LTFT (New to the forum)

[pormgb]

Hi All,

Im doing some logging to better understand my tune, while looking a short logging session I notices my LTFT go as high as 12% when coming off the gas, LTFT don't seem to increase when revving the motor. is this the result of fuel cut? also my O2 sensor voltage are not equal in open loop but even out by the time I get to closed loop.

Here is a little more history around my logging!!

I have a LS1 in a Porsche 944 that I drove for the first time last week, on my second trip the car started to bog down and stalled at a stop sign but I was ably to restart the car. When I got the car home, I checked the plugs and 7 out of the eight were fowled (black). I then replaced the plugs and set a new gap to .055, I then started the car and captured "LS1 May 26 Idle + REV.efi", I've been looking at this log file to determine the problem. One other thing, the car has been very hard to start when warm, I have not restarted it when warm with the new plugs. The car hasn't been tuned on a dyno, the current tune was done by a speed shop to match my specs.

[joecar]

Hi pormbg welcome to the forum :cheers:

In closed loop, the HO2x1 voltages have to be cycling several times per second (from above 600mV to below 300mV and back up).

Can you post the log file.

[pormgb]

Hi pormbg welcome to the forum :cheers:

In closed loop, the HO2x1 voltages have to be cycling several times per second (from above 600mV to below 300mV and back up).

Can you post the log file.


Thanks!!

I've uploaded two log files, I've also added a little more content.

[pormgb]

I ran the car today with new plugs and had the same problem, I captured two runs;

May 28th first drive = car driven from cold then shut off, rough drive with hesitation

May 28th after drive hard start = I restarted the car and had to put my foot on the gas, the car struggled to reach idle, plugs on the left hand sided were black.

Could this be an O2 sensor problem? leaking injectors? exhaust leak?

[SSpdDmon]

Have you tested your coils to make sure you have spark? What has been done to the engine (or is it stock)?

[pormgb]

Have you tested your coils to make sure you have spark? What has been done to the engine (or is it stock)?

By looking at the plugs It appears all cylinders are firing but, I'm thinking of buying new coils.

Here are the motors specs;

- LS6 Block, fresh rebore with new pistons
- DIY ported 806
- Camshaft 226/229 .575/.578 116 LSA
- Hooker Headers, CATS
- LS6 Intake with 28lb Injectors, Delphi 85mm MAF, K+N filter
- Aftermarket FPR (58 PSI at regulator)

The car starts instantly and will idles OK, if it gets warm and is shut it down, its very hard to restart the car. When it finally starts, it runs very rich for a second or two then idles roughly until the plugs are cleaned.

Thanks!!

[joecar]

Log file May 28 First Drive.efi‎ (http://forum.efilive.com/attachment.php?attachmentid=10973&d=1306640490) shows the NBO2's not functioning correctly.
Log file LS1 May 26 Idle + REV.efi‎ (http://forum.efilive.com/attachment.php?attachmentid=10954&d=1306466014) shows the NBO2's functioning, but the engine is not under load (i.e. just being revved in neutral).

The oiled element filter will deposit oil on the MAF sensor which will make it read wrong;
you would be ahead by using a name-brand paper element filter (you will need to clean the MAF sensor using CRC MAF Cleaner).

[joecar]

I ran the car today with new plugs and had the same problem, I captured two runs;

May 28th first drive = car driven from cold then shut off, rough drive with hesitation

May 28th after drive hard start = I restarted the car and had to put my foot on the gas, the car struggled to reach idle, plugs on the left hand sided were black.

Could this be an O2 sensor problem? leaking injectors? exhaust leak?It sounds like an NBO2 problem.

Test for leaky injectors by observing fuel pressure after engine shutoff.

Test for exhaust leak by listening/feeling for puffs at both ends of exhaust header.

[joecar]

What vehicle was the donor for this engine (looks like 1998 F-body with EGR delete)...?

What FPR are you using...? Does it have a manifold reference hose (I can't tell from the pic)..?

Interesting fuel rail orientation :cheers:

How is PCV/catchcan plumbed, do you have another pic...?

