This is kind of strange. 383 HSR 6 speed 1990 Camaro. The car is running rich all over the board with basically close to stock VE tables in place. The BLMs show 96 pretty much everywhere with the odd 100-118 reading but not many. At the moment all these blm values are in the lower VE tables up to about 60kpa. The engine is getting run in at the moment so nothing extreme.

It is kind of odd though that at idle the spark retardation sits at 2.5deg all the time without any knock counts present. Press the gas pedal a bit and the spark retardation gets lower and goes down to about .9 deg. Let go off the gas pedal and straight back down to 2.5 retardation.

Using Tunerpro to datalog and the Spark Adv Rel. to Ref Pulse will register a value of 23000+ which has to be a value below zero? It does this while the car is idling. As soon as you apply some gas it will give a more real life reading.

I also don't see how this motor can be so rich given the circumstances of using stock AUJP VE tables basically and having the injector constant set at 32 while the injectors are 30 lbs. The VE values for some of the points is down to 46 to achieve the 128 blms. I have only got readings for the lower VE table have not got into the upper one yet much.

Basically the question what causes spark retardation other then knock and why would it be retarding the spark advance at idle?

I set a lower SA in the spark table by a couple degrees where it is idling by 2 -3 degrees and the result was -12 deg retardation from the usualy -2.5.

Might have to check the base timing again to make sure it matches the PROM value.

I attached the datalog to this post.

 

Well the BASE timing is correct at 10deg been checked. If the IAC steps are set to 5-10 at idle it idles like crap and needs a lot more steps then that.

For the sake of it we ran the SAUJP bin made the necessary changes like inj constant, cyl volume etc... All the rest was left stock and it did not run that well. The Idle was crappy, and what we can't get rid of is the Idle retard of 12 deg if we use the SAUJP.

What would cause idle retardation other then knock? Because no knock is present. Could it be something to do with the MSD?

Anyone know or can offer some advice? Obviously if we zero out the retard table it fixes the retardation. But if the ECM needs to pull the timing back then there has to be a reason for it.

I guess the next thing to check is if the shop set the Fuel Pressure right for the HSR.

The car just runs filthy rich all over the board.

 

Idle RPM error spark correction

 

If the error were large enough, would it cause the engine to seemingly have a random stall, after idling fine for a few seconds to a minute? Would the MAP also rise sharply just before, due to this "correction"?

 

So what purpose does this table hold? The car idles at around 60-70KPA and this table has a value of 10 for 60kpa and 20 for 70kpa. So it is taking 20deg of timing out at idle if left like that.

Is there a problem that this table is in effect?

 

Are you sure the XDF file is displaying the proper byte and has the proper conversion? Every XDF I have come across has errors in them and need to be fixed. What ECM & bin mask? What is the XDF ALDL byte number and conversion?

The ECM will add or subtract spark depending on how far the idle RPM is from the target idle RPM.

 

730 ECM, SAUJP BIN, using tunerpro to datalog with the supplied ADS file.

I'll check out the idle rpm vs the target idle rpm.