IAC-No Input Voltage / HIGH TRANS TEMP

Yea exactly. This is why the converter is getting ULTRA hot while I'm sitting motionless in D. I have a good understanding of how they work which is why I was leaning towards the IAC/HIGH idle being related to the HIGH TRANS TEMP. I think the problem is one in the same and will fix both. But yes, I agree that normally when you're driving down the freeway the converter is stalled and locked up not generating heat.

The other thing I agree with you on is that there may be a connector or something that got affected during header install. I have looked and relooked and looked again. I don't see anything out of place. I have a PDF FSM so not flying blind either... I'm not a pro but pretty sure this is an OUTPUT issue with the ECU/IAC. It's not sending the voltage pulses to step the motor closed or open so as soon as you plug the IAC connector in, it's wide open and shoots the RPM up to 17-1900...

 

My writing is all over the map today since I received so many responses from you guys in the last few days.

The only variables that were "touched" doing the DT headers...
-MAF (cleaned it) Used to read 5g/s @ idle and it now reads 8-10g/sec @ idle and the readings seem to be inconsistent
-IAC (brand new) bench tested. Continuity checks out and voltage applied to RSC RSO pins and the step motor moves each direction respectively
-TPS (brand new CHEAP CHINA) After the header install my TPS disintegrated internally so I bought a new cheap China one. Using Torque Pro it appears TPS is functioning correctly. Shows estimated correct percentage butterfly is open throughout the entire range. Idle is like 9.2% or something low 9 which I see/read is in spec.
-O2 Bank 1 Sensor 1 (same one that was already on truck, just swapped over to new DT downpipe. No leak and O2 checks out on Torque Pro system check.

Previous readings before header install
-Trans Temp (city) 190 - 217 (highway towing) 217 - 240's when converter is constantly locking/unlocking.
-Coolant Temp (city) 188 - 202 (highway) 194 steady.
-MAF 5.x g/s


I purchased another cheap China TPS and a new MAF. Going to throw those in later today or tomorrow and plug IAC connector back in. Measure G/S on the MAF and TPS percentage. Hopefully something isn't communicating with the ECU properly which would effect the output to the IAC ...

 

Sounds like you've done everything that I would of at this point.
Is your new IAC OEM? I have read that aftermarket ones are crap. Yes I know the OEM one is very expensive.

I have read that both the MAF and TPS can show correct data but still cause these types of issues.

 

Naw, IAC was cheap china. The problem is. I used the multimeter to determine that I'm not getting voltage on the IAC connector. Not sure switching IAC's would matter. I've also read that as well. Not sure.

 

What year truck? I have a known good IAC if you want to try it.

 

What are your coolant temps?
The ECU controls movement of the valve by
applying a 250 Hz duty cycle to coils T1 and
T2. The electronic circuitry in the ECU is
designed to cause current to flow alternately
in coil T1 when the duty cycle signal is low
and in coil T2 when the signal is high. By
varying the the duty ratio (on time compared
to off time), the change in magnetic field
causes the valve shaft to rotate.

 

It's a late year 99. I might have to take you up on that offer. I would like to rule out circuitry first to make sure I'm not chasing my tail. I really don't know anything about hertz. I understand it's a wave. When the ECU applies 250hz duty cycle (pulse waves) what voltage would show on the connector on each pin respectively, RSO RSC? The weird thing is the step motor is receiving input when it's connected. During the braking process, coming down to a stop the step motor is stepping down as it should. The problem is something is telling the ECU to keep the idle high. I'm receiving data for engine coolant temp on my Torque Pro so I doubt it would be that. What are the chances it's another input that the ECU needs to determine idle speed? I'm going to try this new MAF today because sometimes at idle my MAF is reading 8.9g/s and sometimes it's 10g/s... I've seen 7.9g/s... no consistency. That is one of the parts that I cleaned so maybe it's faulty???

Coolant Temps: (city) 188 - 202 (highway) 194 steady.

