Finally have the truck back... New COS #3, one problem

[turboberserker]

Hey guys,

I finally got the truck back after the hit-n-run, and installed the 2/3bar custom OS (#3). All went well with the conversion (except the silly PLX wideband appears to be fubar) but I have no LTFTs -- nada. I followed the pdf directions explicitly and stopped at the "pseudo open loop" page. Since my WB02 is loopy, I'd like me LTFTs back on for peace of mind...

Any idea where to start? The only think I did was follow the directions to disable LTFT learn at idle.

[GMPX]

Hey guys,

I finally got the truck back after the hit-n-run, and installed the 2/3bar custom OS (#3). All went well with the conversion (except the silly PLX wideband appears to be fubar) but I have no LTFTs -- nada. I followed the pdf directions explicitly and stopped at the "pseudo open loop" page. Since my WB02 is loopy, I'd like me LTFTs back on for peace of mind...

Any idea where to start? The only think I did was follow the directions to disable LTFT learn at idle.

LTFT will not work with Custom O.S #3, the price you pay.
What is wrong with the PLX?, I have found them to be very reliable.

Cheers,
Ross

[turboberserker]

LTFT will not work with Custom O.S #3, the price you pay.
What is wrong with the PLX?, I have found them to be very reliable.

Cheers,
Ross
Not really sure -- it worked like a charm until it sat at the body shop for 3.5 months.

It passes all their engine off tests with no problem, but once the ignition is on, it either shows lean (even with the AFR commanded to 9.0 and the truck barely running from being so rich) or it bounces around wildly (LEAN->13.5->LEAN->17.2->14.5->LEAN->AIR->LEAN->12.0 etc). I guess I have to send it in. (oh and the narrow band voltages during all this are normal).

If LTFTs don't work with COS #3, how is it going into closed loop? :confused: Or is it not really hitting closed loop anymore?

[kbracing96]

Eric,
In COS3, You need to get your VE inline to keep your fuel accurate when commanding anything other then 14.63. If you command 14.63 in {B3647} The PCM will use STFT and the o2's to keep the fuel in line. It's kind of a semi closed loop setting.

Also, when you Autotune, you need to make sure you use 14.7 in {B3647} so the O2's aren't trying to correct the fuel, and you will get accurate maps. Its a little detail that really isn't in the tutorial for COS3 guys, that I had to figure out.

[turboberserker]

Eric,
In COS3, You need to get your VE inline to keep your fuel accurate when commanding anything other then 14.63. If you command 14.63 in {B3647} The PCM will use STFT and the o2's to keep the fuel in line. It's kind of a semi closed loop setting.

Also, when you Autotune, you need to make sure you use 14.7 in {B3647} so the O2's aren't trying to correct the fuel, and you will get accurate maps. Its a little detail that really isn't in the tutorial for COS3 guys, that I had to figure out.

Crap... hehe just tuned for 2.5 hrs with 14.63 from 0-4000rpm 20-75kpa lol. I was wondering why they were all 1.00 or 1.01...

14.7 for all rpms and kpa? Sounds risky at high rpm / kpas...

[BowlingSS]

Crap... hehe just tuned for 2.5 hrs with 14.63 from 0-4000rpm 20-75kpa lol. I was wondering why they were all 1.00 or 1.01...

14.7 for all rpms and kpa? Sounds risky at high rpm / kpas...

You can set the AFR to anything you want except 14.63. That is the only time it will go into the semi-closed loop. At least that is what I understood.

I have never put mine back to 14.63. I check my BEN's all the time.

Bill
:muahaha:

[MN C5]

14.7 for all rpms and kpa? Sounds risky at high rpm / kpas...

You can command a lower AFR than 14.7 to tune with.

[turboberserker]

Yeah, in the light of morning it made sense :)

[kbracing96]

Crap... hehe just tuned for 2.5 hrs with 14.63 from 0-4000rpm 20-75kpa lol. I was wondering why they were all 1.00 or 1.01...

14.7 for all rpms and kpa? Sounds risky at high rpm / kpas...

Ya, I did the same thing Eric. I have mine set to ramp down to 11.5 at 100 kPa 4200 on up and it keeps it dead on all the way up. FWIW, I just drove from WY (4800 ft) down to Phoenix (1100 ft) and I did a autotune log down here and it was for the most part dead on with nothing being more then .02 off. Works pretty darn good if you ask me.