gettaway305

Hey, Ive read all the other threads about code 43, and my situation seems slightly different....

Ok, occasionally ill be driving my car and ill bring it up to WOT for one reason or the other. It starts accelerating fine, but once in awhile it will cough, and throw code 43.
After this happens, the engine totally bogs down, and I have to shut it down and restart it for the code to go away and for it to be ok.

Today though when i shut it down and tried to restart it, It would barely crank, like there was a gigactinc current draw and not enough power getting to the starter. I let it sit for about a minute and then it was fine.

Does anyone know what causes this? It kinda sucks knowing that if you floor it or drive up a steep hill its gonna do this...

RBob

iTrader: (1)

The cough is due to the added timing in an attempt to force detonation. When the detonation fails to appear code 43 is set. With a code 43 in place the ECM pulls ~ 8 degrees (cal dependent) of timing out all of the time.

The loss of timing is what causes the loss of power.

RBob.

gettaway305

hey thanks for the info....how do i fix this tho? advance the timing? its at stock right now (0 btdc)

edit: would this also be causing the engine to barely crank when i tried to restart it?

jwscab

RBob, can you elaborate on this condition? This sounds exactly like what is happening on my brothers regal, running a 305/w a '7747 ecm. He told me every once in awhile, the car will throw the SES, and power will be way down. From your reply, it sounds like the ecm 'tries' to get detonation during a WOT transition and it doesn't see it? Would this be a symptom of a base timing not set to the timing in the ecm(maybe lower or higher by a couple degrees). Scanning the car, it gets a couple of knock counts during start-up, so it seems that the esc circuitry is working properly. Any help would be great!

RBob

iTrader: (1)

The best fix is to patch the code to bypass the forced knock test. If the engine/car is all stock then there may be another problem. What I wouldn't know (running 93 octane to prevent knock?).

The crank problem sounds like: weak battery or bad cable(s) or bad starter, or any combination of the three.

RBob.

RBob

iTrader: (1)

Yep, sounds like the forced knock test could be failing. Does it happen when he's in the throttle a bit? Scan it next time the SES rears it's ugly head. Code 43?

Both the '8746 & '747 ECMs have a forced knock test. The purpose is to prove out the knock detection sensor, filter, wiring, and ECM counter. The test will be run twice while in PE mode (WOT) with an increased level of SA. If no knock is detected code 43 is set and a set amount of timing is removed. Hiway SA and PE SA will not be applied until the forced knock test passes.

The forced knock test can also wreak havoc with drag runs.

As mentioned there are patches to bypass the forced knock test for both the '747 and '8746 ECMs. Copyrighted against those that would want to make money selling these patches. They are available for free to those using them for their own use.

RBob.

jwscab

Yep, thats exactly when it happens, when he's in the throttle, merging with traffic....definitely not a good time for the ecm to be dropping timing.....I'll have to try that patch, though I'm thinking about updating him to a 92/93 cop car ecm/calibration, modified for the 305...is the patch on the GM ecm site? One other quick question....how much timing does it add? I might just have the static timing set too low(set it at 6, and the cal might be more than that, still have to striaghten out the sparkadder vs spark bias for that ecm.) Rbob, thanks for the info, you are the man with this assembly stuff.

RBob

iTrader: (1)

The '747 patch is at the diy-efi site, incoming ftp directory as: ESC_747.zip (case sensitive).

The '8746 patch is available on this site in the diy-prom board. It is attached to the 'patch method demo' thread.

As for the amount of SA to force knock, how about 14 deg for the first attempt and 22 deg for the second attempt (cal dependent). This is added to the current SA value.

RBob.

jwscab

ouch, thats alot of timing, thanks for all your help RBob, I think I'll try this patch stuff and see how it works!