1984 Throttle Position Sensor (TPS)

[Rob]

Folks,

But I am not interested in any "fights", so if you want to help me fix my car problems - great, I am all ears, if you wish to pick a fight, take it to another forum.

I agree.

And I'm not happy with a couple less desirable responses by other members in this thread....

 

[lt1george]

Mike,
In the Helm shop manual for the 1984 Corvette on page 6E2-32 Engine and Emission Controls-Fuel Injection, it states that "Coolant temperature is one of the inputs that control:
* Fuel Delivery * Engine Timing * Knock Control * Idle (IAC) * Converter Clutch * Canister Purge (CCP) * Air Management(A.I.R.) and * EGR."

Your original posts states "180* coolant temp> normal coolant operating temperature." That's why I added my 02 cents to try and help and been there done that before advice. Not looking to cause a fight or disrespect anyone else opinions or helping words. Just trying to show how coolant temperture controls alot and how important is was to be right at 195* temperature on the Crossfire Engine.

 

[muskiemike]

Mike,
In the Helm shop manual for the 1984 Corvette on page 6E2-32 Engine and Emission Controls-Fuel Injection, it states that "Coolant temperature is one of the inputs that control:
* Fuel Delivery * Engine Timing * Knock Control * Idle (IAC) * Converter Clutch * Canister Purge (CCP) * Air Management(A.I.R.) and * EGR."

Your original posts states "180* coolant temp> normal coolant operating temperature." That's why I added my 02 cents to try and help and been there done that before advice. Not looking to cause a fight or disrespect anyone else opinions or helping words. Just trying to show how coolant temperture controls alot and how important is was to be right at 195* temperature on the Crossfire Engine.

lt1george - thanks, I do value your comments, as I currently running the stock 195* thermostat, and about to replace it, and was "KINDA" thinking of a 180*, after your posts, definately will install a 195*.

No harm, no foul . . .

 

[Hib Halverson]

Actually, there are a lot of reasons why the system used in MY82 and 84 wouldn't go into closed loop.

If this were my car, what I'd do is:
1) Solve the code 21
2) Leave the cooling system as is for now other than making sure the coolant is full, has been changed in the last 3 years and the proper 50/50 mix.
3) Connect a scan tester to the DLC and set it to look at serial data.
4) Fire the motor, let it warm to operating temperature and watch to see when/if the engine goes closed loop.
5) if it won't, before I'd change from a 180 to a 195 'stat, I'd run the engine at fast idle for two min. to see if the reason it wouldn't go closed was the oxygen sensor. If the sensor starts sending data, the coolant temp says below 195, the system goes closed, that's your answer.

A problem with early systems having a) unheated O2Ses and b) sensor location closer to the cat than the exhaust manifold was the O2S cooling to the point that it stops sending a useful signal. Confronted with that, the ECM goes open loop.

You, also, can "test" for the ECT influence by temporarily disconnecting the cooling fan leaving the engine at idle. Watch ECT and loop status, if you get to 200 then the system goes closed, reconnect the fan, let the engine cool below 192-195 and observe loop status.

The reason I suggest this is there is a fairly large installed-base of 180 'stats in 81-91 systems, which all have unheated O2Ses. I had a 180 in the 82 my Wife and I once owned and never had trouble with the engine remaining in open loop. Also, while the FSM always says that ECT is one factor the ECM considered when setting the fuel delivery, the 84 FSM does not say what the thermostat value is. The thermostat testing says to observe the value on the thermostat and that it should be full open 25°F above that number and full closed 10°F below that number.

Too bad we don't know how the ECM cal. considers ECT.

Most parts data available today for MY84 says a 195 is the OE stat and that 180 is an alternative.

Lastly, back to oxygen sensors...on a 30-year old car, if the O2S has never been changed, I'd do it now.

 

[muskiemike]

Hib,

Perhaps there is some confusion - my 1984 vet, is running the 195* thermostat, not a 180*.

 

[muskiemike]

Folks,

It was bad TPS - installed a new TBS, set it to .525 volts, and even DID NOT have to reset the ECM or disconnect the battery, it automatically cleared the code 21. The new TPS made a huge difference on cold starts and idling.

Again, MANY THANKS to you folks - this is a great forum . . .

Itgeorge, by the way I installed a new 195* thermorstat (same as the original.

Many thanks to Hib - as provided in-depth info . . .

 

[BigJimZ16]

Folks,

It was bad TPS - installed a new TBS, set it to .525 volts, and even DID NOT have to reset the ECM or disconnect the battery, it automatically cleared the code 21. The new TPS made a huge difference on cold starts and idling.

Again, MANY THANKS to you folks - this is a great forum . . .

Itgeorge, by the way I installed a new 195* thermorstat (same as the original.

Many thanks to Hib - as provided in-depth info . . .

Good Job !!!

 

[muskiemike]

Folks,

Since I've had some excellent comments / results from ya'll, I thought I would ask for a few more suggestions:

1.) I need to replace the upper / lower radiator hoses, I am looking at the Goodyear pre-cut and the Gates cut your own.

Any comments or other suggestions?


2.) Need to replace the oil pan gasket - apparently the original one was cork. Should I replace the old oil pan gasket with Fel-cor "cork", or their Fel-Cor Pro Perm Plus.

Any comments or other suggestions?

 

[djsroknrol]

Sounds like you've got AIC valve problems as well...check them out after you put a new TPS in....

I just recently experienced this with mine so I really hate it when I'm right......glad you got it sorted out

My recomendation would be Gates and cork

 

[Sierra'sVette]

I also have a 1984 and have been experiencing idle issues but no codes have come around yet. It acts as though it wants to die when I stop at a light. Its running at 6/7... RPM but sometimes wants to drop to a 5, I've yet to have it completely quit on me but something's not right. My check engine light does work and isn't on. I'm curious of what brand TPS I should try, I know its been awhile since you bought yours but just wondering which brand you went with. Thanks so much.

 

[Blue89]

OK, I may have missed something here. The FSM says to set the TPS to 5.4 (-+.08) volts and as I read this thread you say .54 volts or am I not seeing the decimal point in the right place?? There are three wires, red, black and white, which of the wires are hooked up to the volt meter and is it set at .54 or 5.4?? Thanks for any help.