I see one coil "remote mounted" (brake master cylinder obstructing...?), is this grounded ok, have you checked spark from this coil using KD-2756...?

Which oil pan are you using (what is reason for remote oil filter)...?

Where is steam crossover outlet tube going to (barely hidden in pic)...?

Nice transplant, looks neat/tidy. :cheers:

[pormgb]

Log file May 28 First Drive.efi‎ (http://forum.efilive.com/attachment.php?attachmentid=10973&d=1306640490) shows the NBO2's not functioning correctly.
Log file LS1 May 26 Idle + REV.efi‎ (http://forum.efilive.com/attachment.php?attachmentid=10954&d=1306466014) shows the NBO2's functioning, but the engine is not under load (i.e. just being revved in neutral).

The oiled element filter will deposit oil on the MAF sensor which will make it read wrong;
you would be ahead by using a name-brand paper element filter (you will need to clean the MAF sensor using CRC MAF Cleaner).

Yes, I saw the O2 sensors working at Idle but when I drive the car I can see the failures on bank 1.

Ill check the MAF and get a different filter.

Thanks !!

[pormgb]

It sounds like an NBO2 problem.

Test for leaky injectors by observing fuel pressure after engine shutoff.

Test for exhaust leak by listening/feeling for puffs at both ends of exhaust header.

I believe I do have leaky injectors, when I shut off the motor, fuel pressure drops to 0 in about 5 min. The injectors probably leak more when the car is warm, thats why I have the warm start issue.

With regards to exhaust leaks, I do have one on the left hand side, wouldn't a leak show (O2 voltage) at idle as well when driving?

[joecar]

When pressure drops it can be either leaky injectors or leaky FPR.

[joecar]

NBO2 voltage with exhaust leak at idle: only if NBO2 is sufficiently hot and functioning correctly.

[pormgb]

What vehicle was the donor for this engine (looks like 1998 F-body with EGR delete)...?

What FPR are you using...? Does it have a manifold reference hose (I can't tell from the pic)..?

Interesting fuel rail orientation :cheers

How is PCV/catchcan plumbed, do you have another pic...?

I see one coil "remote mounted" (brake master cylinder obstructing...?), is this grounded ok, have you checked spark from this coil using KD-2756...?

Which oil pan are you using (what is reason for remote oil filter)...?

Where is steam crossover outlet tube going to (barely hidden in pic)...?

Nice transplant, looks neat/tidy. :cheers:



What vehicle was the donor for this engine (looks like 1998 F-body with EGR delete)...?

I bought the motor as a long block, its an LS6 block with 806 heads, I added the LS6 intake.

What FPR are you using...? Does it have a manifold reference hose (I can't tell from the pic)..?

I'm using the FPR from my old turbo motor, i don't have a manifold reference hose connected, I has a screw that sets base pressure.

How is PCV/catchcan plumbed, do you have another pic...?

My catch can is connect to the vented valley pan cover (LS6), the catch can is then connected to PCV then to the TB.


I see one coil "remote mounted" (brake master cylinder obstructing...?), is this grounded ok, have you checked spark from this coil using KD-2756...?

The engine bay is a bit tight so that coil is relocated so the valve cover clears brake master cylinder. Its mounted with an aluminum bracket, i checked the ground and it tested OK. Im probably going to buy a new set of coils, I don't know the history around those coils, ill look into KD-2756


Which oil pan are you using (what is reason for remote oil filter)...?

The 944 conversion requires the use of a custom oil pan or a Moroso 20140, this pan is modified to clear the crossmember.

Where is steam crossover outlet tube going to (barely hidden in pic)...?

The steam vent is connected to the rad vent on the overflow tank.


Nice transplant, looks neat/tidy. :cheers:

Thanks!! i took my time with this conversion, the look was very important to me, i just need to get it running right.

[ScarabEpic22]

Simply awesome swap. Im pretty sure a buddy of mine in San Jose, CA has a 944 as well, but he's not looking to do an engine swap yet. (Yet :biggrin)

Lets get the NBO2 and exhaust leak figured out, then move onto the injectors/FPR losing pressure.

