Intercooler pump logic?

Dinosgt

Active Member
Established Member
Joined
Jan 15, 2015
Messages
456
Location
tx
Folks:

Can anyone enlighten me on the intercooler pump logic for our cars? In other words, when does the pump come on and shut off? is it engine coolant temperature dependent?

I noticed that my car runs IAT2 temps about 35-40 degrees higher than IAT1 - but after I see about 195-200 or so on engine coolant temp, IAT2s seem to start dropping a bit - I assume this means the pump starting to circulate intercooler coolant?

Is there any reason to not just jump the relay and run the intercooler pump full time?

(Interestingly, the other day I noticed that while idling in the garage, as IAT1 climbed to 140, I turned on the AC, which kicked on the cooling fan - IAT2 started to immediately drop, and ended up at exactly the same temp as IAT1.)

Thanks for any insight anyone can provide...:beer:
 
Last edited:

heatsoaked12

Member
Established Member
Joined
Sep 13, 2011
Messages
815
My 12 gt500, with the stock tune, the pump turns on at IAT2 temps of 115 f then turns off when it gets down to 102 f. If your pump ran continuously, then during traffic or when you are stopped it would constantly collect engine heat into your intercooler circuit and not be able to remove any heat from the charge air path. The pump shuts off to give your heat exchanger (the small rad behind your grill) time to reject heat. If you upgrade your heat exchanger to a fanned unit, you can run the pump all the time as the fans will remove heat even when the car is stopped for long periods of time.
 
Last edited:

Dinosgt

Active Member
Established Member
Joined
Jan 15, 2015
Messages
456
Location
tx
My 12 gt500, with the stock tune, the pump turns on at IAT2 temps of 115 f then turns off when it gets down to 102 f. If your pump ran continuously, then during traffic or when you are stopped it would constantly collect engine heat into your intercooler circuit and not be able to remove any heat from the charge air path. The pump shuts off to give your heat exchanger (the small rad behind your grill) time to reject heat. If you upgrade your heat exchanger to a fanned unit, you can run the pump all the time as the fans will remove heat even when the car is stopped for long periods of time.


Thanks for the feedback. I have spent some more time watching it thru the NGauge, and noticed that regardless of outside temp, it never gets below about 102-104. It can be 50 degrees out, but I never see lower than 104 ish. However, once in a while, if the engine temps begin rising a bit over 194-198, I presume the intercooler pump comes on, because for a very short time, the IAT2 will drop to 95 ish. So, I was wondering why I shouldn't try to run the pumps at a lower threshold "On" level when outside temps are so low to keep the IAT2 nice and low, and avoid heatsoak (not referring to you sir.) :beer:

I usually see, while moving, a delta of about 35 degrees (IAT1 to IAT2), but sometimes temps can creep up into the 135 or so range while driving (of course I can see 165 while siting in traffic, but I understand that without fans there isn't much to be done about that)

Finally, as further support for fans, if I turn on the AC and the engine fan kicks on, IAT2s begin to drop almost immediately. I am sure that the radiator fan doesn't draw like the VMP or Vans fans do...
 

Catmonkey

I Void Warranties!
Established Member
Premium Member
Joined
May 20, 2011
Messages
3,854
Location
Louisiana
My 12 gt500, with the stock tune, the pump turns on at IAT2 temps of 115 f then turns off when it gets down to 102 f. If your pump ran continuously, then during traffic or when you are stopped it would constantly collect engine heat into your intercooler circuit and not be able to remove any heat from the charge air path. The pump shuts off to give your heat exchanger (the small rad behind your grill) time to reject heat. If you upgrade your heat exchanger to a fanned unit, you can run the pump all the time as the fans will remove heat even when the car is stopped for long periods of time.
I have SCT's pro-racer package, the on and off temps are 115 and 100 on the stock tune for my 2012. Most tuners set the temperutures 50 to 60 colder, so the pump does run constantly. I've got mine set at 85 and 75 and once the pump (and fans in my case) turn on, they don't really cycle on and off.
 

heatsoaked12

Member
Established Member
Joined
Sep 13, 2011
Messages
815
For what its worth, when the radiator cooling fan turns on, it does dump a lot of hot air into the intake when the car is stopped. Our filters are not fully sealed from engine compartment. A heat exchanger with fans actually will blow the hot air out the top grill when the car is stopped with engine running. This way it will get rid of the heat from your heat exchanger without dumping it down your intake tube only to try to remove the heat down stream from your charger again. This is why the fanned HX is win/win.
 

