Throttle sluggish when hot

[rottenronnie]

So do I understand this correctly. I have an RC 05 with Paxton and had BG flash the PCM, lower thermostat and fan. Heat soak is still a noticeable issue. So the thought is that the resistor would also help my Paxton flashed PCM by not pulling out so much advance? Or is another way of saying it is that the heat soak problem is more from timing being pulled out than just hot intake air??
What does BG say about this?

Heat Soak is a term that is thrown around a lot here. A general definition of Heat Soak is heat that is inside an engine after it is shut down.
General operating heat (I think) is what you are more concerned with.

Anyway, timing that is too far back (late) will create additional heat in an engine by putting more heat into the cylinder walls (and of course the cooling system) than using the heat more efficiently (with the correct timing) to produce power. This of course adds heat to ALL engine parts (like your intake manifold). But pulling timing back temporarily can prevent pinging and subsequent detonation.
The Stage 2 flash lowered the operating heat coming from the intake manifold substantially in my truck.
Dan Craigin (DC Performance/B&G Flash) told me NOT to use a resistor with the Stage 2 flash. That is good enough for me. You can however move the sensor into the air somewhere outside of the actual engine compartment.
I guess some with the flash have done the resistor mod and said it helped.....So "Try or Try Not...There Is No Do", to f.u. what Yoda said...

 

[HOT RAM]

The correct wire is the dark blue with a light green stripe, not the solid blue one.
Sorry I wasn't clear.

OOPSIE !!!!!!!!!!

 

[HOT RAM]

After talking with several knowledgeable folks,I have decided to remove the resistor from my IAT.Yes,it does prevent the computer from pulling timing by fooling it into reading a lower than actual intake temp HOWEVER it also causes it to run richer.
I have a stock intake,so it isn't very prone to heat issues and as it is a true cold air intake right from the factory,it is reading fresh air anyway and there should be no need to move it either.

So...................."Do or do not.There is no 'try' ." !!!!!!!


I did.Now I don't.


This was mainly a fix for supercharged engines anyway.

 

[nycstev]

After talking with several knowledgeable folks,I have decided to remove the resistor from my IAT.Yes,it does prevent the computer from pulling timing by fooling it into reading a lower than actual intake temp HOWEVER it also causes it to run richer.
I have a stock intake,so it isn't very prone to heat issues and as it is a true cold air intake right from the factory,it is reading fresh air anyway and there should be no need to move it either.

So...................."Do or do not.There is no 'try' ." !!!!!!!


I did.Now I don't.




This was mainly a fix for supercharged engines anyway.

So what are you waiting for..

































Get a SC!

 

[Roe Racing]

This was mainly a fix for supercharged engines anyway.

Actually, we found the issue on the chassis dyno of a naturally aspirated engine.
The engine had been built by Arrow and made 600 crank HP, but was in the low 400's once the engine went in the truck. We started looking for the cause and found out that the engine dyno room was at 60 degrees. Once we put a 10K ohm resistor in the IAT wire to show the PCM a colder temp (keep in mind, we didn't change the actual air temperature or density on this back to back test), the engine picked up almost 80 RWHP.
Later, we got the SCT software and compared the factory PCM ignition timing to IAT values between the Vipers and the Rams. The stock Viper calibration can reduce the timing by up to three degrees for temps over 95 while the Ram reduces is by up to eight degrees for the same temperature.
On a flashed PCM, those strategies should have already been changed. We change them with the SCT programs we make. This is something that pretty much only applies to stock PCM's.

Regards,
Sean

 

[VIPER HP]

I know that heat soak is not a result of timing,etc. What I said was "heat soak problem" and what I should have said was the dramatic difference in performance when the engine is colder vs hot. Maybe the difference is more noticeable with a supercharger because of the hot intake air which in turn is pulling timing out. The timing answer make since because I have always thought the difference has to be more than just hot air.
Anway, I'm trying it and I'll let you know what happens.

 

[rottenronnie]

I know that heat soak is not a result of timing,etc. What I said was "heat soak problem" and what I should have said was the dramatic difference in performance when the engine is colder vs hot. Maybe the difference is more noticeable with a supercharger because of the hot intake air which in turn is pulling timing out. The timing answer make since because I have always thought the difference has to be more than just hot air.
Anway, I'm trying it and I'll let you know what happens.

I wasn't trying to be a pain in the ass (honest).
Heat Soak is just a phrase and not a big deal.

But if you were to call nitrous oxide NOS, that is a very big deal
and will throw me into a homicidal rage.

Yes, they really lose power when they get warm, especially with crappy fuel.

I am all for modding, it began for me in 1968 with my Yamaha 100 "Twin Jet" motorcycle.

I just wanted to let all (or is it 'yall) know it is NOT recommended with a Stage2 flash. That's all 'yall.

