Idling poorly
 

:icon_doh: Just when i thought everything was fine my car has began to idle poorly..I replaced the fuel pump, fuel filter, cleaned the MAF sensor and IAC, got a new CAI and a new exhaust(The old one was rusting through and sucked nads) I noticed I'm low on gas, maybe a few gallons, because I havent had a chance to fill her up all the way in awhile because ive been doing some minor work like replacing small, worn out parts. Could it be because the fuel pump is staving for more fuel to push through the injectors? Should I just start by filling er' up? Before anyone goes off saying "Search the threads" I did and all the similar threads involved them having to pump the gas etc. to keep the car going; mine just idles poorly(around 1k RPM) I can actually see stuff in my car shaking, could it just be the dual exhaust and all its glory? or something mechanical?

what is new on the exhaust? just the muffler? the exhaust won't make the car shake/vibrate for you

if you replaced the manifolds, did you properly reinstall your 02 sensor? perhaps you got a little of something you shouldn't have on the sensor? What did you use to clean your MAF and IAC? Usually when someone says they have an idle problem and then say they cleaned their MAF and IAC, thats usually their problem; either they used something they shouldn't have on those sensors or perhaps damaged the MAF wire

I just used electrical cleaner, I just put on a cat back exhaust as well, should I just get a new IAC?

when did the problem start, in the mist of all these parts being replaced?

pretty much, I mean it was doing it worse before but now its just a little noticable shake, I plan on selling it soon to buy an LT1, work on it, sell it and then get an LS1, kind of work my way up like a ladder. When I bought it it was trashed if you read my garage description, i might just replace the IAC and see if that does it. I dont think the P/O replaced 1 mechanical part on this 16 year old car (Im surprised the starter is still fine) I just hope I troubleshoot this roughness, It doesnt necessarily bother me but if I have passengers I want them to be comfortable know what I mean?

add gas, test the tps and check its setting at idle. if its off it can mess the idle up, also make sure the tb butterflies are not closing all the way when at idle. that means if the buterflies are touching the tb they are two close. should be open a little. could be a valve is not happy, dont remember if you checked the plugs and plug wires or not but that would be a good idea.

I forgot to mention I changed the plugs and wires about 3 weeks ago, Im about to post a video of my car at idle and moving a bit (Just a video I took to test the new front pads and rotors) I want you guys to tell me if it sounds like a normal Idle for a 3.4 (Has a magnaflow catback)

Update* I will upload it later, youtube is being a nazi.

Did you reset the computer by chance. After changing that many components it would probably be a good idea to do it. Also, how many miles are on it. Your injectors could need rebuilding or replacement. Don't pay for new injectors until you exhaust all other possibilities though. My 3.4L had 232,000 miles.....after I replaced a lot of components on the fuel system it increased the amount of pressure in the fuel rail resulting in the exposition of worn out injectors. I replaced them with Accel 17lb'ers and my idle was fixed. Like I said, let that be your last resort....also check to see if your oil smells of gas....if it does, the injectors are causing the problem. I say again....changing the injectors is a 250$ job, try everything else first, unless your oil smells of gas. Alright boss?

One other thing that comes to mind.......did you check ALL of your vacuum lines? Look around the plenum area for any and all lines.....look for cracks in elbows especially. This was big on my 94 3.4L. For 25 bucks I replaced the majority of my vacuum lines and the system became tight again. It idled after that.....but it was extremely rough because of the dripping injectors. That's all I can think of for now.

Just wanted to explain why the vacuum is soooo important. Your 3.4L has a MAP (manifold absolute pressure)sensor on the left rear of the plenum. The computer takes a reading from the MAP and injects fuel into the cylinder partly based on this information. It also takes a reading from the coolant temperature sensor just underneath the plenem next to the right front of the fuel rail. The MAP has to have a tight vacuum system in order to get an accurate read as to how much air is present to inject fuel, and also based on temperature........as I mentioned before. If there is a breach in the vacuum system, there is NO WAY your fuel to air ratio can be correctly determined by the ECM (engine control module). The worst case scenario is that it's all of the above like mine was and I ended up not only replacing most of the fuel system components, but also the vacuum lines and defective sensors. All of this was based on the age and mileage of the engine. I have a sneaky suspicion you might have the same issue as I did. If you do......welcome to the club......that's what the 3.4L does right around that age. Consider yourself properly initiated. what's so funny is that one week it's running perfectly fine.....you do a little preventative maintenance, and the next thing you know all !@## breaks loose.......lol. Look at it on the bright side...once you replace all that stuff, I have good news,the engine runs like factory!!! Also, your fuel mileage will be kick @$$ again!!! Just for the record I ordered a new MAP sensor today. It's the last step to an entirely new system....so what the @#$$.......do it.

An important thing to keep in mind, is that if an engine is shaking at idle and using a stock camshaft, it is misfiring. The most likely cause is ignition, so check the plugs and wires you replaced, make sure the wire are not crossed, or broken internally and externally. and that all the plugs are firing. If ignition is good, than start looking at the various sensors and fuel delivery. If the SES lamp is lit or flashing, get the PCM scanned for codes, it can be a great time and money saver.