[skythunder83]

Hi,

I have send you P message. Please advice :)

thx

[pormgb]

Hi,

I have send you P message. Please advice :)

thx

Hi,

I'm a new user and don't have permissions to read PMs, you can contact me at pormgb@hotmail.com

[pormgb]

Hi All,

I fixed the exhaust leak and swapped out bank 1's O2 sensor, I also installed a new FPR with another set of used injectors. the logs look allot better but the car almost stalls when decelerating, I have to keep the revs up otherwise the car will stall when coming to a stop. The car still has the warm start problem, if I start the car with the accelerator fully depressedbthe car will fire then start on the next turn, this tells the car is flooding. While driving, the car has lots of power and is very smooth, by the way I don't have VSS enabled.

Any ideas? I've attached the latest log file, this was created after I returned form a 10min drive.

[nevinsb]

LS1 in a 944? Nice! I'm jealous.

[joecar]

Question: does the IFR match the FPR (i.e. non-referenced FPR means the IFR has to be sloped)...?

Also check: connect pressure gauge to fuel rail, do key on several times, check that pressure holds for at least a minute (and drops very slowly after that).

If it stalls when decelerating to a stop then this means it's not getting enough air, you may need to address throttle cracker/follower and idle:



Idle Tuning
showthread.php?4661-Idle-Tuning-Helpful-Info-Inside (http://forum.efilive.com/showthread.php?4661-Idle-Tuning-Helpful-Info-Inside)
showthread.php?14439-Idle-Tips-amp-Tricks (http://forum.efilive.com/showthread.php?14439-Idle-Tips-amp-Tricks)
showthread.php?5866-Auto-VE-questions (http://forum.efilive.com/showthread.php?5866-Auto-VE-questions)
showthread.php?14153-scan-tool-wont-log-rafig-or-rafpn (http://forum.efilive.com/showthread.php?14153-scan-tool-wont-log-rafig-or-rafpn)
showthread.php?14435-Need-help-Can-Start-Car-but-dies-when-I-give-it-any-throttle-before-going-to-CL (http://forum.efilive.com/showthread.php?14435-Need-help-Can-Start-Car-but-dies-when-I-give-it-any-throttle-before-going-to-CL&p=129519&viewfull=1#post129519)
showthread.php?7011-ETC-cars-and-IAC-parameters (http://forum.efilive.com/showthread.php?7011-ETC-cars-and-IAC-parameters&p=61455&viewfull=1#post61455)
showthread.php?14544-Working-on-my-idle-tune (http://forum.efilive.com/showthread.php?14544-Working-on-my-idle-tune)
showthread.php?14794-Help-with-open-loop-%28cold-start%29-tuning (http://forum.efilive.com/showthread.php?14794-Help-with-open-loop-%28cold-start%29-tuning&p=133446#post133446)
showthread.php?149-Idle-%28Transition%29-Tuning (http://forum.efilive.com/showthread.php?149-Idle-%28Transition%29-Tuning)

More Idle Tuning
showthread.php?t=149 (http://forum.efilive.com/showthread.php?t=149)
showthread.php?t=5866 (http://forum.efilive.com/showthread.php?t=5866&highlight=RAFIG)
showthread.php?p=86553 (http://forum.efilive.com/showthread.php?p=86553) post #17
showthread.php?t=2630 (http://forum.efilive.com/showthread.php?t=2630)
showthread.php?t=473 (http://forum.efilive.com/showthread.php?t=473)

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showthread.php?t=3568 (http://forum.efilive.com/showthread.php?t=3568)
showthread.php?t=4081 (http://forum.efilive.com/showthread.php?t=4081)
showthread.php?t=5406 (http://forum.efilive.com/showthread.php?t=5406)
showthread.php?t=5940 (http://forum.efilive.com/showthread.php?t=5940)

[pormgb]

Question: does the IFR match the FPR (i.e. non-referenced FPR means the IFR has to be sloped)...?

