My RPMs bounce slightly at idle. There is also on occasional audible miss. If I increase TPS to 4%, RPMs go to about 1100 and the bouncing continues.
First of all, how can I tell if this is hardware or software related? If it's software related, what do you think it is and how can I troubleshoot it?
Please note that this is NOT a stall saver type bounce. It's much more subtle but still very annoying.
First of all, how can I tell if this is hardware or software related? If it's software related, what do you think it is and how can I troubleshoot it?
Please note that this is NOT a stall saver type bounce. It's much more subtle but still very annoying.
It does the same thing cold when in open loop. Idle fluctuating, pulse width wont stay steady, AFR is ALL OVER THE PLACE between 14 and 17. She ain't happy at idle and I can't figure out why. This is a stock TBI 350 with headers and 65# injectors.
Moderator
Quote:
Looking at the data log I see a couple of items that don't seem to be correct. The first is that the SA appears to be low. Only 5* when at 1100 RPM and 25 KPa MAP.Originally Posted by Darkshot
It does the same thing cold when in open loop. Idle fluctuating, pulse width wont stay steady, AFR is ALL OVER THE PLACE between 14 and 17. She ain't happy at idle and I can't figure out why. This is a stock TBI 350 with headers and 65# injectors. At idle the SA is 4 - 5*. This is too low for an L05.
I see that the BPC changes with a change in manifold pressure. So the FPR should be vacuum referenced. When this is done the minimum fuel pressure with the vacuum line off is 18 psi. Any lower and the fuel pressure will drop off too much at low manifold pressure.
The other thing is that the BPC vs VAC table doesn't appear to be set up correctly. The BPC value doesn't evenly track the manifold vacuum. There is a EBL utility to calculate the values for this table. There is also a Excel SS that was provided with the earlier units.
Email me if you want/need the utility. You can also email your calibration to me and I can take a look at it. For that matter I can copy L05 SA & VE tables into it and return it: bobr at dynamicefi.com
For the WB I used 0V for 10:1 and 5V for 20:1 on channel 1. Not exact but gives me an idea of the AFR fluctuation. It appears to be normal as the engine is in closed loop. It oscillates with the AFR, and changes as it should with the throttle blip.
RBob.
Fuel pressure is not vacuum referenced. Its a stock regulator. I do have a TPI pump in there, but the pressure i measure to be a constant 12.8 ~ 12.9 PSI. BPC vs VAC is 135 across the board.
Also, I tried copying the spark tables from stock LO5 bin files you supplied to me and it ran bad. Extremely rough when letting out the clutch when the engine isn't fully up to temp and pinging throughout the RPM range when it is up to temp, especially when accelerating in a higher gear (3, 4, 5) at lower (below 2000) RPM forcing me to downshift when I usually don't have to.
The current Main SA table that I am using has significantly lower values across the board than those LO5 bins from the late 80s/early 90s Caprice cars. Has never made sense to me because my car is lighter and should be able to take MORE than the stock LO5 timing, but it hasn't proven to be the case so I've just been rolling with it.
I do not know if this is related to the bouncing problem I'm having or not.
Lastly - I'm trying to get my car to set up to pass smog at the moment, so i'm somewhat hesitant to jack my timing up because I've had a problem with NOx in the past.
Also, I tried copying the spark tables from stock LO5 bin files you supplied to me and it ran bad. Extremely rough when letting out the clutch when the engine isn't fully up to temp and pinging throughout the RPM range when it is up to temp, especially when accelerating in a higher gear (3, 4, 5) at lower (below 2000) RPM forcing me to downshift when I usually don't have to.
The current Main SA table that I am using has significantly lower values across the board than those LO5 bins from the late 80s/early 90s Caprice cars. Has never made sense to me because my car is lighter and should be able to take MORE than the stock LO5 timing, but it hasn't proven to be the case so I've just been rolling with it.
I do not know if this is related to the bouncing problem I'm having or not.
Lastly - I'm trying to get my car to set up to pass smog at the moment, so i'm somewhat hesitant to jack my timing up because I've had a problem with NOx in the past.
Moderator
In the calibration you sent me the 80 KPa entry of the BPC vs VAC table is 127. The others are at 135. But this doesn't match the data log you posted. There the BPC goes as low as 117.
Best is to use the PromId field of the calibration to keep them sorted. The PromId is also shown on the WUD display. So it is easy to match up data logs with the calibration.
Since there has been a fair amount of timing pulled, I would say that the distributor base timing is off. If the timing is really what the data log showed, the exhaust manifolds would be glowing and the engine would have no power.
There may be a mis-match between the damper & timing tab (there are two different set ups). Or the ring slipped on the damper.
