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low fuel trim out of whack


logick
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Galant VR-4 org Post #: 326873 posted 04/11/06 10:17 AM     Remind Me!  Send Private Message   Edit Post      
I just swapped the 510's for 750's with a new chip. mid and hi trims stayed about the same (mid actually went from 11x to 100 even) and hi is at 103. But low trim is at 82.3 and won't move.

Is this normal with bigger injectors or do I have an issue some place ? trims were all within 10 of 100 on the 510's with the weather change, and right at 100 when i tuned in winter.

Mark

edit : 3xx miles on the setup, so I would asume it has had plenty of time for all trims to change to the right readings.


Edited by logick (04/11/06 10:20 AM)

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atc250r Galant VR4.org Moderator
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Galant VR-4 org Post #: 326913 posted 04/11/06 11:28 AM     Remind Me!  Send Private Message   Edit Post      
Make sure your close throttle switch is working and pull a few PSI out of the base fuel pressure (assuming you have an AFPR). You have room to work with on the mid and high so leaning it out a little with less fuel pressure will work. Is the O2 sensor fairly new and cycling at idle? When the heating element went bad in my old O2 sensor it would be fine while driving but would stop working at idle due to it not getting hot enough.

John



"...if they're so into masochism, they should just really go all out and start modifying Mitsubishis. And using them as daily drivers." - Mike R.

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Lucian Bartik
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Galant VR-4 org Post #: 326933 posted 04/11/06 11:53 AM     Remind Me!  Send Private Message   Edit Post      
Did the new chip also modify the injector dead time? Dead time is most important for low fuel trims and low injector duty cycle. I think the 720s are reported to be very "slow" compared to 450s and other ND injectors.

Edit:

I want to clarify this. low FT=80% (running rich) would mean that, if you had a problem with dead times, they are too big already. This would not be the case with stock dead times for 450s. Maybe those 720s are quicker than your ECU guy thought...


Edited by Lucian Bartik (04/11/06 12:04 PM)

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powerplay
Yes Man
525/2000


Galant VR-4 org Post #: 326951 posted 04/11/06 12:58 PM     Remind Me!  Send Private Message   Edit Post      
When I installed my Denso 660s, I had to adjust the deadtime to get my trims right. My Keydiver chip was set for those injectors. The values Jeff uses are approximations, so a little change can be needed.



Scott
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logick
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Galant VR-4 org Post #: 326954 posted 04/11/06 01:05 PM     Remind Me!  Send Private Message   Edit Post      
adjust your dead time ?? did jeff reflash or are you using some stand alone ? All I have is maft and safc. I don't think this matters much at the track but it's kinda sluggish when driving normal from stops.

I'm going to drop some base pressure for now and see what happens.

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powerplay
Yes Man
525/2000


Galant VR-4 org Post #: 326957 posted 04/11/06 01:11 PM     Remind Me!  Send Private Message   Edit Post      
If you don't have your own burner and software, Jeff would have to change it for you based on what information you provide him. I have been studying about the process for quite some time and I do my own changes. I am still a "babe in the woods" when it comes to what the people know about the ECU/chips like Jeff.



Scott
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CP
Still lingering, kinda like a chili and beer fart


Galant VR-4 org Post #: 326973 posted 04/11/06 01:44 PM     Remind Me!  Send Private Message   Edit Post      
Damn Scott; I learn something new about you every month



-Cy
Resident Spec Miata Racer | '93 Audi UrS4 | '04 Ram CTD | #1788/2000: SOLD

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powerplay
Yes Man
525/2000


Galant VR-4 org Post #: 326995 posted 04/11/06 02:28 PM     Remind Me!  Send Private Message   Edit Post      
Well, I did it because I really didn't like bothering Jeff. He has given so much of his knowledge and time I just felt bad. I read all of the information on the ECU forum and they are a big help to noobies, like myself. I have burned several of my last chips and I don't think I am anywhere close to being done yet.



Scott
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keydiver
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Galant VR-4 org Post #: 327320 posted 04/12/06 01:27 PM     Remind Me!  Send Private Message   Edit Post      
You probably added too much deadtime. The most you want to add is 312uS for the FIC/PTE/Delphi 750cc injectors. If you added 432uS, like the Denso 720's, thats your problem.