Also check: connect pressure gauge to fuel rail, do key on several times, check that pressure holds for at least a minute (and drops very slowly after that).

If it stalls when decelerating to a stop then this means it's not getting enough air, you may need to address throttle cracker/follower and idle:

Done quite a bit since my initial post. yesterday I installed brand new SVO red top 30lb injectors, I set my IFR as per SSpdDmon .tun file and parameters, I also took a bunch of perimeters from his tune file and tuned some of the parameter from idle tips and tricks.

The car runs much better but occasionally stalls, this tells me i have some more tuning to do. Fuel pressure is set at 58 PSI, I stuck a camera in front of my gauge connected to the fuel rail, here are the results;

50 PSI at prime (Key On)
58 PSI running + revving to 4K
Engine off drops to 50 PSI
2 min down to 40P PSI
After about 10 min down to about 29 PSI

This is with new injectors, Porsche 944 Turbo Fuel Pump, external FPR with return.

[slows10]

Did you hook up your vss yet? I swapped in a 411 pcm in a 97 S10 4.3 I did not have the vss connected. It would almost stall coming to a stop, and seemed like it was holding back during acceleration. Generally just ran strange. I hooked up the vss a couple of weeks later and it ran perfect. I believe and also have read that the pcm needs the vss input to run correctly. Hope this helps. P.S can anyone else confirm if the pcm needs vss input for proper function?

[pormgb]

Did you hook up your vss yet? I swapped in a 411 pcm in a 97 S10 4.3 I did not have the vss connected. It would almost stall coming to a stop, and seemed like it was holding back during acceleration. Generally just ran strange. I hooked up the vss a couple of weeks later and it ran perfect. I believe and also have read that the pcm needs the vss input to run correctly. Hope this helps. P.S can anyone else confirm if the pcm needs vss input for proper function?

It's funny you mention VSS!!

I just installed a 34 teeth wheel on my drive shaft with a 24225896 GM VSS sensor, I hooked up the sensor to the PCM but I don't see any pulses when logging. I'm going to do some more trouble shooting tomorrow.

[joecar]

The throttle cracker/follower tables mention MPH... this tells me VSS is required.

How did you connect the VSS sensor (the signal return cannot be grounded)...?

[joecar]

External FPR with return: is the manifold reference hose connected...? This means a difference in whether the IFR is flat or sloped.

[pormgb]

External FPR with return: is the manifold reference hose connected...? This means a difference in whether the IFR is flat or sloped.

I have the reference disconnected, here is my current IFR;

[joecar]

Ok, I was just sanity checking. :)

[pormgb]

Ok, I was just sanity checking. :)

Thanks!!

[pormgb]

I done some logging and found My VSS wasn't working due to a bad connector at the PCM, I fixed the connector and recalibrate the VSS perameters and it now works like a charm, the car also does not stall when coming to a stop.

From a mixture perspective, the car is still not running right, I have to do some more logging to figure whats wrong. The fuel trims show the car is running lean but it smells and feels like its running rich.

[joecar]

Are you getting any misfires...?

[pormgb]

Are you getting any misfires...?

I think I am, I will log on misfires tomorrow and see what I get, my tune had most of the diagnostics switched off so I'm gradually enabling them. This is my first V8 so i'm not sure how these motors run, it seems to be shuddering when accelerating. How do misfires feel? does the misfire pid pick them up?

Thanks!!

[joecar]

Misfire causes unburnt fuel to go past O2S which read this as lean (due to unburnt oxygen)... this causes positive trims even tho you can smell gasoline (if you have cats they glow orange hot).

Misfire can be so subtle that you don't notice, or it can be a severe series of stumbles.

A properly running LS1 will spin up so fast like there's nothing holding it back (even tho it is under load pulling the vehicle).

The PCM will detect misfires properly if the CASE relearn has been performed; there are misfire cylinder count pids.

[pormgb]

Misfire causes unburnt fuel to go past O2S which read this as lean (due to unburnt oxygen)... this causes positive trims even tho you can smell gasoline (if you have cats they glow orange hot).

