Code 43= Electronic spark control. Caused by; Poor electrical connection,open or short in circuit,defective ESC module,or knock sensor,defective ECM

This is where it gets fun;

Symptoms are; rough idle, surging,stumbling,it was spark knocking real bad but i switched to premium and stopped that, and just recently it has been getting very poor gas mileage. The surging and stumbling are intermittent.
When i turn the car on the SES light is off but comes on in like 30sec.

I have checked for my 5V ref. sig. from the ECM its good
The computer is registering a knock when the engine is running and i hit it with a hammer, but doesn't retard the timing.
When i rev the engine it shows no knock but shows knock retard going back and forth from 8-20-8-20. at the same time spark advance is goin 12-24-12-24.

I have replaced the knock sensor twice, and the ignition module. I tried to test the ESC module but can't seem to find it.

I will make sure santa puts a little something extra in the stocking of the person who helps me.

 

On your 91, there is no external ESC module to my understanding (as they are from 89 on back). All the circuitry is contained within the memcal. Also, the ecm will not retard timing unless you are above a predetermined speed, from what I've seen before, its usually 2 or 3 mph that the factory set it to. If you are expecting it to retard timing by producing false knock (hitting the header with a hammer), its not going to happen because you are not moving.

When the car starts up, the ecm forces the engine to knock once or twice to ensure the knock sensor is working correctly. If you hookup a scantool or some ALDL interface to your car, you should see 1 or 2 counts. If it doesn't pickup knock on these tests, it assumes that there is a problem that is not allowing knock to be detected, and either drops into limp home mode or retards the timing significantly (not sure which of the two it does right now).

Can you verify with a voltmeter what the resistance of your knock sensor is? Just place one lead on the threads, and the other at the other end touching the electrical connector. Your symptoms sound like you have the wrong knock sensor for the application.

Did this problem arise after the car was running fine, or after some work was done on the car?

 

All great information from 92blue.

Also, which detonation sensor did you install? There were two types.

 

I had heard about the speed thing but i wasn't sure. I hooked it up to my scanner at work and drove it around the block it didn't register a singal knock.

I haven'tchecked the resistance across the sensor because I had the same problem with the original and i've tried two others from different places.
The knock sensor I have is on the bottom of the block right by the starter and i only have one. I don't know what other types there are but thats where it is.

I've only had the car for five months. The week before Xmas I noticed the SES light would flicker every now and then but it only seemed to do it on decel from interstate. Then the battery went dead and the light stayed off until 2 weeks ago, thats when it just came on one day about 30 sec. after i started it and we've been together ever since

 

I'm going to check the fuel pressure tomorrow. I already checked the timing and it was dead on.I got it up on the lift at work and noticed the fuel filter was on backwards so i got a new one, but it didn't change anything. Just trying to tell yall anything i can think of that would help.

 

Wow, a compliment from Vader!

Not sure why, but that really made my day (however much of the day is left anyway, its kinda late).

Anyway, going back to the topic, your car is only going to have one knock sensor. However, there were two types of knock sensors used on 350 TPI engines. The models from 90-92 (using the 730 ecm) used a ks with a different resistance than the 89 and earlier models. I don't remember the exact value you should get, but I believe the older models had 100k ohms. If you do a search, you should find it easily, its been covered several times before.

Out of curiousity, what do your plugs look like?

 

I haven't checked my plugs yet. will do that today when checking FP. Do you think i will get an accurate reading from my plugs because it was spark knocking real bad for a while before i switch gas, also I don't have a 350 it is a 305 TPI.

 

Had a similar problem with my 88 iroc and come to find out the escm module was junk a wells from autozone installed sometime before the car was bought. Went to GM and got a a/c delco and solved immediatley seems wells rebuilds these. Hope it Helps

 

He doesn't have an external esc to replace like you do on your 88. His is contained within the memcal. Replacing it on his car means getting a new memcal.

 

92 blue, does the tapping the exhaust manifold when the car isn't moving only apply to the cars withou the ESC module?

I'm just asking cause I ran into the testing procedure while browsing a 88 GM shop manual. I see mistakes in the Chilton and Haynes manuals all the time but never encounterd one that I am aware of in the 88 GM manual.

GM made mistakes too but those were in the shop manuals for my 98. They sent me a whole 2nd revision.

 

Its not a matter of whether or not the esc is internal or external. One the $8D code, there is a parameter that enables timing retard after a specified vehicle speed. I have seen this set to 2 or 3 mph in stock trim. If the car is not moving, its not going to retard the timing if it encounters knock. I'm not saying this is how it is with every car. I'm pretty ignorant when it comes to working on cars, all I know/have significant experience with are thirgens. To my understanding that is how the $8D code works.