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CP
Still lingering, kinda like a chili and beer fart


Galant VR-4 org Post #: 333564 posted 04/30/06 03:07 PM     Remind Me!  Send Private Message   Edit Post      
I just put in my new chip, along with 750cc injectors, Supra pump, and Aeromotive AFPR. After a few days, all my trims were at 139%.

I'm still trying to track down the source of my code 41 (see sig), which may or may not be related. I'm running a 3G MAS, stock exhaust, magnecore wires, new o2 sensor, changed the plugs with the oil, and changed the injector resistor pack.

I've got the battery unhooked this afternoon while I re-paint my 93 headlights, so the ECU will be starting from scratch again when I give it power. Base fuel pressure is set at 37psi. Do I need to raise it a bit to bring the trims down? I'm not so sure an SAFC (arriving this week) will be able to do anything about them.


Edited by CP (05/01/06 02:25 AM)

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CP
Still lingering, kinda like a chili and beer fart


Galant VR-4 org Post #: 333749 posted 05/01/06 07:53 AM     Remind Me!  Send Private Message   Edit Post      
Well after hooking up the battery, I was back to 100% for all of the trims. I also turned my boost down to 15psi.

After my 20 minute highway drive to work, my low and mid trims were at 104%, and my high was 118%. As the car sat there during its one minute cool-down, I watched the low move up to 135% (until the car shut off). I expect them all to be at 139% again before week's end; probably sooner.

I'm thinking about completely re-wiring my injectors in the next two weeks. Any other ideas as to what could be causing this (code 41 still)?

Am I super rich or super lean? I notice a tiny bit of smoke (not sure what color as it's tough to tell in the rearview) out the tailpipe when I get on it the first time on every drive (after fully warmed up). It doesn't do this at any other time. Maybe it's just moisture that has accumulated in the exhaust while sitting.

I noticed that Jeff changed the A/F default setting in my chip, from 10.5:1 with the 450cc injectors, to 11.0:1 with the 750s.

It also doesn't like to idle when cold, at least not as well as it did with the other injectors and chip. Is this a base fuel pressure issue (currently set at 37.5psi)?

I'm almost positive this is all due to my CE code 41. I may convert back to the stock injectors and chip for my first track event in 2 weeks, where the car will be at or above 4000rpms for 25 minutes at a time.


Edited by CP (05/01/06 07:57 AM)

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powerplay
Yes Man
525/2000


Galant VR-4 org Post #: 333765 posted 05/01/06 08:40 AM     Remind Me!  Send Private Message   Edit Post      
After you clear the code 41 code, how long does it take before it sets it again?



Scott
525

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CP
Still lingering, kinda like a chili and beer fart


Galant VR-4 org Post #: 333784 posted 05/01/06 09:40 AM     Remind Me!  Send Private Message   Edit Post      
Code 41 resets almost immediately with the car running.

I just went for a 15 minute spin, and my trims are now at 114%, 105%, 122% (LMH). The low moved down quickly as I watched it while idling.



-Cy
Resident Spec Miata Racer | '93 Audi UrS4 | '04 Ram CTD | #1788/2000: SOLD

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keydiver
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Galant VR-4 org Post #: 333884 posted 05/01/06 02:45 PM     Remind Me!  Send Private Message   Edit Post      
Everything seems to indicate that your injectors aren't quite flowing what you expected, since all your TRIMs are high. If possible, increase your base fuel pressure to 40-41 psi. If that isn't possible, we'll have to burn a new chip, with the next lower step of injector compensation. To me, the most important TRIm is the HIGH TRIM, since that one usually is a good indicator of whether your open-loop A/F is on target. (The change from 10.5:1 to 11:1 on those open-loop maps will NOT affect the TRIMs.)
Did you recently have any work done to the ECU? I often find that code 41 (if the car runs fine) is caused by a bad trace to RM101, a resistor matrix that looks at all 4 injector outputs. Some of the traces are very easy to damage. Look for RM101 between the green injector caps, and trace each of the 4 lines to the center pin of each injector driver transistor. The common lead of RM101 is the bottom one, and you can trace it as it heads across the board to TR12. I've also seen acid damage around the caps cause a loss of the bias voltage and cause code 41.

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powerplay
Yes Man
525/2000


Galant VR-4 org Post #: 333885 posted 05/01/06 02:48 PM     Remind Me!  Send Private Message   Edit Post      
Good information Jeff! I think he has swapped ECUs with a known good one and still had the problem. I am sure Cy will fill us in.



