Chasing SES Code 43

[Schurkey]

I still have the problem with it advancing timing too far. (20 initial and 40 total)

My apologies for not seeing this sooner.
Timing light inaccurate? What light are you using?

I did notice with the scanner plugged in that it idles faster than I expected (1k RPM). That drops down slightly when I put it in drive. When I put it back into park after driving around it started idling at 2k RPM. This higher idle went away if I turned off and restarted the vehicle. All this is with the truck warmed up. Temp was staying between 200 and 210 F.

Scan tool is probably not in "Road Test" mode. If the scan tool doesn't provide proper resistance between two of the pins on the ALDL, the computer goes into a high-idle mode.

It's been so long since I've played with that that I don't remember specifics. My scan tool has options for "Codes and Data" which provides the high idle, and "Road Test (C&D)" which doesn't.

I had an issue with my truck throwing a code 43 right at startup. Apparently there are 2 different knock sensors for these trucks. The one you posted is the white one, which is what I had. I replaced it with the black one and it fixed my issue. This is just a thought

I looked up the part number he used, and Autozone shows it as valid for his vehicle.

Autozone could be wrong; and he said he removed a black sensor and replaced it with the white one--so you may be onto something.

 

[echoxozzy]

My apologies for not seeing this sooner.
Timing light inaccurate? What light are you using?


Scan tool is probably not in "Road Test" mode. If the scan tool doesn't provide proper resistance between two of the pins on the ALDL, the computer goes into a high-idle mode.

It's been so long since I've played with that that I don't remember specifics. My scan tool has options for "Codes and Data" which provides the high idle, and "Road Test (C&D)" which doesn't.


I looked up the part number he used, and Autozone shows it as valid for his vehicle.

Autozone could be wrong; and he said he removed a black sensor and replaced it with the white one--so you may be onto something.

I'll look up the exact model timing light but it looks like the Craftsman model model 161213400.

 

[echoxozzy]

Had to take a break from looking at it but have been back at it for a while. I should have done a better job documenting what was done and what changes were noted. I have started doing that more recently but here is what has been changed with the results as best as I can remember.

Replaced MAP Sensor and TPS along with vacuum hoses for MAP Sensor and EGR. This made a big difference. The problem nearly went away. Before it would knock any time I accelerated hard. Now it was much more intermittent an typically not under hard acceleration. It seemed like if it did happen it would be when I accelerated after coasting up to a stop light that turned green before I got there. At this point I did check timing and I was still getting around 20 deg BTDC at idle. I started to think that my concerns about the timing being too advanced at idle might have been a red herring.

I changed out the Temperature Sensor(s). This made no change. I know only one speaks to the computer but the gage on my dash seemed to always read low so I figured I would replace it too while I had the coolant system opened up.

I checked the color of my knock sensor (it is the white one) and drove it for 4 days with no errors. This made me think that perhaps it had been a poor connection. When the light came back on day 5 I played with the wire and it got worse. I tried to route it further away from the larger gage wires attaching to the starter and saw no change.

I replaced the EGR solenoid. When I did this I noticed that the clip that holds the electric plug in the solenoid had snapped off previously (I had forgotten this) so I replaced the connector (kept the same terminals but put them in a new housing). Inspected the terminals while I had them out and they look to be in good shape. Since I was suspecting the wire from the knock sensor to the ESC module I unplugged it and snapped the clip off. Replaced the connector there as well (keeping the terminals). Checked my grounds at the ESC and they were good.

Plugged everything back in and again the problem seemed to have gone away. Drove it all over town for a couple of days and things seemed fine other than I didn't like the way it shifted in to 3rd gear (more on that later).

Near the end of a 2 hour road trip yesterday the SES light comes on while I'm on the highway (cruising at about 70mph). I pull over at a gas station and it is Code 32 (EGR). I keep driving (surface streets now so about 40 mph) and the light comes on again (under moderate acceleration from a red light). This time I check and Code 43 is also present. I disconnect the battery to clear the codes and a few miles down the road it comes on again (Codes 42 and 43 and again under moderate acceleration from a red light). I clear them again and again the light comes on as I leave a red light (Code 43 only).

When I get home I check timing (0 without ETC and 20 BTDC with). I plug my scanner in (USB Scanner using TunerPro RT) and again trace it to an intermittent error.

Decided to drive with the scanner connected since it was tripping consistently but with the scanner connected I do not get an SES. I did get one knock count while I was driving. Probably drove around for an hour with several stops along the way and never got anything. Stopped and unplugged the scanner before I drove home. No SES light on the way home.

I started going back through the tips for intermittent errors in the manual and checked my ground for CKT 483 (4 pin harness to Ignition Module). I am getting around 50 Kohms but am not entirely sure I have good contact with the terminal in the connector. I'm going to rig up something to get a smaller pin in the connector to get better contact and check again. A question on this. This wire goes to the ECM and then the ECM gets grounded (I think behind the passenger head). What should this read? Will the ECM give me a higher than expected reading when I am checking this wires connection to ground? I am under the impression that anything over 5 Ohms is not a good ground.

At that point it was late and I decided it was time to sleep on it.

More details about how the truck shifts. It seems like it gets good power until it gets to around 35 mph where it shifts into 3rd. Then it is sluggish until it picks up enough speed for the engine RPMs to get back up. Sometimes there is a delay in this shift and you will here a short surge in engine RPMs when the transmission is between gears. One at least a couple of occasions this has coincided with the SES light coming on (Code 43). Not sure if this was related but I wanted to point it out.

Next planned steps: Validate CKT 453 connection to ground. While I am back there I may replace the ignition module. I have a new one.

I've read some threads that tied low fuel pressure to some of these symptoms.

I know its a lot of info at once. Thanks for the help. Let me know if yall have any questions.

 

[echoxozzy]

I'm pretty puzzled.

I investigated CKT 453 to ground some more. I still get 50kOhms if I measure from terminal A in the connector to ground.

I checked ECM ground (A12 at ECM to negative end of battery cable) and it was about 1 ohm. This was a relief given how hard that seemed like it would be to get to if it needed to be fixed.

Next I was going to check the resistance on the wire making up CKT 453 (B3 to terminal A of the connector at the distributor). I moved the lead over to B3 and was still getting a good connection to ground. This was with the connector still installed in the distributor.

I was able to check this wire (CKT 453) and it had no problems (< 1 ohm).

I removed the ECM and examined the pins thinking that it may not be making a good connection. They all look pristine.

So it looks like I have a good ECM ground and a good connection between the Distributor and the ECM on CKT 543.

Do I have a problem with the ECM or is it supposed to show 50k Ohm resistance between CKT 453 at the distributor and system ground?

 

[Schurkey]

Post the schematic.

 

[echoxozzy]

Post the schematic.

I'll trace through how I got here as well.

Troubleshot using this flowchart to get to the point where it was determined to be intermittent.

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Checked connections at knock sensor, ESC Module and ECM. They looked good. Checked CKT 485 (C to B7) and it was neither open or shorted to ground.

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Section 2 for intermittent codes got me to CKT 453.

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The manual has schematics showing 453 to ground and 453 to EST REF LOW

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[echoxozzy]

I had an issue with my truck throwing a code 43 right at startup. Apparently there are 2 different knock sensors for these trucks. The one you posted is the white one, which is what I had. I replaced it with the black one and it fixed my issue. This is just a thought

What part number is that. When I look this up I only find the part number that I have.