1993 Corvette 40th Anniversary
LT1 5.7 L
Vin P (8th character)
Stock Engine (absolutely no mods... yet)

Good afternoon. This is my first post on this forum and am confident we will figure out this situation I have. Today was such a nice day to take her out for a spin, but we have spent the better part of the day with the hood up and tempers smoldering. LOL We have searched on here and Google and to no avail we can't seem to find a solution to this issue. We just acquired this little beauty and she is in fantastic condition. We took her for a bath and an engine clean and the wonderful people at the detail shop power washed the engine and soaked the opti spark. After replacing the opti spark and water pump (preventative maint) most of the codes were resolved. However, the TPS was not acting right and had a code 21 and 22 which led us to the parts store for a new TPS. After installing the new TPS, we resolved the code 22 (low voltage) but still have a code 21. With the TPS being spring loaded I am not sure how to adjust it to bring the volume down from 4.34 to .54... Am I missing something?

 

TPS in a 93 is not adjustable. Sounds like the spring tip is not in the hole.

 

From the research performed, the TPS should read .54 and its reading 4.34...what should the TPS be reading? What else could be causing the code 21 (high voltage) if the TPS is not adjustable?

 

I am headed to get TPS #2 since this new one has a spring issue... but there is only one way to put it in if I am not mistaken. I like to think I am pretty mechanically inclined, and have replaced a few TPS' but this is ridiculous. We also have a 95 Z28 and what looks like the same TPS for somewhat the same LT1 set up, the Z28 did not the have issues like the vette is causing now. Just sayin.

 

A reading of 4.34 makes the ECM think the throttle is wide open. .54 is correct at idle but your LT1 is using a % actually.

 

Be careful, some aftermarket TPS sensors are adjustable

 

Good Morning. We would like to thank the both of you (JackDidley and nickgost) for your responses.

We are not opposed to aftermarket parts on certain applications; however, we went to the dealership for the OEM TPS after 2 failed sensors from local parts store. Our Code 21 was resolved, but while connected to the computer the TPS read .74 and we got it down to .66. At idle, the TPS is currently reading .68 and that let us realize there is a 2 hundrenths of a difference (.66) with the ignition on, engine off. JackDidley, you said that .54 was perfect and we are going to get this TPS to .54 (which I am going to set it at .52 so I can achieve that .54). Where we are curious is if there is a spectrum to have this TPS operate perfectly... i.e. .50 - .75? Thank you again for your assistance.

 

The voltage reading should be between .3 to .9 volts with the throttle body closed.

Most people do not have access to a Tech 1 tester so they can't perform the TP Learn procedure (used for the ABS/TCS). It doesn't appear to cause any problems if you don't do the procedure.

 

If you read the top page posted by HOV, the paragraphs on the right, underlined in red explains about the ECM reading the %. You are good to go as it is.

 

Thank you all for your help. I think we are happy with where the TPS currently stands at .68 volts. You guys were so helpful.

Thread closed...

Best regards,

IsleGirl