Getting different AFR's in different gears ? Why ?

[J 98ta]

I just got an LC1 hooked up last week, and did some AutoVe tuning, then went to the track this weekend. I love it, but have a question.

The tune is still an auto VE tune. I cannot seem to get the afr to be the same at WOT in all gears. Seems like the car likes to get rich over the course of a run. 1st gear will be Low 13's 2nd gear will be mid 12's and 3rd will be low 12's in AFR. Why ? I try adjusting the VE richer, and well, it works, gets richer for 1st gear like I wanted it to, but then so does everything else. Seems linear.

Thanks, 'J

BTW: Went 11.58 @ 117 :D

[LSRacing]

WOT is controlled via the PE tables. The VE tuning is only for idle/part throttle driving. Get the idle and part throttle driving right with the auto tune and then go to the track and use the PE VS RPM table to make corrections at WOT.

Jamy

[J 98ta]

Thanks for the reply. I guess I was not clear enough in the question. Given an RPM, say 5600, at WOT it, (the WB) will display a leaner AFR in 1st gear, then be richer in 2nd and more so in 3rd. The graph will slope downhill over the run. I am trying to understand why this happens, so I can attempt to get the same AFR in each gear given the same RPM.

'J

[jfpilla]

Thanks for the reply. I guess I was not clear enough in the question. Given an RPM, say 5600, at WOT it, (the WB) will display a leaner AFR in 1st gear, then be richer in 2nd and more so in 3rd. The graph will slope downhill over the run. I am trying to understand why this happens, so I can attempt to get the same AFR in each gear given the same RPM.

'J

Have you tried disabling cat overtemp?

[J 98ta]

Thanks for the reply.

I just double checked my file. I have B0701 set at Disable. Maybe there are other places I need to change ?

I did notice this before this weekend. But it was with stock type narrow bands, and did not think too much of it.

'J

[LSRacing]

Have you logged the map values at those given rpms to see if maybe you have a diff map value in 1st than you do in 2nd etc... That would be where to start.

Jamy

[J 98ta]

Thanks for the reply, again. :)

MAP is between 90-100 during the run. It usually bounces between 92-97. No real difference in MAP between gears.

'J

[J 98ta]

Here is a screen shot if it helps.

http://j.cz28.com/1161-at-1174.jpg

'J

[GMPX]

Is this running in SD or do you still have the MAF?.

Cheers,
Ross

[J 98ta]

SD, actually still on the AutoVE tune. --> The MAF is still physically there, but is positively not plugged in.

'J

[jfpilla]

SD, actually still on the AutoVE tune. --> The MAF is still physically there, but is positively not plugged in.

'J

You might try scaling table B3605, from 40C to 140C all Maps, with 12.947.

[joecar]

Your trace shows that IAT is decreased alot...
What is happening here...?
Are you going from heat soak to fresh air cool...?

[J 98ta]

jfpilla :

Currently I have that table at 1.13 (I believe same as what you stated, just different form) all potins above 40deg C and above 70 MAP. Is there a reason for making the whole table that way ?

joecar : Yes, heat soak. It was ~50 deg out, and I was running the motor with the fan on, trying to hold ~160-170 deg F coolant temp, and to get some heat into the trans. IAT may be the culprit ? I do not remember/can't find any table that scales fuel based on IAT. Seems that might be the problem ? I might try the old resistor mod this weekend and see what happens.

Thanks for the reply's. :)

'J

BTW: what is B4901 "Charge temperature blending" ?

[jfpilla]

Currently I have that table at 1.13 (I believe same as what you stated, just different form) all potins above 40deg C and above 70 MAP. Is there a reason for making the whole table that way ?

Yes, but not a good one. Since I don't know why your getting those results, it's a "might as well try" idea. Perhaps you're MAP leading into WOT has some affect. Can't hurt to try.

[J 98ta]

Currently I have that table at 1.13 (I believe same as what you stated, just different form) all potins above 40deg C and above 70 MAP. Is there a reason for making the whole table that way ?

Yes, but not a good one. Since I don't know why your getting those results, it's a "might as well try" idea. Perhaps you're MAP leading into WOT has some affect. Can't hurt to try.

OK, thanks. I will give that a shot if the fixed IAT resistor does not change anything. Maybe before sunday I will get a chance, but it is supposed to rain here the next couple of days. Traction is also hard to come by when it's cold out, and not on a track. :wink:

'J

[wait4me]

Piston overtemp protection? That will increase fuel too.. Just a thought

[bink]

Prolly stupid question - but, could it be the O2 sensor heating up with cont. ex. blasts??

[J 98ta]

Bink: I have no idea. I would figure many others would have had the same problem though ?

Wait4me: I did not see that in the tuning software. I did see a table for timing relating to piston protection, but not fuel. Maybe point me in the right direction ?

The only other thing I can think of is if my fuel press creeps up during a run. Problem is, I do not have a fuel press guage. :(

Thanks again,
'J

[caver]

Its very simple.

In the lower gears the engine accerates very quickly. The ecu is reading tables as fast as it can but it is always playing catchup and lags behind .
Additionally the fuel pump has a harder time because of the g forces involved.

Some makes of cars are worse than others but they all do it.