Engine idle issues still part #2

[Rocket Man]

I thought the vehicle of subject was a GMT900.

Toyota also had a hydraulic cooling fan motor. I guess an electric fan motor is yet another archaic design employed by GM that isn't required? Some vehicles run a speed-density tune and don't have a MAF sensor- GM's use of a MAF must not be required, either. Rip out all that unnecessary clutter and drop in a good 'ol tree fifty with a big ol' caw-buh-ray-durr.

He is talking about a MAP sensor, not MAF.

 

[iamdub]

He is talking about a MAP sensor, not MAF.

I know. I was replying to him saying a MAP isn't required and referencing a different car make, as if GM doesn't know something they (or the OP) do.

 

[Rocket Man]

I know. I was replying to him saying a MAP isn't required and referencing a different car make, as if GM doesn't know something they (or the OP) do.

Oh ok, I get it now.

 

[BG1988]

I disconnected both the Map and MAF and it still shows the engine load.
so the computer must be pulling the data out of it's ass on that one


with the map disconnected it was showing 10KPa on it

showed no effect or change as well for idle or revving it up ...


the MAF disconnected showed no effect or change as well for idle or revving it up ...

 

[Rocket Man]

I disconnected both the Map and MAF and it still shows the engine load.
so the computer must be pulling the data out of it's ass on that one


with the map disconnected it was showing 10KPa on it

showed no effect or change as well for idle or revving it up ...


the MAF disconnected showed no effect or change as well for idle or revving it up ...

It’s running on its last known good configuration. It does that so you won’t be stranded. But hey like I said you’re smarter than GM so just leave them disconnected, they aren’t needed.

 

[iamdub]

With those disconnected, the PCM defaults to a base/safe tune so the engine can still run. This is a common test for someone suspecting a faulty MAF or MAP. If you make the PCM ignore the alleged faulty sensor's input by unplugging it and the engine runs better on the PCM's default tuning, chances are the sensor is reporting erroneous info to the PCM.

It's not "pulling the data out of it's ass". It's referring to the tables it has developed for when those sensors were reporting. Throttle angle was part of those tables so now it's making a guess of the engine load based on that. It now can only rely on throttle angle, knock sensors and O2 sensors to calculate the required fuel at a given RPM. It starts out a little rich to be safe.

 

[BG1988]

Yes the map sensor is required for it run correctly


I tapped the top of the sensor several times and it unstuck the diaphragm... idle is smooth now with no random rough idle motor shaking . i'm still going to replace it going to order one since i got some ebay bux

safe mode/ fail safe does not work as the symptoms were identical..

also the CEL went off P0430

catalytic converter temp is 370C (698F)to 500C (932F) depending on load before it was 300C and under it would drop to 100C

etc...

 

[Sam Harris]

When you do, pull all the covers they probably shouldn’t be going into and put love notes that say stuff like “what are you looking in here for?” “NO TRESPASSING” and “Surprise Muddafukka!”

 

[BG1988]

I know. I was replying to him saying a MAP isn't required and referencing a different car make, as if GM doesn't know something they (or the OP) do.

yes the MAP sensor is required with the 6.0 replaced the sensor today only took 30 seconds to swap it out..


Diagnostic complete . MAP sensor was fouled with motor oil clean motor oil that is odd


she idles and accelerates smoothly now.. I have reset the CEL even the auto stop function and v4 work great now...


i know any shop would have charged 100$ for 30 seconds of work...


did not even bother to disconnect the battery as i did not want the A/C actuator to cycle(this damages the actuator) at lest there is a roomer this is the case