1989 Camaro 350 TBI T-5


Alright here's the deal. I am sick of this car, I cannot figure out what is wrong with it. If you give me an idea and it fixes the car I will send you 25 dollars over paypal. And I will trust me.

Car runs fine until something happens. The SES light comes on. The car bogs down, when you WOT it gets VERY loud and the RPMs SLOWLY increase and barely can get over 3000 RPMs and SOMETIMES back fires in the intake. Shut the car down and restart it it runs perfect after that. I will be getting a video of this tomorrow.

When I pull the codes I get 24 and 43.

24. When engine speed was between 1200 and 4400 RPM and throttle position angle was less than 3%, the MAP signal showed low voltage (high manifold vacuum) for at least 5 seconds.
(http://www.austinthirdgen.org/index.php?pid=27#5LTBI)
I just saw this and am unsure on how to fix this... Any ideas?


24. Circuit fault in vehicle speed sensor
(https://www.thirdgen.org/service-engi...error-codes)My car does not have a Vehicle Speed Sensor

43 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 4 seconds or more during normal engine operation.
(http://www.austinthirdgen.org/index.php?pid=27#5LTBI)
Replaced the Knock sensor


43. Low voltage at electronic spark timing circuit
(https://www.thirdgen.org/service-engi...ht-error-codes)
Replaced the ignition module


What I have replaced on the car (was not meant to fix the problem):
Alternator
Battery
Oil pressure sending unit
ECM

 

24. Circuit fault in vehicle speed sensor
(https://www.thirdgen.org/service-engi...error-codes)My car does not have a Vehicle Speed Sensor

What have you changed, that eliminated the VSS?

 

It's an 89 therefor it's a cable driven.

 

Don't be so quick.....My 87 is a mechanical gauge, but electronically riven off a VSS. I don't have the fancy optional GTA digital gauges, but rather the stock mechanical gauges.

Not sure exactly when the change for Camaros was but.....

 

Transmission is cable as well, I had replaced the cable once already. :P

 

Do you have a way to burn chips? You need to turn off code 24 in your tune since its cable driven, you wont have cruise though but hey, you dont now. Otherwise you can buy a cable to electronic converter, that way you can have the cable going to the speedo and the electronic signal going to the PCM.

Does this car have full exhaust and cats?

Oh and code 43, is your set timing connector disconnected or could the connector possible be broke or even missing? If you sure its okay I would say your ignition module is bad.

 

Oops double post

 

Yes it does have full exhaust with cat but there is a tube that is cut leading to the emissions. BUT the car ran fine even with that. Then this problem occured.

Also austinthirdgen says differently then TGO...
24 When engine speed was between 1200 and 4400 RPM and throttle position angle was less than 3%, the MAP signal showed low voltage (high manifold vacuum) for at least 5 seconds.

So that's where I am confused...

 

For code 24 on your vehicle it is a VSS error. The VSS is mounted on the back of the speedometer. It is an optical pickup that senses a rotating bar inside of the speedometer. There is a small buffer box between the pickup and the ECM.

Box is usually lime green or yellow in color. It is mounted on the rear of the cluster. If no scan tool to verify that there truly isn't a VSS signal (no MPH reading) to the ECM I would just replace the buffer and pickup. They are an assembly with a wire between them. A single screw mounts the pickup to the back of the speedo.

While there I would also rotate the speedo by hand and look for the rotating bar. Will need a flashlight to see it while the pickup is removed.


Code 43: runs fine then something happens. This is a failure of the knock system. Once code 43 is activated the ECM pulls 8 degrees of timing out until the next key-off. Which is why the loss of power until you re-start the engine.

The trick with this code is that there are two different items that can cause it. A failure of the forced knock test, or runaway knock counts. The fix for each is drastically different. So you need to know when code 43 is set.

Is it set during high throttle usage? Or just while cruising?

RBob.

 

Alright now we are getting somewhere.
I put in a aftermarket speedometer, taking out the stock so that explains code 24.

The check engine light comes on during cruise BUT I don't know if that is the 24 or 43... But I have noticed when I floor it it bogs down.... ALOT. So I'm going to go with WOT.