Dinosgt

Active Member
Established Member
Joined
Jan 15, 2015
Messages
456
Location
tx
I have SCT's pro-racer package, the on and off temps are 115 and 100 on the stock tune for my 2012. Most tuners set the temperutures 50 to 60 colder, so the pump does run constantly. I've got mine set at 85 and 75 and once the pump (and fans in my case) turn on, they don't really cycle on and off.

Great data - thanks very much. Why wouldn't we just run a relay or jumper to the IC pump to run it all the time? Pump life?

It just seems odd to me to limit the downside to 10o degrees when the car starts pulling timing soon thereafter (temp wise)

For what its worth, when the radiator cooling fan turns on, it does dump a lot of hot air into the intake when the car is stopped. Our filters are not fully sealed from engine compartment. A heat exchanger with fans actually will blow the hot air out the top grill when the car is stopped with engine running. This way it will get rid of the heat from your heat exchanger without dumping it down your intake tube only to try to remove the heat down stream from your charger again. This is why the fanned HX is win/win.

I know the fans are the way to go - I have read just about every thread on it. Certainly would help with the incessant heat soak. I guess I was trying to avoid taking the car apart with only 5000 miles on it. I'm also terrified of the bumper removal... I am sure I will screw up the paint.

thx again...
 

railroad

Well-Known Member
Established Member
Joined
Dec 9, 2003
Messages
2,118
Location
warrior, al
I would get educated on the Killer Chiller, before going with the fan cooled heat exc. I did the VMP heat exc and it works great compared to no fans, but would have gone with the Killer Chiller and still will. I think the front bumper comes off with it also. I did it, with a little tape on the fenders and a set of helping hands, no issues.
 

Catmonkey

I Void Warranties!
Established Member
Premium Member
Joined
May 20, 2011
Messages
3,854
Location
Louisiana
It just seems odd to me to limit the downside to 10o degrees when the car starts pulling timing soon thereafter (temp wise).
There are a few tables that begin to pull timing at 100 degrees of air charge temps, one is temp based, the other load based. At high loads, the PCM will begin progressively pulling timing at 100 degrees and will pull about 3 degrees of timing by 125*, 6 degrees by 150*. So it's already pulled almost 2 degrees of timing when the intercooler pump kicks on. Sort of easy to see why a tune add so much more power when you have insight of the factory programming.

I know the fans are the way to go - I have read just about every thread on it. Certainly would help with the incessant heat soak. I guess I was trying to avoid taking the car apart with only 5000 miles on it. I'm also terrified of the bumper removal... I am sure I will screw up the paint.
It's looks way more intimidating than it really is. There are a few vids on youtube that will show you how to remove the bumper cover. If it's any consolation, I replaced my engine at 4,500 miles.
 

heatsoaked12

Member
Established Member
Joined
Sep 13, 2011
Messages
815
I know the fans are the way to go - I have read just about every thread on it. Certainly would help with the incessant heat soak. I guess I was trying to avoid taking the car apart with only 5000 miles on it. I'm also terrified of the bumper removal... I am sure I will screw up the paint.

thx again..


My 12 has 10k on it now, pulling the bumper was way easier then I thought. I was also worried about scratches and cracking the paint but none at the end of a day in the garage. Even pulled my bumper off twice because I forgot the bumper padding out. :uh oh:
 

Dinosgt

Active Member
Established Member
Joined
Jan 15, 2015
Messages
456
Location
tx
There are a few tables that begin to pull timing at 100 degrees of air charge temps, one is temp based, the other load based. At high loads, the PCM will begin progressively pulling timing at 100 degrees and will pull about 3 degrees of timing by 125*, 6 degrees by 150*. So it's already pulled almost 2 degrees of timing when the intercooler pump kicks on. Sort of easy to see why a tune add so much more power when you have insight of the factory programming.


