1 instead of the normal 12.4:1 ratio that WOT uses.

My cell # was 15, which is the cell the ECM normally uses at WOT, but my Intergrator values continued to cycle just as they normally do in closed loop. Also, my BLM was set at 148 when normally in PE mode at WOT both the Intragrator and BLM values are frozen at 128. I checked and "Learn" mode was still "ON", when it normally is "Off" in PE mode.

My O2 voltage readings were in the 500/600 range, which is much lower than the desired 825/850 mv range that WOT needs.

On one run I remained at WOT til the car hit 104 MPH and the system remained in the close loop mode all the way.

I can email the Diacom traces to anyone that's interested in seeing this strange condition. I'd never had this happen before and when I posted on the CorvetteForum to see if anyone else had a similar problem one guy responded that he had the same thing happen to him. He said that lowering the TPS voltage to 4.5 corrected the condition.

So in summary, I was at WOT but the ECM was still in closed loop. As a result the engine was running lean based on the O2 readings.

Any ideas?

I plan to try re-adjusting the TPS voltage to 4.5 and test again, but my friend has the Fluke digital volt meter. I should be able to get around to it tomorrow.

I'll post the results.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

 

Might double check you diagnostics manual for max TPS. If set too high the ecm drops out of PE. Usually doesn't code since there is a min time for it to set a code. If you see 14.7 AFR at WOT a sensor is generally out of range. (see previous post)

 

I re-adjusted my TPS voltage to 4.52 at WOT and set the idle voltage at .57. Haven't had a chance to make any other blasts since the change, but I'll post when I do.

I put up a post on the CorvetteForum about the problem I had with the voltage set at 4.82 and got a couple of replies that other guys had the same experience when theirs was set too high.

Could be that it works for the Turbo Buick but not with the ECM the Vette uses (7165).

Jake

 

Not to burst your bubble, but anywhere from 70-80% of max TPS setting will enable WOT on the 7165 ecm, which is 4.0 volts.

 

I was playing around with the tps and discovered that also. When its to high at wot the car runs like sh$t. I have found the best wot setting on mine to be 4.2@wot, .53@idle

------------------
87z 383,afr 190's, crane hyd roller(224/230-.509/.528,112 sep),Ported and polished mini ram, 24lb inj, 3.42 gears, strange 12 bolt, tremec 5spd, , 1,3/4" slp headers.(stock 305 hypercrap chip), other stealth goodies.
Runs 14's all day long.

 

By the way, I found that my TV cable wasn't affecting my WOT voltage. I measured the TPS adjustment at WOT with the TV cable connected. Then, I unhooked the TV cable from the TB linkage, and pulled the throttle to WOT again- same voltage.

So having too high of a voltage at WOT isnt' good either? Wow. How can you figure out an optimum voltage- or is "trial & error" the only way?


------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

This topic has peaked my interest and I've never seen a discussion on it before.

I, too, would like to know how max TPS voltage effect WOT performance.

My thinking was that once the ECM goes into PE mode it receives its fuel and timing info from maps programmed into the PROM. So I concluded - any maybe I'm wrong on this - that once in PE the actual TPS voltage was of no consequence, as long as it remained above the level to allow PE to continue.

So I'd like to hear more on how the actual voltage effects the engine's WOT performance.

I realize now that going too high in TPS voltage causes a problem at WOT PE, but I'd like to know more about optimizing TPS voltage at lower voltage levels, 4.0v and above.

Thanks,

Jake - Not to be confused with my namesake.



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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

 

TPIS and some other company (right now I can't remeber who) sell TPS voltage enhancers. Has anyone tried these? They're a bit expensive ($90), but you get the same effect (I guess) in just a plug and play application. No resetting base idles and whatnot. Anyone know anything about them?

