Mine has quite a bit of carbon in it, and my uncle (who had the car before me) told me about when he changed the FPR, that he noticed ALOT of carbon build up, and that was at least a year or two ago. So this weekend im gonna take off the plenum and runners, and go take em to the car wash, and high pressure wash them.. hopefuly i will get some more throttle response and better gas milage. Anybody done this or anything simular??

Also, while the plenum and runners are off, what kind of porting etc. can i do with just a dremel tool? i know i can't do too much, and i might even wait till after i get it dynoed and then port it, and then dyno it again.

------------------
- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

http://www.geocities.com/david_angel_16

 

you can knock down the humps on the bottom right where the air enters the plenum. i wouldnt waste money on a dyno before and after the plenum porting, you arent going to gain much hp, maybe 1-2 if your lucky.

 

here is my number one tip for getting that carbon out, go to advance auto or walmart or whoever has it and buy some PURPLE POWER it is the best stuff i have ever used, i just recently did my plenum and it takes carbon off like no other, i took it to the parts store that i work at, and i tried a bunch of stuff, from carb cleaner/brake parts cleaner/wheel cleaner/castrol super clean etc. i even tried pyroil wheel acid, and none of them worked . purple power all the way

------------------
87 IROC-z 305 TPI
Borg Warner T-5 fresh rebuild
10-bolt 3.73 Richmond gears rebuilt GM posi,
formerly BW 9-bolt w/3.45 gears(broke it)
Ported Plenum and Runners Homemade AFPR
ACCEL 8.8 wires, High output coil,and cap & rotor
Bosch platinum + 4 plugs
Ram Air w/ K&N filters,
MAF sensor screens removed, TB coolant bypass
Polyurethane tranny and torque arm mounts
Dynomax catback w/custom tips
K&N oil filter,Mobil 1 synth, Futura GLS Super Sport tires 265/50/15 rear and 235/60/15 front mounted on 86 monte carlo SS rims ,

400 sbc and a 6 spd in the works

 

I took mine to a friend who has his own shop and he put the runners and plenum in carb cleaner over night (it is in a 5 gallon pail). After washing and drying (compressed air) you could eat off of them! Completely spotless inside and out.

------------------
87 GTA 350 TPI, 700R4,
K & N, Accel cap/rotor/wires, SLP airfoil, ported plenum

 

Is there any reason companies make carb intake cleaner AND fuel injection intake cleaner??? I got some of the FI intake cleaner, and it mentioned on the bottle something about a protective or special coating on the inside of the intake on FIed cars, and that carb cleaner and the such should not be used to clean the inside of fuel injection intake systems.

 

What i think they were talking about is that older formulations of carb cleaner probabky had all kinds of weird chemicals that would mess up an oxygen sensor or something for example. It might even have said that it would not burn and form a coating on the O2 sensor or leave deposits or something givinug you that idea. Probably something like that

------------------
Ed Maher - Moderator @ The TPI & Carb Boards
92 Z28 Convertible - Quasar blue / Tan top
305 TPI A4 2.73 - 14.7 @ 93.6
Stock except ported plenum and dual cats
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die

 

i'm not sure but i think that O2 sensors dont like carb cleaner. so fuelinjector cleaner is safe to run.

------------------
86 IROC
43,000 miles
305/700R4/3.23 gears
maroon, gold stickers, black interior, T-Tops.

current mods.
shift kit
headers
cat back exhaust

mods planned for this winter
cam
3.73 gears
subframe connecters

 

ya, thats why u can use brake parts cleaner on ur intake, but you can't use carb cleaner on ur brakes. the carb cleaner leaves a film that protects and keeps the carbon off or somethiing, so u can imagin this film on the brakes. but im gonna just try high pressure, cause i gotta have my car, and i think hot water and soap should do good, then maybe use some carb cleaner to get the "film effect" just hope i don't accidently put it on wax!!

how much do yall think it should cost for gaskets? about $20??

------------------
- David
88' GTA 5.7L TPI MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass, Gutted CAT, Flowmaster 80 Series

http://www.geocities.com/david_angel_16

 

What makes the inside of the plenum such a mess is the oil residue from the PCV mixes with the carbon and makes a sticky sludge. I tried brain damaging toxic chemicals with limited success. Bead blasting just pushed it around, and made the beads sticky and unreuseable. Then I took an acetelene torch and heated the whole plenum until the sludge turned to ash. Quick bead blast cleaned tha ash off.
I also discovered that the large vacuum hose fitting on the back of the plenum is made of a low-melting point metal like tin or something.
Before putting the plenum back on, I drilled a 1/4" hole through the EGR passage and through the divider between the EGR and PCV passages in the plenum.
I then plugged the hole to the outside, and plugged the two EGR outlet in the plenum behind the throttle body.
This forces EGR gasses to go through the PCV passage, back down to the baseplate, and get distributed through the cold start/PCV distribution holes in the baseplate.
I've run this way for a thousand miles - no problems, tomorrow I will look down the throttle body and see how dirty it is.
If this works out I will next try to plumb the PCV line that goes to the throttle body into the baseplate in a mirror image of the driver's side PCV.
Why? I had the urge to eliminate the mess at the source, and I am obsessive-compulsive.
Why not disconnect the EGR entirely? I live in smoggy So. Cal. and I don't like to add to the problem.

[This message has been edited by Kevin 88 (edited October 19, 2001).]

 

Breathment,

If I were you, I wouldn't even bother taking it apart unless your definitely either going to do some porting or upgrading to make it worth it. Otherwise, just cleaning it isn't even going to be noticeable. Wait to do it until you have a reason to take it off. Thats my opinion.

Bugs

------------------


[This message has been edited by Bugsbunny2 (edited October 20, 2001).]

 

I have a question on the sludge build up in a plenum… first off I am getting horrible gas mileage, so I figured that I would check the vacuum ports on the back side to my AFPR and MAP sensor. The plenum is off an 88 350TPI system converted to a speed density 90-92 system. I do not need the HVAC vacuum port since the engine resides in a jeep YJ, so I am using the two ports individually to the AFPR and MAP. My question is that I pulled the vacuum hoses off and the nipple to the MAP is larger and sucks in a whole lot more vacuum at idle than the AFPR vacuum nipple. Even though the nipples are a slight change in size the vacuum difference is huge, do you think that I may have build on that back one that is preventing a good vacuum?

 

fuel pressure regulator port and the map nipples are the same size gm part 14082470.

casteroil's superclean is way way better than purple junk.

 

Oh... maybe that is the problem i may be having??? The nipples that i have on the 88 plenum are different size and defiantly vacuum flow is different... thanks for the part number!!! Will get them tonight and replace and hopefully fix the problem.

 

np