Running Super lean at idle

[Justin85]

Just seeing if anyone has had any issues similar too this.. When I start the car it runs fine for a little while then the 02's drop into the 100's and the car starts a really funky idle. The Scanmaster and Powerlogger show me that all the parameters are within spec until the 02's start dropping. and even at that point all the other Scanmaster numbers are rock solid on point.

The car has blown the Hotwire fuse on the alternator a few times.

I also notice that when the cooling fans kick on the car idles completely normal.. the 02's jump right back up into the 800's and the car purs like a kitten but once the fans kick off the idle starts going up and down and the 02s drop back into the super lean 100's.

Just curious if this might be a ECM issue or a wiring issue? I'm not really sure what too look for at the moment. I changed out the fuel pump relay just incase that was fried but the issue was the same.

 

[Ttype6]

Just seeing if anyone has had any issues similar too this.. When I start the car it runs fine for a little while then the 02's drop into the 100's and the car starts a really funky idle. The Scanmaster and Powerlogger show me that all the parameters are within spec until the 02's start dropping. and even at that point all the other Scanmaster numbers are rock solid on point.

The car has blown the Hotwire fuse on the alternator a few times.

I also notice that when the cooling fans kick on the car idles completely normal.. the 02's jump right back up into the 800's and the car purs like a kitten but once the fans kick off the idle starts going up and down and the 02s drop back into the super lean 100's.

Just curious if this might be a ECM issue or a wiring issue? I'm not really sure what too look for at the moment. I changed out the fuel pump relay just incase that was fried but the issue was the same.

What is your Block learn number when it leans out?

 

[mikestertwo]

Sounds like an electrical grounding issue. Have you modified the electrical grounds in any way? Grounds good on the back of the right head?

 

[Major Nutz]

Had that same issue, turned out the MAF sensor was bad.

 

[Justin85]

What is your Block learn number when it leans out?

BL is 122
The grounds should be good I did installed the motor two years ago and did the right head ground
I tried a good know MAF at Richard Clarks and it did the same thing.

 

[Justin85]

I cant really go get accurate numbers at the moment as the battery died and I cant take the car for a learn drive because of the snow and salt.
Last summer everything looked on point besides the 02's jumping around.

 

[Ttype6]

I cant really go get accurate numbers at the moment as the battery died and I cant take the car for a learn drive because of the snow and salt.
Last summer everything looked on point besides the 02's jumping around.

It will learn idle if you let it run long enough to go into closed loop unless you have an aftermarket chip with open loop idle.You'll know it has gone into closed loop when the O2 numbers start bouncing around and the decimal point stops blinking and is on solid.The O2s are supposed to jump around during closed loop operation.

Do you still have the flexible air inlet hose between the MAF and turbo?

 

[SCOOBY DOO]

Put a fresh Denso 02 sensor in it...and try it again. When in closed loop...warmed up...the 02's on the SM will move at about 1 per second. Slower than that or locked up...the 02 sensor is done.

 

[Justin85]

I've swapped two Denso 02 sensors into this car both brand new just too rule out that, also sorry I should mention this car is running a 6.1 TT chip with a 6262 Turbo, 60 lb injectors, alky, Stock engine runs good at full boost but cant idle for shit. It has blown the hotwire fuse a few times last summer, Im sure thats related to this problem, I'm leaning more towards a electrical issue.

 

[Ttype6]

I've swapped two Denso 02 sensors into this car both brand new just too rule out that, also sorry I should mention this car is running a 6.1 TT chip with a 6262 Turbo, 60 lb injectors, alky, Stock engine runs good at full boost but cant idle for shit. It has blown the hotwire fuse a few times last summer, Im sure thats related to this problem, I'm leaning more towards a electrical issue.

The TT chip will run closed loop idle the first time the engine is run after a battery disconnect or power is removed from the orange computer feed wire. This means that it will be able to learn idle a/f ratio idling in park and in gear plus it performs a computer reset.

 

[Justin85]

Correct , thats not my issue though, I've driven the car all summer with this issue never figured it out.

 

[Ttype6]

Correct , thats not my issue though, I've driven the car all summer with this issue never figured it out.

It would be nice to see what the BLM numbers do when the fan turns on. It's not uncommon for the fan to cause issues with the MAF,but it's always in the opposite way. In other words,the idle is smooth until the fan comes on.

 

[Darkstar72]

I noticed in your sig it says you run a MAF Translator....since it's free and easy to try I would try setting idle fuel setting in the translator to 3.5% rich. Perhaps that will help. IDK. Just spit balling here.

 

[Ttype6]

I noticed in your sig it says you run a MAF Translator....since it's free and easy to try I would try setting idle fuel setting in the translator to 3.5% rich. Perhaps that will help. IDK. Just spit balling here.

The oxygen sensor will see the difference and remove fuel after closed loop operation.

 

[Darkstar72]

Yes...I can see that you would not want to change the setting BEFORE you take it on the initial 20 min drive for the chip to learn idle settings, but once it starts to idle in open loop on the second drive, as I assume the 6.1 chip has the same open loop idle operation as the 5.7 chip, then it won't matter what the oxy sensor is sending back to the ECM.

 

[TexasT]

what is the fuel pressure doing when the fan turns on? How does the voltage look when the load of the fans is introduced?

 

[Clark6]

What type of fuel pump you have in there? how old is it? could you take a volt meter & check voltage at the fp connection under the trunk at idle? to see what voltage is there? ( I just did this to my car is why I ask lol) Needed some more grounds by the tank.)

 

[1 RARE T]

No alternator output at idle causing a lack of fuel pressure? Idles up / increased draw with fans, alternator charges.

You said it runs fine driving down the road. RPM would be constantly above idle.

Put a meter on the alt and battery.

 

[Justin85]

No alternator output at idle causing a lack of fuel pressure? Idles up / increased draw with fans, alternator charges.

You said it runs fine driving down the road. RPM would be constantly above idle.

Put a meter on the alt and battery.

I had to recently swap alternators out as the rebuilt AC delco would not charge. I'll have to check them with a meter.

 

[dank GN]

What’s your fuel pressure set at? Does it raise 1:1 with boost? If your alternator is giving you issues it probably is the resistor that’s wired in with the light on the dash . I have had similar issues awhile back and I would tap on the alt light on the dash and it would magically put out 13.8-14.0 volts lol