Unusual idle occurance after injector replacement/IFR adjustment

[VTC_WS6]

I went ahead and installed a set of injectors I purchased a while back, Accel 42# units as I recall, and after adjusting the IFR to match I've been able to get the car running, however I have the strangest of occurances when the car first starts. For the first 3-5 seconds my LC1 is reporting normal AFR levels (14.6-15.0), but the engine then immediatley changes tone and begins to chop very heavily, almost to the point of stalling and all the while the LC1 begins to report excessivley high AFR levels of 20+!! This will last for approx. 45-60 seconds with no input from me after which the engine magically "snaps out of it" and resumes a normal idle tone and the LC1 immediatley richens up to normal levels. Now i'm not 100% sure on the accuracy of the LC1's readings during the abnormal phase simply because of the heavy lope/reversion and it's possible effects on the numbers but there is no doubt something fishy is going on here.

I'm attatching my current map in the hopes somebody might catch on to something I've overlooked in my quest to bring my car back to 'normal' since the injector swap, any help or input is much appriciated :cheers:

[hquick]

MIne does the same with the SVO 42's. Doesn't go particularly choppy but does the sudden lean swing thing and then back to commanded after about a minute or so.

[DaddySS]

Dumb question maybe, but isn't your air pump giving you the high afr reading while it cycles during initial start up?

[VTC_WS6]

No air, no egr, no cats.. very perplexing, especially since it was just fine on the previous set of squirters. I'm even contemplating swaping out my old injectors and going back to the previous tune just to see if I've developed some odd mechanical issue or if it's truly just a 'weird' case unhappy PCM.

[VTC_WS6]

Ok I just performed a dead cold start up with the scanner running. I'm going to attatch the log so everybody can take a look but after reviewing it here's what I see. As soon as the engine comes to life it momentarily idles at a normal AFR, at this point I was logging idle properties of approx. 75-78kpa, 25*C ECT and idle speed of approx. 600-620 rpm, than suddenly you see the AFR rocket up to 20+ with the kpa, ECT and rpm remaining basically unchanged.... baffling!! Something is causing the PCM to pull a tremendous amount of fuel for about 45-60 seconds before giving it right back and the car goes back to idling normal. If nothing esle I certainly hope I can pique some curiosity out there :help2:

BTW although my vision is getting blurry from the hours spent pouring over the info in here, its amazing what I'v picked up in just a few hours, good stuff in here guys! :cheers:

[jfpilla]

While you're in open loop actual AFR is not tracking Commanded B3605. When it goes to closed loop Stoich is taking over.
Suggest you look at the VE's. VE's being off is usually what causes AFR to not track in open loop.

[hquick]

Hi Jf,
Mine does the same but I'm running OLSD???

[VTC_WS6]

While you're in open loop actual AFR is not tracking Commanded B3605. When it goes to closed loop Stoich is taking over.
Suggest you look at the VE's. VE's being off is usually what causes AFR to not track in open loop.

Question in regards to this, according to B4201 the engine determines to run the 'cold temp timer' if it's less than that particular value (9*C in my case), then according to B4203 it'll run the 'normal engine temp' timer if it's over 75*C, but what happens in between? From what I can see these timers dictate when the PCM can enable CL yet I don't see a value for temps between 'cold' and 'normal'? And as a side note, if I were to enable B4206 'Enable O2 with open loop commanded fuel', then the O2's could assist the PCM in maintaining proper AFR even if my VE's are somewhat askew yes?

[jfpilla]

Question in regards to this, according to B4201 the engine determines to run the 'cold temp timer' if it's less than that particular value (9*C in my case), then according to B4203 it'll run the 'normal engine temp' timer if it's over 75*C, but what happens in between?
xxxxxxYou should be looking at B4205.

From what I can see these timers dictate when the PCM can enable CL yet I don't see a value for temps between 'cold' and 'normal'?
xxxxxxSee B3605.

And as a side note, if I were to enable B4206 'Enable O2 with open loop commanded fuel', then the O2's could assist the PCM in maintaining proper AFR even if my VE's are somewhat askew yes?
xxxxxxYou have a wideband, tune it properly. VEs have an impact under
4000rpms in assisting fueling when the maf can't handle it.

