Computer Diagnostics and Tuning Technical discussion on diagnostics and programming of the F-body computers

A couple easy questions

Old May 7, 2004 | 11:29 AM
  #1  
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A couple easy questions

I used freescan to download data. A couple questions are:

It shows a colums with spark timing and knock (in degrees). Lets say that the timing says 38 and the knock says 2.2 degrees. Does that mean it was set @ 38, but after the KR it was actually at 35.8 degrees? Or does it mean that it was 38 dgrees after the KR of 2.2 degrees?

If my O2 mV readings are .995, does that mean the sensor is picking up a lean conditions, or is it picking up a rich condition?

The map seems to go up to 1.0#, is this volts or bar? What is the conversion to KPa?

In some places I am getting 9 degrees of KR. The map is .94-1.04 and the timing says 19-21 degrees. My O2's are .940 to.990 range. Anyone have an idea why I am getting knock?

Lastly, how do youadjust your IAC counts on tunercat?

Last edited by RealQuick; May 7, 2004 at 11:40 AM.
Old May 7, 2004 | 12:53 PM
  #2  
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From: Hell was full so they sent me to NJ
Re: A couple easy questions

It shows a colums with spark timing and knock (in degrees). Lets say that the timing says 38 and the knock says 2.2 degrees. Does that mean it was set @ 38, but after the KR it was actually at 35.8 degrees? Or does it mean that it was 38 dgrees after the KR of 2.2 degrees?

****The data log shows the timing the PCM is actually calling for. It shows you the programmed value MINUS the retard value. Apparently the program was seeing "40deg advance" in the tables and offsets, and as a result of the retard it was only calling for 38deg advance.
=======

If my O2 mV readings are .995, does that mean the sensor is picking up a lean conditions, or is it picking up a rich condition?

****0xx mV would be lean, 9xx is rich. Actually, at WOT, low 800's or below could be too lean.
========

The map seems to go up to 1.0#, is this volts or bar? What is the conversion to KPa?

It appears it is giving you a value that corresponds to 100kPa. I am assuming when you say MAP goes to 1.0 that you mean at WOT, or if you are reading the barometer.
==========

In some places I am getting 9 degrees of KR. The map is .94-1.04 and the timing says 19-21 degrees. My O2's are .940 to.990 range. Anyone have an idea why I am getting knock?

****Could be a response to "real" knock... could be a response to "false" knock (mechanical noise from various engine components). Put some 100 octane unleaded in it and see if the knock goes away. You also need to look at the IAT and the coolant temp to see if either is extremely high - that can cause knock. Can we assume you are running "premium" fuel? Could be carbon buildup in the combustion chambers causing excessive compression ratio. It obviously isn't a case of running lean, because you appear to be running very rich (based on the limited accuracy of the stock O21 sensors at low A/F ratios).
============

Lastly, how do youadjust your IAC counts on tunercat?

****You can't adjust "counts"... you can only adjust the target idle speed. If IAC counts are outside the normal range (20-40 at idle) you need to look for the cause of the problem. A vacuum leak, or a throttel stop screw that is out too far will cause the counts to approach "0", and you may lose control of idle speed. A non-responsive IAC motor or plugged IAC passages could cause the counts to run higher than the "normal" range.
=========

Have you read this:

http://members.aol.com/InjuneerZZ/ScanMast.htm
==========

I have your data logs.... I just haven't had a chance to look at them.

Last edited by Injuneer; May 7, 2004 at 12:55 PM.
Old May 7, 2004 | 01:22 PM
  #3  
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Just wondering.. did you ever lower your injector constant to see if that dropped your BLMs?

I read the last thread had up about your tuning problems and I am still confused about why the car is acting the way it is. Almost seems as if you have a large vacuum leak of some sort by looking at the fueling data and O2 sensor outputs alone but since the old injectors worked fine.. then that theory goes out the window.

160 = lean
.0xx mv O2 reading = lean
strong fuel smell = rich

makes no sense if you only changed injectors.
Old May 7, 2004 | 01:51 PM
  #4  
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Over the years I have looked at hundreds of data logs, and this is really one of the oddest ones I have ever seen.

Appears you started the car at record #104. From #104 thru record #1990.... a period of almost 5 minutes.... the data for most sensors doesn't move at all.... for example the airflow is locked at 10.71GPS, IAT is locked, IAC is locked..... everything just sits there for 5 minutes.

