Just wanted to drop a quick update. I dropped my truck off this weekend and the service department called me this morning and said I was correct...the cats are plugged up big-time. They are replacing them under a factory recall. Good thing they were under recall. They also told me that the codes also show some misfires and the plugs are original and could've contributed to the problem. They quoted me $369.00 to replace the spark plugs, so I gave them the go ahead. Everything I had read up to this point lead me to believe that the cats were no good. I had hardly any power in the truck. I am anxious to drive it with new cats on and see what I had been missing. I wonder how long they had been going bad.

 

Bringing this thread back. Still having problems. Since my original post I have replaced spark plugs (again), replaced all ignition coils and boots, replaced the throttle body, repaired a leaky coolant hose that was leaking onto the right bank ignition coils, replaced the restrictive y pipe with a collector-style y pipe, tested cats, installed a flowmaster big block muffler, and replaced the PCV valve. All the work except for the exhaust done at the dealer. Note, throttle body was covered in sludge on the engine side of the plates.

After the coils, throttle body, and coolant leak repair, I got the van back and it ran like brand new. So much power, fuel mileage was restored, happy guy. took a 700 mi. trip towing 7-8k, the drive to my destination was trouble free, pulled grades with ease, plenty of power on tap, even got 9mpg with a 24ft enclosed in tow.

The drive home was miserable. had to keep it up around 3k rpm to keep speed on the highway (hwy5 central CA). I didn't calculate gas mileage, but it was 350 miles, I went through almost 60 gallons, two full tanks just about. Seemed plugged up or choked up. Checked air filter-good. Downshifts even on the slightest grades... Took it back to the dealer. No codes, everything is normal. Drove it today, got the same intermittent miss at idle and up to about 1500 rpm. When driving at speed and rpm got below 1500, the miss became very violent. This went on for about 3 miles, until I decided to give it full throttle, and it was fine after that.

This is so annoying.

 

Have the O2 sensors been replaced?

I had cats replaced under factory recall on a Mustang. Ran great for a while then ran like a broken legged dog. Missing, huge loss of power, terrible gas mileage. NO codes. I drove it with the O2s unplugged and it ran great except for lousy gas mileage.

Replaced the O2 sensors and fixed everything. Turns out, the dealer does not replace O2 sensors under the recall but they are just as contaminated as the cats. The newer model computers should be reporting a code. jim

 

No, they haven't been replaced. My problem is intermittent, so I would think bad o2 sensors or cats would be more of a consistent problem... Any thoughts?

Had the miss occur today again, only for aabout 10 seconds in a parking lot. This is really driving me nuts!

 

what is a vehicle health download ?