[Thumper]

Sorry to hijack, but i have a noob question.
Why is your MAP pressure so high at idle? My logs show around 55-60 KPa at Idle for my car. What would cause this difference?

[VTC_WS6]

Sorry to hijack, but i have a noob question.
Why is your MAP pressure so high at idle? My logs show around 55-60 KPa at Idle for my car. What would cause this difference?

Low idle speed + 112LSA cam = less vacuum present in the manifold during idle would be my asumption.

[VTC_WS6]

xxxxxxYou have a wideband, tune it properly. VEs have an impact under
4000rpms in assisting fueling when the maf can't handle it.


Alright, i'm gonna go ahead and work with the VE map in the idle area and see what kind of results I get. I'm also going to go ahead and perform an 'AutoVE' run through since I noticed on an extended cruise that my LTFT's were maxing at 25% indicating my map must be especially off. Thanks for the input thus far!

[Thumper]

Low idle speed + 112LSA cam = less vacuum present in the manifold during idle would be my asumption.

I have a cam with a 114lsa. My manifold pressure is lower than the posted log.
Just intereseted to know.

[VTC_WS6]

**PROGRESS!!**

I know I'm fielding my own audience here but I'm too happy to see some kind of progress to keep it to myself!

So after taking in some of the advice I've recived in this thread I decided to go ahead and take a few 'blind' stabs at a few different calibration properties and see what kind of results they deliver. As of right now I'm still stuck with two main concerns, first is a major lean surge during initial startup, and second it the surging and hesitating while driving accompanied by a maxed out 25% LTFT. Basically anytime the PCM would deliver less than 25% additional fuel in correction to the commanded the car would buck and surge and I'd see the AFR swing wildly lean.

Attempt 1: Add 25% to Main and Backup VE maps.
Result: Initially the startup lean surge was delayed compared to previous logs, but it still ended up at 20+ AFR till the vehicle went CL and the O2's slowly brought it back to normal AFR. Same thing while driving, lots of bucking anytime the LTFT would drop from 25% accompanied by a major lean spike. Failure.

Attempt 2: Add an additional 15% to Main and Backup VE maps.
Result: This was performed as an 'off the side off the road' update so I don't have any cold idle logs, but initial startup was still extremley lean till the O2's kicked in, driving was no different with lots of bucking whenever I'd enter a new part of the map and LTFT's droped as the AFR would rocket up to 20+. Failure.

I then got the bright idea to trace some steps. The only real change to the map of note since I installed the injectors has been the IFR table and now the VE maps which yeilded little to no change in outcome.. what if I was chasing the wrong tail? I immedaitley pulled off and shut her down, switched over to the calibration and dropped the IFR rate figuring if such an increase in VE yielded no increase in stable fueling, maybe i'm starting with less fuel than I thought?

Attempt 3: I reduced the IFR some 15% and reloaded the PCM.
Result: Initial startup keeps the AFR 'normal' for a few more seconds but still goes to 20+ untill the O2's come into play, I do notice the car then idles at normal AFR with only 20% LTFT. Take it for a drive and I FINALLY see some results! Bucking is virtually gone, LTFT's are hanging in the mid-teens with steady AFR readings, alas I'm getting somewhere.

This leads me to two conclusions. First, I either way over calculated my IFR numbers, or I don't actually have 42# injectors, and second, my VE map may not be nearly as off as I though. Either way i'll put some more tinkering into it tomorrow, drop the IFR some more and start a little more logging to see of I can't get it down to where I need it. Either way I'm just glad to finally see the light at the end of the tunnel. And big thanks to you guys for helping!
:master::master:

[hquick]

From what I understand....decreasing the IFR richens everything globally. Alot of tuners use this method.

[VTC_WS6]

From what I understand....decreasing the IFR richens everything globally. Alot of tuners use this method.

That's basically what I was counting on. In my case I deduced that because I was making what I belive to be rather large changes to VE with zero results, maybe my IFR was off to begin with, causing the PCM to run max increase (LTFT) to keep the AFR's where commanded.

