Ok so here is my problem. Last August, I had a dead cylinder, so I replaced the coil... problem solved. So, fast forward to 4 days ago, I was headed to school and noticed a slight power reduction on the highway. So, I figured it was one of the ofther coils going out, which it wasnt. Codes came up as catalytic converter and MAF sensor. I cut out the cat and replaced it with straight pipe. So, now when I let the car sit over night, it starts right up, runs good for about 10 min, then runs like it has a heavy load on it and dies 3 seconds later. I then have to wait another 10 to 15 min before it will start again... run for 5 min and die... so I checked, I have fuel pressure, I was going to change the plugs out (they need it anyway) but was told it could be something completely un related. I have been told to change out the 02 sensor. I think I am supposed to have a up stream and a down stream, but there is only a down stream on my car. Any ideas? Any help would be muuuchhh appreciated! Kristina would like to run again!

specs:
V6 3.8l 5 spd
105,000 mi

 

I would lean more toward MAF, especially since you getting the code

 

also without the cat your throwing an o2 code possibly making your car go into limp home mode

 

Your car won't run too well with just a downstream sensor, you need to look closer. There is a possibility that your exhast is clogged, check for kinks in the pipes and a clogged up muffler, especially if the cat internals disintegrated and got blown into the muffler.

 

Get an 02 simulator past the cat and check the maf.

 

Yup, sounds like the maf!

 

You should have 3 O2 sensors on your car. The upstream are attached to the exhaust manifolds and there is one on each side. The Downstream is just behind where the cat used to be. Near the trans mount.

IT sounds to me that your car is not liking going into closed loop mode. Could be bad or missing O2 sensors or the MAF is bad. Get that all checked out.

Massey

 

its running good then running like crap cuz its prolly in open loop and when it goes into closed it runs like poop. closed loop needs to read the two O2 sensors and they should read different becusae of the O2 sensors. you NEED that cat for it to run efficiently, so get a new one and put it on. catalytic converters BARELY effect high performance at all. deleteing your cats for more power is something a honda kid would do... not saying thats why u did it, just saying