Topic: Engine lean code?

[jcsanders79]

I have had a check engine light for months now! Started with a catylitic converter, then  a 1st bank O2 sensor, then the crankposition sensor and now its engine running lean.  The guy at the parts store told me to get some electrical cleaner and clean my MAP sensor real well & some intake cleaner to clean the throttle body.  Is this good advice to get rid of the code?  Any other suggestions?  Got a stage one chip, CAI, 62mm TB, TB spacer, header and mustang injectors if that helps?

[lanulos89]

any vac leaks??

[Torch_Ind]

any vac leaks??

and or exhaust leaks

[Bounty Hunter]

I recommend a new MAP sensor.

If you're going to clean the throttle body, take it off the jeep, remove all sensors, and give it a good bench cleaning.

Jet Performance now makes an air/fuel ratio gauge that uses the OEM o2 sensor.

[jcsanders79]

any vac leaks??
[/quote

Don't know, any suggestions on how to find them?

and or exhaust leaks

There was but I fixed it before the code showed up.

[95 Lowbuck]

One good way to find a vacuum leak is to go to your local auto
parts store and buy a combo. vacuum tester, brake bleeder kit.
Then check every vacuum line that comes off the intake manifold,
even the brake booster. The only one that shouldn't hold vacuum
is the breather comming off the valve cover.
If nothing found, buy some starter fluid and with the engine running but COLD,
spray some around the base of the Carb/TB. and listen for an idle change.
I think I had the same Check Engine code as you, (#53), mine turned out
to be a combination of a bad manifold port plug and the O2 sensor.
But then again, my engine is also bone stock.

[jcsanders79]

Well cleaning the map sensor and TB didn't get rid of it so I guess I'll start vacum testing lines.  Its actually running better than it has in a long time.  On a side note I finally bored my intake out to 62mm and that mod is worthless until you do this!  Much different.

[sharpxmen]

Well cleaning the map sensor and TB didn't get rid of it so I guess I'll start vacum testing lines.  Its actually running better than it has in a long time.  On a side note I finally bored my intake out to 62mm and that mod is worthless until you do this!  Much different.

a vacuum leak will not result in a lean mixture, worst that can happen is to have your idle rpm increased (unless the leak is at the MAP sensor  or on the same line - but in that case you would have bigger problems than the check engine light). In closed loop the computer adjusts the AFR using the O2 sensor output, at WOT (wide open throttle) doesn't matter anyway since the engine would suck in as much air as possible.

The vacuum leak does have an effect on engines that have MAF sensors or that have a carburator

Engine lean code would result from the computer trying to adjust the mixture and not being able to do so - this means that in closed loop based on the O2 sensor input the ecu was unable to alter the mixture and was reported lean - that most likely will happen when you have a fuel filter problem, fuel pump problem, fuel injector problem (can be plugged or an electrical problem preventing it to release fuel - in this case the engine would idle roughly).

[sharpxmen]

Just to add a note to my previous post - i am not sure if in open loop when the ECU runs on a preset air/fuel map if it will monitor the O2 sensor output - i mean i don't know if the lean code was reported in closed or open loop, if the latter you might want to look at the fuel pressure under load with WOT on a long uphill and see if it goes down - that would mean there is not enough fuel flow so would be either the pump or filter.

[aw12345]

Open loop means no feedback control of the fuel mixture.  Lean codes are set when the oxygen sensor does not toggle rich for a certain amount of time at cruise speed.
The first thing to check would be to run it at full load and at wide open throttle and see if it holds back or in other words it lacks power but as soon as you ease up on the axxelerator some it will accelerate again, if so clogged fuelfilter or a bad fuel pump is the cause (or anything that causes the pump not to run at its full capacity)
If it does not do that I would start looking at fuel injectors, try to clean the injectors with injector cleaner or have them cleaned.
A vacuum leak can have some effect on the engine running but if its real bad it would cause a trick rich condition. Small vacuum leaks would be hidden by the ecm adkusting fuel delivery to the engine which you can pick up with a good scanner by looking at fuel trim

[sharpxmen]

Open loop means no feedback control of the fuel mixture.  Lean codes are set when the oxygen sensor does not toggle rich for a certain amount of time at cruise speed.

what i was wondering was if it would report a lean code in open loop (would it monitor the O2 output in open loop mode - i understand that it will not adjust the injector duty cycle during open loop but rather work on a preset fuel map).

[95 Lowbuck]

My mistake on earlier thread, it would be error code #52.
It's my understanding that if the computer has to fatten up the fuel mixture
more than it's parameters have been set, it tells you so by saying your lean.
Error code #51 would be the opposite.

[sharpxmen]

i guess in that case would be fuel related (pump, filter or fuel return valve). Can't think of anything else as if there was a leak would be compensated by the MAP output and the engine would have a high(er) idle rpm.

[aw12345]

No lean code in open loop since the O2 sensor is not generating a voltage yet.
The newer 3 and 4 wire sensors with the built in heater go in closed loop fast.
Still open loop no voltage fluctuation, means not be able to generate a code

[chrisfranklin]

Well cleaning the map sensor and TB didn't get rid of it so I guess I'll start vacum testing lines.  Its actually running better than it has in a long time.  On a side note I finally bored my intake out to 62mm and that mod is worthless until you do this!  Much different.

When you say "this" at the end, are you talking about cleaning out the map sensor and TB (well not TB since you are putting in the 62mm that's presumably clean already)?