When tuning WOT with my '98 PCM, I see that sometimes Commanded PE is requested as early as 2625RPM, and at other times, it holds off until 3500RPM or higher. The only other pattern I see is that the MAF Hz is usually in the 6000 range when it enters PE.
We don't have the PE enrichment rate table in this PCM, so what combination of variables is used to determine when PE fueling is enabled? What can I do to get into PE at an earlier RPM with this OS?
make sure your PE Delay is set to 0Originally Posted by JimMueller
and make sure you set your PE Throttle Pedal Hot/Cold tables to values that makes sense for your tune...
-Scott -
I have the delay at 0; PE throttle hot/cold tables are all 10; PE Enable MAP is 85. Guess I'm stuck.
Lower the enable map....
It has to meet all requirements to go into PE
Rpm, map, and tps
You will want to put the tps tables back to a more reasonable value as I'm sure there is no need to be in pe at 10% tps.
Those are the settings put in by Bob Morreale, instructor at The Tuning School (http://www.thetuningschool.com) when he tuned my car on 2/20/14. His justification was to primarily use MAP to determine PE entry by almost taking TPS completely out of the equation. Counterpoint?
There is no counterpoint necessary
If it doesn't work for your set up then it is incorrect
Lower the map value to fit what you want to do on your car
The PCM is doing exactly what you are commanding it to do
The reason there is a TPS table is because you can have the same map value at multiple tps positions
The solution for you is to lower the map values and bring the TPS values up to match what you are trying to accomplish
What I want to do with the car is to have the PE fueling ramp in as fast as possible without changing OS's. If I go WOT in the 2000RPM range the fueling starts at stoich and ramps into PE, I don't see a way to into enrichment fueling any faster with this OS.
I've told you how to do it....
not sure why you wont listen to what I have suggested...
it works fine when you use the PE settings the Correct way...
What you have been shown in "the Tuning School" is not the only way to tune PE...in my opinion, its actually quite incorrect as it will lead to unstable results as you are experiencing....
the proper way to set PE is to command what you desire in the PE table for target AFR.
set the MAP enable to a low enough value to match the conditions you are trying to achieve
Set the TPS Hot/Cold Tables to fit for what you need it to do at various RPM's
Set PE Delay RPM to a lower value than you want PE to be allowed to kick in
at 2000 rpm and 50% TPS you arent going to hit 85kpa...so you need the MAP enable value to be lower and the TPS value to fit what you are trying to do...
if you need a more gradual transition between stoic and your desired PE value based on MAP... then you can set the OLFA table to Ramp up to your PE value.
the ECU will automatically use whichever value is Richer between the PE/OLFA tables
(I often use this to allow partial enrichment when you are at part throttle but higher KPA values that are not technically High Load...example: 45% throttle / 70 kpa / spirited acceleration)
the Enrichment is plenty fast on the 98 pcm...something like 12.5ms changing from Commanding stoic to commanding PE value if I remember correctly
your PE Enrichment problem is NOT related to the Enrichment rate...its related to how you have the TPS/MAP/RPM/DELAY values set up.
when you actually understand how the ECU works, you can make it do anything you want....and the 98 will do exactly what you want once you set up the parameters correctly.
Last edited by S2H; 02-22-2014 at 10:22 PM.
-Scott -
I really don't like the "someone told me so" reasons for doing things.
Scott is right.
There are cases where you should use MAP to enable and set TPS low but on most n/a setups setting MAP low and using TPS to enable works very well.
Regardless, you need to play with those settings to get what you want. I just worked on a 98 yesterday and within one frame on the scanner it goes from Stoich to PE.
In your first post you describe the problem differently, stating that it comes on at different RPM's, are you saying that this only happens under 2k rpm and when it does happen it delays anywhere between 2625 and 3500rpm??
