PROBLEM: When the car is started cold, the idle is actually fine but when put into Drive or Reverse, the idle starts putting up and down, and when I press the throttle it bogs and has no power really. The way I have been able to drive the car is just by pressing more gas when backing up (although it gets pretty slow/powerless), and keeping acceleration real low when the engine is cold. After the engine is warm, I almost never see any problems. I did get the SES code read several weeks ago and it came up as running lean, P0171 if I remember correctly.

I brought it in to a mechanic shop and had them take a look. The car has about 104K miles, battery replaced at ~80K, plat ngk plugs at ~85K, trans fluid changed at 60K, PCV valve at 70k, alternator at 90K. After spending around 2 days on it they really couldnt figure it out. I had a friend take a look prior to this and he said he could definitely hear a vacuum leak so I mentioned that to them. They tested all over for the vaccum leaks and couldn't find any. He saw the problem and after reading several technical service bulletins, he came to the conclusion that is has to be the ECU, and needs to be reprogrammed, which only the dealer can do. When I got it back from them the SES light was off, so I assumed they reset the codes, and the SES light didn't turn on for a bout a week, but it has been back on since.

Now I've read alot of the threads about the IACV and ECU problems, the MAF sensor problems, as well as the intake manifold gasket problem, but am not quite sure what the problem could be. Any help is greatly appreciated.... Max is dieing

 

check for vacuum leak?

 

yeah they did and said after looking all over they couldn't find any. Do you think that they could of missed it?

 

it can't hurt to check behind them.. do you know how to?

if not then rent a vacuum gauge from autozone or advance auto and follow the directions on it.. do you have any mods to your car?

 

they said they used a colored spray and used it by all the tubes while pulling on the throttle to see if it was sucking it in. No mods.. recently brought it in to reweld a whole in what i think is called the midpipe of the exhaust. I will rent it and see what I can find...

 

color spray? isnt that thing gonna clog the tubes?

 

i doubt it was anything that would do that... it sounded like it was pretty standard procedure

 

if the rpm's are bouncing it's most likely the IACV or MAF.

just have them tested.

 

don't be to quick to come to conclusions,

Check the Following.
O2 sensors
Vaccum Lines
MAF
IACV
Fuel Pressure Regulator
Throttle Position Sensor.

 

Allow me to jump in. So a couple of weeks ago, after having read "Clean-MAF-under-$10" thread, I tried just that, and my CEL went off (which was, P0171).

I made a ~250-miles trip a week ago and and on the way back home, the light came back on. Not only that, my MAX started to make rattling noise when rpm is b/w 1,000 and 2,000 (which I was told today actually may something to do with transmission fluid running low).

Idle on start-up is very rough, as rpm stays around 1,200 to 1,400 for a while and settles down after a few minutes to 600.

So I took my car to a local Big'O Tires today and was told that there may be an evap leak (btw, what does evap stand for?), but they didn't have the equipment to test it so recommended that I go talk to the dealer (which I'm not excited about).

The code they pulled out at Big'O was the same P0171, but I looked up the list of codes and they have a different one for evap leak... Is it still possible for me to get P0171? My ultimate question is, should I go to the dealer and have them inspect my car, or should I try another garage, which may be cheaper?

One other thing, I didn't do the ECU relearn after cleaning the MAF. Could it be the cause of my problem too? Any info would be appreciated and sorry for jacking the thread.

 

Replaced the MAF sensor... and it works!!!! Posting this now for future reference on searches..

Dave B quoted me about $80 but I needed it before this Thursday so I bought it from the local dealer for $130 with tax. It included the whole assembly, not only the MAF sensor itself.

Even for $130, saved me lots of money!

 

my car has same problem and it was coil i change all coil and now working good

 

Evaporative emission control system

 

Did you get a check engine error code when this happened? I am thinking I have same problem. But have not been able to check fault code yet.