sluggish idle / check engine light - had codes pulled

[kirkyg]

About 3 months ago I had posted on here about a problem where at lower rpms under acceleration I had a problem with a hesistation that gradually got worse. After diagnosing and replacing a bad ignition coil everything ran perfectly fine.

Originally I never even got a check engine light. Just over the past couple of days I've noticed that as i come to a stop and have my clutch engaged (out of gear) i noticed that the rpm's would stay at around 1100rpms and not until i came to a complete stop would they drop down in the 700rpm range. Previously it would drop to 700rpms well before I came to a complete stop as I coasted towards a stop light etc.

About 2 days after I first noticed the idle issue my check engine came on and the car started really rough and idled unevenly. It has been doing this for the past couple of days.

I had the codes pulled and here is what the print outs say from Autozone:

P0171: Fuel trim bank one condition
the PCM has determined that during testing, the fuel system for bank 1 was too lean.

Probable Causes:
1) If bank one and two codes set together suspect fuel pressure or MAF Sensor
2) Oxygen sensor defective
3) Ignition misfire
4) Fuel injection problem

P0174: Fuel trim bank two condition
the PCM has determined that during testing, the fule system for bank 2 was too lean.

Probable Causes:
1) If bank one and two are set together suspect a fuel condition or MAF sensor
2) Failed H02S21
3) Ignition misfire condition
4) Fuel injector problem
5) Engine mechanical condition

P1150: Lack of H02S21 switch - adaptive fuel at limit
ECM could not adjust fuel trim because of a lean or rich condition

Probable Causes:
1) Fuel pressure high or low
2) MAF sensor dirty/defective
3) Vacuum leak on engine
4) Leaking fuel injector or fuel pressure regulator

Due to bank 1 and 2 both pulling codes I went and bought some CRC cleaner, took out my air intake filter and then sprayed onto the little prongs inside the MAF sensor that were exposed. They did not look dirty and I liberally cleaned them with the spray. I unplugged the battery reset the PCM.

After reinstalling everything I started the car. Of course the check engine light had gone off but i got a very rough idle as before.

Can anyone help me with this problem? Could the fuel injection system just need to be serviced since I had that ignition coil problem before?

Kirk

 

[nyuk98gt]

kirkyg:

Lean condition can result from a bad coil-on-plug (COP) or a bad O2 sensor. If fuel is not burned then there is excess oxygen leaving the PCM thinks there is a lean condition. Check the intake from the air filter to the throttle body because there could be a leak. Unmetered air will cause a lean condition. There's a plug in the intake on the bottom side near the back of the engine. It is glued or welded in but there have been a couple of guys reporting the thing has fallen out. Feel around or use a mirror to confirm the plug is in there.

Do you have access to a datalogger (Xcal2 or Predator or CarCode or ???)? Data is what you need to look at or you'll spend a lot of loot replacing parts that might not need to be replaced.

HTH,

Chris

 

[kirkyg]

I did inspect in detail the intake from throttle body to filter. It all appears to seal perfectly. I don't see any cracks or loose fittings with the hoses that connect. I did re-seat the intake connection to the valve cover on the drivers side to make sure that wasn't the problem.

I don't have access to what your talking about. I just took it up to autozone and had them scan it. If i have to i'll take it somewhere but money is very tight for me right now. Last time i took my car somewhere it cost $70 bucks to diagnose and I ended up paying another 70 for parts just for a damned COP.

This particular problem does not have the same symptoms that my previous misfiring cylinder required a replacement coil.

Kirk

 

[007]

Replaced your IAC?

 

[kirkyg]

No I haven't replaced it yet and i bought the car new. I has about 85k miles now. I don't want to play wild goose chase though because I still plan to sell the car in the near future. How much does it cost...i assume use motorcraft only right?

Kirk

 

[99GrandTouring]

Lean conditions are most likely cause by intake / vacume leaks, occasionally exhaust leaks can cause this due to excessive air being drawn into the exhaust then read by the 02's as having lean (excessive oxygen) mixture. More than likely its an intake leak.
A trick we use everyday in the shop to find intake leaks is to start the vehicle get a can of throttle body /carb cleaner (must be 02 sensor safe) and slowly start spraying over the areas of the intake that could be possibly leaking (around the gaskets, vacume lines, esp vacume line connection) you will notice the idle of the vehicle change when you find the leak, to make 100% for sure stop spraying let it start ideling as normal then just hit the spot again where you think the leak is, if it acts up again then theres your leak.
Hope this helps.

 

[kirkyg]

Thanks. That's what i really needed is a good testing process to figure out whats going on. I think you may just have figured out my problem. I'll give it a shot this weekend when I get some time to pop the hood.

I'll post back when I test it out.

Does anyone else have any suggestions? Thanks,

Kirk

 

[MaxedGT]

Lean conditions are most likely cause by intake / vacume leaks, occasionally exhaust leaks can cause this due to excessive air being drawn into the exhaust then read by the 02's as having lean (excessive oxygen) mixture. More than likely its an intake leak.
A trick we use everyday in the shop to find intake leaks is to start the vehicle get a can of throttle body /carb cleaner (must be 02 sensor safe) and slowly start spraying over the areas of the intake that could be possibly leaking (around the gaskets, vacume lines, esp vacume line connection) you will notice the idle of the vehicle change when you find the leak, to make 100% for sure stop spraying let it start ideling as normal then just hit the spot again where you think the leak is, if it acts up again then theres your leak.
Hope this helps.

