What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

code 43?

jpdrake

jpdrake

1/2 ton status
Joined
Oct 31, 2005
Posts
381
Reaction score
2
Location
mass/ cape cod
im very limited in my tbi know how. ive just rebuild my 88 350tbi. <new egr valve new knock sensor.> got it registed today threw the plates on took the top off and went for a ride in it for the first time in over a year. it just dosnt have that crisp throtle responce, runs real rough from idle to 1200rpm. can i get some help? i need to pass MA emisions by next fri.
 
I was told anytime you have thrown a code to disconnect a battery cable at the battery and touch it to the other battery post with that battery cable connected to clear the codes. ie take the negative loose at the battery and touch the negative cable to the positive cable while it is connected. Can anybody confirm this for me??


My howell service manual shows Code 43 to be electronic spark control (ESC) circuit.

non scan diagnostics

-ignition "off" clear codes
-idle engine for 1 minute or until service engine soon light comes on
-ground diagnostic terminal and note code

if no code 43:
diagnostic terminal ungrounded
connect tachometer
engine running at about 1500 rpm
trans in p/n and at normal operating temp
tap engine block in area of knock sensor and check for rpm drop

if RPM drops:
problem is intermittent. If no other codes were stored see ECM intermittent codes or performance in section 2

if no RPM drop:
see ECM system check in section 9

if you still show a code 43:

-engine idling
-back probe emc terminal B-7 with a voltmeter to ground and note voltage.

if under 6 volts:
ignition on engine stopped recheck voltage at ECM terminal B7

if over 6 volts replace ESC module

if still under 6 volts:
ignition off, disconnect ECM A-B connector, Ignition on and recheck voltage

if over 6 volts replace ECM

if under 6 volts:
disconnect ESC module check Voltage from ESC connector Terminal B to Ground, it should read batter voltage.

if OK check for open or short to ground in circuit 485. if not open or shorted to ground it is faulty ESC connection or ESC module.

if not battery voltage repair open in circuit 439.

That is all I can give you at this point. Good luck with all that gobligook!!
 
70jimmy said:
I was told anytime you have thrown a code to disconnect a battery cable at the battery and touch it to the other battery post with that battery cable connected to clear the codes. ie take the negative loose at the battery and touch the negative cable to the positive cable while it is connected. Can anybody confirm this for me??
Click to expand...

I would say not only no, but hell no! Obviously fuses are designed to prevent electrical problems from frying components, but I wouldn't take any chances.

All you have to do is pull the ECM fuse on the fuse panel (if that's where it is for TBI) for 10 seconds and the codes will be cleared.
 
still having problems. replaced the esc and map sensor replaced knock senser, checked volt they were above 10. took a hammer to the side of the block above the knock and no change in throtle. now if im going down the street and lay into it at all the engine light comes on.

becoming very frustated!!

could my computer be faulty?
 
Did you use sealant or teflon tape on the knock sensor? If you did. Pull the sensor and clean the threads. The sensor needs a good clean contact to the block to work right.
 
Did you follow the troubleshooting procedure for code 43 posted above? You can't throw parts at these problems, you are much better off if you want to spend money on something, buying a good scanner. Even then, not needed for most diagnostics.
 
I'm having similar problems in my 350tbi. jpdrake, did you ever figure out the problem with yours? Mine has had the knock sensor and ESC module replaced. Still getting an engine light. I tried bridging the plug-in with a paperclip and got code 43. I'm going to try the troubleshooting procedure posted above today and see what I can find out. can anyone help?
 
I'm too lazy to go look, is it possible too far advanced or retarded base timing could be a cause for this?

What does code 43 indicate?
 
From troublecodes.net:
The ECM did not detect a knock signal during near wide open throttle operation with coolant temperature above 194* F or the knock signal was present for 5 seconds or more during normal engine operation.
Click to expand...

I'm guessing something mechanical may be knocking like crazy and the timing keeps retarding to try and get rid of it. The core issue combined with this retarded timing could be the cause of it running like crap.
 
Without a scanner, this isn't going to help you much unfortunately:

http://www.thirdgen.org/techboard/t...-need-know-where-knock.html?highlight=maf+esc

First off, I'd check base idle. Should be 0* I think for TBI truck. According to the manual, it LOOKS like if knock is detected even at idle, the timing should retard. If that's the case, your "normal" idle (ESC bypass connected in other words, not setting base timing) advance should be below normal if for some reason the ECM thinks there is knock. I can't comment on timing at idle, although I tend to think it's around 20*. If someone else can say, that might help you. If your idle timing is "normal", tapping the block while watching timing may well show that idle does or does not retard.

This would obviously be a heck of a lot easier with a scanner, since you can watch and see if knock counts start adding up.
 
i havent driven it in awhile for some reason i think it just went away. i have been driving it like a little ol man when i used to lay into it is when it would throw a code but i cant recall seeing it for awhile. w/ the gas prices ive been driving the k1500. as it gets warmer ill start driving it more paying more attention. since ive rebuilt it ive realize more of a sputter or stall as i accelerate through a corner the only thing i never replaced was the throtle body b/c i could afford it. im thinking i could use a new tbi and fuel filter. but i also am not sure that was causing the knock. im sorry i could help more right now.
 
thanks for the input guys, yea i have that problem too when i'm going at lower rpms the engine sputters a bit. i have had my engine rebuilt too and the fuel filter was changed so I know it isn't coming from that. The SES light doesn't stay on all the time, it only comes on when I lay into it a bit more or accelerate more on the highway with the cruise control button. I had an exhaust leak at the downpipe joint from wheeling a bit in the snow over the winter and since I had that fixed i haven't noticed the problem as much, although on the highway yesterday i did get the SES light again. checked and it was code 43 again
 
thats the exact problem ive had. when you punch it or pass on the highway. i think all it takes is just a little knock or ping from somthing to light it up. i have a guy at the chevy dealership, he used his lap top went to a troubleshooting site put in code 43 and printed out a trouble shoot map <try this if not then this> didnt work. i dont know what the causeing factor is, ive just been driving like a lil old man.
 
5 months later still have the same problem, becoming angry. shouldnt it have enough hp to spin the wheels in the rain? i mean wtf. some mornings when its cold it almost like hits a "power band" like on a dirt bike and i get excited for 10 sec b/c it feels like it should be. any one have something new to offer im still thinking or replacing the original tbi or maybe new injecters?
 
It's strange because I just hooked up all my sensors for my TBI conversion and I just got a code 43 yesterday with a similar performance issue.

From what I understand, this code could either be caused by the knock sensor failing a test where the ECM advances the timing enough to cause a knock. If the knock isn't detected in that situation, it throws the code because it thinks the knock sensor is bad or not connected.

It can also be caused by the ESC module receiving a signal from the sensor that a knock is occurring more than just intermittantly. (like for 5 minutes straight).

I've noticed when mine threw the code, that I could hear a kind of knocking somewhere under the motor. This leads me to believe the second cause might be what I'm experiencing. The noise wasn't a motor knock as far as I could tell, but it might have been somewhere in the clutch or a bracket. My theory is that the ESC module is picking up some other noise and assumes it's a knock, which then retards the timing, which causes the crappy performance.
 
i replaced the knock sen and esc when i rebuilt it last year. soon as i get into the throttle it lights up.
 
One problem I have ran into with Knock sensors is the wire. Make sure it is not close to a spark plug wire or any other wire that carries a lot of current. The plug wire can induce voltage spikes in the knock sensor wire and the ECM interperts them as knocks
 
You must log in or register to reply here.

Latest Posts

Top Bottom