Negative LTFTs at WOT, Fix???
#1
On The Tree
Thread Starter
iTrader: (25)
Join Date: Mar 2004
Location: Dayton ohio
Posts: 140
Likes: 0
Received 0 Likes
on
0 Posts
Negative LTFTs at WOT, Fix???
Hi, I'm trying to figure out why my 402 is randomly going lean. I noticed that my Long Term Fuel Trims are going from 0 to -15 at WOT and this is when the car starts to go lean. You can actually watch the injector duty cycle go from 66% down to 53% when the LTFTs drop. How can I fix this?
I can email anyone the graph of this taking place as a powerpoint file if this would help. Thanks, Brian
I can email anyone the graph of this taking place as a powerpoint file if this would help. Thanks, Brian
#5
TECH Regular
iTrader: (5)
Join Date: Nov 2001
Location: Washington Crossing, PA
Posts: 422
Likes: 0
Received 0 Likes
on
0 Posts
Yes, this sounds more like you are never getting to open loop at WOT. You should log the FTC at WOT and make sure that it's 15 or 22 (more likely, the latter). If not, then you need to dig into what switch is keeping it out of open loop (e.g., TP%, Engine Temp, etc.).
#6
On The Tree
Thread Starter
iTrader: (25)
Join Date: Mar 2004
Location: Dayton ohio
Posts: 140
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Fran D
Yes, this sounds more like you are never getting to open loop at WOT. You should log the FTC at WOT and make sure that it's 15 or 22 (more likely, the latter). If not, then you need to dig into what switch is keeping it out of open loop (e.g., TP%, Engine Temp, etc.).
I looked at all the sensors that I can think of would cause this and they look great. What gets me is that when this takes place all the sensors stay the same so it makes me think it is tuning related, but I don't know. I notice my lights dim when I go WOT. Could this have anything to do with the negative LTFTs? I think it is from my belt slipping on the alternator.
#7
TECH Regular
iTrader: (5)
Join Date: Nov 2001
Location: Washington Crossing, PA
Posts: 422
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by 6speeder
I looked at all the sensors that I can think of would cause this and they look great. What gets me is that when this takes place all the sensors stay the same so it makes me think it is tuning related, but I don't know. I notice my lights dim when I go WOT. Could this have anything to do with the negative LTFTs? I think it is from my belt slipping on the alternator.
The dimming at WOT, I think, is a separate issue (unless, of course, the controller supply droops below 4 volts, but I think the car would just shut off then). That's odd... in and of itself. Perhaps a slipping belt.
Please check the FTC at WOT.
Trending Topics
#9
On The Tree
Thread Starter
iTrader: (25)
Join Date: Mar 2004
Location: Dayton ohio
Posts: 140
Likes: 0
Received 0 Likes
on
0 Posts
Ok, I think the dimming is coming from the alternator slipping because there is rubber next to the pulley on the alternator, but it still does drop to 11.4 volts as soon as I get on it. I logged it last night and the cell it was in for the most part was 22 at WOT.
#10
TECH Regular
iTrader: (5)
Join Date: Nov 2001
Location: Washington Crossing, PA
Posts: 422
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by 6speeder
Ok, I think the dimming is coming from the alternator slipping because there is rubber next to the pulley on the alternator, but it still does drop to 11.4 volts as soon as I get on it.
Originally Posted by 6speeder
...I logged it last night and the cell it was in for the most part was 22 at WOT.
If you have a contiguous stream of data with TP% at 100 and the FTC is not steady at 22 (without being in a "transition" region, i.e., shift), then there's something that is overriding the PE Enable TP% vs. RPM table. That's probably the first place to check. Have you done something with the tune, recently, to cause these issues? However, if you have a contiguous stream of data with TP% at 100, FTC at 22 and LTFTs at -15, that's a problem that would extend beyond the capabilities of any tuning software, that I know of, to deal with. There may be a problem with the PCM. I hope that's not the case.
I hope all this rambling is helpful and not confusing. Good luck!