RBob.
Best is to use the PromId field of the calibration to keep them sorted. The PromId is also shown on the WUD display. So it is easy to match up data logs with the calibration.
Since there has been a fair amount of timing pulled, I would say that the distributor base timing is off. If the timing is really what the data log showed, the exhaust manifolds would be glowing and the engine would have no power.
There may be a mis-match between the damper & timing tab (there are two different set ups). Or the ring slipped on the damper.
RBob.
Oh man, this is scaring me.
The LO5 is a crate motor bought and installed new in about 2002. What can we make of this BPC issue? There's no modifiers for it anywhere? I am 100% sure that the .bin that I am running is the one I sent you - 135 across the board and 127 or something like that for the last value ( i forgot to mention that last value when I said "135 across the board"). I will go check it again. I also checked the dumps and I see the same thing that you see - a changing BPC.
And about the timing....I'm not really sure what to say. Is it possible that I have buildup in the cylinders? ANYTHING else that could do it?
Something is fishy here it seems!
The LO5 is a crate motor bought and installed new in about 2002. What can we make of this BPC issue? There's no modifiers for it anywhere? I am 100% sure that the .bin that I am running is the one I sent you - 135 across the board and 127 or something like that for the last value ( i forgot to mention that last value when I said "135 across the board"). I will go check it again. I also checked the dumps and I see the same thing that you see - a changing BPC.
And about the timing....I'm not really sure what to say. Is it possible that I have buildup in the cylinders? ANYTHING else that could do it?
Something is fishy here it seems!
Moderator
BPC changing, I found it: EGR. Forgot all about that, sorry. Took a while as I checked other items first then went to the code. Sure enough, the EGR will change it to adjust the PW.
Just make the last entry 135 and all is good with the BPC value.
As for the spark timing, I'm not sure what to say. Maybe it was assembled with the wrong damper. At this point if it runs OK, then you must be close with the true spark timing. Wouldn't hurt to check other the firing order, plug gaps and so on.
Back to the bouncing RPM. In the log you sent when the engine is in closed loop. The RPM change coincides with the O2 sensor feedback. And the INT moves +- 1 during this time. This is a sign that the proportional gains are off.
I usually adjust this table:
PRP - Gain Muliplier vs Airflow
Only in those areas that require changing. Note the data log at idle the airflow (G/S) is 14 - 16 at idle. Reduce the 0 and 16 rows by a few percent of the value in the table.
When you are holding the throttle open the airflow is 28 - 30 gms/sec. So also reduce the 32 gms/sec row by a small percentage of the value in that row.
Give it some time to see if that worked. Note that the proportional gains are only active in closed loop.
Which is a little confusing since you mention that cold idle does the same thing. Most likely there is something else causing the fluctuating cold idle.
RBob.
Just make the last entry 135 and all is good with the BPC value.
As for the spark timing, I'm not sure what to say. Maybe it was assembled with the wrong damper. At this point if it runs OK, then you must be close with the true spark timing. Wouldn't hurt to check other the firing order, plug gaps and so on.
Back to the bouncing RPM. In the log you sent when the engine is in closed loop. The RPM change coincides with the O2 sensor feedback. And the INT moves +- 1 during this time. This is a sign that the proportional gains are off.
I usually adjust this table:
PRP - Gain Muliplier vs Airflow
Only in those areas that require changing. Note the data log at idle the airflow (G/S) is 14 - 16 at idle. Reduce the 0 and 16 rows by a few percent of the value in the table.
When you are holding the throttle open the airflow is 28 - 30 gms/sec. So also reduce the 32 gms/sec row by a small percentage of the value in that row.
Give it some time to see if that worked. Note that the proportional gains are only active in closed loop.
Which is a little confusing since you mention that cold idle does the same thing. Most likely there is something else causing the fluctuating cold idle.
RBob.
Wow.
Turns out when I was setting my timing to stock 0*, I had bumped that stupid little dial on the back of my timing light to 17*. That's right I was throwing in 17 extra degrees of timing this whole time and I didn't even notice it until the smog guy checked it and failed me for it. All the times I double checked it I can't believe I failed to check that dial. (It's a new timing light, my old one didn't have the dial.) That explains everything.
Back to square one!
Turns out when I was setting my timing to stock 0*, I had bumped that stupid little dial on the back of my timing light to 17*. That's right I was throwing in 17 extra degrees of timing this whole time and I didn't even notice it until the smog guy checked it and failed me for it. All the times I double checked it I can't believe I failed to check that dial. (It's a new timing light, my old one didn't have the dial.) That explains everything.
Back to square one!