RPM bouncing

[GaPrix]

So while I"m idling, sitting at a stoplight, wherever. My rpms will dip up and down. It will drop then the engine will pickup attempting to stabilize i suppose. Sometimes it'll drop so low as if the engine will acti like its starting to die then surge up to say a 1000. Everything else seems normal while actively driving.

[xennith]

check out this thread. I started it. I'm still having the problem, but it seems to improve slightly every time I fix something. The only thing I know for sure is that my fuel pressure is about 8-12 lbs too low. I just replaced the filter so the only other things I can think of is the pressure regulator. There are a lot of suggestions on there about what to try. good luck

 

 

http://www.w-body.com/showthread.php/50471-3.4-Idle.-Suggestions

[GaPrix]

Thanks, I'll can check on those, filter could be clogged probably time for a change anyway.

[leadfoot2]

Had that same problem with my Impala. First tried cleaning Idle Air Control Valve (IAC) with slight improvement. Then I replaced it and also cleaned my throttle body. Hope this info helps you. Good luck

[GaPrix]

I already had cleaned the IAC made a tremendous improvement (it was solid black), may try a j/y one and see if its any different.

[xennith]

I replaced TPS and IAC and now fuel filter, all new and it still isn't perfect although each one made it slightly better.

[gp1991]

mine did this since i got it, and then it got so bad to the point where it would drop so low and die, and i replaced the the fuel pump relay and it has not come back for months and it fixed it instantly. im not complaining lol, but before i replaced that i got a ses light for low voltage to the fuel pump or something like that.

[GaPrix]

so would a crack in the uim cause this?

[AL]

yes, vacuum leak

[GaPrix]

Replaced the uim and it seems to have nearly fixed the issue, its been so long that i've had a steady rpm gauge its kinda wierd. There is just a very slight change at idle now, say 700-600 i'm assuming is normal (Idling at operating temp for about 15mins). I did come across some liquid assuming oil on the tps connectors, not sure how that happened. And I seafoamed it too.

[GaPrix]

Okay, replacing the uim didnt fix it, it started back maybe 1.5 weeks after install. This is everything I've done, seafoamed - (oil, intake, gas) changed oil - royal purple, fuel filter, cleaned iac and the other one tps again. Now it idles right and funs better than ever. I'd guess it was a clogged filter.