After taking out the O2 sensors thanks to some tips from posters, i replaced the cat and truck runs great!!! thanks...would have never suspected a cat could effect it that much. wow!!!



1998 Dodge 1500, 2wd, 5.2ltr efi, 120.000miles, super clean truck.starts and revs no more than 1500rpm, ran codes and nothing. here is a list of things i have done regardless of no codes on Mac tools OBDII scanner. Originaly ran fine and just started lossing speed an dpower till only idle power was left!!!

1. New Throttle sensor
2. New plugs
3. New pick-up in distributor
4. New cap and rotor
5. Replaced PCM
6. New coil
7. tested fuel pressure-50ps key oni-52ish running. So i assume not the fuel filter?

All that made no difference???, was told cat, but would it not rev up in park even if it was plugged? idles not bad most of time. in the morning cold sometimes reves up to 2000rpm, if it missfires a bit, i hold down the trottle and huge gushing air noise from the TB until is settles and idles again, then push the fuel pedal and past 1500rpm just sounds like 4 barrels opening and then slowely dies to a stop. CRANK sensor??? but would it not run at all if it was that or pull a code? MAP sensor?, would it cause this that bad?

 

with everything you've tried it wouldn't hurt to cut the cat off with a sawzall. if it turns out to not be that then you can go to the parts store and get a female to female connector and a couple clamps and put the pipe back together. a plugged cat will only let it rev to a certain point depending on how plugged it is.

 

If it does turn out to be the cat check out your muffler while your at it. I had a 95 s10 once that the cat went out in and it would do the same thing idle fine but when you gave it the throttle it would slowly die and when it went it sent some of the catalist into the muffler stopping it up.

 

clogged cat will prevent rev-up irregardless of transmission gear. another quick test is to remove the front 02 sensor to see if it revs any better.

 

My Ram once did a similar thing and that was the oxygen sensor..check that

 

I had the same problem in an old Chevy Caprice I used to own. I disconnected the muffler just after the cat, jammed a big screwdriver into the cat, and then jammed my tire iron into the cat and wallowed out a bit hole right down the center. Then I cranked the car and blew a big cloud of soot out into the driveway. It ran great, so I hooked up the muffler and kept on driving. Of course, I wasn't worried about getting it to pass an emissions test.

 

FIXED!!!!!!! Was the cat!!!!

 

They are called motor chokers for a reason!