Koer Code 45

[bkimball]

I have a 1988 5.0L GT convertible, 5 speed, that is essentially stock except I recently replaced the stock air cleaner with a K&N unit.

I've noticed recently that the idle doesn't "stay put" and when I'm on the road WOT and let off of the gas the RPMs might drop to around 1500 and then eventually down to 800-1000 or so. It makes shifting a bit tricky and gets worse as the engine heats up. At idle when the A/C kicks in the RPMs go wild (down to 200, up to 1000, down, etc). The engine itself is running smoothly, not knocking or anything like that.

The last week or so I think the exhaust has gotten very rich as I have had trouble with backfiring when I goose the throttle. It seems to me that just changing the air cleaner can't do all of this, so I ran the KOEO and KOER tests to be sure.

KOEO came back code 11 (OK so far), but the KOER test came back code 45, indicating a thermactor/diverter/cable problem.

I'll be honest that I'm just a novice with just enough knowledge to be dangerous, but I know how to use a torque wrench and change the oil. I've read several of the threads in this forum to understand that the thermactor is really an exhaust/smog issue, not an air cleaner one.

The Mitchell manuals indicated that one possible problem (aside from the diverter) is the cable harness assembly next to the EGR valve going bad, but I really don't know how to tell for sure. I'll probably end up taking the 'stang in to the pros, but I would love to know what's really going on.

I do have some equipment, like a meter and a vacuum gage for another car, but I don't know where to connect the gage. I ran the cylinder test, came back code "9".

Thanks,

Brad

[PKRWUD]

There are 2 solenoids on or near your pasenger side strut tower. Both have vacuum lines going to them, as well as a 2 wire electrical connector. Inspect these vacuum hoses and make sure they aren't cracked or damaged. One has a round electrical connector, and the other has a rectangle shaped connector. Disconnect and plug the vacuum hose going to the solenoid with the rectangle shaped connector, and repeat the KOER test. Does code 45 come up again?

[bkimball]

I think I've located the solenoids, there are three of them. The one on top of the strut have red and green vac lines going to it and the other two are below it. They both have white/black vacuum lines and it looks like they go to a cable harness that has a line that connects to the EGR valve. Are the ones on the bottom the ones I want? I think so.

I attached a picture of the passenger strut area. Each solenoid has a vacuum line on the bottom, and one at the side. But I didn't notice a rectangular one (but it's hard to get my hands into that space).

Can I assume the black line is the vacuum source and the white line goes to the accessory that uses it?

[PKRWUD]

Okay, the lower two solenoids are the ones I was referring to. The one with a red wire and a lt. green/black wire is the important one for right now. Find the diverter valve that it's vacuum line goes to. It will be in the smog pump hose. Disconnect and plug this hose at the diverter valve. Repeat KOER test. If code 45 comes up again, the divertor valve needs to be replaced. If it does not come up, the problem is either in the solenoid (with the red & lt. green/black wires), or the vacuum hoses going to it.

Take care,
~Chris