What a difference!

[Paul Higg]

On the advice of Junk and others (which I greatly appreciate!) I removed the throttle body, cleaned it and replaced all the gaskets. It was a total mess. I also found numerous hoses that were cracked and the PCV plastic tube under the fuel rail cover not even in it's hole! So I put it all back together but I had a lot of difficulty with the throttle position sensor.

So, I ordered an adjustable TPS from Eckler's and got it today and RIGHT before I was going to install it I got a phone call from Junk!!!! (THANKS JUNK). Installing it was simple. He told me the correct way to do it on the 94 LT1 is when you are standing above the right tire looking at the TB, the tab on the TB will be in the horizontal position. Then hold the TPS and turning it to the two o'clock position place it on the tab then turn it counterclockwise until the holes line up. Now, the adjustable one has a jumper plug that goes in-line with the plug that goes to the TPS. Take a digital voltmeter and connect it to two of the leads and with the key to on and with it closed you should have a certain voltage as well as when you have WOT.

So I did that. Then I removed the jumper plug and plugged the factory plug in after tightening it down. I started the car and it purred like a cat. Then because you cannot erase history codes by removing the battery (per the FSM) I went to module 4 and 9 according to the manual and erased them with the ENG/MET buttons. They erased just fine.

Last night I adjusted the throttle cable and the cruise control cable exactly as described per the FSM. Since I have a later year 94 I didn't have to go the drill bit/torque wrench route. I adjusted it with no problems and because of cable stretch over the years I moved the cable on the cruise diaphram back one hole. I was having a REAL bad time with it holding speed up and down hills, it would lose 5 or more MPH going up and gain the same going down hills.

Then I took it for a drive. I was having a REAL bad off-idle bog. I'd be at a red light and totally stopped and when I punched the throttle it would hesitate, stutter, and almost want to backfire.

The test drive amazed me! I stopped in the middle of a road where the limit is 55 and from a full stop punched it, HARD, and it spun the tires!

Then I used the GPS to see if the cruise would match it and it did down to the exact MPH. But, what really amazed me was the fact that the cruise was now ROCK SOLID. It didn't budge not ONE MPH up or down those same hills! And it has MUCH smoother shifting too, it is an auto. So all in all it was WELL worth the work.

Just thought I'd share this with the forum and thank everyone who assisted me. I appreciate it.

Paul

 

[So Bay Vetter]

I'm not clear . . . so, was it the TPS all along?

 

[KOPBET]

Good job Paul.

Way to go Junk!

 

[Paul Higg]

Thank you Kopbet, Junk really is one of the most thoughtful and considerate and helpful people I have ever met.

Vetter, I think it was the TPS all along causing problems but Junk also thinks it was the combination of crud, cracked and open hoses that all added up to the bog. But I am convinced that the TPS has REALLY increased efficiency and performance. One three wire variable resistive circuit is enough to make the car run very poorly. It is a great feedback loop design but there is no redundancy built into the system. If this thing fails the car is basically out of service!

Paul

 

[B17Crew]

Good to hear that you resolved the problems you were having! It’s a reminder for all of us to inspect the various hoses and belts on our cars. I’m going to go over mine after work.

We’re lucky to have Junk, that’s for sure!

JUNK for President in ’08

B17Crew

 

[Paul Higg]

Thanks B17! You are right, Junk for prez!!! He has my vote. I don't know if you have ever spoken to him on the phone but Junk is the nicest, most soft spoken and helpful mechanic I have ever talked to. What a great guy, we need more like him.

I gotta tell ya, driving it today was amazing. I think the TPS has a LOT to do with better performance. I am now getting perfect shifting, I am getting better mileage, the cruise is dead on. The old TPS was just slap worn out. Think about it, this variable resistor sits there on the throttle body and it gets moved 100% of the time. I am surprised it has lasted this long. With a resistive circuit they can wear out (I ought to know as I used to replace them on aircraft). When they start to go bad they produce flaky voltages and then lower voltages. Now that the EBTCM and ECM is getting higher and cleaner voltage it is running much better.

Paul

 

[JimBobC4]

I've had similar results with theTPS sensor on supercharged Pontiac motors. I was suprised at the difference a few millivolts could make.

How was the one you purchased adjustable ? were the slots elongated on the screw holes so it could be spun ? Or did it have an actual adjustment potentiometer ?