It's looks way more intimidating than it really is. There are a few vids on youtube that will show you how to remove the bumper cover. If it's any consolation, I replaced my engine at 4,500 miles.


Thanks very much for the data. That's exactly why I don't get why the factory set up doesn't turn on the pump until ~105 degrees. But even with added fans, wouldn't we still have the same problem (Unless you also change the 0n/off set points thru a tune)?

However I do get that the fans will make a huge difference in heatsoak, since we can keep the IAT2s down by moving air over the HE. But it seems that without keeping the pump running, we artificially limit the lower end of the temp range. So - w/o a tune - is there a way to keep the pump running by jumping a relay somewhere?
 

Dinosgt

Active Member
Established Member
Joined
Jan 15, 2015
Messages
456
Location
tx
I know the fans are the way to go - I have read just about every thread on it. Certainly would help with the incessant heat soak. I guess I was trying to avoid taking the car apart with only 5000 miles on it. I'm also terrified of the bumper removal... I am sure I will screw up the paint.

thx again..


My 12 has 10k on it now, pulling the bumper was way easier then I thought. I was also worried about scratches and cracking the paint but none at the end of a day in the garage. Even pulled my bumper off twice because I forgot the bumper padding out. :uh oh:

Thanks for the encouragement, and glad to hear no damage when you did it...
 

Dinosgt

Active Member
Established Member
Joined
Jan 15, 2015
Messages
456
Location
tx
Yes. You could rig a remote switch, based on these instructions/pictures.

I tried this today - I was bummed to see that the pump ran even with the car completely off. I was hoping to do this for "key on" to keep it running while I was driving, but want it to switch off after I shut it down.

I am trying to get IAT2 under 105 as the outside temps are dropping now, but with the stock restrictions on the pump cycling on after 105 or so, it wont go lower. Want to see how low I can get it without fans...

Any body have the wiring diagram for the pump?


Thanks...
 

Norton

Long-time SVT Enthusiast
Established Member
Joined
Dec 11, 2012
Messages
3,167
Location
Colorado Springs, CO
I tried this today - I was bummed to see that the pump ran even with the car completely off. I was hoping to do this for "key on" to keep it running while I was driving, but want it to switch off after I shut it down.
That's why I suggested "you could rig a remote switch," which is required to prevent the pump from running all the time.

If anybody has wiring diagrams, Snoopy49 will.
 

Snoopy49

Well-Known Member
Established Member
Joined
Jun 12, 2012
Messages
6,690
Location
California
Charge Air Cooler Pump Wiring Diagram.jpg
 

Dinosgt

Active Member
Established Member
Joined
Jan 15, 2015
Messages
456
Location
tx
Wow - thanks gents. Really appreciate it! Now isnt it odd that this thing is wired to an 'always hot, circuit?

So, next step - rather than a switch that I may forget to shut off given my advanced age, should I try a 'key on' relay that jumps 3 and 5 in the CAC relay?

Again - thanks
 

Snoopy49

Well-Known Member
Established Member
Joined
Jun 12, 2012
Messages
6,690
Location
California
You should be able to accomplish what you want by disconnecting the green line (pin 2) from the from the cac relay control and connect it to ground.
 

Dinosgt

Active Member
Established Member
Joined
Jan 15, 2015
Messages
456
Location
tx
You should be able to accomplish what you want by disconnecting the green line (pin 2) from the from the cac relay control and connect it to ground.


Snoopy - thanks for your feedback. I am a clueless ME (EE wasn't my thing), so I am not really confident in electron flow. Do I just ground pin 2 from inside the fuse box? Is that essentially what the PCM does to trip the relay?
 

Users who are viewing this thread



Top