1987 Fifth Avenue - Lean Burn Question

Steve Reinis · 2004-02-09T03:06:20+00:00

Again, here I am with something regarding my 1987 Fifth Avenue with the318/2bbl and "LeanBurn."I removed the carb and intake the other day and cleaned out all of thepassages. There was a bit of black goo in the EGR passageways, but nothingthat stopped it completely up. Either way, I soaked the intake in parts dipand everything looks new now and is clear as can be. Got it all reinstalledand took the car for a test run. It still has the surging and stumbling,whether or not I'm under a load (ie: driving the car) or just revving theengine in neutral.Okay, so... Just for the hell of it, I pulled off the vaccum line going tothat vaccum modulator on the aircleaner.... You know, the one attached tothe LeanBurn computer. At idle, it didn't make any noticable difference inengine performance, but as I revved up the engine, it was SMOOOOOOOTH!Smooth as can be and stayed smooth! No stumble, no surging! So I left themodulator disconnected (vaccum line plugged) and took it for a short drive.Once again, it accelerated smooth as can be and took off like a rocketwithout hesitation or stumbling. So under load or in neutral it runs GREATwith that line disconnected and plugged.It shocked me how smooth it was.SO, what the hell does that vacuum modulator tell the computer? I didn'tfeel like tearing into the computer housing to see what it was attached to.I'm ditching LeanBurn come this summer and converting to standard carb andelectronic ignition, but in the meantime can I leave that modulatordisconnected without hurting the engine? It's not going to cause me to runtoo lean and hot or anythng else horrible? The smooth performance I gainedwas really quite spectacular.Thanks,-Steve

Feb 09, 2004 21 Replies

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Dec 22 years ago

I own an 88 fifth ave with the same problem. I have replaced the egr valve ( along with 700.00 dollars worth of other stuff )and to no avail it still runs like crap. I am ready to push it off a cliff!!! anyway I have emmisions I have to pass where I am at. so my question is could it be something else besides egr?

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bongobonnell66 10 years ago

Where does the vacumn line connect to from the computer..

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