------------------
Modifications list on my Iroc:
Engine Specifications and Relevant Information
Displacement: 305 Cubic Inches (5.0 Liter)
Induction: Tuned Port Injection
Rear Axle Ratio: 3.42:1
Transmission: Borg Warner World Class T-5 Manual
G92 Performance Package
N10 Dual Catalytic Converters
Z28 Performance Package
Engine Modifications:
K&N Conical Throttle Body Clamp-on Air Filter
160 Degree Thermostat
Secondary Fan Switch By-Pass
MSD Cap, Coil, 8.5mm Wires, Rotor, and 6A Ignition
Accel HEI Module
JET Adjustable Fuel Pressure Regulator
JET Fan Switch
Quaker State Hi-Performance Oil
Computer Modification:
Ed Wright (Fastchip.com) Stage 2 Performance Chip
Interior Modifications:
Macewen White Gauge Face Overlays
Auto Meter Phantom Oil Pressure Gauge in A-Pillar
Hurst Comp/Plus Shifter
Kenwood CD player and 7x10's Mounted in Rear Cargo Well
Exhaust Modifications:
Gutted Catalytic Converters
3" Intermediate Pipe
Flowmaster Crossflow Muffler
3" Chrome Tail Pipes
Suspension Modifications:
Addco Sway Bar End Links (Polyurethane)
Gabriel Hi-Jacker Air Shocks (Rear)
(Will soon install a Spohn Tubular Panhard Bar)
Exterior Modifications:
5% Window Tint
GTS Taillight Blackouts
(Will soon install Black GTA rims)
Best 1/4 Mile Dragstrip Pass To Date:
Solo:14.739 Seconds @ 94.42 MPH
With Passenger:15.009 Seonds @ 93.51 MPH
A Run of 14.5 Is Possible, But I Have to Wait for My Shifter Springs to Arrive (Mine Are Missing for Some Reason). The Run I Know Which Should Have Achieved This Was Against a Mustang Who Ran a 14.865. I Was Ahead By An Entire Car-Length the Entire Run Until My shifter Hit the Gate For Fourth Gear, Causing Me to Miss the Gear and Grab a Very Disappointing 15.810. What Makes This Story Even Worse to Tell, Is The Fact That I Believe I Had My Best Reaction Time On This Run; a .605 Second Reaction.

 

I'm interested in those too. My Z (w/ the stock chip, which I know is a big problem) runs like $hit unless I lower the tps idle voltage to .35 or so. That means my WOT voltage is way below 4.6v.



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87 IROC-Z, 5.7, auto, 3.27, leather, !cat, Holley fpr, K&N'S, SLP 1-3/4" Jet-Hot coated headers, SLP .218/.224 .495/.502 cam, Comp 1.5 roller tip rockers, $uperPITAram, Edelbrock lower intake, Holley 52mm tb, Dynomax\Flowmaster catback. Coming Soon(?)- Fasttrack/Accell DFI

1989 Pontiac 20th Anniversary Turbo Trans Am - 160,000 miles, K&N filter

 

Like in the initial post, the WOT voltage and the idle voltage can be set independently.

The movement of the lower portion sets the WOT voltage and the movement of the upper portion of the TPS sets the idle voltage.

So wiggling the top and bottom will let you get what you want for both conditions. That's how I was able to adjust mine.

Jake -Not to be confused with my namesake.

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

 

Here is my 2 cents on this. I think TPS WOT readings are just over 4.0 volts. You don't want it too high or you will get codes and problems, such as above. If you have a scan tool, you can check WOT conditions. Mine reads about 4.33v, and the O2 reads around 900mV during the WOT conditon. The O2 reading should be max at WOT.

My idle TPS is around 0.59v. I recall adjusting the minimum idle speed, by turning the idle stop screw. The car would not idle (at 450) during the procedure to set minimum idle. I think the TPS idle volts was about 0.52 before adjusting. I never touched the TPS itself. Remember, this sensor is just a pot that adjusts from 0-5volts. There are min and max values that the ECM looks for. GM says idle should be 0.54 +-0.075. If you set the base idle on the high side, but within the range, you will get a little more on the top end, closer to 5 volts. This should help to guarantee getting the WOT condition that you desire.

Hope this helps!!!

------------------
Best ET 14.413 @95.57 without
pulling valve covers or manifolds.
Also with stock 2.77 rear end!!!

 

Can't say as I've ever had any problems doing this in the past, I've done it quite a bit on my own, and various customers cars over the years, but, It might not work every time I suppose. The hoopty that TPIS and Caspers Electronics sell basically does the same thing. It allows you to set the base reading, and then above about 70% throttle it sends 4.70 or better to the computer to emulate a correctly set TPS. I've seen these, and even installed one on a car with a nonadjustable TPS. Yes they do work, no, their not worth the money (my opinion), when the sensor can be adjusted.