Occasionally while cruising though.

 

Your confusing yourself, you mean thats code 24.

What is the condition of your engine? Could it actually be knocking?

 

Good catch. I understand which is which I just mixed it up. :P

 

Here are several threads that explain the code 43 failures.

https://www.thirdgen.org/forums/tbi/...code-43-a.html
https://www.thirdgen.org/forums/tbi/...code-43-a.html
https://www.thirdgen.org/forums/tbi/...code-43-a.html
https://www.thirdgen.org/forums/tbi/...de-43-esc.html

Figuring out whether it is the forced or runaway knock portion failing is important.

RBob.

 

Okay, I am 95% sure it is a force knock.
Now I am selling this car, so I don't want to spend too much money on it...

The links you posted are VERY helpful.

 

Alright I just bit the bullet and bought a timing light. I disconnected the est (tan/black wire) and I don't even see the line that tells you the timing. I think I found the source of the problem. I am letting the car cool down but it there any tips on how to loosen that bolt under neath the distributor? I just can't get it.

RBob if this is the problem can you please send me your paypal information?

I will let you know.

 

crow foot wrench or a stubby wrench will work too. not the easiest to get to in the car.

 

Alright I was able to play with the Dizzy. I moved it so the timing was like in the picture.

The car got a SIGNIFICANT amount of power. I accidently span tires living my development. That hasn't happened since I got the car. I am going to readjust it tomorrow so it is right on the dip.

The car threw code 43 once and I took it for some WOT runs at a parking lot. Temperature did not start getting hot anywhere near as fast. I did about 10 WOT runs total hitting a max of 60 mph in second gear. Also I did 40 mph constant up and down it as well. It threw it once while just driving not WOT... That means it is getting 245 knock signals am I wrong?

Just to make sure what is a knock? I'm guessing it's when the piston hits a valve or such?

 

a knock is exactly what it sounds like. could be from pistons valves rods crank anything that makes a knock, then you even have spark knock (detonation) all can set off the sensor

 

That's what I kinda of figured. How does the ECM force a knock? That's what I don't understand...

 

To force knock the ECM adds spark timing to cause the engine to detonate.

You mention getting a code 43 just driving. How are you going about checking for the code and when it happens?

RBob.

 

Well I took out the fuse near the battery for 30 secs put it back in and waited till it turns on then stopped and checked it.

How does that cause it to knock?

 

detonation, or spark knock is what is the ECM looking for.
under certain conditions the ECM will advance the timing up to a point that it should see a knock signal from the knock sensor.
if it doesn't see a knock signal on the first test, it will run the test a second time and will add even more timing advance. if it doesn't see knock this time, it sets code 43 and turns the CEL on.
it runs the test every ignition cycle.

 

I got the timing set perfect and it was running good just throwing the code every once a while. No over heating either. Today it hit 220 which it hasn't done in a few days... I'm going to check the timing again...

Any other suggestions?

 

Have you ever taken the rad cap off & let the engine run, up to operating temperature, to verify that the water level is good?

Engine cold, the water level can look good, until the thermostat opens, then watch the water level DROP, if it is low.

 

Done 5-6 times in the past 3 days.

 

(Non-vehicle specific...) For timing in general, the engine computer will get inputs from sensors monitoring the following...

Crankshaft position
Engine speed (RPM)
Engine load (manifold pressure or vacuum)
Atmospheric (barometric) pressure
Engine coolant temperature

So if a sensor for one of the above is not functioning properly, then the computer would get wrong information, and therefore set the timing wrong.

The most complete testing / troubleshooting instructions for these things would be in a factory service manual set (And specific to your vehicle). Also instructions for setting the base timing.

Then as to the diagnostic codes, in addition to problems with the sensors, there can be problems with connectors or the wiring. A terminal in a connector can be not as "tight fitting" as it should. Or a wire might be rubbing against a sharp metal object and shorting. Or a wire which has had a lot of movement may have a break in it and this intermittently connects/disconnects.

You can test for this with a recording multimeter and a "wiggle test" where you "wiggle" the wires.