JSmith

iTrader: (5)

I've got the articles up. You can view them from my webpage. Let me know what you think and if I should add some stuff or if I'm wasting my time.

RED2K

Greg if you still have my cam install pics use'em but I think Ryan's is probably better. I have a bunch of odd ball size NOS jet combos if you want.

GREGGO

iTrader: (2)

Copy compliments to:

David Cairns
Teching In
Reged: 04/16/03
Posts: 49
Loc: Orange, CA




Got this from Autotaps mailing list. Have you considered that it might really be the throttle position sensor, just like the code says?

Mike Fahrion back again with this week's topic for fellow shade-tree mechanics. Today's topic is a wear-out prone mechanical device called the Throttle Position Sensor (TPS).

When I was studying electrical engineering, I took a couple mechanical engineering courses since that field always interested me too. My mechanical engineering professor loved to quip "Electrical devices are inherently unreliable, mechanical devices are inherently reliable." I took a lot of verbal abuse when I tried to argue that the opposite was true (and I don't think I helped my grade any either). I submit today's email as supporting evidence for my opinion!

Even though today's vehicles are fuel injected, they still have a throttle plate that is controlled by your right foot. That's what controls how much air flows into the engine's intake manifold. As you push harder on the accelerator, the throttle plate opens further. The TPS is attached to that throttle plate and its electrical resistance goes up as a contact within the sensor slides over an increased length of wire.

Using three wires (power, ground and output) the vehicle's computer sends a voltage through that variable resistor and measures its output. Using that information (and a bunch of other stuff), the computer knows how heavy your right foot is and decides how much fuel to inject.

As you might guess that sensor can wear out (after all, it's a mechanical device in my book). Or, it can get corroded or dirty. Then what happens? The voltage it puts out either gets "stuck" or it gets jumpy and the voltage bounces up or down as you press the gas pedal. Any of this leaves the computer pretty confused. One symptom is engine hesitation when you try to accelerate. It will often (but not always) set the check engine light. Typical trouble codes are P0120 P0121, P0122 and P0123.

So - how do you tell if it's bad? I love this one - you can make the diagnosis from the drivers seat while listening to your favorite radio station. Plug in AutoTap or another scantool that supports real-time data, and read the Throttle Position Sensor voltage with the key on, engine off. I suggest using the "Graph-It" feature of AutoTap to be sure you don't miss anything (jobslike this one make graphing an invaluable feature!). Now, slowly press the accelerator to the floor. You should see a smooth line on your PC or Palm. It should start down around 0.5 volts and rise to around 4.5 volts (exact values depend on the vehicle). If the line is bouncing down to 0 or up to 5, the sensor's bad. If it's stuck at a constant value, the sensor's bad.

This is an easy sensor to replace. You'll find it attached to the side of the throttle body (conveniently located at the top of the engine!). There's a wiring harness and a couple screws to remove - that's it!

Note that some throttle position sensors require a simple adjustment once they're installed. This usually involves installing it loosely and checking its voltage in the idle position.

There is a newer type of TPS that no longer uses wear-prone mechanical contacts. The new style uses a magnetic field to generate the signal. I don't know what vehicles use the newer type of sensor but it seems like a good idea.

Happy Repairs,

Mike Fahrion
www.autotap.com

GREGGO

iTrader: (2)

Corvette
-1997-1999 LS1....199.207 .475/.479 117
part #'s...12554710/12560964 (changed par# in mid 1999)

-2000......LS1....198/209 .500/.500 115.5
Part # 12560968

-2001-2003 LS1....196/207 .467/.479 116
Part # 12561721

-2001-2002 LS6....204/211 .525/.525 116
Part # 12560950

-2002-2003 LS6....204/218 .555/.551 117.5
Part # 12565308

F-Body

-1998-2000 LS1....198/209 .500/.500 119.5
Part #'s 12557812/1256965 (part # change mid 1998)

-2001-2002 LS1....196/207 .467/.479 116


LR4, LM7, LM4

-1999....191/190 .457/.466 115.5
Part # 12560966

-1999-2003....191/190 .457/.466 114
Part # 1256097 (Some 1999's had this cam)

LQ4, LQ9

-1999-2000 LQ4....191/190 .457/.466 114
Part # 12560967

-2001-2003 LQ4....196/207 467/.479 116
Part # 12561721

-2002-2003 LQ9....196/207 467/.479 116
Part # 12561721

GREGGO

iTrader: (2)

Throttle body bypass thread

GoldenVelvet

Auto math, car jokes, and more

Really good auto math

BADMOFO

I don't know how to do a link...but here is a cool place to check out tire size. http://www.miata.net/garage/tirecalc.html

BADMOFO

Check this out for tire size comparisons!
http://www.miata.net/garage/tirecalc.html

JSmith

iTrader: (5)

I guess I should've thrown these up awhile ago. Anyway, here they are, better late than never.

Door mirror removal/installation of aftermarket mirrors.
http://members.tripod.com/jsmith9953...s_mirrors.html

Door handle removal/installation.
http://members.tripod.com/jsmith9953...s_handles.html

Let me know how they work our for you or if you need anything else.

Texas Terminator

here are a few good ones i found:

http://home.att.net/~jroal/index.html
http://smiley.tzo.com/fbody/atap/atap.htm
and of course http://ls1edit.slowcar.net/