Mystery CE light

[1slow95]

I have a weird problem with my car now. Last summer I unplugged the O2 sensors and ran it that way for a while. This of course caused the CE light to come on. I eventually decided it ran better with the O2's so I replaced them. The CE light still comes on. I pulled the codes:
511 - ROM failure (SCT chip installed)
327 - EGR
565 - Canister Purge Solenoid

I've had all 3 of those codes since I installed the new engine and never had a CE light. I unplugged the battery for about 3 days, but that didn't help.

The car is running kind of rough and the idle is messed up. It has a surging idle now when it was just about rock solid last year. It also feels like it loses power while driving or something. It's like I'll be cruising at 55-60mph and it's going along fine, then it feels like it bogs down for a second. It doesn't really feel like a miss, just like it lost some power for a second. It still seems to run fine at WOT.

 

[Chythar]

I wonder if your vacuum lines to the EGR and CANP are cracked or not hooked up. These are the solid plastic colored lines running from the EGR, intake and smog equipment into the passenger fender.

If you unplug the EGR connector vacuum hose, does your engine run better? The EGR should only be functioning at part throttle, but if vacuum isn't consistent it may open at the wrong times.

 

[1slow95]

EGR and Canister Purge are both deleted, hence the codes for them. But it's been that way for a couple years and never gave me a CE light.

 

[Chythar]

Codes don't always cause a CE light, it depends on the severity of the code. I presume the chip is tuned to remove the EGR, though I presume not because you have a code for it. Is it possible the chip shifted in the socket, and you're back to the stock tune? Could the chip have failed?

 

[HISSIN50]

How long has it been since the KAM was cleared?

Though the EGR and purge solenoid should be turned off, you could add resistors to the signal wiring to give a baseline reading and shut the CEL off. Something close to a 3 watt, 80 ohm resistor should work for both.

Note that I haven't done this personally.

Good luck Mike.

 

[1slow95]

How do you clear the KAM? I left the battery unhooked for a couple days after the O2 sensors didn't make the CEL go off. That was about a month ago.

I tried turning the chip off and pulling the codes, which gave me the same thing minus the ROM failure. I didn't try driving it that way though.

I told the tuner to turn off the EGR when he tuned the car, but I'm thinking he forgot to do that since I get a code for it. I have the EGR still plugged in and it's rigged so the plunger is halfway down. I did that about 2 years ago and it cleared the CEL I was getting, but it still listed the error code. Maybe it just needs readjusted or a resistor put in place?

Or is it possible for a code to only show up while the engine's running? It doesn't come on until the engine has been running for 3 or 4 minutes.

 

[HISSIN50]

You can spit a code while the engine is running (only). If it's not critical, the EEC shuts off that function or ignores it (a CANP code would something unimportant like that).

Disco'ing the battery should have cleared the KAM (discharged the cap's in the EEC so it forgot all the stored codes and adaptive strategies).

I like your idea to check the position sensor's plunger position (voltage).

 

[1slow95]

I just ran a KOER test and got some new codes.
311 - AIR not operational bank 1
314 - AIR not operational bank 2
412 - Cannot control RPM during KOER self-test high RPM check

I have a Fox IAC which could be the reason for the 412 code. I thought I saw a code 211(PIP failure), but I must have missed the first flash of the CEL. I ran the test a second time and came up with 311 instead of 211.

Could a slipping belt cause the car to run a little rough? I swapped back to the original alternator pulley and I couldn't find the right belt size so it's a little bit loose.