hi, guys i have a ford f250 with a 5.4l 2v engine and lately it started to shake when it idles. i have changed all the ignition coils and spark plugs, the injector are fine, but i cant seem to pinpoint the problem. the weird thing is that there are no codes. the fuel trim on bank 1 is around -8 and bank 2 is at almost positive 20 and higher. does anyone have any suggestions? thanks

 

My 5.4 2006 truck had similar issues with the fuel trims out of whack. It turned out to be the passemger cat was broken and plugged up. After changing the cats with high flow units the truck ran great. Just a suggestion. Put a pressure gauge in the O2 sensor 1 location if possible and take a reading while running. The pressure should be around 2psi or so for a good flowing sytem. Any higher indicates a restricted exhaust. Terry

 

Check, clean or replace IAC as needed.

 

Vacuum leak, oxygen sensor, cat problem, base mechanical problem.

Check for vacuum leaks by listening for them, or spraying some brake cleaner at the base of the intake. Pressure sensor for the cats, scanner with data ability would be helpful. Compression test too.

 

If it's shaking it could be a bad fuel injector clip that attaches to the fuel injectors. The electrical clips that attach to the fuel injectors as well as the coil on plug connectors get brittle and break.

I had the same issue. It was a bad fuel injector connector.

Rent or borrow a noid light test kit. Unplug one by one and use the noid light to see if it lights up. You can rent a kit at autozone or orielly.

Good luck!

 

If your bank 2 fuel trims are that high I'd look for a vacuum leak. That would also show itself most when idling and disappear under load.

 

thanks for all the suggestions, i will give it a shot this week, but i did want to point out that the exhaust seems to have a rattle in it at idle. i have never herd this type of noise since i have had the truck.

 

I also think that vacuum is the place to start. The 2v 5.4 is an older version and a cracked pcv tee is so often the issue.

 

Go underneath and give the cats a little pound with your fist or a rubber mallett. See if the rattle is inside them.

 

Agreed my guess it the rattle is from the Cat...

 

ok so i am here to report my findings. i have not found a solution yet but so far i have check exhaust back pressure which is good, not clogged, i also checked for vacuum leaks by spraying brake cleaner around the intake and i used smoke to see if there were any leaks. i could not find anything. the only thing i saw was that there was smoke coming out of the iac tube that connects to the intake hose before the throttle body. is that normal? the truck still hasn't given me any codes and its getting really bad gas mileage.

 

No, that isn't normal.

 

as soon as i put the smoke through the brake booster line it came only out of that iac hose. as soon as i disconnect that hose the truck just dies. it wont even start up if that hose is not connected. can it be a problem with the iac valve itself?

 

Yes, IAC issues are not uncommon.

 

thank you for the info, i will go ahead and take off the iac and have a look at it this week. thanks.