Scott
525

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CP
Still lingering, kinda like a chili and beer fart


Galant VR-4 org Post #: 333945 posted 05/01/06 06:10 PM     Remind Me!  Send Private Message   Edit Post      
Quote:

If possible, increase your base fuel pressure to 40-41 psi.




Done. I also grounded the firewall plug and set the idle to roughly 900rpm, which was factored into the chip.

Quote:

Did you recently have any work done to the ECU?




No. I swapped in another ecu with my chip (450cc and stock fpr then) a few months ago and nothing changed. But it's running like garbage right now.

Quote:

I often find that code 41 (if the car runs fine) is caused by a bad trace to RM101, a resistor matrix that looks at all 4 injector outputs.




The car doesn't run fine. Does the resistor matrix consist four black boxes with three legs that stick out towards the green boxes?

Quote:

Some of the traces are very easy to damage. Look for RM101 between the green injector caps, and trace each of the 4 lines to the center pin of each injector driver transistor.




The workshop:


Quote:

The common lead of RM101 is the bottom one, and you can trace it as it heads across the board to TR12.




The one on the far right that heads off into the distance, looking at the five horizontal pins near the bottom of this picture...



What I think you're talking about is the bottom four pins (of that verticle row of 5) that follow the fat traces to the tops of those triangular fat blobs:



Quote:

I've also seen acid damage around the caps cause a loss of the bias voltage and cause code 41.




My caps are a few years old (7378E) "Paul"


Edited by CP (05/01/06 06:45 PM)

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CP
Still lingering, kinda like a chili and beer fart


Galant VR-4 org Post #: 334094 posted 05/02/06 07:51 AM     Remind Me!  Send Private Message   Edit Post      
Well I upped the bfp to 41psi with the hose removed, and it seemed to do a bit of good last night while up to temp. The car had some trouble idling this morning when I started it up after the ECU reset...very low idle and stalling. This is WITH a working ISC and FIAV, but with the EGR blocked. This also happened while the engine was relatively cool when the revs drop to idle, such as when coming to a red light. After a partial stop and go drive to work, trims are 139,135,107 (LMH). The exhaust also stinks (I guess this is the one GOOD reason to have a leaky exhaust underneath the car in this case).

I'm thinking another chip is in order. The guy at FIC said these Delphi injectors typically flow less than advertized (780cc from Delphi, sold as 750s by FIC, since they typically flow 745-760cc when tested). Maybe I should get a chip for 720s? What base fuel pressure should I have the chip set for...37 or the current 41 I'm at?


Edited by CP (05/02/06 07:54 AM)

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keydiver
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Galant VR-4 org Post #: 334109 posted 05/02/06 08:45 AM     Remind Me!  Send Private Message   Edit Post      
Quote:

What I think you're talking about is the bottom four pins (of that verticle row of 5) that follow the fat traces to the tops of those triangular fat blobs:







Yes, exactly! Use an ohmmeter to check for continuity (<1.0 ohm) between each of those 4 legs on the matrix to it's respective connection to the driver transistors. It looks like it has been resoldered, and if any one of them is open you will get code 41.

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CP
Still lingering, kinda like a chili and beer fart


Galant VR-4 org Post #: 334115 posted 05/02/06 08:58 AM     Remind Me!  Send Private Message   Edit Post      
The fourth one up (2nd from top) is dead. I tested all 5 from pin to pin, and that's the only one I don't get anything for. It doesn't read at that first pin it appears to go through either. But it does read from that pin to the driver. So my problem is from RM101 to R112. What's my next step given this new information? Is there anything else I can test that may be code 41 related? Please advise...

Oh, my trims were looking better when I got home after putting in 50 miles today: 139, 117, 107 (LMH). And I've upped the pressure to 43.5psi.


Edited by CP (05/02/06 04:05 PM)

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keydiver
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Galant VR-4 org Post #: 334264 posted 05/02/06 04:11 PM     Remind Me!  Send Private Message   Edit Post      
Well, that makes it easy! Just solder a small jumper wire from the transistor's pin directly to the RM101. No more code 41!

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CP
Still lingering, kinda like a chili and beer fart


Galant VR-4 org Post #: 334271 posted 05/02/06 04:25 PM     Remind Me!  Send Private Message   Edit Post      
So far, so good. No CE light with the new jumper. I got so excited I forgot to take a picture...sorry.