However, regardless of whether or not the car is moving, it should register knock counts. In other words, if you had a laptop or scan tool hooked up, you will see the knock counts go up. You will not see the timing retard though.

Look at it like this...the knock sensor reports knock. Thats all it does. The ecm is the one that decides what to do about it.

As far as Haynes and Chilton manuals, well, not sure what to say. I think the best use of the Haynes manuals I have seen is to put between your tranny pan and the jack so you don't dent it. Chiltons is a bit better, but you don't want to trust any of its torque specs, wiring diagrams, or anything else really.

I guess I am just spoiled after working with a GM manual myself. Well worth the big price tag.

 

Gotya on all counts. Even the GM shop manual has it wrong on that one cause it says to tap the exhaust manifold. It doesn't say get the shop rookie to tap it as you drive down the street.

I agree on the correct use of those aftermarket manuals too. If they were the only thing to depend on, it would be done wrong.

 

Well, your 88 isn't a speed density setup (the $8D code I was referring to was on the 90-92 models), so I'm not sure if it will work the same way or not. Does the manual says to tap the exhaust manifold and check if the timing moves?

There was a post I came across were someone lost a cam, lifters, and starter to a screw up in a Chiltons manual on adjusting valves. I have a copy of that same manual lying around, and mine is wrong as well. I think it mentioned to turn the rocker nuts a turn and a half, or something really funny like that.

 

Yes, I was asking about cars with an ESC module. Was wondering if the shop manual was wrong for the testing procedure. The procedure for the 88 says to tap it and watch the scan tool.

Damn, now I can't drive down the street with the wife hanging over the fender tapping on the exhaust manifold....

 

The procedure you mention will work if you are watching knock counts on your scan tool. That will show you if the knock sensor is working correctly. Suppose you start the car, hookup your scantool, and knock counts are at 1 or 2. Tapping the exhaust should bring it up one. What won't work is if you tap the exhaust and are tring to determine if its working or not by watching it the timing moved.

 

Should retard the timing if it's working as it should while being "knocked on" with a ESC equipped TPI car. The count should be close to the amount of knocks administered. If it has real knock then the count will be high. False knock would give an error eratically if the sensor is not up to par.

Do I have that right?

 

This had me rolling on the floor. I could just imagine something like that happening on my street

 

My scan tool only says yes if it is seeing a knock and no if it doesn't. I haven't checked my FP yet or my gap been kinda busy but i'll check tomorrow. Is there anything else you guys can think of to check. How would you check a memcal?

 

I've seen this very similar problem.... It happened because the alternator went out causing surges and low voltage and fried part of the ECM (GM Mech's have confirmed and Denied this will happen, ive seen it in a s-10 and my 91 bird[rest its soul]), causing the EXACT problems you described.

My suggestion based on my past experience with my 91 Bird (few years ago), is to obtain a used ECM from the local yard and try it.

I am guessing a 87% chance that will fix it for you.

 

Yatzee!!! I replaced my alternater right before i started having the check engine light come on. Would it be the whole ECM or just the memcal thats bad.

 

its on the internal board inside the ECM that blowed in the ones I have seen, two to be exact. So in my past experience, you would have to replace the whole ecm possibly sparing your memcal, be best to find one just like yours and use the ECM and Memcal from it.

 

I checked my plugs today and they looked surprisingly good. I could not check my fuel pressure because the fitting I need has flown the coupe. I have to replace my sending unit anyways so i'll just put a new pump on while i'm in there.
Now I know this is dangerous on here but I am going to ask yalls opinion. What fuel pump should I use or are they all pretty much the same.

 

In my opinion/experience, go with a Walbro pump. Its the same price or slightly more than a generic fuel pump. They are very durable, and put out more fuel than stock replacement pumps. If you do a search, you'll find lots of people are using them. The holley $160 in tank 255LPH fuel pumps you see in Summit are actually Walbro pumps with holley's name on it. If you aren't going to be dropping in a fuel hungry engine anytime down the road, stick to a 190LPH Walbro pump.

I'm running a Walbro 255 in my car. I think Automotive Performance Engineering has the best prices on these pumps. Very nice people to work with, I've dealt with them before.

 

Thanks for all your help. I'm taking my car to an electrical shop mon. for a second opinion even though i'm 99% sure you are right I'll let you know what they say

 

I hope all goes well. Let us know, I cant stand to see someone with car trouble, I know how much it hurts.

 

Ok, finally took my car to a nieghboring shop and had their tech look at it and he said he doesn't think it needs the whole ECM, just a new chip. So anybody got a good chip thay need to get rid of

 

The problem was the 5 volt ref signal to tha knock sensor is supposed to step down to a 2-2.5v when you plug it in and mine is going from 4.96v to 4.75v.