I'm about to finish up my odds-n-ends with my engine today but when i checked the ecm for a code it set the other day, it came up 43, which is supposedly electronic spark timing or control circuit problems... what do i need to do to troubleshoot this? the ecm itself is already suspected bad for a couple of other things that do not pop codes, but before i replace it, i need to know if there are any other related components that can effect this code 43, such as the ignition module, etc. thanks.

KAM

 

"Code 43 in aisle twelve - Code 43 in aisle twelve!"

Awright, what did you do?

You might want to check the connections at the HEI module, since the EST relies on its signal and feedback.

You could also check the connection to the detonation sensor. If you suspect a sensor, you can dummy it out with a resistor for testing purposes. Early cars would require a 3,900 ohm resistor, and later cars would require a 100K ohm resistor to "fool" the ECM into thinking the sensor is connected and working.

 

I just finished dealing with a code 43.........but it was in isle 13

I think on the speed density cars, the ESC is built into the chip. I know it is for mine, I have a 91. Anywho, I checked around, did a lot of searching and found that I needed to check my knock sensor since that will also throw a code 43 if it's bad.

disconnect the knock sensor
put the ingition in the on position
grab a multimeter and test from the knock sensor wire to a ground it should read between 4-6 volts. if its more or less, read the lower 2

if the voltage is between 4-6 vols
probe the knock sensor terminal and the block you should get a reading of 3300 and 4500 ohms
if its between the two check thde harness and sensor connetor if thats ok remove ecm and be sure the mem-cal is properly seated into the ecm, if the memcal is sat in perfectly... replace the memcal.
If the ohms are not between the two, the knock sensor is bad


IF NOT :the voltage is over 6, the wire from the knock sensor could be to closed to secondary igiition wires or the wires is shorted to voltage or its a fulaty ECM.

IF NOT: voltage is less then 4, the wire is open or shorted to a ground or its a faulty ECM


My knock sensor was bad, hope you fix it! Keep us posted on the results!

 

yea, i'm talking about the '91 here... i'll check the knock sensor. hopefully that's it. i put another ecm in it yesterday, but that was because the suspected fuel pump switch inside it. anyways, that code set in both ecm's.

the deal with the fuel pump switch is that everytime i have the ignition on (eng not running) and "activate" ANY lights, the fuel pump will cycle on. this could be headlights - park lamps then heads - will cycle each time, fog lights, hit the brakes, shift in reverse and it does it, too. a friend of mine that works in the electronics field came over to help me, and we found a screwed up ground (sort of) and the problem went away. well, when i put everything else back together, the problem recreated itself and here i am chasing this electron around... so if i don't find it, i'll have to take it to a shop and let them do it.

hopefully i'll get to the knock sensor today and will post feedback. thanks for your help.

KAM

 

It's good that you checke dthe grounds, but your description indicates a possible power problem as well. The recycling off the fuel pump whenever you turn on a load means that the ECM loses power, re-POSTs, and runs the FP prime cycle again. Your intermittent connections could be anywhere from the battery and starter to fusible links and grounds - Anywhere.

The ECM connectorsa have already be disconnected and reinstalled at least once, so that would tend to help wipe them clean. You may want to check the underhood connections for problems, some of which may be related to teh ESC issue.

When I mentioned checking the connections at the HEI module, that's what I menat. The S/D cars do not have a separate ESC module, but still use the HEI module. You'll find it in the base of the distributor, and the ESC relies on that input to operate properly.

 

well i did find a loss of power at the knock sensor. it was reading no voltage. found the break in the wire and repaired it, got a 4.8 or so out of it. disconnected the battery for a few minutes and turned the key on for a few, shut it off, then read the codes. the code is now cleared, but i didn't have the engine running, so i don't know if it'll pick it up again or not when i do get it started again. which brings me to my next issue and it's another repeat. today, it would not start again. yesterday, i set everything as i thought i was doing it right, had the engine running good and even got to take the victory lap around the block. well, that was short lived. today, it did not want to start at all, and did the same thing it did a couple of months ago when i attempted the first starts on it. it'll crank, but not start and if i put some throttle in to it, it runs like the timing is way off, or cylinders not firing. i had found 3 bad spark plug wires last time and a bad coil wire, and the other day, it lit off without any help. today i'm back to square one.

vader, on one of my other posts, you put up the IAC and TPS article, and i need to clean my IAC and put it back together, but i cleaned the entire throttle body (removed it). so hopefully tomorrow i will get that back on and see what happens, but can the no volts to the knock sensor cause the ignition not to fire, or am i still paddling up the creek?

KAM

 

today turned out to be much better... yesterday i cleaned the entire throttle body and iac pintle, etc. put it all back together today, and varoom! took a couple of try's to get her started, but i did and she stayed stable. she surged a couple of times while the computer was doing its thing, i guess, but other than that, seemed to be ok.

i didn't have any help around today, so will have to wait to set the iac and timing, but other than that, looks like she's about ready for the exhaust.

the code 43 stayed cleared, too, once i repaired that wire and cleared the computer. while it was running today, no codes appeared.

KAM

thanks for the replies to this post - you guys are a lot of help.