 

[HOT RAM]

I wasn't trying to be a pain in the ass (honest).
Heat Soak is just a phrase and not a big deal.

But if you were to call nitrous oxide NOS, that is a very big deal
and will throw me into a homicidal rage.

Yes, they really lose power when they get warm, especially with crappy fuel.

I am all for modding, it began for me in 1968 with my Yamaha 100 "Twin Jet" motorcycle.

I just wanted to let all (or is it 'yall) know it is NOT recommended with a Stage2 flash.

If someone doesn't have a Stage 2,it is highly unlikely that they have the desire to do any modding anyway

 

[HOT RAM]

So what are you waiting for..



Money,money,money !!!!!!!!!!!!!!!!!!!!!!

I am so broke i can hardly pay attention !

 

[rottenronnie]

Actually, we found the issue on the chassis dyno of a naturally aspirated engine.
The stock Viper calibration can reduce the timing by up to three degrees for temps over 95 while the Ram reduces is by up to eight degrees for the same temperature.

Regards,
Sean

Does it pull even more than 8 degrees on the quad cabs?

 

[VIPER HP]

So I wonder if this is the fix to the power robbing heat soak problem that Boomer used to talk about, but would only install if he was doing your Supercharger installation. Is it Boomer?? Is the secret out now?
If so, Boomer you should take some credit for discovering it some time ago!

 

[VIPR PWR]

where can you get the resistor ---is there a part number---is there any other fix's

 

[VIPER HP]

My Seat Of The Pants Dyno says this just might fix the heat soak power reduction problem! I put in a 10k resistor. If this works I may sell my Paxton and buy a Roe supercharger just out of respect for SEAN ROE'S great knowledge and disclosure. Sean if you read this how did you determine if this was enough resistance to keep the pcm from still pulling out timing on a really hot day?? What about a 20k or 30k resistor??

 

[nycstev]

Sean mentioned 4.7 ohms . The more resistance you add the "colder" it will think it is and the richer it will run. For that matter you can just unplug it and you will have infinite resistance corresponding to about -30F ( i think) Where
10 or 20 ohms interpolates along that scale is ??:rock: :bebored: :elefant: :nurse: :toilet:

 

[Roe Racing]

10K ohm is as high as we tried, though I recommend 5K ohm (+/-).
From memory, I think 5K took the PCM’s perceived temperature down by about 20 degrees.
We used a scan tool to record the IAT value and ignition timing.
I think the ignition timing stayed about 2+ degrees further advanced.
Basically, you’re still letting the PCM do it’s job of reducing timing, just no so excessively.
All testing was with a stock PCM.

Regards,
Sean

 

[HOT RAM]

10K ohm is as high as we tried, though I recommend 5K ohm (+/-).
From memory, I think 5K took the PCM’s perceived temperature down by about 20 degrees.
We used a scan tool to record the IAT value and ignition timing.
I think the ignition timing stayed about 2+ degrees further advanced.
Basically, you’re still letting the PCM do it’s job of reducing timing, just no so excessively.
All testing was with a stock PCM.

Regards,
Sean

So.................why won't this work WITH the Stage 2 flash ? :dontknow:

 

[Prof]

I need pictures...are they here?

 

[SRT-11]

OK to sum up all this madness:

For us Floridians with all kinds of warm weather and NA engines, will this mod make an improvement in sluggish throttle repsonse?

Is it in any way dangerous/unwise to retard/advance the timing with this method if the actual outside air temperature is as high as 95-100 degrees (and humid!)

Where is the wire on NA engines, is the IAT like a MAF module? is it the unit that plugs into the tube on the stock intake?

 

[rottenronnie]

So.................why won't this work WITH the Stage 2 flash ? :dontknow:

Because with the Stage 2, the issue has already been addressed and the flashed ecu requires normal voltage (without a resistor) to operate properly.

I just made this all up but it sounds good to me...
But I think it may be actually true...

 

[rottenronnie]

OK to sum up all this madness:

For us Floridians with all kinds of warm weather and NA engines, will this mod make an improvement in sluggish throttle repsonse?

Is it in any way dangerous/unwise to retard/advance the timing with this method if the actual outside air temperature is as high as 95-100 degrees (and humid!)

Where is the wire on NA engines, is the IAT like a MAF module? is it the unit that plugs into the tube on the stock intake?

As an emergency measure, the truck's ecu pulls out a lot more timing out than the Viper car when it starts to ping. As the Viper car is unlikely to see towing duties, and isn't nearly as heavy, not as much timing is cut back. Although the Viper is still a heavy pig compared to the 3100 lb. Z06s.
Too much timing during hot weather with a hot engine that is using a fuel that is too low in octane, pulling a boat up a mountain at w.o.t. with the a/c on is a bad thing. Although add alcohol to the mix (except the driver) and the right company, and it could be a good time for all.
The manufacturer's are protecting our investments and of course theirs during warranty especially.