[DaddySS]

I'm glad to hear you're making progress. Keep us posted.

[VTC_WS6]

Well I did a little more tinkering today but no breakthroughs. I'm glad SD and TAQuickness have shared some info latley how basic tune ideas and fundamentals because I think i'm at the point where I'm going to revert to either a true stock tune and work up from there or at least go back to my tune before the injectors were installed and go from there.

I dropped the IFR about another 5% and as expected I saw the LTFT drop even further, but what bugs me is that i'm running a relativley low IFR (at least based on what I belived my injectors to be) and my VE's are all screwed up from my previous attempts to get my car inline. And even though drivebility has improved I'm getting more bucking and a rougher idle than I did when I was having those huge lean surges. Basically I've got a mess on my hands and I want to start with a fresh slate so..

I'll definatley keep you guys updated as I progress and try some new approaches based on my readings and hands on tinkering. More to come woohoo!!

[Lennart]

We installed 42# Delphi injectors in a 5.3l last weekend along with a Whipple and a cam.
After my initial approach of using 6.1xxxxg/s I also got LTFTs at 25%. I then reduced IFR to 5.03 and got LTFTs from -5% to 10% with some areas very close to 0%.
The VE table is raised quite a bit, too. Too bad we could not hook up the wideband as the connector did not fit .

[hquick]

Just for the sake of it....here's my current tune and a log from this morning.
I'm running OLSD and have the VE table pretty well dialled in. Cruising is absolutely spot on.
Lately I've been toying with the lean tip-in and rich decel/lean...after decel (won't see that in this log as I re-enabled DFCO).
You can see that my VE table looks like no other???
Waiting for my RR to arrive so I can play with the injector settings (pulse widths..etc) a little easier.

[405HP_Z06]

Good info, any progress?

[hquick]

My biggest problem is I don't know enough about injectors.
The second issue I have is that there is next to nothing available in the way of info on the Bosch greentop 42lb injectors.
So...at the moment...with the help of people such as Justin....I'm just toying with my injector settings. I have noticed that the slightest changes to the voltage offset table can make you go full lean on decel without DFCO enabled.
Also...with the oddball L31 and van tune...it seems to be the only tune which utilizes table B4002. Every other tune I've looked at has that set to 1 across the board.
I've ordered a book on EFI tuning so I'll hopefully be able to get some more of this stuff to sink into my thick head.

[Goldfinger911]

I had a similar start-up problem and I solved it with changes to B3650. My V was already tuned very close to spot on and I didnt want to make changes. I am running OLSD as well. It was from a thread I read on a similar topic. Here is what my table looks like now.

1.000000
1.000000
1.000000
0.999512
0.999024
0.998047
0.996582
0.994141
0.989258
0.978516
0.960938
0.930176
0.930176
0.930176
0.930176
0.930176

[hquick]

So far I've dropped my min pulse width 50%...I don't see any differences or feel anything different in the way the vehicle drives.

[405HP_Z06]

So far I've dropped my min pulse width 50%...I don't see any differences or feel anything different in the way the vehicle drives.

Howard,
Have you done anything to {B4004}? When the commanded pulse rate is less than {B4003}, the PCM defaults to {B4004} for the minimum pulse rate.

What about {B4005}, did you change anything here?

[405HP_Z06]

My biggest problem is I don't know enough about injectors.
The second issue I have is that there is next to nothing available in the way of info on the Bosch greentop 42lb injectors.
So...at the moment...with the help of people such as Justin....I'm just toying with my injector settings. I have noticed that the slightest changes to the voltage offset table can make you go full lean on decel without DFCO enabled.
Also...with the oddball L31 and van tune...it seems to be the only tune which utilizes table B4002. Every other tune I've looked at has that set to 1 across the board.
I've ordered a book on EFI tuning so I'll hopefully be able to get some more of this stuff to sink into my thick head.

I hear you, it seems that these injectors are difficult to tune totally correct and no one is sharing the offsets, etc. I have a brand new set of these that I was going to install but decided to use the FAST/ASA/GTP 36lb's instead because the table's are available.

[hquick]

4003 & 4004 are set the same. I haven't played with 4005 at all.