TPI upper plenum
 

I got my 88 iroc from my grandfather, he was the original owner bought it brand new, now like a month ago I changed the thermostat. now taking apart the throttle body to get the the thermostat housing, i noticed very heavy carbon build up and oil residue within the throttle body and upper plenum. What could cause this, granted i know the car is 18 years old now and was taken care of but not like i would, i have look online and some service manuals but it didnt say much to the cause of it. Should I take it apart and clean it or just try and find a upper plenum piece? I know i can purchase various thottle bodies and runnes but no upper plenum piece. Any advice would help alot.



1988 Iroc Black Exterior/Grey Interior
305 TPI

welcome!!!!

welcome to the site :)

the oily build up is normal so there is no need to replace the entire plenum. If you really want to, you can remove the throttle body and the upper plenum and clean them with some throttle body cleaner.

yeah the build-up is just residue from over time and is nothing to really worry about, you can clean it and it'll be fine. and if you have it all apart to clean it, you may want to look into porting it even. If you do buy a new upper, keep in mind you need a 85-89 version for a MAF system and 90-92 is speed density. and BTW, you can do the thermostat on a tpi motor without removing any part of the intake, just the one U-shaped coolant line to the TB, i just did it on my monte last week.

Ok that is what I thought. At the time when the thermostat went, the car was stalling randomly and it was pissing me off because i took it too 4 different mechanics and they couldnt find out what the problem was. So i figured that since i have to do change the thermo, i wanted to see how things worked, so i took some things apart and that is what i found, I only cleaned the throttle body and low and beyond having the residue and oil build was causing not enough air when at it and stalling when there was no gas.

I was just thinking of taking it off and cleaning it. I have to see how hard it is to port it, because I am limited on my tool selection right now and i dont think i have the rigth equipment to do so.

the biggest "simple improvement u can make to the upper plenum is,right were the tb mounts.when u remove the tb and u look inot the plenum u will see right behind the openings there are 2 places were the casting protudes just die grind those smooth.if ya can take a picture of the plenum i can better explain,but u shoudl be able to see it no problem

Want a new plenum? I have an exchange service. Check out my website Corvetteplenum.com -I almost always have a plenum or two up on ebay. Search for "TPI plenum". I will be starting a new auction tommorow as The last one just ended with a "buy it now" I have a plethora of MAF '85-'88 plenums right now.

mikey how you been i sold you a upper plentum last year we met up at your job i drive the red s10


if you looking for some more power pick up a ported upper plenum and runners from mikey

Oh hey man, How you been? I am still struggling with my bussiness. In the meantime still stuck at the post office. Got any plenums?-Mike

my firend doug has a complete intake that he wants to sell

i'll call him up and find out the price all i got for a tpi is a fuel rail and fuel injectors

Yeah, let me know. Thanks Dude!