ok guys .. i just got this v10 f350 superduty 4x4 cclb

runs good but sometimes it runs rough on idle .. i think it starts loading up and then it sound weird..


i have a scanner and i can look at the live data but i dont know alot about live data..

when it starts acting up the fuel trims are all over the board..

i think they should be around close to the same rite?

the two worst ones are
lt ftrm2 is around -24.3 and st ftrm2 is around 32.8 ..

when its not doing it fuel trims are withen a few points of eachother

also when im on the throttle getting up to speed you can feel the truck surge.. like a slight power on off type thing



what do you guys think... ???


also i know these things dont get good milage but i only get about 8mpg empty around town .. going easy on it..

i was hopeing for around 10 .. i dont know if there related ..

 

I get about 8 around town too, have you cleaned the MAF, and how do the cop boots look? Miles on the plugs? ANy CEL lights? I know nothing about the data you are reading. What year is your truck would help too.

 

truck is a 99

plugs coils maf pvc egr fuel filter .. all new

cleaned the sensor that controls the egr i forget whats its called.. cleaned the idle air valve..

also cat has been removed..

im not sure of the condition of the o2 sensors but i dont know if that would do it ?

 

Here are some of the basics for live data (ballpark figures ) :

Fuel Trim (STFL and LTFL) : should be between -10 % and +10% ,

IDLE RPM : around 650-800 rpm

SPARK ADVANCE (Ignition Timing) : 15-25 degrees at idle, about 45 degree at high idle

O2 SENSORS : Voltage 0.1- to 0.9 Volt (ideally midway around0.450 Volt ),

When a sensor"s reading is out of range , that does not mean that it is not working right . It may be registering correct , but something else may be mulfunctioning .

You mentioned plugs changed , may be open up and check/clean throttle area . If that is already clean , get a fuel-pressure reading see if the fuel pump is acting . Run an injector cleaner , may be an injector acting up .

Good luck,

 

throttle body area is really dark and dirty..

fuel pressure is withen spec i already tested that..

so mabey ill run a few tanks of cleaner threw it and clean the throttle body

 

Vacuum leak? Maybe at the silly elbow on the front of the throttle body. Those fuel trims are crazy even for at warm up.

 

check the mass aiflow wiring rubber plug they fall off when replacing air filter and idle rough

 

We're you able to clear the rough idle?

I also noticed in my truck when throttling to about 1,500 RPM the engine oscillating (throttle head still).

I have the issue as we'll and have been trying to repair it with no luck thus far.

 

I had a similar issue with my 2000 SD last year. Tried the free scans at Autozone and with a snap-on scan tool at work. they showed many possibilities of what it could be. Took to Ford dealer, it was a formed vacuum hose on top of motor that was cracked (sorry i cant remember which one). Low cost part low cost labor, $85 though for scan. If not for the dealer scan, I would have chased the issue for a long time.

 

Thanks. I had a look at the vacuum lines and couldn't find anything. Looking for other suggestions. I have made the following repairs (not just for this issue):

Cleaned the MAF
Replace air filter
Replaced all plugs and coils
Replaced alternator
Replaced fuel pump
Checked vacuum

 

Check your pvc elbow. Just follow your pvc valve up a lot of times they rot from heat. Also I have the same issue I'm going to put a cat back on I was told it effects the whole system. I replaced all hoses. Iac tps cps mass flow all cops and plugs. And fuel pump I got the truck with the cat removed I just found one from a guy parting his out. He started it up ran great cut the cat off stumbled at start up and ran like crap. But def check that hose pcv runs into the throttle body. Get a replacement if needed autozone 12.99. My trims are good at startup then 30 sec later wacky like yours. I'll let you know if the cat solved my issue. When I get it on cold here so not enthused on being on the ground lol. But going to try Sunday

Also if you replaced the fuel pump. Did you change out the fuel filter too ?

 

Rock dog is your cat still on your truck or removed ?

 

Sounds like the same issue! My CAT was also cut off. Very curious if this fixes the issue. I did change the fuel filter as well and replaced the PVC and checked the line. All seems in good shape. I also just ran a tank of seafoam and a separate tank of Chevron (Techrolean) and just completed a 300 mile drive. Runs very we'll at 2k with no oscillation. But still runs like crap between 500 and 1,200. Please let me know what the result is. I was going to take it to the dealer but ran out of time before the trip.

 

Just dropped it off at the shop. Should know something by Friday.

 

Long term fuel trim does indicate a rich condition... but
the short term fuel trim is trying to do the opposite.
Did you do any work on it ? What does bank 1 report ?
ltftm should be around 0 (plus or minus 5) and stftrm should constantly be switching from plus to minus.