I still can not locate the vacuum leak which is probably responsible for my poor brakes.
(Also, the engine has a slight surge, hunting for the idle speed)

When I have the engine idling, I can hear a vacuum leak back near the distributor. I have removed and checked all of those small vacuum lines around the distributor. No cracked or loose lines.

With a 1/2" tube with one end stuck in my ear, I can kinda tell that the vacuum leak is coming from under the SuperRam plenum, about where the EGR is located. Can the EGR have a vacuum leak?

At this time, I have removed the plenum. The EGR looks OK and is properly bolted down to the intake manifold base.

What can I do or check?
TIA



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'87 L98 TPI IROCZ, AFR190 heads, 3.70 gears, ZZ9 cam, 2400 Art Carr TC, SLP 1 3/4" headers, SLP cat-back, no cat, no AC, no MAF screens, Accel manifold base & SuperRam, Edelbrock double roller timing chain, MSD ext coil & distributor, trans cooler, 52mm TB with airfoil, TB coolant bypass, AFPR(58psi), K&N filters, Hotchkis lowering springs, my custom chip, Lay Ind. ram air kit, SS Brakes 1LE upgrade 12" rotors dual piston calipers, 265/45R16 Kumho V700 tires.
ET 13.39sec @ 107.21mph
'90 Eagle Talon AWD, no rust thru 9 winters
'99 Camaro SS, red, 6-spd, T-tops, Mcleod clutch, Pro 5.0 shifter, MAF processor, Direct Flow airlid, K&N filter, next mod: 4.10 rear gears
313.7Hp & 320.6ft-lbf, ET 13.55sec @ 105.1mph

 

Doc,

Take a hand vacume pump, attach to EGR tube. Pull slight vacuum and hold. If vacume drops, then there's a leak in the diaghram. Also, the gasket under the EGR, any chance it might be damgaed or torn if you ever had it off. Each time I've replaced mine, I scraped old gasket residue off and coated both sides of new gasket with hi-temp rtv before replacing EGR and bolts.

Also, double check where rigid vacume tubing goes into the rubber boots (90 degree boots). I've had a couple that were loose and didn't seal well.

Also, since the nipple for the brake vaccum tube is screwed into the manifold base not far from the EGR, any chance that tube is split or the nipple is bad.

Especially since the plenum is off, I'd consider replacing ALL vacuum tubing for new tube or hose.

Finally, anything like a temp sensor in the bottom of the plenum, or the ports/bolts in the back of the plenum (like on my MAP sensor), are the threads sealed with either rtv or permatex?

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KevinP92Z
92 Z28 383 SLP cam,SLP headers,SLP 2ontheLeft,Trick Flow TW heads & pistons,Edelbrock base,Accel SuperRam,52mmTB,Scat Crank & forged ConnRods,MSD 6AL,SLP convertor,Baer 13/12" Track,Moser axles,Hotchkis,Genuine GM 3.42s,SLP HD Torsen,17x9" chrome SS rims
96T/A w/SLP Ram Air,SLP 2ontheLeft, Bilsteins, Baer, Hotchkis, Genuine GM, Torsen
76 4X4 Blazer 400TPI project

 

Kevin,

Thanks for the reply. The EGR has not been off the maniflod since I installed the Accel base about 3 years ago.

I'll check the EGR as you suggested and replace the vacuum lines. The lines are still the OE factory ones, they're 14 years old!