Anybody that has had problems, did you clear the computer after you were done? If you did then i'm sorry for steering you down a dead end.
Chris

------------------
Torque is KING!
All pray to the god of grunt! When ye thinkth ye has been whupped than shall ye meet the mighty Buick! For none can surpass her majestic power, and all will yet try. All pray to the god of grunt. For the King of torque has arrived!
1. 82 Camaro+ 1. 455" Buick+ 1. N2O plate = YOUR WORST FRIGGIN NIGHTMARE!!!
Da Problem Child
ProbChldR@aol.com

 

After I went back and reread my post I need to add step 9.5.

9.5 With the key off, disconnect the battery voltage to the computer, either by disconnecting the orange one wire (looks like an O2 connector) connector coming out of the positive cable at the battery, pulling the ECM B fuse, or unhooking the negative battery cable from the battery. Reconnect and then try it. Hopefully this helps.

------------------
Torque is KING!
All pray to the god of grunt! When ye thinkth ye has been whupped than shall ye meet the mighty Buick! For none can surpass her majestic power, and all will yet try. All pray to the god of grunt. For the King of torque has arrived!
1. 82 Camaro+ 1. 455" Buick+ 1. N2O plate = YOUR WORST FRIGGIN NIGHTMARE!!!
Da Problem Child
ProbChldR@aol.com

 

Good point, but I always disconnect the battery to clear the memory and any codes after I make adjustments. Want to give the new settings a fresh sheet to work with.

I then drive the car at normal speeds and vary my throttle settings to allow the ECM to re-learn.

Thanks,

Jake



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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

 

I just wanted to ad one thing to this subject. Every time I want to erase all codes on my ECM, I disconnect both cables, negative and positive, just like my mechanic told me to and I do notice that it runs smoother every time versus just disconnecting the negative cable. Give it a try, it won't cost you anything but 30 seconds
Rick

------------------
'88 GTA 350
Headers, catback, free mods, Xtreme energy cam, and intake pieces
13.51@104.27, but can run better as it is.

I just put a new 2100-2300 RPM TQ Converter. I hope a 13.20 or better

RAPTOR, the baddest bird on the planet
AIM HIGH!

 

I also wanted to know if someboody has tried that little box that plugs between the harness and the TPS. I know TPIS, Jeg's and Summit sells them for $90.
Thanks, Rick

 

If that device sets WOT to 4.70, then what's all this I hear about a TPS shouldn't go too high above 4.0 volts? What kind of problems would too high of a WOT TPS voltage cause?


------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

I believe going over 5.0 volts will give you a SES light. So 4.xx volts should be ok.

------------------
1989 IROC-Z 5.7L

 

I truly would not even worry about what was initially posted here. WOT Power Enrichment mode is enabled before 4.60 volts. You don't need 4.60 volts to get Power Enrichment WOT mode. In fact, adjusting your WOT voltage could, in fact, cause problems exactly as Grumpy pointed out. What I would worry about is just ensuring that your throttle blades open all the way.

Tim
PS My TPS voltage is well below what you have stated and I have zero problems.

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's after installing Hooker LT Headers and reducing weight.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

I feel stupid asking this but what is WOT? If what your talking about will make my Z run better i want to do it but i dont exacly know what your talking about.
Thanks

 

Wide open throttle

------------------

1987 Iroc 350
GTS headlight/tail light covers
Camaro SS Wheels w/Sumitomo HTR ZII 275 rear, 255's in front
K&N filters
Adjustable Borla cat back
Large tube runners
ported plenum
Holley afpr
SLP 1 3/4" headders (not installed yet)
FUTURE GOAL:
To go really F'in fast!!!

Some pics of it at
http://albums.photopoint.com/j/Album...949&Auth=false

 

Traxion, thanks for the info. Why would it drop out of PE, though? Does the computer try to set an error code? If your WOT voltage is less than mine, then I guess I don't have to worry, but by now I'm curious


------------------
-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!