Then it appears to kick into closed loop. The Cell 16 BLM's are 160, and it is pushing the INT's way up, yet almost all the O2 readings are 0xx mV. But... the injector pulse widths are "normal". Appears you may have the wrong injector constants.

Then, at the very end, the whole record goes screwy. At record 4321 the RPM mysteriously leaps from 900 to 3925, then drops to "50", and then the target RPM shows up as 3187. And the whole time it is showing 9deg of knock retard. Appear you shut the engine down at this point? Appears the clock dropped to "0". Is this the only time you have seen the "9deg" knock retard that you talk about in the above post?

And what were you doing while it was sitting there idling for 11 minutes? Every so often, the TPS voltage creeps up above 1.00V, the RPM starts to rise, and the MAP goes way higher than it should with 1% to 4% TPS, but its only following these "bursts" that the O2 sensor mV's come off rock bottom. Were you diddling with the accel pedal?

I would check the injector constants as noted in the post above. I would try and slot the TPS sensor so you can get the closed throttle voltage down closer to 0.50-0.67V.

It's adding fuel like crazy but the O2 values are on the bottom. The only time they move is when the TPS suddenly moves.... look at record #2029, 2260, 2399 (right side only moves, and only after the TPS has closed back down), #3109. Every so often the right side sensor seems to start showing 300 - 800mV, if only for a second or so. Seems like the sensors aren't working right... poor ground? Bad wiring job?
Old May 7, 2004 | 01:56 PM
  #5  
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Re: Re: A couple easy questions

Originally posted by Injuneer
****The data log shows the timing the PCM is actually calling for. It shows you the programmed value MINUS the retard value. Apparently the program was seeing "40deg advance" in the tables and offsets, and as a result of the retard it was only calling for 38deg advance.
=======

Cool.

****0xx mV would be lean, 9xx is rich. Actually, at WOT, low 800's or below could be too lean.
========


It appears it is giving you a value that corresponds to 100kPa. I am assuming when you say MAP goes to 1.0 that you mean at WOT, or if you are reading the barometer.
==========

I dunno, the column reads various numbers from .3-1.0X.

****Could be a response to "real" knock... could be a response to "false" knock (mechanical noise from various engine components). Put some 100 octane unleaded in it and see if the knock goes away. You also need to look at the IAT and the coolant temp to see if either is extremely high - that can cause knock. Can we assume you are running "premium" fuel? Could be carbon buildup in the combustion chambers causing excessive compression ratio. It obviously isn't a case of running lean, because you appear to be running very rich (based on the limited accuracy of the stock O21 sensors at low A/F ratios).
==========

I run 93 octane. IAC is 54 and the coolant is around 81 DURING THE KNOCK.


****You can't adjust "counts"... you can only adjust the target idle speed. If IAC counts are outside the normal range (20-40 at idle) you need to look for the cause of the problem. A vacuum leak, or a throttel stop screw that is out too far will cause the counts to approach "0", and you may lose control of idle speed. A non-responsive IAC motor or plugged IAC passages could cause the counts to run higher than the "normal" range.
=========

Have you read this:

http://members.aol.com/InjuneerZZ/ScanMast.htm
==========

I have your data logs.... I just haven't had a chance to look at them.
I have a print out of it. It answers some questions. Very good write up. Please look at the logs when you have time.

Thanks fred.
Old May 7, 2004 | 02:09 PM
  #6  
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Originally posted by turbo_Z
Just wondering.. did you ever lower your injector constant to see if that dropped your BLMs?

I read the last thread had up about your tuning problems and I am still confused about why the car is acting the way it is. Almost seems as if you have a large vacuum leak of some sort by looking at the fueling data and O2 sensor outputs alone but since the old injectors worked fine.. then that theory goes out the window.

