Timing Advance vanishes

[Blue_Thunder]

Check lifters and rockers may be a lobe going out, bad lifters. also check TPS .54 volts. It doesn't rev up when it acks up? Try thirdgen.org

Not a mechanical issue, and the lifters and rockers are good. As far as tps, what do you mean rev up when it acts up? The rpms (and engine noise) goes from a load to no load from the sound and the rpms just stay steady. Then it picks back up (albeit slower). I'll check to see if I have any dead spots in the tps this weekend.

[WMCCjames]

Sounds like the classic tpi knock retard to me.


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[Blue_Thunder]

Sounds like the classic tpi knock retard to me.


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James, is there a way to fix that?

[hoogiesngrinderz]

Did you use a 350 ESC? Faulty knock sensor or overtightened? Did you put the knock sensor wire on the fan switch that is in the cylinder head?

Fan switch (cylinder head) should be a white wire and knock sensor will be blue (low on the block, passenger side). They both have the same connector and often get switched.

[Blue_Thunder]

Did you use a 350 ESC? Faulty knock sensor or overtightened? Did you put the knock sensor wire on the fan switch that is in the cylinder head?

Fan switch (cylinder head) should be a white wire and knock sensor will be blue (low on the block, passenger side). They both have the same connector and often get switched.

I used a ESC for a 350 (the old one was for the 305). As far as incorrectly wiring the knock sensor, that I will double check, as I don't use the fan switch (being my car is an 86 thats computer controlled). So, that may have been crossed. I plan on replacing the knock sensor this winter as well. Ive heard the earlier 3rd generation f body knock sensors were less sensitive than the late model 3rd generations as well.

The new ESC module has helped, but the timing issue isn't gone. I'd understand better if the car was either correctly or incorrectly detecting a knock and then the timing returns to normal. But the timing stays retarded until I shut the car off. Thats whats throwing me off. Doesn't make any sense to me.

[hoogiesngrinderz]

check the wiring. My 89 uses the temp switch to control fan #2, fan #1 is computer/AC controlled.

I'll look through the .bin and see if there are any tables that would cut timing for a longer length of time if a certian condition is met.

[Blue_Thunder]

check the wiring. My 89 uses the temp switch to control fan #2, fan #1 is computer/AC controlled.

I'll look through the .bin and see if there are any tables that would cut timing for a longer length of time if a certian condition is met.

I have a single fan and in 86 its all computer controlled, so no fan switch (I haven't had time to check the wiring on the transplanted engine though). And the only thing that I can think of that might be causing an issue would be a code 43, but then again I don't know how it would keep timing retarded until the vehicle is shut off.

[hoogiesngrinderz]

Switching the knock sensor and temp sensor wire will cause a code 42 or code 43 when engine reaches a certain temp, likely setting the ECM into limp-mode (runs off the calpak)

Edit: But being that you have a single fan, I'm wondering if there is supposed to be a fan switch between #6 and #8 cylinder as a backup?

Second Edit: The 89 motor did have a fan switch in the passenger side head. Make sure the knock sensor wire isn't plugged into it.


Hell, I could just stop by and take a look

[Blue_Thunder]

Switching the knock sensor and temp sensor wire will cause a code 42 or code 43 when engine reaches a certain temp, likely setting the ECM into limp-mode (runs off the calpak)

Edit: But being that you have a single fan, I'm wondering if there is supposed to be a fan switch between #6 and #8 cylinder as a backup?

Second Edit: The 89 motor did have a fan switch in the passenger side head. Make sure the knock sensor wire isn't plugged into it.


Hell, I could just stop by and take a look

Knock sensor is wired correctly, so thats not the problem. I was able to get the car to act up and then get it scanned (with the engine running). I have a code 43 that is hard set. I couldn't get the code to clear with the engine running. As I have already replaced the esc module, the flow chart for that code is saying it will either be an open wire in the circuit somewhere, or the ecm itself is bad.



Edit: Digging around on Thirdgen.org on code 43 information.

I am reading that a loss of the ESC signal to the ECM will cause the ECM to constantly retard the timing to its maximum. Which is whats going on with my car.

As for the actual esc functional test, at WOT with the engine temp above 194* the computer adds a ton of spark advance (This is what I feel as though the car gets an unusual burst of power) until it detects a knock. If it does, the test is passed and there are no problems. If the computer doesn't detect a knock during the test, then it will retard the timing to its max.


I read that using high octane fuel (I use 93) can also cause this code to set. And I am wondering if my piggybacked chip could be causing issues as I have the original 305 chip piggybacking a JET chip for an 87 camaro with a 350.

After I replaced the esc module it sometimes passes that functionality test. Where on the highway at WOT, it will pull hard (the test is being applied), then the timing will be retarded (fails test), then come back and pull again hard, only for the timing to be retarded at maximum again. From then on the spark advance is non existent until I shut the car off.

[hoogiesngrinderz]

Timing should go high enough to get 93 to knock.

Ohm the wiring to check for open circuits or shorts and double check the initial timing (-6* BTDC) Wont cost you anything except some of your time.

If that all checks out I'd replace the KS, try another ESC (I think I might have a spare 350) then lastly I'd try a different ECM.


Hope you get it sorted out.