I turned the fuel pressure back down to 37 and reset the idle. My trims are still high, but hopefully they'll go down a bit with time. In the first 15 minutes of my drive, I saw for the first time the high trim dip below 100%. It's up around 115% now, but we'll see how it goes for the next few days.

I couldn't have done this without Jeff's invaluable help! THANK YOU JEFF

I'll keep updating my progress, so stay tuned. SAFC will be here next week...


Edited by CP (05/02/06 06:25 PM)

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CP
Still lingering, kinda like a chili and beer fart


Galant VR-4 org Post #: 334272 posted 05/02/06 04:26 PM     Remind Me!  Send Private Message   Edit Post      
What injector would this correspond with, and is there anything in the logger that I can look at to see the effects on that particular cylinder/injector?



-Cy
Resident Spec Miata Racer | '93 Audi UrS4 | '04 Ram CTD | #1788/2000: SOLD

Posts: 8936 | From: West Simsbury, CT | Member Since: 08/30/04 | IP: (24.61.18.197) | Report this post to a Moderator

CP
Still lingering, kinda like a chili and beer fart


Galant VR-4 org Post #: 457256 posted 03/28/07 05:01 PM     Remind Me!  Send Private Message   Edit Post      
I've got more fuel trim strangeness going on with my car.

Jeff has been playing with the timing maps for me. The first chip I've been using for about a year had worked pretty good with my setup. I had all the trims right around 100%, but I was getting up to 16 counts of knock sometimes no matter how much I messed with the SAFC. A/f's were between 11.8 and 10.5. The knock was the issue with that chip.

I was told to set the base timing back to 3*, which cut those knock numbers in half, and made the car much more lively.

Recently Jeff burned another chip for me. The idea was to mess with the timing maps to get rid of the knock, and get the base timing back to 5* where it belongs. The only changes I can gather he made to the chip from looking at the chip description printout compared to the last one:

"30% expanded maps"
"15* timing on top map"

I've actually had two chips with these settings. With the first new chip, the car drove alright for a few days but then all the trims pegged at 81%, the idle started creeping up, and it was blowing a bit of smoke out the tailpipe. I didn't touch the SAFC settings, which were all right around 100% with the previous chip.

The second new chip had the same settings. He guessed that I'd killed the first chip when installing it. This time I grounded myself, wore latex gloves, and made sure not to touch any of the chip legs upon installation.

After a few days the trims were all heading downhill again. So the car was running mega-rich. Since then, I've more than doubled my low settings on the SAFC to try to get the trims to come up:

Old chip low New chip low

1K: -7 -17
2K: -6 -10
3K: +1 -5
4K: +1 -5....

This has helped for the most part. My mid and high trims are in the mid-90s now. But my low trim is all over the place. When I got to my driveway this afternoon and stopped, I watched the low trim go from 108% to 81% in about 25 seconds and remain there, and I didn't touch the SAFC.

Anyone have any ideas as to what may be going on to:

1) cause the car to run SO rich with the new chip, given that the only changes were to the timing maps?

2) cause the low trim to move around so quickly and tend to stay in the low 80s?



-Cy
Resident Spec Miata Racer | '93 Audi UrS4 | '04 Ram CTD | #1788/2000: SOLD

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s_firestone
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Galant VR-4 org Post #: 457280 posted 03/28/07 06:19 PM     Remind Me!  Send Private Message   Edit Post      
CTPS? TB Butterfly gap? Bad condenser(by the coil)? You could have some RF noise infiltrating a connection somewhere. Leaking injector? Fuel pressure fluctuating at idle(unstable pump voltage) or pulsation? Could the AFC itself be contributing to the problem? Coolant temp sensor or connection?

Does it happen when slow rolling? or only after you stop?

I would pull the plugs and see if its just in one cylinder or if all of them are the same then its something fooling the ECU.



Stephen Firestone
1992 GVR4 #918 of 1K

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CP
Still lingering, kinda like a chili and beer fart


Galant VR-4 org Post #: 457290 posted 03/28/07 07:10 PM     Remind Me!  Send Private Message   Edit Post   
All trims returned to normal operation (100% +/- 4%) when I re-installed my old chip last week while Jeff burned another one for me (cuz he thought the first one was bad).



-Cy
Resident Spec Miata Racer | '93 Audi UrS4 | '04 Ram CTD | #1788/2000: SOLD

Posts: 8936 | From: West Simsbury, CT | Member Since: 08/30/04 | IP: (24.63.52.27) | Report this post to a Moderator


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