Erratic idle after highway driving

[smokenblack]

2005 F-350 6.0 105K. Truck starts fine every time, idles and drives normal. Only after holding highway speeds for more than 15 minutes and coming to a stop the engine begins to lope erratically and intermittently. Hit the go pedal and moves right along only with an occasional surge in power. Only current code is for glowplug on a single cylinder. Cleaned EGR valve, changed oil and both fuel filters, air filter is clean, removed programmer and returned to stock tuning and nothing changes. Any ideas?

[Mhatlen]

Nice driver front tire thingy there,lol You have a scan tool to check ficm/icp/ipr when its doing it?

[smokenblack]

Originally Posted by Mhatlen

Nice driver front tire thingy there,lol You have a scan tool to check ficm/icp/ipr when its doing it?

Thanks, I enjoy her daily.
Yes..what should my baseline readings be and/or what am I looking for?

[Mhatlen]

Ficm should be 48 volts +or_ at all times and all speeds.

The ICP should be around 580 at idle and IPR around 21%

You can take the values of icp/ipr:

koeo
idle
1500
2500

All need to be taken at 190* +or_

Post those and will look up where they are ideal.

Also if you can see egr desired and egr position you can rule that out.

It may be a injector causing you the grief ??

[smokenblack]

Will post data as soon as I can. Truck hasn't missed a beat the last 2 days with the scanner hooked up in record mode!

[smokenblack]

Is it normal for my EGR position voltage to always be 0.00V? This value never changes, always 0 at idle, acceleration and cruise. All other values shown above right on the money.

[Mhatlen]

No the egr is controlled via map sensor and pcm adjusts as necc, you may check wiring harness to both. It should be throwing a cel either way.
Do you have a custom flash for your pcm where it was rolled back and egr is deleted as far as pcm goes?? PHP I believe does this with his tunes.

You can always probe your egr plug it uses 5 volts max in operation IIRC.

[smokenblack]

I returned the PCM to stock programming to see if the tune was the cause of the erratic idle. I never looked at the egr position voltage with the tune installed. No CEL with stock or custom tune. Could the EGR valve be bad or not moving causing the position voltage to always be 0?

[Mhatlen]

Can you track both: actual position and desired for egr with your scan tool?
It would be worth the time to pull it and see if its coked up, also take close look at the o-rings if they are leaking.

Do you have a way to check fuel pressure? have you put in blue spring for fuel pressure regulator

[smokenblack]

No way to check fuel pressure and and I have not done the blue spring installation. I will check and see if I can view position and desired together.