I have a 1991 Chevy Blazer 4.3/AT/4x4/VIN "Y"

Okay, so I have had a code 43 for a while and when the SES light is OFF, the truck runs pretty good, when the SES light comes on, the truck runs like crap... really rough and lacking power.

So, what else is in that circuit that could cause that code besides the knock sensor?

If it is, where is the knock sensor and how do I get to it? I know it is on the driver's side and a PITA to get too.

So for those who have done it... how do you access it? I cant see it... at all.

Do I need to remove some things to get to it?

AHHHHHHHH!

 

Electronic Spark Control is stuck in retard mode. Maybe a bad ignition module on the distributor.

 

Cant be the IgMod, I had it tested 7 times and it passed.


Could it be the ESC module itself?

 

Spark advance is controlled by the ECM/PCM through the ignition module. When you have this problem, do you check the timing to see if the spark advance is working, or stuck in base timing mode?

 

hello im new at this site. but i have a simliar problem SES light is off got the code 43 truck runs like crap shakes real bad. died on me after climbing up a hill one day left me sit. but got it towed home an then it ran again. has no power at alll real strong gas smell when running so its gettin plenty of feul. just cant figure it out? should I replace the knock sensor and which one should i do first? sounds like it wants to die cant accelerate at all have it floored and well nothing lol. does anybody know???

 

Code number 43 is not the knock sensor its the fuel delivery system. Sounds like either your fuel filter, fuel pump or fuel injectors are clogged. If your car only does it after your car has warmed up then it might be your Ignition control module. The 4.3L have a common deal where the ICM don't work correctly when they are worn out as in your car feels like its starving for fuel and has no *****. But I would still suggest to replace the fuel filter then the ICM. You can also take the ICM to any parts store and they have a tester to make sure the ICM is working in correctly.

 

Yours in deffently your ICM real cheap thing to fix.

 

First I don't think they had a VIN Code "Y" in 1991. Just a Vin Code "Z". I'm not showing a Code "Y" past 1984 but book could be wrong. A Code 43 is not the knock sensor on these but it is the Electronic Spark Control circuit not to be confused with Electronic Spark Timing (Code 42).

 

I am in the process of replacing mine right now and am having a very difficult time removing it. Facing the fire wall it is to the right and below the Oil Pressure swtich at the back of the block next to the firewall. So far I removed the bolts for the throttle bracket for a little extra room. The problem I am having is that all my sockets have been slipping. There is no room for any kind of wrench other than a socket. I have tried deep well, 6 point, 12 point sockets, standard and metric sockets, 3/8 drive & 1/2 drive. My attempt today will be with a basin wrench I got from Home Depot. (A vertical pipe wrench) If I can get it to turn even a little bit than I will have no problem removing it and installing the replacement. The socket size is 22MM. To remove the connector just squeaze the sides and it comes off very easy. I will let you know later today if I had success in removing the old one.

 

So far I have not been able to remove the knock sensor. Next up is to remove all the plug wires and the distrubitor for a little extra room. Maybe I can get on the knock sensor with a box end wrench, channel locks or even a pipe wrench. If that does not work I might end up having to pull the engine. It is so hot in Biloxi, MS that I can only work so long before I got a call it quits. I was able to get a bite on it with the basin wrench but I could not get the knock sensor to turn. I know if I can get it to rotate just a little bit then I know I can get it out. If the sockets were not slipping on the knock sensor I could had it done it 10 Min. Now it is going to take me hours.