TBI Code 43

[randomguy]

Ive been doing a lot of searching on this code and it seems there are a few different things that trigger it with my circumstance maybe being the most common. Truck runs fine, no engine light at start up, good power. However, once warmed up I will get a knock under load and then a short time later another knock under load which throws an engine light.

Based on many Google searches it appears this may be the result of a defective sensor. I’ve read several posts suggesting that once the coolant reaches a predetermined temperature the ECM tests the knock sensor by advancing timing until a knock is detected. If no knock is detected it performs the test a second time and if no knock is detected throws a light and a code. At this point the truck feels like it loses power and gas mileage sucks(10 mpg on a stock 350/700r4 with stock tires). Is this the ECM retarding the timing to prevent knock because of the knock sensor code?

I’ve got a new plug and AC Delco sensor on the way to swap in. The person I bought the truck from told me this code started showing up after he changed the starter. It seems logical to me the plug and/or sensor may have been damaged during starter replacement. I will update this thread when I have it swapped in.

 

[randomguy]

Replaced the knock sensor with AC Delco #213324. Also replaced the plug with AC Delco #PT308. It was easy, just took the passenger side wheel off. Very little coolant came out.

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Still throwing a 43 code when it does the self test after engine warms up. I can hear the pinging when it does the self test and that’s the only time it pings. Engine is quiet and smooth other than that. One thing I have not checked is the base timing. I will do that when my timing gun gets here.

 

[c1500deathtrap]

Make sure you have a good watertight connection on the connector side, Preferably soldered. Get a new pigtail if you need to. And make sure it has good contact with coolant, no sludge or goo in the hole it sits in.

 

[randomguy]

Make sure you have a good watertight connection on the connector side, Preferably soldered. Get a new pigtail if you need to. And make sure it has good contact with coolant, no sludge or goo in the hole it sits in.

I used a crimp connection that came with the GM pigtail and sealed it. The threads have good contact with block. I didn’t punch the sludge out of the hole as I read from multiple sources this isn’t needed.

I think the sensor is good. The old one was definitely bad and would throw a code as soon as the engine warmed up. Now it’ll run just fine on flat roads. I took it for a 10 mile drive this morning to warm it up and the code did not present. Checked the timing and it is spot on 0*.

Drove to town and as soon as I hit a grade I can hear pinging and the engine light comes on which causes the ECM to pull timing and reduce power. Shut down and restart and all is well until I pull another grade. I can drive down the freeway in overdrive without any pinging until I hit a steep grade. Where it gets weird is if I run the truck in 3rd instead of OD I have no issues at all. No pinging, no engine light.

I’m running 87 octane fuel right now. I was down to 3/4 tank so I put a bottle of Lucas Octane Booster in and filled up with 6 gallons of 92 octane fuel. This had no effect.

I’m a little stumped. Should I look at my ignition system or play with the timing? I may need to spring for an ALDL cable and do some data logging.

 

[joep88cheyenne]

Old school thought came to mind.. I think.(mind may have issues) that I had read/been told that some pinging may be heard under load/pulling a grade in OD. and a shift to next lower gear would solve that. Doesn't eliminate it as next grade need the drop out of OD. That was before cel/ses lights and computers. Like I said old school.

 

[evilunclegrimace]

Try running some top engine cleaner through the system. You could have excessive carbon deposits on top of your pistons.

 

[randomguy]

Well I started looking at the simple stuff. First my coil is arcing so I’ll need a new one. Also my EGR valve is bad. EGR passages are not blocked but the valve will not hold vacuum. I am not getting a code 32 but will be replacing. Additionally I am going to do the plugs, wires, cap, and rotor as everything looks old.

 

[DerekTheGreat]

I'm following this thread for sure. My old engine did pretty much exactly the same thing. It running on 7/8 was what I thought to be the culprit. It would run fine if I didn't goose it, but the instant I got on it, ping city followed by code 43 & no power like you mentioned. You're right about the timing being pulled, the GM fuel injection manual I've got for '87 says that if this code is triggered, the computer reverts the ignition to base timing. Until I got that motor replaced, the freeway was brutal with base timing haha.

It could indeed be carbon build up... When they swapped my engine they also reused everything from the old one. Co-Part sent them a long block so that ruled out my aftermarket dizzy & ESC module as I thought those could have also been suspect. "new" used engine runs like a top, I've even got the timing set to 1 degree. Old engine had 225k abused, hard miles on it. Had a burnt valve in cyl. #1 and used oil excessively, like 1 quart every 600 miles. New valve seals didn't make a dent with oil consumption. Perhaps there was too much slack in the timing chain too, I'm not an expert though. Was happy to have that boat anchor replaced with a proper unit though.

 

[randomguy]

Engine is a Goodwrench crate and only has 110k on it and was installed in 1997. If I’m reading the code on the EGR right they installed a new valve at the same time.

I tested the EGR solenoid today and it appears to be working fine. My valve will open but since the diaphragm leaks it takes a lot of vacuum to open. My guess is that’s why it’s not tripping a code 32 but is bad enough, in combination with the bad coil, to cause pinging under load with light throttle in OD with the torque converter locked.

Should have my parts in a few days. Anyone have any tricks for removing the EGR? The driver side bolt is almost impossible to get to. I really don’t want to remove the throttle body. I’m thinking if I remove the coil I might be able to put a box end on the bolt.

 

[randomguy]

All parts ordered, hopefully I’ll have time to at least replace the valve and coil before next weekend.

Drove it again today and am certain it’s the EGR. Light load, light throttle, EGR solenoid activated no pinging. High load, light throttle, EGR solenoid activated and there is pinging. I managed to replicate the problem in 3rd as well.

Makes me wonder if the ECM has a fuel or timing setting for when it engages EGR.