SES Light on for two years now, (CODE 44) only comes on during idle in traffic probably once it reaches a certain temperature. Once you start cruising SES goes off. I have changed every item in this vehicle that would need to be changed you name it I changed it. The only items I haven't changed is the Opti spark. I just changed the cats to Magna flow. The car only has 58 k miles. I also sent the ECM out to be checked and the report stated it was fine. I changed the 02 sensors twice thinking they may have been defective. Smoke test no leaks, there is no exhaust leaks prior to 02 sensors. I'm thinking it's a poorly calibrated Prom in the ECM.


There are possible 8 causes of SES Code 44 1) 02 Sensor defective or wires defective, Sensors changed twice, (2) Lean Injectors (Dirty or Blocked) replaced with Accel injectors, and replaced spark plugs, (3) Water in fuel (not an issue), (4) Exhaust leaks upstream of 02 sensor not the case, (5) Fuel pressure to low (replaced fuel pressure regulator and fuel pump this year), (6) Vacuum leaks, (did a smoke test twice no leaks) (7) MAF sensor reading lower airflow than is present, 92 and 93 don't use MAF. (8) The last item could be a poorly calibrated PROM in the ECM that I would think would have been noticed when I sent the ECM out to be checked. So, with the above said, I'm thinking if I'm going to get a new PCM possible from Jet performance thinking if I'm going to get a prom get one that gives more performance

 

Did you replace the plug wires too? If not, check in the dark to see if there is any arcing.. Any cylinder that has issue with not burning all the fuel on a batch fire system, 92/93, will cause O2s to read wrong.
Also, check your alternator for proper charging. You said this happens hot and at idle. If alternator isnt charging great or battery is dying, you will get SES>

 

Since we're throwing darts parts at it, you might as well try a new map sensor.

Additional potential sources of error: ethanol content of the fuel (likely), oxygenated fuel (likely), incorrect injector offsets (likely), poor airflow distribution in manifold (likely), high barometric pressure relative to baro reference, unusually high air density (mine shaft air), poor inlet air temperature compensation or IAT measurement error (likely)..

 

I replaced the spark plugs but not the wires, I didn't change the wires because they are good wires the name escapes me, but I did buy new wires AC Delco Gold series and intend to change this winter. The alternator is fine checked and have no problems with voltage. One diagnosis about a year ago, and that is how long I have been fighting this problem the mechanic said it was an ECM problem, so I sent it out came back no problems. So, I ordered a Jet stage 2 performance chip/prom and will go from there thinking it could be the Prom in the ECM. The plug wires will be changed if the problem still exists after the chip/prom change. Just to give an example of the problem, this morning started approximately 1/4 mile first red light, I stopped waiting and idling for light to turn green light came on. Started to move and increase speed approximately another 1/4 light went off. Stopped at another intersection idled waiting and light did not go on but upon entering the on ramp to highway light went on for about 1 mile then was off approximately for 25 miles of highway driving at 70-85 miles per hr. Came off highway stopped at several lights no SES light came on until I arrived at my destination. Strange!

 

There are some very heavy hitters in here with a ton of knowledge. My SES issues always stemmed from battery and alternator. Mine was, at one time a bit different, in that I had March underdrive pulleys.
But, after sitting for months on end, my battery, even if charging was bad, Finally I started using a battery maintainer. Its a hard fault to find without Tech 1 or 2 to see while driving.
An Alternator on the bench doesnt give the same real world driving when hot and under load. For a quick test, turn everything on, one at a time, in gear and see when the SES light comes on, while watching the volts on your dash.. It should be 13.5 to 14.2 roughly, most of the time.

 

Access to scanner? Integrator and block learn aka long and short term fuel trim. Does o2 bounce from .050v to .095v ? What are cross counts? What is fuel pressure with and without vacuum to fuel pressure regulator? Disconnect AIR hose off check valve an see if makes a difference.

 

Did that! Fuel filter also, all that you can think of has been replaced> I'm thinking it's the PROM in the ECM. We will find out shortly