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Code 42 and 43

nutt7

nutt7

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Ahwatukee, AZ -> JBLM, WA
I am having a similar issue as indicated here

I hosed off my engine and it started stumbling and missing and idling rough and I think backfiring (hear POP and loss of power under hood when hitting the gas at low RPMs). Today it threw code 42 and 43. Am I looking at replacing my ignition module or that module on the 45 degree bracket on the pass. side of the manifold?

People seem to interchange EST, ESC, and ICM. I don't know exactly which one pertains to code 42 and 43.

I also removed my knock sensor to drain my block and upon reinstalling I torqued in more than 10 ft/lbs as indicated in another post. It did work fine for a few days, until I hosed my engine.

Any suggestions?
 
Probably just dry out the distributor. Then disconnect power to clear codes and you should be fine. Everything else is pretty water proof. Even distributor to a point...

Code 42 is for EST/ICM in distributor. It's the brains of spark advance. It will also set when you check timing with bypass wire disconnected.
Electronic Spark Timing
Ignition Control Module

Code 43 is the ESC which is the module on the bracket. It is the brains of the knock sensor.
Electronic Spark Control
 
eagle mark said:
Probably just dry out the distributor. Then disconnect power to clear codes and you should be fine. Everything else is pretty water proof. Even distributor to a point...

Code 42 is for EST/ICM in distributor. It's the brains of spark advance. It will also set when you check timing with bypass wire disconnected.
Electronic Spark Timing
Ignition Control Module

Code 43 is the ESC which is the module on the bracket. It is the brains of the knock sensor.
Electronic Spark Control
Click to expand...

Thanks for the clarification. I put wd40 on a rag and wiped the inside of the distributor cap yesterday, with no difference. All wires and connections are clean and dry. I tried soapy water around dizzy and wires, one arced to a vac line, that was it. All codes were cleared before the test drive. Uh oh, I think...if not, the 42 was from when I checked the timing but I am fairly certain I reset it.

Could a faulty ICM alter the timing in such a way that it would knock and trip code 43?
 
Could be?

Code 43 is a failed test. Once each startup the ECM will preform a test after certain conditions are met. Usually at highway speed under load. It will force spark advance to produce knock, if no knock is found it failed test.

EST is what advances spark for test, but with what you have said it is more likely the knock sensor no longer working properly to hear forced knock test.
 
I need to determine if my 42 code was due to my timing check. If not, I will replace the ICM and check drivability. If it was, I plan to test a few wires at the ECM and if I get nothing conclusive I want to try this to test the knock sensor: I don't have a scanner, but what do you think about this:

In that PDF that you posted in the sticky, it says that if a knock is detected before the engine gets to 194 degrees, it will skip the knock test when it warms up. I was thinking of starting the engine, tapping on the block to generate a knock signal so the ECM will skip the test, and then checking drivability. Will that work or did I misread? I would knock and check timing, but its just me today and the rpms need to be 900+ to see a timing change. I can't check timing, knock on the block, and hold rpms above 900!
 
If you end up buying the EST/ICM get a AC delco. Aftermarket ones are just a can of worms including timing changes!

I do beleive that test will work, but if knock sensor reads a hammer and does not read knock test then Code 43 will come back, not to mention knock will not be handled correctly.
 
Do you know how much voltage drop the ECM wire from the ESC (485) sees with knock? I snuck a small gauge wire in the 485 pin and reconnected it to the module to monitor that signal to the ECM. With just the key on (not running), I saw a 1/2 volt drop or so on the wire I tapped into the connector. It went from 9.1V to 8.6V when tapping a hammer next to the knock sensor. Is this a functioning knock sensor and module?

If it matters, with the harness to the ESC disconnected, the knock wire to 12V supply wire was 11.4V not running, and the ground terminal to 12V supply wire was 11.5V and 12.1V directly to the battery.
 