 

Have you disconnected battery to reset memory, forcing the ecu to relearn the idle?

 

have you cleaned the engine ground wire that was removed really good with some sand paper?

 

Multiple times. No effect. Dalandser provided me with a write up link that I followed. I just wanted to clarify that I was doing the process correctly. With the engine warm and running at idle, if I disconnect the IAC connector and take multimeter would I be seeing voltage on either of the outside pins RSO RSC? The write up says 6-7.5v on one pin and 8-9v on the other pin. Middle pin should have battery and it does. My outside pins have .02 with engine running at idle. Maybe there's only voltage when the ECU is telling motor to do it's thing one way or the other? Maybe having .02 on the two pins while the engine is idling doing nothing is normal??? Going out to take throttle body off to put new TPS and MAF on and reconnect IAC and look over any of the other inputs wiring... NO CEL so I doubt there are any OPENS in any of my circuits...

 

BUMP

Trans TEMP ****RESOLVED*****

From my build thread.

BUMP!!!

Ya regrese EL HONCHO!

Finally got some trans maintenance done. Ordered the wrong trans filter. Apparently the A340E 2wd and 4wd filters are different. I was absolutely embarrassed to see how disgusting the fluid was. There was a thick sludge covering the mesh filter and bottom of the pan. There was only 3 out of the 4 magnets in the pan so someone has been in there before I owned the truck. I feel like the biggest douche bag for saying that I have NEVER dropped the pan on this trans in the 12 years that I've owned it. I put the new filter in and used the included rubber gasket so I don't ever have to scrape FIP gasket off again.

I decided to throw a trans cooler on there as well while I was doing the new fluid/filter. Purchased the smaller Hayden 11"x7.5" cooler without fan. Ran it inline with the champion 3 row. Filled up fluid to correct level so I don't puke all over the under belly per my last few fluid changes LOL. The truck shifts like absolute butter now out of P into R or D. Driving shifts are butter like they always have been. Fluid temps in a 45 minute test drive never got above 220 and that was only because I was in an IN n Out drive through for 12 minutes. Sustained airflow through the grill and this thing is sustained around 195 now.

My only concern that I had is how well it would do with the fluid warm (190) then have it in D for a period of 10 minutes or more IE long drive through wait or border wait/stopped traffic. I knew that it would start to heat up with prolonged stop and go or just plain stopped with truck in D without a fan. In the spot that I have it mounted currently I think I'd have to cut out the inside of the plastic grill to have enough space to mount a small 7" pusher fan. After I hit 220 in the drive through, pulling out and minutes later on the freeway the temp had already fallen to 190'ish. Right around 205 by the time I was putting the truck in P back at the CRIBO.

Overview: Trans temp is now good with airflow. Parked with the truck in P, trans temp falls to 185 or so. Parked with truck in D and the temp does still slowly go up albeit I bet it takes twice the amount of time to climb to 220 now. Problem I see is if you're in stop and go to where you can't keep putting it in P then you'd pry want a pusher fan.

Going to look into a small pusher fan. Otherwise, my TRANS TEMP CONCERN is now marked as RESOLVED. If I had to guess, combo of filter EXTREMELY clogged and horrible fluid condition. Trans cooler is definitely MONEY WITH AIRFLOW.... NO AIRFLOW and I think it needs a pusher fan.

Still have a little higher than normal IDLE as well but jury still out on what is causing that issue. It's reasonable enough to drive but still annoying. 1250rpm cold start, 1350 when it's warm, 1500-1900 when you put the truck in P after driving it (BUTTERFLY VARIENCE) Back to 1350-1450 if you BLIP the throttle real aggressive to 4 or 5k and let off suddenly it falls back to a reasonable 1350 but still annoyingly high.




ONE LOVE!!!!

 

More than one mechanic has told me you cant always trust the readings from the obd scanners... Maybe an infrared thermometer? Possibly scan another trans at running or idling temp to have a base to compare?