cliffyk

Both of those codes are for the rear sensor on the driver's side (HEGO-22)--is that the one that is not connected? You can look then up and see possible causes, etc here.

Also as others have said the rear sensors have nothing to do with engine management, they only monitor the catalytic converter efficiency--and since you do not have those you will need MIL Eliminators of have the rear sensors (and the heater monitors) disabled in the tune.

Did you buy the car in a private sale or from a dealer? It is illegal for anyone to sell a vehicle that does not meet Federal emission standards, without notifying the buyer in writing. However in a private sales that really doesn't mean anything. If you bought from a dealer and did not receive such a notice bring it back and make them fix it or refund ALL money you paid.

Any flack call your state's Attorney General/environmental protections offices--they love that kind of stuff...

turp23

I fixed the O2 sensor with a new one, and a longer wire. Erased the codes. Now I am getting P0300 and P1504. It misses pretty bad under acceleration. What now? I have a 26 mile ride to work tonight, should I take it to see if it will kick a more specific code?

jojobanks

the p0300 is a random missfire.

the p1504 is an intake air circuit malfunction

the p0300 could be caused by the 1504. Still, the first thing I do when I get a p0300 is change the fuel filter. It's inexpesive and really easy to do.

To me... it kinda looks like the PO had a tuner on his car and when you bought it, he took it off before you returned to pick up the car.

I wouldn't drive the car any more than you have to until you get this issue figured out. You could end up causing more damage especially if you're getting detonation right now. I would take the car to a reputable shop and have them take a look at it. That way you have documented evidence of the issues in case this ends up being a court issue.

JRad405

This link suggests checking wires or plugs for your p0300 issue. It's typically what you would do for a misfire anyway.

http://www.moddedmustangs.com/forums...263-p0300.html

P1504 - intake air control circuit. Check your IAC valve. it may be worn out or dirty and needs to be replaced or you could try cleaning it first.

turp23

I fixed it. The car finally threw a misfire on cyl 8 code. The spark plug was a chalky orange on the outside below the coil boot. So I replaced 5 of 8 plugs and the coil on cyl 8. FWIW, whoever uses the search function in the future and finds this thread useful, AZ Accel replacement coil is garbage. The boot doesn't fit flush to the surface, leaving the spark plug tube open and I dont like it. Plus, there is no bolt hole to bolt it down. I am not happy about that. But all of the coils had some furry orange stuff on the springs, which I assume is D grease. I cleaned them off, and regreased them.

Why only 5 of 8 plugs? Becaus the PO rounded of 3 of the coil bolts. Fun! But It did run good again. Until the next day. Then I replaced the other 3. And it ran good again. Until the next day, when it rained. The hood scoop is leaking, so I think that has something to do with it. There are three holes drilled through the hood under the scoop. For what, I have no clue. I guess I have to do it all over again, and again. Until I plug the holes under the scoop. Could rain water and hose water cause this much trouble?

turp23

Correction- There are 5 holes behind the black grill in my hood scoop. The rain water poors onto my engine when I open the hood through these holes.

turp23

Geez, the more I dig the more I find. It must be a hood from another car. It has vents under the scoop for it to be functional. Someone also drilled out every hole in the honeycomb insert. Water everywhere on top of my intake. I just cant win, but I aint giving up.

stevednmc

Plug those Holes! Get RID of those coilpacks! Especially if those coilpacks dont bolt down, rainwater can get into the sparkplug bore and kill that spark. I kinda wonder if the orange fuzzies you are seeing isnt rust tbh. Go to the hardware store and buy some rubber plugs to fit in the holes stupidly drilled into your hood. Whover did that shuld be smacked! If they wanted a functional hood scoop the shoulda intalled a shaker system!! You can buy a replacement honeycomb insert from late model resto or a junkyard or CJ pony parts i think. Easy to remove and replace. But yeah...that is a good bet thats causing your issue.