greasemykey Posted January 14, 2012 Report Share Posted January 14, 2012 i have a 03 cadillac escalade esv. the reason im posting here is the cadillac forum was not much help and since this is almost the same vehicle i thought i would ask you guys. i just got home from a deployment and started up the truck and while trying to merge onto the highway the truck seems to lose power past 3K CEL starts flashing. so i limp her home and hook up my scanner. i get bank 1 rich, bank 1 cat below threshold and multiple cylinder misfire. i checked the fuel pressure after i changed the filter and at idle i have 45 psi and if i give her any throttle it drops to 40psi. but why the cat code and the rich code? is my cat bad or the fuel pump or both? Quote Link to comment Share on other sites More sharing options...
2001silverado364 Posted January 15, 2012 Report Share Posted January 15, 2012 (edited) I'd start by replacing the driver side o2 sensor. Front one, NOT back. It's throwing a code for the back as well because of the difference between the two sensors not being in spec. I had the exact same problems when I crossed some wires wiring up an afr gauge once.But first to make sure it's the o2 sensor just get under there and unplug the two front ones and take it for a spin. BTW, what's happening is the o2 is stuck rich and telling the computer to lean out to the point it starts misfiring. Edited January 15, 2012 by Mr. 3/4 ton SS (see edit history) Quote Link to comment Share on other sites More sharing options...
greasemykey Posted January 15, 2012 Author Report Share Posted January 15, 2012 I had heard something like that before but i could not find any posts anywhere. im going to go try that now and see what happens. wish me luck Quote Link to comment Share on other sites More sharing options...
2001silverado364 Posted January 15, 2012 Report Share Posted January 15, 2012 Alright. Quote Link to comment Share on other sites More sharing options...
greasemykey Posted January 15, 2012 Author Report Share Posted January 15, 2012 ran WAY worse. couldnt even get it to shift to 2nd Quote Link to comment Share on other sites More sharing options...
2001silverado364 Posted January 15, 2012 Report Share Posted January 15, 2012 With the front o2's disconnected it should have went into open loop, and ran fine, maybe slightly rich. The next step I would do is to switch the sensors from left to right and vice versa, clear the codes, and see if the code stays with the o2 or the left bank. If it ran WAY worse without the o2's it could be the maf sensor(dirty) as well. Quote Link to comment Share on other sites More sharing options...
greasemykey Posted January 15, 2012 Author Report Share Posted January 15, 2012 With the front o2's disconnected it should have went into open loop, and ran fine, maybe slightly rich. The next step I would do is to switch the sensors from left to right and vice versa, clear the codes, and see if the code stays with the o2 or the left bank. If it ran WAY worse without the o2's it could be the maf sensor(dirty) as well. going to try and clean that in the morning. the truck does have 106K on it. but what about the fuel pressure. it does seem kind of low does it not? Quote Link to comment Share on other sites More sharing options...
2001silverado364 Posted January 15, 2012 Report Share Posted January 15, 2012 (edited) If it was the fuel pressure, it would throw a lean code(pos. fuel trims), thus having to add more fuel. A rich code means negative fuel trims, meaning it's having to take away fuel, because something(o2 sensor) is telling it it's too rich. But yeah, I agree 40 psi is on the low side, should be about 55-60. But..., you have an 03 and that means return style fuel system, so did you unhook the vacuum line off the regulator when you tested to get full pressure? Edited January 15, 2012 by Mr. 3/4 ton SS (see edit history) Quote Link to comment Share on other sites More sharing options...
greasemykey Posted January 15, 2012 Author Report Share Posted January 15, 2012 no i did not. well im glad i dont have to buy a fuel pump now that should save me a buck or two. but now i have to figure out where the issue is. bank 1 is on the passenger side right? Quote Link to comment Share on other sites More sharing options...
2001silverado364 Posted January 15, 2012 Report Share Posted January 15, 2012 No, driver's side. engine cylinders 1357. Quote Link to comment Share on other sites More sharing options...
greasemykey Posted January 15, 2012 Author Report Share Posted January 15, 2012 so should i just try leaving the drivers side unplugged? Quote Link to comment Share on other sites More sharing options...
2001silverado364 Posted January 15, 2012 Report Share Posted January 15, 2012 (edited) Well you could, but if you had both disconnected earlier(and it still ran bad), I don't see any reason to. Just make sure you actually had the front(before the cats) o2 sensors unplugged and not the rear. Did you check to see if your fuel pressure stayed up for a while after the vehicle is turned off or did it immediately go back to 0? Edited January 15, 2012 by Mr. 3/4 ton SS (see edit history) Quote Link to comment Share on other sites More sharing options...
greasemykey Posted January 15, 2012 Author Report Share Posted January 15, 2012 Well you could, but if you had both disconnected earlier(and it still ran bad), I don't see any reason to. Just make sure you actually had the front(before the cats) o2 sensors unplugged and not the rear. Did you check to see if your fuel pressure stayed up for a while after the vehicle is turned off or did it immediately go back to 0? i did and it stayed up Quote Link to comment Share on other sites More sharing options...
zippy Posted January 15, 2012 Report Share Posted January 15, 2012 Sounds to me like the driver side cat is plugged. I would recomend pulling the head pipes down and checking both. Quote Link to comment Share on other sites More sharing options...
greasemykey Posted January 15, 2012 Author Report Share Posted January 15, 2012 Sounds to me like the driver side cat is plugged. I would recomend pulling the head pipes down and checking both. im guessing that may explain the rattling sound i am hearing when i try and accelerate. Quote Link to comment Share on other sites More sharing options...
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