Bouncing idle after replacing fuel filter

Last week I replaced my fuel filter just for maintenance reasons. After that, my car would idle steady at about 2K RPMs when cold and then drop down to about 900 and bounce to 1600/1700. Before i changed anything, while my car was warming up, it would bounce a little bit when the temp guage would rise, but once it reach operating temp, it ran and idled perfect, no bouncing at all so i never bothered fixing it, but now it does it all the time.

While replacing the fuel filter, i removed the Neg. battery cable for the entire procedure, thus by the time i got the car running the ECU would have been reset (that was one possiblity for the fix, so the ecu could re-learn the clean fuel flow)

At this moment I am cleaning out my IACV and adjusting my FITV. I screwed my FITV valve in a few turns, and then backed it out about 1 1/3 turns (just so it doesnt idle so high when cold) Then im cleaning my IACV out with Intake cleaner, while doing this the cleaner coming out was basically clean, and there was no junk on the screen either. At this point i dont know what it could be. Ive been checking for vacuum leaks but havent had any luck.

What am i missing???

Here’s my update… I let everything dry and put it back together. Started it up and immediately noticed a difference, too good of a difference. The car idles like its going to stall out when its cold 500-600rpm but it warms up and idles around the 700-800. Yay right? Well I need to take it apart and unscrew my fitv another turn (so it idles higher cold)

The problem now is, when I was putting everything back together, I broke the vacuum line off of the top of the TB that points toward the passenger side, the line runs to the MAP sensor on the fire wall… is this the reason why I was a CEL on? Help meeeee! Haha

Pull the code for the CEL? We can’t tell you why the light is on… your ecu, however, can.

But yes that could in theory cause a MAP fault code.


The problem now is, when I was putting everything back together, I broke the vacuum line off of the top of the TB that points toward the passenger side, the line runs to the MAP sensor on the fire wall… is this the reason why I was a CEL on? Help meeeee! Haha[/QUOTE]

Fix that vacuum line and stop messing with that screw until you know every vacuum line is in tip top shape

So here’s my update… I checked the ecu code and it was the MAP sensor (5 fast blinks). So before I went and bought a new TB since the MAP vacuum plug on top broke off, I plugged the hole, and then put a splitter into the EVAP canister vacuum and then the CEL went away… it feels really goofy though. When I start it, it acts like its going to stall out, then the idle picks up to normal (1500 after setting the fitv out for cold start) and then idled down to about 900. Im ok with that but it seems like it hesitates really bad on take off. Im in the process of running Gumout through the system to hopfully clean the injectors and fuel system, and I may try new spark plugs after that.

Does the MAP and EVAP splitter seem bad or not a good idea? Im just hoping its not hurting anything…

Give it its own original vacuum source location and then do the idle reset procedure.

Fine fiiiiine. haha The vacuum line broke off flush with the throttle body. So i might take the throttle body off, and drill the old line out and see if i can find a metal line of similar size and fit it in the hole and JB weld it to seal/hold it in place (I cant believe i just said JB Weld on my car :-/ But it would beat spending $60-$90 on a used TB. My current TB is in awesome condition and is very clean, so if i can keep that, id like to (Most every used one i find looks like crap). If this idea fails, then ill end up getting a new (used one). But i figure its worth a shot!!

ohh it broke…dang…broke flush you say? hrmm if you can get a plastic fittings from one of the parts shop and shove it in there and then jb weld it and be extremely careful not to break it the next time you remove that vacuum line then I’d say go for it.

this is a link of what I’m referring to. Its not the size that you may need but just a picture for reference.

probably what i would do.
I mean you could drill it, tap it, screw in a nice metal fitting…
but it’s just a vac line.
if you do it right no one would ever notice the difference, not even your engine.

stick with metal though, just safer that way.

Thanks for the advice guys! Im going to see if I can match the size line that broke off with metal but we’ll see what the crappy parts stores have locally. Im currently waiting on a throttle body gasket to arrive at the local parts store and ill replace that while im in there. And ill try to post pics in case anyone is curous how I did it, or has had this happen.

In the meantime my car is running like craaaaap! When I start it, it sounds likes its missing terrible and sounds really throaty and deep. Im hoping its because im stealing vacuum from the EVAP and the MAP isn’t getting enough vac.

So for an update, I undid the split into the EVAP line, and moved the split to the FPR line so it would be close to the MAP. That got rid of the CEL and the car runs like a champ. The idle is still a bit high and it creeps a bit. Ill fix the original MAP vacuum on the TB soon enough, and then work on my creeping idle (I might need to bleed the coolant system now)