This guys right on. The high idle problem you started out with may have been the start of a vacuum leak that's become worse over time.
Spray under the intake as well if you don't find anything on top.

 

[blackink00]

could be a clogged fuel filter or a fuel pump going bad. i would hook up a fuel pressure guage to it and see what the pressure is when its idle and see how bad it drops down. if its the pump make sure you change the filter along with it

 

[kirkyg]

This guys right on. The high idle problem you started out with may have been the start of a vacuum leak that's become worse over time.
Spray under the intake as well if you don't find anything on top.

I found exact where the 'leak' must be coming from. I sprayed with the MAF cleaner I had (no residue spray) over the intake starting from the base where the filter connects all the way up slowly making sure to hit the two hoses that connect on the side. Once i reached where the intake connector meets the throttle body my idle smoothed right out. I retested by stopping and allowing the idle to get choppy again and then spraying thoroughly again verifying the the idle was smooth again.

I inspected the top of the hose and didn't see anything that looked wrong with it. What should I do now, pull it off and then reinstall it to make sure it was installed correctly? I'm 95% sure I reattached it over the lip completed to begin with. Any suggestions are welcome. Thanks,

Kirk

 

[kirkyg]

I just went back out and started the car, loosened the screw clamp and re-fed the rubber back over the throttle body lip. It still runs rough. It always evens out when i spray on the front section of the lip of the rubber but when i inspect it I don't see any cracks etc. I also looked over the throttle body itself and dont' see any cracks there either. What gives?

Kirk

 

[Dragstr05]

I just went back out and started the car, loosened the screw clamp and re-fed the rubber back over the throttle body lip. It still runs rough. It always evens out when i spray on the front section of the lip of the rubber but when i inspect it I don't see any cracks etc. I also looked over the throttle body itself and dont' see any cracks there either. What gives?

Kirk

That makes NO sense at all...

Seriously reading the posts there are only so many causes it can be. You obviously have a problem with both banks, so that eliminates coils and injectors.

It would help to know what your fuel trims are at. Knowing what the fuel trims actually are would determine if its a lean or rich condition, which you did not specify.

I had problems with my IAC and no codes. I have also seen plenty of MAF's go bad with no codes.

Next step, IMO is to find out if its a rich or lean condition and we can go from there.

 

[kirkyg]

This is with codes (posted at the to of the thread). I have a service engine soon light on.

What does fuel trim mean and how do i get you the information you asking for?

Kirk

 

[WFOranger]

With both those codes being thrown the mass air flow sensor or a low fuel presure problem are usually responsible. I would do a fuel presure check and see if it is in specs. then check your mass air. their are a couple ways to do that. the easiest is to unplug it and see if it changes the way the car runs. If not the sensor is bad if it does the sensor should be good. If it was a vacuum leek i don't think your car would go back down to 700 it would just stay high.

 

[kirkyg]

wouldn't it be the other way around...if unplugging the potentially bad sensor makes the idle smooth wouldn't that mean it was definitely bad?

Kirk

 

[MaxedGT]

I just went back out and started the car, loosened the screw clamp and re-fed the rubber back over the throttle body lip. It still runs rough. It always evens out when i spray on the front section of the lip of the rubber but when i inspect it I don't see any cracks etc. I also looked over the throttle body itself and dont' see any cracks there either. What gives?

Kirk

It sounds like there's a leak in that area. Could be throttle body gasket or worn throttle shaft. Take the throttle body off and check for leaks as you disassemble.
It'd an easy re/re and then replace the throttle body gasket if all looks good. Check the throttle shaft for wear by wiggling the shaft purpindicular to the shaft and see if there's excessive play.

How do you spell perpindicular?

 

[kirkyg]

where is the 'gasket' located. I did not see anything inbetween the rubber air intake and the throttle body metal. There was a clamp that i screwed down.

Kirk

 

[WFOranger]

No is wouldn't be the other way around. If the sensor is bad I would be like it wasn't plugged up anyway, because its not sending in input to the ecm.

 

[MaxedGT]

where is the 'gasket' located. I did not see anything inbetween the rubber air intake and the throttle body metal. There was a clamp that i screwed down.

Kirk

The gasket is between the throttle body and intake manifold.

 

[kirkyg]

I attached two photos. One shows (circled) where I am spraying the areosal (sp?) cleaner at that evens the idle. The other shows the unplugged MAF cable to test as suggested previously.

When I unplugged the MAF and started the car it didn't completely smooth out the vehicle. It did seem to make a small difference in the quality of the idle but not completely smooth.

If it were the MAF sensor would the check engine light go off after the idle smoothed out or would it stay on regardless because the sensor wasn't sending a signal?

I keep inspecting the intake area and I dont' see any leak. I also don't believe its the intake gasket because that is located to the right of where I'm spraying. I tried application of the cleaner undernearth the throttle body where that gasket most likely is and the idle stayed rough. Any more thoughts?

Kirk