160 = lean
.0xx mv O2 reading = lean
strong fuel smell = rich

makes no sense if you only changed injectors.
I sent you logs today, but the email got returned. I have new data showing the O2's in the 700-900mV range. I originally had 50.99 for fuel inj. constant for the 48lb/hr Accels (assuming they are 48's, I bought used). I then lowered it to 35 like you and Fred said too. The car idles better and no more codes. Less surging at idle. Changing the injector constant is all i did. I believe the lean readings were false since i could smell fuel. A co worker has an alcohol funny car and he mentioned that if there is way too much fuel, the O2 sensors pickup the O2 in the fuel and will give a lean voltage. I dunno. I will try your email again with my new numbers.
Old May 7, 2004 | 02:25 PM
  #7  
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Originally posted by Injuneer
Over the years I have looked at hundreds of data logs, and this is really one of the oddest ones I have ever seen.

Appears you started the car at record #104. From #104 thru record #1990.... a period of almost 5 minutes.... the data for most sensors doesn't move at all.... for example the airflow is locked at 10.71GPS, IAT is locked, IAC is locked..... everything just sits there for 5 minutes.

Then it appears to kick into closed loop. The Cell 16 BLM's are 160, and it is pushing the INT's way up, yet almost all the O2 readings are 0xx mV. But... the injector pulse widths are "normal". Appears you may have the wrong injector constants.

Then, at the very end, the whole record goes screwy. At record 4321 the RPM mysteriously leaps from 900 to 3925, then drops to "50", and then the target RPM shows up as 3187. And the whole time it is showing 9deg of knock retard. Appear you shut the engine down at this point? Appears the clock dropped to "0". Is this the only time you have seen the "9deg" knock retard that you talk about in the above post?

And what were you doing while it was sitting there idling for 11 minutes? Every so often, the TPS voltage creeps up above 1.00V, the RPM starts to rise, and the MAP goes way higher than it should with 1% to 4% TPS, but its only following these "bursts" that the O2 sensor mV's come off rock bottom. Were you diddling with the accel pedal?

I would check the injector constants as noted in the post above. I would try and slot the TPS sensor so you can get the closed throttle voltage down closer to 0.50-0.67V.

It's adding fuel like crazy but the O2 values are on the bottom. The only time they move is when the TPS suddenly moves.... look at record #2029, 2260, 2399 (right side only moves, and only after the TPS has closed back down), #3109. Every so often the right side sensor seems to start showing 300 - 800mV, if only for a second or so. Seems like the sensors aren't working right... poor ground? Bad wiring job?
Fred, you reading the old log. i sent you a new one this morning. the log only goes up to 2968. The numbers are alot better due to me changing the inj. constant from 50.99 (which is the old data) to 35 which is in the new data i sent this morning to your aol account. Please check the new one out and let me know what you think. Thanks fred.
Old May 8, 2004 | 10:17 AM
  #8  
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The new log shows that the Cell 10 BLM's have now dropped to 108. The left side seems like it is pretty much in balance at that point, indicating you need to increase the injector constant by about 5.... try values in the range of 40-42#/HR. The right side seems to be having more of a problem, since the short range correction (INT) is pulling still more fuel out.

What are the exact mod's on your car? Aftermarket TB? Altered MAF sensor? The MAP seems to jump up excessively for the amount of throttle rotation it is indicating. That's when you start getting the knock retard.
Old May 8, 2004 | 11:10 AM
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Originally posted by Injuneer
The new log shows that the Cell 10 BLM's have now dropped to 108. The left side seems like it is pretty much in balance at that point, indicating you need to increase the injector constant by about 5.... try values in the range of 40-42#/HR. The right side seems to be having more of a problem, since the short range correction (INT) is pulling still more fuel out.

What are the exact mod's on your car? Aftermarket TB? Altered MAF sensor? The MAP seems to jump up excessively for the amount of throttle rotation it is indicating. That's when you start getting the knock retard.
Sorry I didnt answer earlier. I have the fiollowing relevant mods:

Ported heads
XE230/236 114LSA 4 degrees adv.
ZO6 MAF
52mm BBK TB
Jet Hot LT's
Accel Ignition

Question for ya, does the ecm retard timing using the burst knock constant (set @ 3.1%). Does it retard timing until knock goes away, or does it retard is based on this percentage? Does it use the knock tables. My PE table for knock has 7.00 in it. Does that mean will get 7 degrees or retard if it picks up knock? I emailed you new logs @ 40 inj. cnst.

I want to get the inj. constant right, so i can tune WOT next Sat. on the dyno. Thanks Fred.

Last edited by RealQuick; May 8, 2004 at 11:17 AM.
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