Old ltft was -6 on one side -8 on the other. Installed new MAF and now they have gone to -13 and -18...

Clearly I'm running rich.. stft bounces around plus or minus 5

I figure vacuum leaks if they were positive but no idea what would cause negative aka rich condition.

Where do I start?

No codes

My code reader says evap not ready but not sure if that's a valid status with a D2?

 

Anytime you change the MAF, 02 sensors, or do a tune up it's always a good idea to reset the adaptive settings. That way it goes back to default and then learns off the new hardware vs installing new hardware which is running off the old and sometimes INOP settings from the previous hardware.

It's not a requirement to do it, but it is recommended for the best results. I use my Nanocom all the time for it now whenever I work on a D2. LR used to charge to reset adaptations & all I can say is = EASY MONEY.... Takes like 5 seconds with the proper equipment.

 

my ltft went o zero when the battery was disconnected.. I assume that meant the adaptive cleared?

am I correct there are 2 temp sensors on a disco 2? 1 for water temp on dash and what we see on scan gauge and 1 someplace else that feeds the ECU?

 

This question has been something of a point of debate ... are the adaptive values reset when the battery is disconnected? Some have said yes; I don't recall anyone saying no.

 

Can anyone confirm if there are 2 temperature sensors? 1 in the radiator and one behind the alternator. Which does what?

 

The engine coolant temperature sensor is the one located in the intake manifold behind the alternator. The engine control module (ECM) uses the signal from the sensor to manage fueling, to manage the SAI system (if equipped), and to send a signal to the temperature gauge in the instrument cluster. This sensor also drives the output from the ECM that is displayed in the UltraGauge for coolant temperature.

The gearbox (transmission) temperature sensor is mounted in the transmission oil cooler that is mounted adjacent to the radiator.

My truck does not have an engine coolant temperature sensor mounted in the radiator, nor is there any indication of one in my copy ofthe RAVE.

 

The ETM lists the one in the radiator as the "Sensor - Thermostat Monitoring". The guy I bought my 03 from told me he would occasionally get a temp related code (he didn't elaborate on which one) and eventually found this connector unplugged. After reconnecting it the code stopped. He didn't say there were ever any problems with the gauge and as mln01 points out, and we're all painfully aware, the coolant temp gauge is buffered by the ECU. My guess would be that the radiator sensor is monitoring the coolant temps there to report any problems with the thermostat. Stuck open would possibly trigger a code for operating temps being too low, which may be what the 03 was doing prior to reconnecting it, not sure how stuck closed and an overheat would be reported. In any event, I don't believe it would impact fueling.

 

Thanks Ahab

At this point I'll drive it some more as I've only put about 15 miles on it. Worst case I suspect a purge valve starting to fail but not bad enough to throw a code.......? Or maybe ow sensors old and slow to react

 

SAI equipped D2’s have a sensor on the radiator. If the engine doesn’t warm up quickly enough it will throw a P0126 fault code. My 04 with SAI will toss this code & it’s kind of a PITA with a 180F thermostat, but at the same time I know it’s running cool.

 

Fuel trims went -18 and -25. Suspect the new MAF is defective. Will put the old one back in...