How do you adjust ltft cells 19 and 20?
A little more info.
I have the vortech supercharger with a 2.5" pulley on it.
I had the 2.75" pulley in. Then I put in the 50lb injectors. I sent the pcm to ed wright for tunning the injectors. With his tune it was running very lean at idle +25 and really rich up top. I ended up taking the car up to him. He put the tech 2 on it and saw the LTFT and said I had a vacuum leak.. So I spent for ever trying to find a vacuum leak. I tore the motor apart several times. I finally got LS1 edit. I played around with the ifr table. He had it set in the high 6's. I ended up getting the ltft around-2 -3 with the ifr set to the mid 4's. The car idled great. I adjusted pe and was good to go. Now I have the 2.5" pulley on and twin intank walbro's. Fuel pressure is around 62 PSI. I can not get the car to idle. with the ifr's in the mid 4's it is reading lean at idle and rich up top again. I had tunned pe before I realized my ltft were off. So I made 629RWHP. But I can't get it to idle. When in open loop it sounds like it has a cam in it and vacuum is around 13". If I give it a little throttle it clears up and vacuum goes up to 15". I have now adjusted injector offset to what someone posted for 50lb injectors. It didn't seem to have any affect.
My problems are in fuel trim cells 19, and 20. I adjusted ve below 1200rpms and it has made no difference in those cells.
I need to know what to adjust to affect those cells.
I have the vortech supercharger with a 2.5" pulley on it.
I had the 2.75" pulley in. Then I put in the 50lb injectors. I sent the pcm to ed wright for tunning the injectors. With his tune it was running very lean at idle +25 and really rich up top. I ended up taking the car up to him. He put the tech 2 on it and saw the LTFT and said I had a vacuum leak.. So I spent for ever trying to find a vacuum leak. I tore the motor apart several times. I finally got LS1 edit. I played around with the ifr table. He had it set in the high 6's. I ended up getting the ltft around-2 -3 with the ifr set to the mid 4's. The car idled great. I adjusted pe and was good to go. Now I have the 2.5" pulley on and twin intank walbro's. Fuel pressure is around 62 PSI. I can not get the car to idle. with the ifr's in the mid 4's it is reading lean at idle and rich up top again. I had tunned pe before I realized my ltft were off. So I made 629RWHP. But I can't get it to idle. When in open loop it sounds like it has a cam in it and vacuum is around 13". If I give it a little throttle it clears up and vacuum goes up to 15". I have now adjusted injector offset to what someone posted for 50lb injectors. It didn't seem to have any affect.
My problems are in fuel trim cells 19, and 20. I adjusted ve below 1200rpms and it has made no difference in those cells.
I need to know what to adjust to affect those cells.
They are. I have been looking at them all day. Cell 20 is the first cell it goes into at closed loop. Then it goes to cell 19 when purge startes engaging. If i give it just a little throttle it goes to cell 22.
I have my ifr at low 4's. In open loop after start up, the vehicle idles fine. No surging or roughness. As soon as it goes closed loop in cell 20 the ltft are -8 -9. But the idle is hunting and running rough and vacuum drops to 10-12". All the fuel trim cells are running rich at the top of the map scale for that cell, and a little lean at the lower map scale for that cell. I have adjusted the whole ve table from 40-140. The fuel trims don't seem to change. But the engine does seem to react to the changes.
Any suggestions?
Any suggestions?
On The Tree
Joined: Oct 2003
Posts: 175
Likes: 0
Originally Posted by 30thta436
I have not been able to get the car to idle correctly in these two cells.
I can find maps and info on cells 1-15 but nothing above that.
I can find maps and info on cells 1-15 but nothing above that.
http://www.efilive.com/forum/viewtopic.php?t=474
Originally Posted by Fetumpsh
Have a read of this thread....
http://www.efilive.com/forum/viewtopic.php?t=474
http://www.efilive.com/forum/viewtopic.php?t=474
I have read that. It tells what the cells are and when they are used, but not how or what to adjust to make changes in those upper cells.
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TECH Resident
Joined: Jan 2002
Posts: 754
Likes: 0
From: USA
Unless you changed (via PCM tuning ) at what temp the PCM goes into closed loop,
cell 20 is a COLD idle cell (open loop) before getting to 120 degrees water temp and cell 19 is the closed loop idle ( with no A/C on )
In most cases of this type of problem with a SC'er the problem is the design of innercooler, where MAF was installed and the pop off valve.
I have seen at idle RPMs where MAF should be reporting about 1 lb/min air mass and output frequency should be about 2,800 Hz instead reporting like 5 lbs/min with an output around 5,000 Hz.
Meaning the PCM is being told there is a high amount of air mass when there should not be thus a design issue causing high idle and decel fuel trims.
cell 20 is a COLD idle cell (open loop) before getting to 120 degrees water temp and cell 19 is the closed loop idle ( with no A/C on )
In most cases of this type of problem with a SC'er the problem is the design of innercooler, where MAF was installed and the pop off valve.
I have seen at idle RPMs where MAF should be reporting about 1 lb/min air mass and output frequency should be about 2,800 Hz instead reporting like 5 lbs/min with an output around 5,000 Hz.
Meaning the PCM is being told there is a high amount of air mass when there should not be thus a design issue causing high idle and decel fuel trims.
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Originally Posted by Team ZR-1
Unless you changed (via PCM tuning ) at what temp the PCM goes into closed loop,
cell 20 is a COLD idle cell (open loop) before getting to 120 degrees water temp and cell 19 is the closed loop idle ( with no A/C on )
In most cases of this type of problem with a SC'er the problem is the design of innercooler, where MAF was installed and the pop off valve.
I have seen at idle RPMs where MAF should be reporting about 1 lb/min air mass and output frequency should be about 2,800 Hz instead reporting like 5 lbs/min with an output around 5,000 Hz.
Meaning the PCM is being told there is a high amount of air mass when there should not be thus a design issue causing high idle and decel fuel trims.
cell 20 is a COLD idle cell (open loop) before getting to 120 degrees water temp and cell 19 is the closed loop idle ( with no A/C on )
In most cases of this type of problem with a SC'er the problem is the design of innercooler, where MAF was installed and the pop off valve.
I have seen at idle RPMs where MAF should be reporting about 1 lb/min air mass and output frequency should be about 2,800 Hz instead reporting like 5 lbs/min with an output around 5,000 Hz.
Meaning the PCM is being told there is a high amount of air mass when there should not be thus a design issue causing high idle and decel fuel trims.
If that maf problem is what you say, do you have a suggestion?
TECH Regular
Joined: Nov 2003
Posts: 434
Likes: 0
From: Dallas
I agree with Team ZR1. I only see cell 20 for the first few minutes after a cold start - it bounces around between cells, 19,20 and 22 until closed loop operation.
You might try the Fuel Air Multiplier table to adjust the open loop, non-PE fueling.
You might try the Fuel Air Multiplier table to adjust the open loop, non-PE fueling.