Runs rough at low idle or go slow - no bad codes showing! - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat

1987-1991 Parley with regards to your 1987 to 1991 Bonneville, Olds 88 or Buick Le Sabre Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 08-20-2003, 03:31 PM   #11
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a: Haynes manuals tend to be very generic (note it shows the Fiero style IAC).
b) I have always reset but driving above 38 mph for a while with the engine in closed loop.
c) description that came with the new one is essentially correct.
d)have made an o-ring from a piece of cardboard before (think that is still in my Fiero)
e) bad coilpack will usually show up as a missfire at low rpm/moderate load (like a hill at 50 in cruise with lockup engaged
d) coilpack in photo is a Magnavox which is thought to be marginal - Jacobs is better. Has anyone ever upgraded the whole ESC/colipack unit to the later Delco with individual coils ?
e) Secondary ignition (coilpack, plug wires, plugs) problems usually do not set codes.
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Old 08-22-2003, 10:05 PM   #12
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Well I had been following this but it went dead for awhile so I thought you got it.

This is what happened to my L27 powered 91 Regal.

The symptoms were - one day I noticed a stumbling stagger at cruising speed. In other words regardless of MPH if the gas pedal was just maintaining speed it would be rough. The next day it was more noticeable. The third day it was bad. If I floored it it would run nearly right but there was still some noticable problem same with idle not bad but something was wrong. Crusing speed it would buck and kick like a ------

I removed my pressure regulator to replace it because I had a new one in case. I have never had a LN 3 - C so I dont know what the regulater is like. On the early LG engines it was self contained. On the L27 it goes into a housing. Well the housing was full of a black stuff that would grind to a fine powder in my fingers. I pulled the fuel rail and found the inside of the feed of my injectors were chock full also. Now back to the tank. I got a new tank and new sending unit. On the Regal the lines over the tank separate just past the sending unit and are two short pieces from there to the filter got them new also. I believe all old H bodys have one piece fuel lines from the inside of the tank to the filter and include the rubber flexable part. Anyhow thoses lines were full of the black stuff. However in the tank it was only in the tank baffel but the inside of the steel tank was clean. Which meant it got in the tank through the return line. So I cut one of my old line up and ripped it lenght wize with the band saw and found that the lines had actually rusted on the inside , you know that slate rust and it all broke loose and contaminated everything. It was a new one on me.

Now I was really worried I was going to be buying 6 new injectors at $7?.00 each because everyone said you cant clean them. After carefully digging at them with a dentist type thingy I decided that would do it so I tried air, I only have 120PSI and that didnt do a thing. Then I tried a water flush with the garden hose, nothing. Then I got out my 35.00 Campbell Hausfeld air pressure power blaster cleaner thingy. It syphons what ever type of cleaning fluid you want and sprays it in a mist sorta like a spray gun but at 120 PSI with kerosene I had spotless injectors in a matter of seconds.

BTW its a good all around tool. I have used it to syphone bleed brakes. Just hook the clear plastic hose to the bleeder valve. I have also used it to paint those hard to get to places I have sandblasted underneath of my cars. Syphon old brake fluid out of the reservoir, powersteering also. It needs to have the spray nossle put into a large coffee can with hole in plastic top and a rag sealing it however so it doesnt mist all over the place. It needs the nosle in the end to work properly also so it will only spray.

Any how all this and one can of injector cleaner and the car was running tops again. I would sugest pulling your rail and looking at your injectors, at this point anyhow. I was amazed at how easyly they all came out and went back in. Just do it like the manual says. I have the Haynes.

Also fuel pressure is critical if you havnt done the pressure test.
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Old 08-25-2003, 05:00 PM   #13
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Default Runs rough at low idle or go slow - SOLUTION FOUND!

Hi all!

It appears that the real problem to this was simple ...

Two spark plug wires at the coil pack were full of chaulky like corrosion.

I had pressed on them to make sure that the connection was tight, and it felt OK.

While the shop was putting in a new O2 sensor, I thought I'd make sure they connections were tight and clean... and :o I found this.

So I don't know how much of the problem was O2 sensor, or IAB valve. But it'* likely that it was simply those dastardly wires...

THANKS to all who gave great suggestions, I think I'll continue to use all of them!
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