Controlling PE on 98?

[crewchef]

Is there anything different on a 98 w/ regards to defining PE ratio

I'm having trouble getting commanded AFR (commanding 11.5 to get 12.4). VE and MAF have been tuned and all LTFTs are -3 to +1. Scaled higher range MAF numbers 10% higher to check for change and saw little to nothing.

While searching and digging I noticed this in the help file;


V8 Power Enrich Fuel EQ Ratio vs. RPM: This is the main table that is used to tune WOT fuel for post 1999 V8 engines. The values in this table are Equivalence Ratio's (Fuel/Air multipliers or AFR divisors) ie. values greater than one are richer, values less than one are leaner. The values relate directly to the Stoich AFR and the resulting commanded AFR is Stoich divided by this PE equivalence ratio. Eg. if the multiplier is 1.1 then the commanded AFR will be 14.7/1.1 or 13.36.

Do I have another table I need to be working with to set desired AFR at WOT?

[WS6FirebirdTA00]

You have to tune the tables correctly with a wideband to get the commanded and actual to match. Fuel trims will not cut it as they do not do anything for WOT/OL.

[LinearX]

You have to tune the tables correctly with a wideband to get the commanded and actual to match. Fuel trims will not cut it as they do not do anything for WOT/OL.

Based on what he posted from the help file, it reads like the PE EQ ratio vs. RPM tables is used for 99+ ECMs. Specifically, he's done an LS1 swap into a gen3 T/A with a 98 engine/ECM. I think it's safe to assume that is still the table that he sets for PE AFR, correct?

I was under the impression, however, that on the 98 and earlier ECMs, that the number in the table was multiplied by stoichiometric instead of divided by like in the 99+ ECM. Am I way off base here?

For the record, he just send his HPT interface back to be upgraded to Pro, and he has an LM1 that he's going to be logging with. In the past, he's had to log both HPT and the LM1 and compare.

[WS6FirebirdTA00]

good, a wideband will help out a lot being able to scan it. As far as the PE, I am not sure what is going on with the description. If you check it out in the roll over feature in the editor window, it does not say that. I do not recall it ever being different.

[crewchef]

You have to tune the tables correctly with a wideband to get the commanded and actual to match. Fuel trims will not cut it as they do not do anything for WOT/OL.

Some clarification there as I was mixing LTFT and WB information. I was only using LTFT as reference to where basic tune is. Normal driving/cruising the car stays pretty close to dead on Stoich. Occasionally look at LTFTs just to see if narrowbands are adding any correction and there is some going on but it's minor. That makes me think I at least understand the process and have gotten that part right. LinearX is correct in that up until now I've been having to use two different logs/devices and do compares. WOT area is pretty easy to compare though. In both logs it's evident where it starts/stops and LM1 is showing 12.3/12.4. That's what I want (for now) but I'm commanding something much lower to get it.

Besides the PE table question I'm also concerned if I'm getting the MAF table correct at higher frequencies and/or if the values I'm inputting are getting ignored because of some table saying that's too much air. I scaled the high end frequency settings up higher to see if it would change AFR and didn't see much if any change.

My current MAF flow numbers are +30% higher than stock. Remember this is a custom CAI on a 3rd Gen. Big K&N cone, 4" pipe x 28", hump hose to MAF and then a 90 into TB. Also has an LS6 intake. MAF has ported ends and is descreened. Have stock one on the bench, may change over and test w/ it.

Anyway, a lot of discussion but back to basic question. Is there something different in the 98 OS that would make me tune PE differently?

[WS6FirebirdTA00]

post up your scan/tune, but no, it should be the same.

[crewchef]

Laptop off w/ son will try to post tonight.

[LinearX]

I hope I didn't muddy the waters with my post, Tony.

I don't know where I came up with the notion that PE is done differently on the 99+ vs. the 97-98 ECMs.

[crewchef]

I hope I didn't muddy the waters with my post, Tony.

I don't know where I came up with the notion that PE is done differently on the 99+ vs. the 97-98 ECMs.

No your good, more people pondering the better. Just going to dig on this thing until I come up w/ something. May back burner this until interface comes back and I can get some good solid logs.

The more I ponder on this I think it may be MAF related. We'll get the interface back and start fresh w/ new SD tune for VE all the way up and then do the MAF and see where we are. I did find some notes on latest tune, MAF scale is actually 19/20% higher than stock not 30%.

[Bill@HPTuners]

99+ software came out before 98's & therefore the help file for that portion was probably created initially for 99+'s and was simply never changed, however the 98's use the pe table just like the 99+'s do.

[LinearX]

99+ software came out before 98's & therefore the help file for that portion was probably created initially for 99+'s and was simply never changed, however the 98's use the pe table just like the 99+'s do.

Thanks for setting me straight, Bill. I dunno where I came up with the notion of them being different. I guess I'll have to flush that incorrect piece of information.

[Bill@HPTuners]

Actually since its in the actually help file(the scroll over help looks correct) I can update it for the next public release more than likely.