Could Use Some Help/advice

[Kegomatix]

You guys are my last hope, I can't seem to find any answers across the forums.

I have an 89 LX 5-spd. When I get in and start it up and drive off it drives amazingly. About 10 minutes in it's like a switch flips and it starts running like crap. Smells rich, starts bucking real bad trying to maintain a constant speed, backfires at WOT, and occasionally surges at idle.

Today I tried something new, and shut it off while waiting at a light, then started it back up. It ran perfectly again, it's like it resets something in the computer. Eventually, the problem will start back up.

Also, the check engine light comes on when the problem starts. I've ran the codes and all I got was 85, which is understandable because the charcoal canister has been removed.

Any ideas? I can't figure this out and it's driving me crazy here because when it runs right it runs soo damn good and I would like it to be that way all the time haha.

 

[jrichker]

What did you get for engine running codes? Are you sure that the vacuum line on the bottom of the upper intake manifold was capped when the carbon canister was removed?

Code 85 - CANP solenoid - The Carbon Canister solenoid is inoperative or missing. Check vacuum lines for leaks and cracks. Check electrical wiring for loose connections, damaged wiring and insulation. Check solenoid valve operation by grounding the gray/yellow wire to the solenoid and blowing through it.
The computer provides the ground for the solenoid. The red wire to the solenoid is always energized any time the ignition switch is in the run position.

Charcoal canister plumbing - one 3/8" tube from the bottom of the upper manifold to the rubber hose. Rubber hose connects to one side of the canister solenoid valve. Other side of the solenoid valve connects to one side of the canister. The other side of the canister connects to a rubber hose that connects to a line that goes all the way back to the gas tank. There is an electrical connector coming from the passenger side injector harness near #1 injector that plugs into the canister solenoid valve. It's purpose is to vent the gas tank. The solenoid valve opens at cruse to provide some extra fuel. The canister is normally mounted on the passenger side frame rail near the smog pump pulley.

It does not weigh but a pound or so and helps richen up the cruse mixture. It draws no HP & keeps the car from smelling like gasoline in a closed garage. So with all these good things and no bad ones, why not hook it up & use it?


The purge valve solenoid connector is a dangling wire that is near the ECT sensor and oil filler on the passenger side rocker cover. The actual solenoid valve is down next to the carbon canister. There is about 12"-16" of wire that runs parallel to the canister vent hose that comes off the bottom side of the upper intake manifold. That hose connects one port of the solenoid valve; the other port connects to the carbon canister.

The purge valve solenoid should be available at your local auto parts store.

Purge valve solenoid:

The carbon canister is normally mounted on the passenger side frame rail near the smog pump pulley.
Carbon Canister:

 

[MFE92]

I have the same problem, and I've been through the whole damn car with a breakout box and can't find a thing wrong with it. The reason it "flips a switch" is that's the point where it goes closed-loop, using all its sensors to trim the fuel and timing delivery. My solution, much as it pains me, was to unplug the O2's. It runs like a champ at all times and even passed emissions. One of these days I'll throw a new ACT sensor in it because I've seen them work black magic before, even though mine was technically "in range" when I tested it. You can see my thread here and the things I checked and the suggestions others made, maybe there's something in there that can help you. http://www.stangnet.com/mustang-for...s-eec-iv-diagnostic-help.853435/#post-8585611

 

[Kegomatix]

The engine running codes just came up with 85. The light only comes on when it starts running rough, but will turn off as soon as I shut the car off. I'm wondering if it is a different code than 85 when it does come up. I need to go over everything tomorrow to make sure the charcoal canister was removed "properly."

MFE92, I'm going to give that a shot, thanks for the tip. Emissions aren't required for that old where I'm at.

 

[Kegomatix]

Bookmarked that thread, going over that thoroughly tomorrow. Your problem is about the exact same as mine. When I was under my car last time I caught a glimpse at my 02 sensors. They looked newer, and if I were to take a guess I'd say they looked Bosch.

 

[Kegomatix]

Couldn't help myself, went out and disconnected them and it ran like a dream. Amazing, I forgot what it was like to run so well. It didn't give me a CEL, either.

 

[FastDriver]

damn... Even though I don't run an EEC anymore, I'd really like to know what the hell is going on there. I would've guessed the fuel pump was cavitating at high temps, or the TFI module was getting hot and acting up, but unplugging O2s wouldn't fix those problems. Seems like the next logical progression would be to replace them and see what happens, but if that doesn't work, then my guess would be the wiring has shorted or the computer box itself is bad. Anyway, I'm subscribing...

 

[Kegomatix]

Yea, I'm still confused. I would really like to get to the bottom of this haha.

 

[ACSPONY]

The O2 sensors provide a closed loop feedback system right? Taking them out runs an open loop? What changes does the EEC make when the O2s are out of the equation?

 

[Kegomatix]

Well, problem solved. I went over everything with a fine toothed comb and found a portion of the wiring harness on the passenger side that leads down to the o2 sensor to be completely melted and messed up. I removed that entire section, re-wired and extended it so I could bypass the header completely. It corrected the violent bucking, and the terrible performance at WOT and running rich.

I still have the surging idle, so that is a separate issue. I'll probably start looking into that next weekend, it is very occasional and doesn't really bug me right now. Aside from that all I need to do is fix a header gasket leak. I ordered the copper performance gaskets and ARP locking bolts so that should do the trick. Pretty good day, glad my car is running normal again.. (knock on wood)

 

[stykthyn]

Good to hear. Glad you got that ironed out.

 

[2000xp8]

Well, problem solved. I went over everything with a fine toothed comb and found a portion of the wiring harness on the passenger side that leads down to the o2 sensor to be completely melted and messed up. I removed that entire section, re-wired and extended it so I could bypass the header completely. It corrected the violent bucking, and the terrible performance at WOT and running rich.

I still have the surging idle, so that is a separate issue. I'll probably start looking into that next weekend, it is very occasional and doesn't really bug me right now. Aside from that all I need to do is fix a header gasket leak. I ordered the copper performance gaskets and ARP locking bolts so that should do the trick. Pretty good day, glad my car is running normal again.. (knock on wood)

Don't be surprised if the surging idle is the leaking manifod gasket.
This has happened to me.

 

[FastDriver]

Wow, cool. Thought it might be a wiring short. Easy/cheap fix. Good work!

 

[Kegomatix]

Thanks, it was because you said that that I decided to dig around more and check all the wiring, so thanks!

 

[Kegomatix]

Can't wait to get my new gaskets on.. Would you guys recommend using the copper high temp spray to help seal it? I keep blowing the felpro gaskets.

 

[MFE92]

Where exactly was the wiring burned through? Any way to get a pic?

 

[Kegomatix]

This picture is the general location of where it plugs in (underneath the MAF).

This is where it plugs in, you can kind of see where it goes down, now in front of the engine rather than through the header. It runs from there, to about the bottom of the block and top of the oil pan where it splits into two directions, one toward the o2 sensor, and the other goes toward the front of the engine.

It used to just run directly through the header on that side, so most of it was either crispy and falling apart or just melted.
Sorry I couldn't get better pictures or any from underneath, storms rolling in.

 

[MFE92]

That's helpful, thanks. I'll have to have another dive into the wires.

 

[FastDriver]

Sweet, man. That makes me feel good. I've been sporadic in getting on the forums lately. So, it's nice to hear that I'm still helpful. I appreciate the feedback!