Manager Forum

Hello everybody.....Hope the New year is treating everyone fair..

Got a Gremlin Durango..
2004 Dodge Durango 4x4..5.7 liter,, 56k Customer blew up engine last year. Had a shop install a reman engine,but had a mild cam installed...Codes P0172 and P0175 popped up.
They told him he needed a cold air intake system and throttle body spacer.. He had that installed.. Codes came back..
He brought truck to our shop for diagnosis.. Found o2 sensors acting up and very rapped switching,,,,Replaced All four O 2 sensors.. Cleared codes...Light popped back on a few days later.. Suggested replacing Catys since maybe they got damaged when engine blew... Installed OEM style Walker Catys....Road tested vehicle and light popped back on ...Same codes...But O2 sensors switching in cycle ok, staying steady .....??????????
Possible cause of repeating codes???????

Stumped; what am i missing or is cam the issue? Other shop who did cam install claims they have done plenty of these cam swaps with no issues?????

You will need to look at the freeze frame records and see when the code set, was it at idle, cruise, or under a load. Could be a vacuum leak, low fuel pressure, or any one of a number of non related to engine replacement issues. I would be interested in fuel trims under various conditions. That is the most important PID to be looking at for a lean code.

Those are rich codes, and an incorrect cam CAN cause this. Check idle vacuum. Needs to be at least 13. What's the fuel pressure? Check the MAP sensor for accuracy too. I had a Hyundai once that had rich codes that turned out to be a partially stuck open purge valve.

If you check all the outside influences and come up with nill, then suspect the cam.

ricmorin wrote:Those are rich codes, and an incorrect cam CAN cause this. Check idle vacuum. Needs to be at least 13. What's the fuel pressure? Check the MAP sensor for accuracy too. I had a Hyundai once that had rich codes that turned out to be a partially stuck open purge valve.

If you check all the outside influences and come up with nill, then suspect the cam.

Hahaha, when I read the post the first time I swear I saw 171,174 not 172,175. Big time ooopps on me!!!

ricmorin wrote:Those are rich codes, and an incorrect cam CAN cause this.
If you check all the outside influences and come up with nill, then suspect the cam.

I definitely agree with this after tinkering with performance cams. Assuming that all the inputs of the sensors are within specs, the cam is at fault. Now, having said that, there is some engines for which a performance computer may be available or a performance chip, or perhaps its as simple as reflashing the PCM with performance software. Here's the thing. Anytime a performance camshaft is installed, the airflow and the air to fuel ratio through the engine is usually altered and the PCM picks up on this. Beings the PCM is at stock settings, it flags codes, hence the need for performance PCM or software.

When I worked for Dodge a customer built a 5.9 for a Dakota using all factory performance parts (cam, injectors, heads,pistons). After several months of messing with it he sent the ecm out for an upgrade to handle the mods. The stock ecm didnt play nice.