84 T/A, carbed, 350 swap.

Ever since I had my carb rebuilt and got it installed, my CEL is showing a code 43. The car sat for 9 months (last October through July this year and wasn't throwing the code before).

I've tried a different known-good ESC module, different known-good knock sensor, and put a new pigtail on it just for good measure. If anything, the reading shows up almost immediatly now instead of after 4-5 min of driving (CEL light before would be off for 4-5 min of driving before throwing the code). Yes, the new knock sensor is for a 350, yes the ESC module is for a 350. Sould I swap back to a 305 sensor and module because the ECM would be looking for that (Doesn't seem smart enough to know the difference but...who knows)?

I work at sears and tried hooking up our OBD I reader to my car but I get nothing but "cannot connect to vehicle" readings from it. This is irritating because Alldata says to hook up a reader and look for the "knock signal" while trying various trouble shooting ideas.

I guess my last gasp is to try a different ECM. I've got one from a carbed 86firebird, would this swap ok or do I need one specifically from an 84?

Does anyone else know what could cause these knock problems or have any other ideas (outside of actual engine issues)? I need to get this fixed because I'm taking the car overseas (England) with me in February and it won't pass their inspection with the light on. I've managed to get everything else up to snuff but this...and it's driving me nuts! Any help would be greatly appreciated.

 

 

Do you know if an ECM out of an 86 carbed car will work in an 84 carbed car?

 

I don't know how strict the inspection laws are where you're at but,you can drive around the "hood" and find the crapiest looking inspection shop you can find. They might not care about the light being on

Theres some places in my town where you just pull up,show your insurance, and they slap the sticker on your car

 

Yeah, I know a couple places that pass my buddies 2002 WS6 with the LS7 motor in it. Only i'm going to England ijn February. I was going over their inspection criteria and it's ugly...makes California look easy. Which is why I need to get the dang light fixed. hehe

 

 

If they don't scan for codes unplug the bulb..

 

LOL I suppose that is always an option to get it to pass as it is the only code being thrown. Since as far as I can tell Code 43 really doesn't affect much else other than retarding the timing which only really hurts my gas mileage and power a bit. That does however...not "Fix" the problem. lol

 

magnetic pickup coil will trigger it

 

GM used the same ECM on many models.Check the serial numbers.If both ECMs have the same #s they will work.Just switch the proms.I think 87 was the last year for the "older" type ECM.

 

I cross referenced the years and they seemed to work...so I swapped them. No issues but still the same light so I swapped them back so I have the original now in the car.

 

Well, would it always be this simple! I went and was exending my harness this weekend so I could route my wires differently and get them off of the intake. One of the wires I moved was the knock sensor wire that previously ran along the top of the intake next to the plug wires, then over the wires and down the side of the block to the sensor. I am now running the wires up and over the AC dryer box and down into the fender so the knock sensor wire now drops down between the AC condensor and dryer box instead of going over the valve cover. No more code 43!! YAY no more staring at the damnable check engine light!

So, for the record, plug wires CAN induce a voltage that will be picked up by the knock sensor ECS module which will cause a code 43 to be thrown.

 

Sensative little bastard!Glad its resolved.