Truck is becoming hard to start and idles rough. While idling the cab bounces up and down mildly.

I did some tests today and the findings are as follows:

At idle I am getting 13.8-13.9 volts at the batteries and 13.9 volts at the alternator measured with the voltmeter, with NO acessories on. These numbers drop to 13.2-13.3 and 13.4 respectively with all acessories on.

According to my SCT at idle with everything on I am getting 13.0. With acessories off it jumps to 13.7.

I tested the FICM and I am getting about 47.5 with key on and at idle.

I then pulled the ICP sensor and there is no noticeable change in sound or RPM at idle. Plug it back in and again no change. I tried this several times with negative results. The ICP was replaced a few years ago. When it went bad the first time the idle was jumping up and down and the truck would die. It is not currently experiencing those symptoms. Just a steady rough idle.

Any opinions?

Thank You

 

What is FICM LP ( logic power and VP vehicle power)? check when cold start first thing in the Morning, have you cleaned the MAP connection to Intake, also check the Map hose for splits.

 

I don't have the means to test LP. I will look into the MAP.

Oh and no DTC's according to SCT.

thanks

 

check FICM At KOEO Crank and Idle Cold

Also check it Hot under a WOT Condition

Alt Looks Good

Check ICPV--ICp--IPR%

Might be Stiction going on alittle too Have you change oil recently??

 

OK, you really need a way to Monitor the trucks Values and temps it's very Important, In the tech folders there's a volt meter test for the Ficm. I'll see if I can dig something up for Ya.

 

Here you go Bud.

 

Thanks but I tested the FICM and it was within spec.

 

I recently had voltage issues. Was seeing p1378 FICM supply voltage low. Was having rough starts, rough initial idle. Found that my driver side battery terminal had cracked. Actually it was split in two. A film of corrosion had built up and the alternator was unablevto properly charge the battery. Over a period of time the battery deteriorated to the point of hard starts/rough idle.

Check your lugs for damage, not only battery post contact but at the crimped end of the lugs, negative and positive. Maybe you have already done so. If you havent , it would be easy to do so. Load check the batteries next, individually, to ensure they are at their proper strength /CCA. Check ground straps for damage and good electrical connection. Hope you find the problem!

I needed to replace my positive cable. The whole shabang.

Eric

 

your only seeing one side of the FICM that's Main, you need to see VP and LP the solder joints break, also double check the 3 connections and pins they bend real easy. Benny had Mentioned ICPV ( volts ) the Pig tail will give some weird results stalling , bucking , high rpms, and wack volt values. you should get at least a Scan Gauge and enter the X gauges

 

any smoke?

 

A real small puff of whiteish smoke at start up.

 

Is the Torque app for Android capable of extracting the info I need or do I need something like a ScanGuage II?

 

I think so you may need the OBD connection, lets let the torx guys chime in

 

Torque app will display real time data and pull codes. It and my Edge showed that I had something wrong. Torque App on a tablet in the truck while you're running down the road looks cool...BTW!