ITSAV

iTrader: (1)

ok....so went and looked over the tune some more...and realized I think the tune is fine, its the coolant that is the issue. On my dash it shows what my coolant temp is, but on HP Tuners or anything I plug into my obdII sensor it doesnt register my coolant temp.....I think thats why my idle is jerky on start up, cause it only happens when it is cooler outside, like on a day where its 80 degrees out, it really doesn't even do it.

I tried searching for this kinda issue on the forums and really didn't come up with anything. Is there anything in particular that would allow the coolant temp to show on my cluster but not on anything through the OBDII?

isis

iTrader: (1)

Friend of mine had this exact problem on his STI. Ended up replacing the ECU after chasing wiring and signals for a day.

DMM

Pull the sensor lead off the sensor (on the drivers side head) and see if the PCM sets a DTC for it.

vmapper

iTrader: (8)

I would think the sensor is fine if the dash temp is working...

ITSAV

iTrader: (1)

**** hope this isn't the case, cause than I got to pay for a new ECU plus the credits for hp tuners again

brack86svo

I would think if the cluster is getting the coolant temperature reading, that the ecu should be fine. The info is transmitted through data links on these cars if I'm not mistaken. When you hook to the OBD port, you are pulling from the same data link. It could be some sort of issue through hp tuners. Have you tried any other types of scanners?

ITSAV

iTrader: (1)

I have one of those Elm 327 Bluetooth devices for the Torque app, and that also shows no coolant temp as well.....

Sweetwilliebrownjr

Sort of off topic, but interesting: coolant can build enough of an electrical charge through electrolysis, that it will prevent the spark plugs from grounding and cause misfires. Absolutely no point to me posting this.

vmapper

iTrader: (8)

It would appear you have a two part problem, one being the ECT being read issue, the other, the ACTUAL reason as to why idle is fine in warmer temps vs colder.
Have you tried a 'reset'? pull the battery and fuses?

Then rescan the PID for SAE ECT, see if you get values then.
Again, I dont see how your dash gets engine temp in your digital selection, but not through the BUS. (there is only one sensor).
There are many things that would be affected by the ECM not seeing coolant, including going into CL. When at operating temp, are you in CL?

After we get SAE ECT sorted out, I will then say its the tune. (RAF table is where I would start) most tuners dont bother or are not good enough to adjust this time sensitive table from Cold startup AND interpolate values COLDER than what their shop ambient is.. to cover the entire table. (its also a PITA as you get one shot at it... otherwise, you wait for a long time to cool)
What are your STITs/LTITs on cold startup? are they maxed at the default 3g/sec?
Histograms are your friend to see what the delta is, when you zero out your trims AND turn off adaptive learning. LTITs are reset via fuse /battery pull, I dont think the VCM controls for these caddies are available to reset Idle Trims.

I guess FIRST, we need a coolant read.

ITSAV

iTrader: (1)

well my friend found the coolant issue....I'm not sure exactly which wire for the coolant sensor ...but one of them was loose on the ECU, so he soldered it back in place, and bam now have coolant temp....so this next weekend we will prob grab the laptop, and go out again I think we will have much better luck with correcting the start up

vmapper

iTrader: (8)

Ill be dammed..
Loose wire on the ECU, who would have thunk...
Guess that rules out the monitoring station being on the same BUS.