Ok, so here's what I did:

Cleared memory. Started engine. Tapped on knock sensor area (engine cold, <194 degrees). Truck ran great, no rumbling, no pops, until it was consistently over 194, when I got it to pop. Could not replicate. No SES, couldn't get it to turn on. Stopped vehicle and turned off ignition for a minute. Started it up. Was easily able to get it to pop and rumble under load w/low rpm. After a few minutes, the SES light turned on, once I ran the A/C and applied gas at low RPM. So I get home, with truck still running, I tap the block and the SES light goes away! The manual says it will, if it receives a knock. Checked codes: 43 only, no 42.

So the ECMs knock test failed, but I got it to see a knock with the hammer. This seems like it is more likely to be the ignition module, since this is in charge of advancing the timing for the knock test...sound ok? Did I overlook anything?
 
I also removed my knock sensor to drain my block and upon reinstalling I torqued in more than 10 ft/lbs as indicated in another post. It did work fine for a few days, until I hosed my engine.
Click to expand...
I'm still stuck on this. A hammer will produce a bigger noise then detonation.

But it could also be a faulty ground in that circut, your in AZ so no rust issues but you did have problems after getting wet right?

Where was the arc of spark you were talking about? Did that get fixed? 40,000 volts really meeses up EFI 12 and 5 volt signals.

Now you mention a running issue as well, so your theory of a bad EST is valid. This is also the only part of this system that will be intermittent and still run, won't set a code and can't find with scanner! Even if a parts store still has equiptment to test an EST it has to be done properly at least three times, if fails any of three then it is faulty. That said when it's in rig it is way hotter then test and still has been found faulty but run. But they also still run fine to 300K miles!

I break my rule of replacing parts without diagnoses for this EST module becuase of all this. It's a very important part and AC Delco new replacment is $50. Don't even think of saving a few dollars on aftermarket! The screws that mount it are grounds. Must use the heat disapating paste underneath when mounting.

Check reluctor wheel while in there for cracks on magnet between metal pole pieces, look for massive green corrision on pickup coil, wires and plug. Check shaft for play and gear slop. How many miles on that distributor? complete new AC Delco distributor with the EST cap and rotor is about $250. Again don't even think about a cheap aftermarket. All new ones come with melonized gear which our flat tappet TBI engines did not have but roller cam TBI engines did.
 
The dealer wanted $90 something for the module. I don't know where else has AC Delco ignition modules...I can search some more. I just don't want my truck down while waiting on one.

The dizzy might have 10,000 miles on it. Everything is clean inside of it. I could only find one arc in one spot, haven't fixed it yet...it also runs better when cold, it seems that if the arc was a major problem it would be consistently the major issue. The arc was coming from a wire right off the cap.
 
RockAuto has the EST for $50.

Trying to make a rig run good with spark arcing is like trying to swim while carrying lead weights... :doah:

When an engine is cold the ECM adds fuel for choke, when warm, popping and rumbling when accelerating indicates lean. These 2 would be... check fuel pressure.
 
It's running and you don't know you need one? Why waste money on one that only God knows what it will do to timing or how long it will last? :waytogo:
 
Yeah, but it also runs like crap and I don't know why. I hate throwing parts at my truck too, but I think I will do this one, and if it doesn't change anything, well then I have a spare. Wish me luck.
 
Well, it got better...no more codes. It still stumbles and bucks under load.

I did learn some stuff tonight though! I waited til dark and checked for arcs again (last night it wasn't toooo dark). I saw more arcs and sprayed some soapy water to enhance the show. Probably saw 10 or so arcing spots. One looked a little low and diffused so I focused my vision on it and turned on my flashlight...I was staring right at the coil windings. It is arcing internally and can be seen through the winding cover! I did this from a few angles to be sure it was the coil. I tested it earlier with an ohmmeter and it checked out. I waited until it cooled and checked again...no coil arcing. I think it only does it when hot, which coincides with some previous issues. I will replace it tomorrow (as well as plugs and wires) and post back.
 
It was the coil...after installing it was no longer rumbly, then I replaced the wires and plugs and all my idle blips are gone...

Thanks for the help :thumb:
 
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