Dale

iTrader: (12)

Getting check engine light code 43. Never gotten this code before on any of my cars. "low voltage to electronic spark control". What would cause this? Bad alternator, bad wiring, bad something before the spark control?

I'm at work now and dont have any of my wiring diagrams. Would like to pick up what ever needed part on my way home to fix it tonight.

RBob

iTrader: (1)

This is a knock detection system error. It can be caused by a number of items. Which item can be narrowed down by when the SES lights up for that code. It it happens shortly after starting the engine then the knock module or wiring to/from the module, ECM, and power may be the issue.

If the SES lights shortly after or during heavy throttle usage, then the forced knock test may be failing. This is done by the ECM once the engine is up to temperature and the ECM goes into PE mode (WOT). Timing is added to force knock to occur. If it does occur everything is OK.

If after 2 attempts to force knock fail to produce knock (as seen by the knock detection system), code 43 is thrown and timing is reduced (will feel a loss of power after that).

The forced knock test can fail from too high an octane fuel, or improper base timing. Engine mods can also affect this test. Of course a bad knock sensor or module will also cause this to fail. Although you could probably hear the poor engine knocking away.

RBob.

Dale

iTrader: (12)

ok, so no buying parts and just test **** for tonight.

I dont know when/what was going on when the light came on. I dont think I ever went WOT at lunch. I didnt hear knock, but I'm part def and exhaust is loud and radio was on.

running 87 oct gas

Engine is 350, but its still on a 305prom and unsure what knock and ESC parts are in the car, or even what has been done to the TB. This is the part I hate about getting a "new" car.

Dale

iTrader: (12)

Ok, after searching I found a few possabilitys. Checked some last night.

1. Timing was at 14deg, set it down to 2-4'ish. Still get code, but fixed my strange idle and hard to start.
2. timing chain is good, timing mark doesnt bounce
3. Pickup coil not tested yet
4. ICM not tested yet
5. knock sensor, dont know which one it is
6. KS module, label is to worn to know which one it is.
7. ECM/Prom..

Ok, I put a used/new 305 5sp ecm/prom in the car because it had a 305auto. I know I have a 350 but at the time I couldnt think of a 3505sp ecm/prom I could look for. Maybe this new ECM is bad or is seeing things the other one didnt?

What kinda car/trucks could I go look for in the junkyard to get a 350 KS module, and 350-5sp ECM/Prom?

RBob

iTrader: (1)

The knock sensor is on the passenger side of the engine block, down near the pan rail in front of the starter. It is threaded into a drain hole, so removing the sensor can cause the block to drain of coolant.

After a number of years sediment can build up. So when removing the sensor maybe a little coolant will weep out, maybe not. Don't know until the sensor is removed. Torque spec for sensor is 11 - 14 ft/lb.

Up top in the stickies is the info for a 350 sensor & module.

I doubt a 5sp/350 ECM calibration will be found. GM never made that combo for a TBI, at least for cars.

To test the knock detection system it helps to have a scan tool. This will show the knock counts. If you have one connect it for the next test.

To test: on a warm engine (up to temperature), raise the engine speed to 1200 RPM by the throttle. Then using the end of a broom stick 'thud' the block on the passenger side. The RPMs should dip down as the SA is retarded. Then recover as the retard decays out.

Do you know what the 350 came out of? Or what it has for heads/compression ratio/cam? It may be that the chamber is detonation resistent and the forced knock test is failing.

RBob.

Dale

iTrader: (12)

So knock sensor is in same spot as v6. Got it.

Block was to be replaced obviously. It looks dirty so it was along time ago. I have personally visually verified it to be a 5.7 block via stamp on left rear flange. Person I bought it from said he ran the numbers and it is to be a 91 block. Inside specs are unknown, but it seems to have a big cam.

I have tunerpro, but I have not downloaded the scan file, or hooked it up. Guess I need to try that this weekend.

So no prom code, $hit. Guess I may have to get that prom stuff and find someone to teach me.

thanks for the help rbob!

Dale

iTrader: (12)

ok, let the car idle for a bit. Then at idle hit with broom stick, no rpm jumps in sync with hitting it.

Ran rpm up to 1500, attempted to hold it. Hit with stick, nothing.

Says sensor or module is bad correct?

RBob

iTrader: (1)

There will not be any retard at idle. If the ECM did pull timing the engine would stall, so knock retard is disabled during idle.

If no dip in RPM while holding at 1500, then the system isn't detecting knock. Could be the sensor, module, wiring, or ECM.

RBob.

Dale

iTrader: (12)

Ok. I swapped back in my auto ecm, going to give it a few days. If no code, I'm going to put my manual prom into the "auto" ecm and see what happens.

Dale

iTrader: (12)

Been looking, some trucks came with a 350 TBI 5sp, but the ecm part number is different. Anyone ever looked into this ECM and see if a full ecm swap is possible, or just swapping proms is possible?

RBob

iTrader: (1)

Can't swap the PROMs between different ECMs. By this I mean a PROM from a '7747 won't work in a '8746 ECM.

A lot of the TBI ECMs are hardware compatible. Just different code bases. This means that 99% of the connector pins are the same.

Where the differences can be is in which pin controls what. And, what functionality is available. An example is the f-body ECM using an IAT, where many trucks do not.

RBob.

Dale

iTrader: (12)

So basically, my best bet is to have someone custom burn a prom. Or me buy the equipment and have someone show me what to do. Which is what I need to do, but all that lingo is to me.

No codes so far after 40'ish miles. Really thinking its the ecm I bought.

Dale

iTrader: (12)

Drove around on auto prom/ecm for a few days again, no code.

Put the manual prom into the auto ecm, Code within 6 miles.

Code lit up when I was under heavy throttle. No knock noticed at time of code.

RBob

iTrader: (1)

99% that would be the forced knock test failing. It may be that the auto prom has the calibration set up to not do the test.

If the auto prom drives OK you could stay with it.

RBob.

Dale

iTrader: (12)

It trys to die at idle. I'm going to stick with it tell I can start learning this chip burning stuff.

BigBoi4Lyph

This is perfect information i just have a question. I got a code 43 at wot on the freeway at about the 110-120 mph range and the ligth stayed on untill i turned the car off about 30 mins later and hasent come back since but i havent done 120 mph either.So this info it proably the KS test fail or what not.How do i test this or verifie that my KS that is bad or is it even my knock sensor.Also i dont think im gettin any knock retard but my car didnt want to go past 125 ish mph either89 camaro 5.7 tpi.Thanks

XxGeinNothingxX

iTrader: (1)

I was searching through threads instead of posting new and found this one which seems as the problem. I am throwing a 43 and like explained above, I was driving, hit the throttle hard, car sounded funny and felt sluggish, almost thought it wouldnt go once stopped. So I am gessing it sthe knock test. I do know that my car was jsut recently retarted at the shop to pass emissions, could this be the problem? What else could I check, should I replace the knock sensor? My car did this a while ago too, but the stopped for about 3 months until last night. Once I turn the car off, and back on its back to normal. Last time this happend, the light would not always come on every trip, I could go weeks without an issue and sometimes days. So what do you guys think?