Idle A/F

[B shaw]

I have tried the recommended process for the smoother idle as stated in another thread here. Drive the car to warm it up, then stopped and let it idle for 3 minutes exactly. Nothing changed at all. My A/F still fluctuates between 14.6-15.2. The only thing I can do to smooth the idle it pull fuel until it reaches the 15.0 mark. It will stay extremely smooth at that reading, but another problem presents its self. After changing gears or when using light throttle the reading will remain at the lower limit of lean. However, if I simply go from one gear to the next and use no throttle it will read filthy rich. No matter how I try to adjust fuel curve it will do this.

It seems I can have either fluctuating A/F at idle and reading good while driving or the other way around. I'm simply trying to get it good enough to drive around until I take it to get tuned. My other vehicle is an 04 deville so I'm unable to tow the supra down to tuning concepts. My question is which would be the better setup or is there a way to get both smooth idle and good A/F while driving. Also does anyone happen to know what the supra idles at in stock form as far as the A/F reading?

 

[B shaw]

The only code being shown is AC related and I know why that is. I've checked codes, cleared codes, then drove around and checked again. Also did leak down test and no leaks anywhere. Spark plugs are new but I checked them anyways and no damage or corrosion. Wires carry spark to plugs, and with spark going to all six plugs its safe to say coil packs are in working order as well. Air meter is not throwing code and fuel pressure is within spec as per tsrm. I'm baffled as to why it will not idle smooth.

 

[jetjock]

Closed loop A/F will always be around 14.7 although many of these engines tend to idle a bit leaner. What is the code and what makes you think it's AC related?

 

[B shaw]

It's code 51. The manual I have says its ac related. When engine is cold it idles rich, no problem there. Once warmed up is when it starts to fluctuate. This morning it's staying between 14.6-15.0, more on the lower end occasionally reaching 15.0. I know there's only so much you can do with a safc-II( I plan on the e-manage blue or ultimate in the future).

 

[Nick M]

51 indicates the IDL contacts are open, which tells the PCM you are not at idle speed. Having your foot touch the accelerator pedal during the test will also trigger the code.

 

[B shaw]

Ok. Ill look more into that and see what I can find about correcting the open reading.

 

[jetjock]

As I suspected...

 

[MightyAl]

I had this problem and it was the adjustment on the throttle rod was not allowing the IDL contacts to be made on the TPS. I chased my tail for a few weeks before discovering the throttle cam wasn't hitting the stop. I adjusted the rod and the engine ran better then ever.

 

[B shaw]

Are you talking about the little bolt with a nut under the the lever the throttle rod connects to? I have checked everything that was on the write up on code 51 by jj and everything is within the specs listed in the write up. I did adjust the screw I was talking about so it makes contact and the code is still there. I even checked the back of the plug as mentioned and its a good solid connection.

 

[3p141592654]

The 3 minute delay referred to in the other post was specific to his condition. It has no relevance to your problem.

 

[B shaw]

After following the write up from jj it appears the code is still there and everything checks out just the way he said it should. However, the car now runs a little worse than before. It will not boost over 15psi without hitting fuel cut (I was able to hold 20 before). The turbo is glowing after one 3rd gear pull. 51is the only code being shown aside from the obvious over boost. It's my 2nd vehicle so no worries about needing it up and running ASAP. I will be getting back to it after work throughout the week and this coming weekend.

 

[Nick M]

If you hit fuel cut for abnormal turbocharger pressure, you have to have a 34. If you don't have 34, you did not hit fuel cut.

 

[B shaw]

Yes the code for over boost is now showing up after I followed the write up. Nothing was changed, just tested and adjusted the stop screw on the bottom of throttle lever. I'm at work right now doing pmcs on vehicles, I will be able to look more into it possibly today if not then this weekend.

 

[Nick M]

Nothing in the write up will lead to overboost. Double check your work and you will find a loose connection. Or a crack.

 

[B shaw]

Only thing disconnected was the ic to 3000 pipe and leak down was done after connecting everything back. Only thing I can think of is somehow something is now making a better connection and readings are accurate now. But that doesn't really make any sense given what was done. The car will be sitting after I'm off work today. What's baffling me is the code 51. Step by step as per the write up it passes. Also, the ac works like a champ. The ac switch is not on and my feet are nowhere near the gas pedal.

 

[jetjock]

What is there to baffle? Measure each of the three inputs involved to determine which is causing the code. Simple. I'm guessing you only think you tested it. Kind of like how you were sure the code was AC related before...

 

[B shaw]

The only reason I thought it was ac relatedwasbecause the ac system was removed from the vehicle, I just found out my buddy installed it and had it charged for me when I got back to the states. I did not know he did that. Ac works fine. I have never attempted to use it until this past weekend due to it being cold here. That is completely my fault for assuming. I followed the write up word for word. Even took the tps off even though I was getting the correct reading (under 2k). It still checked good. I then measured between terminals as per tsrm and it came out within spec as stated in the tsrm. I did attempt to set timing before I put any miles on the car, as I did not know it was throwing codes or that it would be a waste of time. I know that now. Timing however is holding at 13*. I will go back and double check my work this weekend. Just got told today that we will be held after at work since this is a short week and they want to make up for everyone being off Monday.