 

[B17Crew]

Thanks B17! You are right, Junk for prez!!! He has my vote. I don't know if you have ever spoken to him on the phone but Junk is the nicest, most soft spoken and helpful mechanic I have ever talked to. What a great guy, we need more like him.

I gotta tell ya, driving it today was amazing. I think the TPS has a LOT to do with better performance. I am now getting perfect shifting, I am getting better mileage, the cruise is dead on. The old TPS was just slap worn out. Think about it, this variable resistor sits there on the throttle body and it gets moved 100% of the time. I am surprised it has lasted this long. With a resistive circuit they can wear out (I ought to know as I used to replace them on aircraft). When they start to go bad they produce flaky voltages and then lower voltages. Now that the EBTCM and ECM is getting higher and cleaner voltage it is running much better.

Paul

It’s always good feeling when you successfully resolve a drivability problem. So far, I’ve been lucky and haven’t had any issues with my car. I always follow posts like this because I learn a lot.

Haven’t spoken to Junk in person, but I have a high regard for his advice. Junk knows his stuff!

B17Crew


JUNK for President in ’08

 

[Toms007]

Paul, it's good to hear your problems have been worked out. I'm still working on mine, I'll get to the bottom of it (at some point), sometimes gets really frustrating.

 

[Paul Higg]

Hi fellas,

Jim, you were right, the holes are slotted so with the meter connected to the wires you can adjust it by moving it fore and aft. It comes with some nice red knurled machined aluminum screws and washers so you can install it until it is just tight enough to move it back and forth for the adjustment. And yup, just a few millivolts makes all the difference in the world!

B17, it does feel good, especially when you can do it yourself and save hundreds! I follow posts too because I learn a LOT from others. :cool

Tom, thanks. I hope you get it all worked out soon. What exactly is wrong with it?

Paul

 

[kcrick]

Hey Paul! Our cars are "twinkies" white with gray! Mine's in the shop getting head gaskets....yuck! I should have it back Friday...I hope the shop can get the throttle body and TPS together! Maybe they'll need to call Junk! I'm hoping that my crazy "odo err" problem turns out to be a bad ground and fixes itself in the process...have you had any CCM problems with yours?

 

[Paul Higg]

Not one problem, thank goodness. I really like this Vette, it is my first and I have wanted one from when I was 6 years old. Mine is in the shop for a right manifold which broke in two places and a complete u-joints replacement. I just do not have the tooling to do it.

Paul

 

[Toms007]

Hi fellas,
Tom, thanks. I hope you get it all worked out soon. What exactly is wrong with it?

Paul

Just running real rough, no power.

 

[Paul Higg]

Any codes?

Rough at all speeds?

Clean the throttle body?

TB hoses?

Misfiring cylinders?

Plugs or wires?

I suppose you already thought of all of these.

Paul

 

[LT4man]

Good job, Paul! Glad to hear your Vette is running like it did when it left Bowling Green.

Amazing these vehicles run so well so long but then finally something wears out.

I keep knocking myself on my head because I have yet to replace many items on my LT4. In fact, I have only replaced my cap & rotor and my water pump. Tune-up parts, but that is it!

SAVE THE

 

[Paul Higg]

Thanks LT4!! You and Junk were very helpful and I appreciate it. I have never experienced so much knowledge and helpfulness.

Paul

 

[LT4man]

Aw, shucks! You don't have to thank me. I was happy to be on the team. Just doin' my job!

These Vettes of ours are plenty fast. Make sure you don't have any spontaneous appointments with the long arm of the law! :L

WILL SOMEONE PUHLEASE SAVE THE

 

[Paul Higg]

LT4 you may not believe this but I feel I have a guardian angel. I am 49, I have had two motorcycles and never dropped one, I have never been involved in a wreck and I have had many, many new and used cars. I have also never gotten any kind of ticket. Like I said, you or others may not believe it but it is true. I just thank God for that. I am not superstitious, I believe in the Lord and I am not afraid to admit it to the world, even on a forum.

 

[LT4man]

What would we be if we could not give thanks to our God in front of others? Did Jesus lurk around behind trees and bushes healing the sick and unfortunate? Of course not!

I am the first to admit I am powerless without Him.

I am especially happy He has been watching over you.

WE MUST SAVE Someone Or At Least SAVE THE

 

[Paul Higg]

Thank you LT4, I do however fear this forum will be soon receiving some very sad news. I cannot divulge it now as it was just PM'd to me. I will be off the computer in prayer with the Lord.

Be at peace with the Lord my friend in Christ.

Paul