Misfire can be so subtle that you don't notice, or it can be a severe series of stumbles.

A properly running LS1 will spin up so fast like there's nothing holding it back (even tho it is under load pulling the vehicle).

The PCM will detect misfires properly if the CASE relearn has been performed; there are misfire cylinder count pids.

Thanks!!

[pormgb]

Are you getting any misfires...?

Done some logging and here are the results;

[joecar]

Ok, you're not getting any misfires... problem is then something else.

If you have any airleaks this will make trims go positive.

[WeathermanShawn]

Have you calibrated your MAF and/or VE Table to account for the +LTFT's?

[pormgb]

Have you calibrated your MAF and/or VE Table to account for the +LTFT's?

That's my next step, so far I've been replicating VE tables from cars with similar cams, Intake, E.T.C.

I'm not sure how this calibration is done, I think with AUTOVE/CALC VE, need to do some more reading.

[WeathermanShawn]

If you want to stay closed-loop and MAF, check out the CALC.VET: http://forum.efilive.com/showthread.php?15236-A-New-Twist-on-CALC.-VE-Table..Computing-the-Entire-VE-Table.

AUTOVE us also a great way to tune via wideband..especially if you decide more on SD -Open-loop. In essence they utilize the same concepts of Tuning via Fueling/Fueling corrections.

Your + LTFT's could be an exhaust leak, inaccurate O2's, or airflow being underreported.

The goal is slightly negative trims if remaining closed-loop..:)..

[pormgb]

Ok, you're not getting any misfires... problem is then something else.

If you have any airleaks this will make trims go positive.

Ok, Thanks!!

I may have air leaks but they are very difficult to fix due to my header setup.

[pormgb]

If you want to stay closed-loop and MAF, check out the CALC.VET: http://forum.efilive.com/showthread.php?15236-A-New-Twist-on-CALC.-VE-Table..Computing-the-Entire-VE-Table.

AUTOVE us also a great way to tune via wideband..especially if you decide more on SD -Open-loop. In essence they utilize the same concepts of Tuning via Fueling/Fueling corrections.



Your + LTFT's could be an exhaust leak, inaccurate O2's, or airflow being underreported.

The goal is slightly negative trims if remaining closed-loop..:)..

Yep, I may have exhaust leaks but they will be very hard to fix due to my header setup. I have contemplated going open loop but ill need my wideband to be accurate, the possible exhaust leak would cause a problem. With regards to negative trims in closed-loop, does this mean you can compensate for the O2 that is seeing the leak?

[WeathermanShawn]

No, not to compensate.

Tuning always goes better when your Trims/MAF/VE are tuned, but mechanical issues have to be solved first..

[joecar]

Is there a way to seal the exhaust leak, either exhaust putty or aluminum foil...?

[pormgb]

Is there a way to seal the exhaust leak, either exhaust putty or aluminum foil...?

Yes, I have sealed the drivers side header, I don't hear any leaking so I think its ok. I only had problems with the drivers side because the header was modified for the conversion, I also have my wide band in the drivers side collector and it show about a 14.5 at idle.

What I can do is go open loop (AUTOVE) and use my LM1 in the passenger side O2 sensor position, this way I know there are no exhaust leaks. I don't think I really need to run closed loop.

[pormgb]

Got the car running quite well today, I modified Cranking VE + some mixture parameters and that fixed my warm start problem, the car no longer stalls after I installed and calibrated VSS. I'm preparing to do a AutoVE, I installed my LM1 in the right hand collector and it tracks very close to the LC1 in the left collector, this tells me that I either have two equal exhaust leaks or I fixed the LH exhaust leak. I copied a VE table form a tune file utilizing 333-333 cam, I'm using a 226-229, I see no LTFT above 3K but am seeing some below.

I'm going through the AutoVE tutorial, one I get it figured out and executed I think it will fix my LTFT variances.

I'm probably going to have to pull my tranny and get my Flywheel, PP and Clutch balanced, i have a bad vibration coming through my shifter from 2k up.