Sorry if I wasn't clear earlier, hopefully this will be easier to understand... While on the dyno last week (I don't have the graph or files yet unfortunately), when the pull started at around 3000, the AFR went right to commanded (12.x) through the end of the pull. I wanted to see the torque curve earlier in the RPM's, so we began a pull at 2000RPM and ran it to 6500; on that pull, the AFR began at stoich and gradually ramped into PE fueling after a few hundred RPM instead of immediately going into PE fueling. We do not have any logs for that pull, but hopefully once I get the graph it will be easier to see. The instructor said this was a result of not having access to the PE enrichment table in later OS's.
Post #1 was referring to a street log from months ago I have with WOT pulls in it, as I was trying to see if that's how it was before. But I was minimizing table PIDs for the benefit of polling rate while tuning VE so I don't have TPS in the log. I'll have to capture new logs.
if that Instructor cant make it enter PE sooner...
then he should not be teaching...he doesnt know what he is doing if he cant make the PE come in....
I've tuned HUNDREDS of 98 LS1 cars....with ZERO ISSUES
Just because somebody has a "Tuning School"...does not mean they know what they are doing on all situations...
I've been tuning for over 16 years and even I still get stumped from time to time.
post your tune and a log of it happening... and when I get a chance I'll make a couple of changes and send you back the file....it will come on when you need it to
-Scott -
I can't currently duplicate it, the source of the concern was merely the results on the Mustang dyno results screen, roughly between 2000RPM and 3000RPM where the AFR was ramped down from what appeared to be stoich to PE. The LTFT's after I came home were in the positive teens in the range of 1200>2400RPM & 25>55kPa. Perhaps as a result that skewed the AFR on the dyno? My lambda error at WOT is showing significantly off near 2000RPM, not sure if that's the difference between my AFX mounted in the collector and it's wiring vs. his clamped to the tailpipe and its wiring... or if it's truly off and I need to adjust it.
This past weekend I cleaned up most of the LTFT error in the VE tables but haven't begun to check MAF yet. Current tune, and some dated logs attached.
Only 5 files allowed per post, here's the current tune.
Try logging commanded eq, as your equivalence ratio pid is the inverse of lambda. And you need to tune your Maf/VE to correct the very lean fuel trims.
Russ Kemp
Last edited by Russ K; 02-25-2014 at 12:03 PM.
Done; future logs will include Commanded EQ Ratio. Which log are you referring to on the very lean fuel trims? The most recent VE table reflects the fuel trims in '02-23-ve-ltft-2" log. The earlier '02-23-ve-ltft' log definitely was lean. Both of those were done in the same weather back-to-back.
The lean log was 02-23veltft
Russ Kemp
this thread is GREATlove the attitude
heres a File that should make a change to how PE reacts...
I still need to see another log to see what changes I need to make still as I can only guess and see how close I get and then make more changes once I see what this one does
also, heres a picture...
you can see that your PE is doing exactly as you commaded in your previous file...
it comes on when you hit 10% throttle and 85 kpa
Capture.JPG
something else I added is a blend in the OLFA table so that PE will gradually come in when you havent met all criteria.
it will be on full by 85 kpa even if you havent met the TPS/MAP requirements
it will also only be partially rich from 50 kpa up if you havent met TPS/MAP requirements
theres no reason to be 12.5 at part throttle unless you are getting closer to 85kpa..
all you will do is hurt power and fuel mileage by going into PE at 10% throttle and low KPA...
example being you are just cruising down the road and put your foot down a little bit to speed up and pass another car but you havent really gone Full throttle...maybe you are only at 35 or 40 % throttle...no need for Full PE...it would be overly rich for best power at part throttle
obviously if you stab the throttle, and it sees 100 kpa ish, its going to go Full PE as you will have met the TPS and MAP requirements.
-Scott -
The OLFA table is only used when in open loop. And once TPS/Map PE threshold has been met, then the richer of the PE table or OLFA table will be used.
I'm sure Jim's issue is that the Maf/VE tables aren't matching the commanded PE table at the lower RPM. And his AFR error histogram is inaccurate because he is logging equivalence ratio instead of commanded eq.
Russ Kemp
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