Well this is a technical question but is a non-thirdgen question. Well my friend has a 93' Jimmy w/4.3L, V6, CPI (Central Port Injection). The problem being, (after numerous repair shops and EGR's), that engine idles rough and wants to stall. Tune up has been performed and did not help plugs, wires, rotor, TPS, etc.... The only code I can pulled is a 32 (EGR system). It also puffs a little black smoke. So it's running rich, right? Does anybody know what could wrong? I told him to try replacing the O2 Sensor and see what happens but I am unsure or familiar with V6's CPI. Any Info Is Appreciated. Thanks.

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88' IROC-Z, 350 TPI, 700-R4

 

Pull the EGR out and clean the piece of carbon out of the pintle. I have done this at my shop 4 or 5 times in a year to some of my customers 4.3's. What you really need to do is find a garage that has "MotorVac". The intake tract and valves are carboned up and when a bit breaks of it jambs the EGR valve open. The valve does not need to be replaced for this but if you don't get the engine clean inside it will keep happening. These vortec v6's are really bad for this. Once you get it clean, run a good fuel system cleaner like Techron every 3rd or 4th tank of gas.

 

You really only have two options, remove the intake and clean out all the carbon,

Or, go to a parts store, and ask for a Tomco "Clean Screen". Its an EGR gasket w/ a screen in it to keep carbon out.

Carbon builds up inside the manifold and then breaks free and gets stuck in the EGR valve. I haven't seen many people have much luck w/ trying to clean out the manifold w/ it still on the car, but I guess its worth a try. But you will still have to remove teh EGR valve and remove the chunk thats in there now.

There is also a revised PROM that makes the computer cycle the EGR valve more to help pass chunks through.

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'97 Bonneville SSE

 

Also, do not rule out the CPI unit, or the "spider", as these are notorious for leaks at the pressure regulator and tubes to the poppet valves, which causes nearly identical symptoms to those you describe. A faulty CPI unit can cause an EGR failure (too much carbon in the exhaust coking it up), and I'd almost bet everything I have that this is your root cause. My dad had the exact same symptoms with his S-10 and went through many EGR valves, and then we pulled the intake and found "washed" regions in it where the liquid fuel from the pressure regulator and tube leaks had cleaned it. We ordered a new injector unit (a very sorry GM design, IMO), installed it, and it runs like a top with no more EGR failures. They are pricey, but can be had for under $300 at www.vandevere.com. Just my $0.02.

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1990 IROC 350
Mods: Too busy trying to make it run right to mod it.
Airfoil, Dynomax cat-back, MSD coil, 180 t-stat, Bald Eagle tires,
Hypertech fan switch, Accel 23# injectors, Holley module, ported plenum,
Ported Daytona Yellow stock base, Moroso valve covers, other stuff,
Streetdampr, Ruger P95DC, hot wife, new oil filter, !cats, !TBC, !AIR.
18.0 @ 85MPH since I'm one big-a$$ MF
"It's better to have and not need than to need and not have."

 

I guess were gonna look at the CPI Unit. Well The EGR Was Replaced Yesterday Night. so it's clean so far. Can you use a fuel pressure gauge To Check Them Or visually inspect them? I have heard the FP regulator in CPI Units is inside them and cannot be replaced. Looks like were gonna removed the intake and clean it out. Thanks again for the help guys.

CPI Sucks!!!!

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88' IROC-Z, 350 TPI, 700-R4

[This message has been edited by mystikkal_69 (edited September 08, 2001).]

 

when we get these conditions in at work with a repeating egr problem we recomend the upper intake be removed and clean the egr passages. the problem is it's usually loaded with carbon and every time a piece breaks loose it gets stuck in the valve. really a common problem, but that's part of having that wonderfull cpi...