Intake air temps with an exhaust brake.

[AH64ID]

Can someone with an exhaust brake and a monitor that shows IAT (Intake Air Temp) do me a favor. Watch your IAT's the next few times you run the EB, both decelerating and idling, and tell me what you see. Do they go up or stay the same?



I never noticed it before my cam but my IAT's go up 6-10* about 1-2 seconds after the EB comes on, decel or idle. I am 99% sure it didn't stock, and is due to the cam actually having an overlap and being ground for flow not emissions. .



Purely a curiosity. Thanks!

 

[TCDiesel]

Plenum temps (IMT) don't change, IAT may change some 10-30 no need to worry ,The only time the IMT will rise is at idle.

 

[AH64ID]

I guess I am reffering to what you call IMT. On my OBDII reader the intake manifold temps come up as IAT.



I have no doubt its 100% normal and 100% fine, but more curious if I missed it with the stock cam or its new with this cam.



Say driving and IAT (intake manifold) is at 60*, if I decel the EB will kick them up to near 70*, if I decel without the EB they stay at 60* until stopped for a few minutes.



I am just trying to determine if its from increase overlap and a better cam profile, or from stale air in the manifold heating up from residual block heat.

 

[NIsaacs]

I would think the temp rise would be normal with E/B on. In fact, I wonder if at high rpm engagement if there is even a small amount of vacuum? With all three of my trucks I show boost at high rpm deceleration. As soon as I hit the E/B the boost gauge slams to zero. I have always wondered if my gauge showed vacuum if there might be a small amount?



Nick

 

[TCDiesel]

The IMT is taken form the MAP sensor,the IAT is taken form the the sensor just after the intake filter. Watch your IMT with truck at idle, it will raise quickly W/O EB on Now try it with EB and report Back.

 

[AH64ID]

I would think the temp rise would be normal with E/B on. In fact, I wonder if at high rpm engagement if there is even a small amount of vacuum? With all three of my trucks I show boost at high rpm deceleration. As soon as I hit the E/B the boost gauge slams to zero. I have always wondered if my gauge showed vacuum if there might be a small amount?



Nick

I notice the same thing and the boost is from the flow still spinning the turbo. I doubt there is a vacuum as your essentially stopping all the flow thru the motor, so no draw is occuring.

The IMT is taken form the MAP sensor,the IAT is taken form the the sensor just after the intake filter. Watch your IMT with truck at idle, it will raise quickly W/O EB on Now try it with EB and report Back.

The Service manual calls them both IAT, one is Inlet Air Temp, the other is Intake Air Temp. The one labled IAT on my Scan Gauge is Intake Air Temp off the MAP sensor, as I can watch grid heater operation on it.



But at idle the IAT(IMT) will rise, not super fast but it does rise slowly from radiant heat from the block and radiator heating the IC and intake manifold. If I turn the EB on it rises much faster at firt (that 6-10*) then the normal slow climb.



But I still would like to hear from someone with an Edge or some other OBDII style monitor tell me what intake air temp does with the EB on during a decel, with the stock cam.

 

[TCDiesel]

Pictures ... ... .

 

[AH64ID]

Pictures ... ... .

That just happens to be how that display show's them. The one that gauge calls IMAN TMP is what mine calls IAT.



So I am guessing that exhaust brake is on in 2 of those? If so that's what I figured, the cam profile has more overlap on the aftermarket and the intake seems to get a little of it (like 2nd gen trucks) with the EB on. It's not much becuase the temp only goes up a few deg, if it was alot the 400*+ EGT's would rise it more than 10*.

 

[TCDiesel]

Did you notice the rail pressure... EB increase fuel use at Idle. . on CR... ramp the RPMs and the rail pressure will also increase.



Those 3 pictures at 700 Rpms

 

[AH64ID]

I missed the x1000 on the Fuel psi part. That must be an 03-04? When I ran a RP gauge it idled higher than that, but I do recall a noticable RP jump.

 

[TCDiesel]

I missed the x1000 on the Fuel psi part. That must be an 03-04? When I ran a RP gauge it idled higher than that, but I do recall a noticable RP jump.

Yep... the 8 hole...