Stock truck idle problems after flash..?

[samh_08]

My cousin has a 2003 chevy silverado 6.0L that I just registered and read his PCM. I didn't change anything related to idle (or so I think) and now it idles way to low in gear and wants to stall. I tried bumping up all desired idle speeds 125rpm but the truck doesn't respond to the changes. It will idle fine for 10 seconds at the speed I want it to idle, then it will drop off and start acting funny.

Another issue I have is that I get 'Reduced engine power' every time I reflash the computer. I clear the code and then its fine..Never had a problem with that code before EfiLive. Any ideas?

I have the stock and modded (should show everything I changed) file attached. Please advise, Thanks.

[joecar]

Sam,

You read the PCM and then after that the idle was wrong...?
Did you wait at least 15 seconds with key off after reading...?


I would do this:

flash stock tune back in (cal-only flash), wait 15+ seconds with key off;
make sure key is OFF, disconnect the battery for a few moments, reconnect it, and now see what idle does.

if that doesn't work, then do a full flash of the stock tune and see what idle does.

[SSpdDmon]

http://www.motownmuscle.com/forums/images/smilies/hmm.gif


What's done to the truck??

[samh_08]

Stock truck, no mods done except for the PCM flash I just did.

Joecar, the idle situation first started after I did the reflash and yes I waited 15 seconds or longer.

Did you look at the tune I put in it? It shows pretty clearly that I didn't touch anything to do with idle. So why would I suddenly have this problem?

[joecar]

During the flash, did some other module talk on the serial bus or did some accessory use vehicle power...?

What state is the vehicle battery in...?

How are you powering your laptop...?

http://www.motownmuscle.com/forums/images/smilies/hmm.gif

[samh_08]

I made sure I had everything shut down as always. All doors shut, ect, ect.

Vehicle battery is good and the laptop was on 95% battery power. I have reflashed my own PCM dozens of times without any issues like this..?

Any ideas?

[samh_08]

Have you guys stumped?

[joecar]

Yes (me at least).

[samh_08]

It doesn't make any sense to me. That is the ONLY issue I am having with the settings I changed. I didnt touch any idle tables and everything else I have changed, the vehicle has responded.

There has to be a solution..I really dont know where to start so just start thinking out loud of what you would do in this situation..

[joecar]

Try this: full flash the stock/original tune back in.

[samh_08]

Ok. Would trying to do a full flash of my tune do the same? I thought you weren't supposed to do full flashes if you weren't changing OS's..?

[joecar]

I would try full flashing the stock tune, and see what your idles does...

Then cal-only flash you changed tune, and see what that does.

Typically, there's no point in doing a full flash if you're not changing the OS... but this is a special case.

[samh_08]

I just tried doing a full flash of the stock tune. It still does the same thing, but on a MUCH smaller scale and its barely noticeable. When I had the modded file in, it was pretty noticeable. I narrowed it down to having to do with turning the A/c on and off. I even tried putting the desired idle speeds at 1200 with the same result. Whats the deal...?

[joecar]

My guestimate is that something has physically changed with the TB/IACV by coincidence with when you flashed it (i.e. not necessarily caused by flashing).

[samh_08]

Its not throwing any codes..? What am I supposed to do about this? Im not just going to throw parts at it. Everything else is completely fine and normal. Is there something else I can change to try and remedy this situation?

[joecar]

You said the idle is different...

I take the problem still happens with the stock tune...?

Start with unplugging/inspecting the connectors to the IAC and TPS, and then remove the IAC and inpect/clean the pintle and passages...
might also clean the throttle blade;
see what happens...

do you have cable throttle or DBW throttle...?

[samh_08]

DBW throttle body. I just checked connections and all that good stuff. No issues what so ever. With the stock tune, I dont think the average joe would even realize there is a issue, but yes it still exists in the smallest sense.

When I flash my tune in the PCM, the truck responds to everything I've changed, but it does not want to idle consistently when its in gear, or the a/c is on. I've messed with all of the A/C idle tables with no luck. Is there a known issue in this OS or why am I having such odd problems with a stock truck that was fine before tuning?

[Highlander]

Get it reflashed from a tech 2.

[samh_08]

Get it reflashed from a tech 2.
Could you please elaborate? I know what a tech 2 is and all but I want to know why I should have to do that..

Thanks

[Highlander]

Because that will ensure you get the latest calibration and that everything get's put back in it's place. If your flashing back is not working at all I am sure this will fix it.

Go to the scanner... activate DVT and reset idle trims and all fuel trims.

[gmh308]

My cousin has a 2003 chevy silverado 6.0L that I just registered and read his PCM. I didn't change anything related to idle (or so I think) and now it idles way to low in gear and wants to stall. I tried bumping up all desired idle speeds 125rpm but the truck doesn't respond to the changes. It will idle fine for 10 seconds at the speed I want it to idle, then it will drop off and start acting funny.

Another issue I have is that I get 'Reduced engine power' every time I reflash the computer. I clear the code and then its fine..Never had a problem with that code before EfiLive. Any ideas?

I have the stock and modded (should show everything I changed) file attached. Please advise, Thanks.

Was it running/idling fine before you re-flashed?

[samh_08]

Running fine and had a very slight idle drop problem. The flash just really magnified it. I disabled the a/c spark torque tables and that helped, along with adding a bunch of a/c compensation airflow. I also just flashed my 2000 silverado with one a/c related problem from the flash. I get a whole bunch of spark retarded from the a/c and it is quite noticeable under acceleration.

Why is there 2 a/c related problems with stock trucks with none of the a/c tables changed from stock? Is it some underlying issue that happens when these trucks are flashed with EFIlive?

[geoff]

Check to see if you have a dirty throttle body. If you reflash the computer it will reset any idle adaptive learning that the PCM has done and if the throttle body is dirty it will idle like crap.

The solution is to thoroughly clean the throttle body and then start the truck and let it run for a couple of minutes in neutral AC Off, then in gear AC off and repeat both steps with the AC on.The first time you try to restart it after cleaning the throttle body it may be difficult at first, but should start with a little pedal after a couple of tries. After that it should start up just fine and idle and run fine.

I would also recommend putting all of the idle tables that you have adjusted to 'fix' the problem back to stock before doing this.....

[gmh308]

And possibly the fuel trims were having a large effect before the flash, and now they have been reset.