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Thread: Idle AFR changing whilst Idling

  1. #16
    Fuel Injected! Terminal_Crazy's Avatar
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    Quote Originally Posted by Terminal_Crazy View Post
    Thanks, Iíll post up the last run that I did tomorrow.
    I've definately been fighting this since I built the motor.
    I've uploaded the last 2 decent runs I did.
    The bin used will vary slightly but I've only changed VE tables as I've been chasing the WB AFR up and down.


    Thanks for looking

    Mitch
    Attached Files Attached Files
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  2. #17
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    Still not sure if it is a mechanical problem, bad tune or a mix of both.
    Do you have older logs with the other sets of injectors.

    You got constant knock at lower loads. Mixed side intermitten lean condition at low load conditions.
    I suggest you start all over with your tune. I can make a starter bin and work from there.
    That way we can rule out the bad tune hypotesis.

  3. #18
    Fuel Injected! Terminal_Crazy's Avatar
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    Quote Originally Posted by kur4o View Post
    Still not sure if it is a mechanical problem, bad tune or a mix of both.
    Do you have older logs with the other sets of injectors.
    It's always been off 1 side. Nothing has ever made much difference.
    Injectors we replaced. Then swapped side to side & centers to outside.
    Not sure if i can ID logs with the previous injectors, I'll have to check.

    [QUOTE}
    You got constant knock at lower loads. Mixed side intermitten lean condition at low load conditions.
    I suggest you start all over with your tune. I can make a starter bin and work from there.
    That way we can rule out the bad tune hypotesis.[/QUOTE]

    Again it's always been like that. Since going OLSD the car has run and felt miles happier especially at 11-13:1

    I'll try anything you can think of.
    A new tune would be interesting.
    MAF is still on the car, just disabled as I have been trying to get the VE sorted.

    This probably explains why the VE tables end up looking like a toblerone!

    I still think this could be an issue with the inlet manifold, vac leak underneath.
    I switched to synthetic oil a couple of hundred miles ago.
    Car still drinks oil andsince the switch the manifold has started leaking at the rear china wall.

    I've been reading/Youtube on PVC valves so can check that tomorrow night. Prompted by the rear seal starting to leak.

    I'm open to suggestions on how to pinpoint the Vac leak to the manifold before I pull it. 2 sets of gaskets cost me about 80 USD last time

    Another thought on something I read was the bolts for the push rod guides on the AFR heads breaking into the Inlet Ports.
    I remember using LACO Thread sealer on the Head bolts and pretty certain I used it when installing the push rod guides.
    Something else to check.


    Cool.
    I await your response.

    Thankyou

    Mitch
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  4. #19
    Fuel Injected! Terminal_Crazy's Avatar
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    OK
    Got a couple of Datamaster logs with the 32Lb Bosch III's.

    Interested to see what you see in them !

    Thankls
    Mitch
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    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  5. #20
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    Earlier logs have much more consistent 02 data.
    I suspect the injectors just don`t open at low PWM{below 2ms} condition at random intermitten rate.
    It could be the pcm can`t handle it or the injectors are garbage.

    You can bring back the smaller injectors. Reload factory VE, Spark, Individual cylinder trims and all knock retard related tables.
    Fix the injector data flow and offset. Low pulse width correction are really important. I see all zeroed at the latest bin
    Increase cylinder volume to 935.

    Reseal the m22 plugs and retighten the header bolts.
    The knock could be real or false. Lowering total advance will show if it`s real
    If it is false you will have to find out what`s causing it.

  6. #21
    Fuel Injected! Terminal_Crazy's Avatar
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    Quote Originally Posted by kur4o View Post
    Earlier logs have much more consistent 02 data.
    I suspect the injectors just don`t open at low PWM{below 2ms} condition at random intermitten rate.
    It could be the pcm can`t handle it or the injectors are garbage.

    You can bring back the smaller injectors. Reload factory VE, Spark, Individual cylinder trims and all knock retard related tables.
    Fix the injector data flow and offset. Low pulse width correction are really important. I see all zeroed at the latest bin
    Increase cylinder volume to 935.

    Reseal the m22 plugs and retighten the header bolts.
    The knock could be real or false. Lowering total advance will show if it`s real
    If it is false you will have to find out what`s causing it.
    OK thanks.
    I'll check a few things this weekend and chuck the 32lb Bosch III's back in.
    Anyone got ANY specs for the Bosch III's or any recommends for anything better with some proper specs?

    Why the cylinder size to 935. The motor is a 383 so cyl volume should be 783.70cc

    IS the injector adder the time taken for the Injector to open and stabilise flow?
    Would increasing this make any difference? (presumably not if the injectors can't open anyway in this time )
    Zeroing them seems to be the only consistant info I have for these.

    How would the PCM/injectors cope with a huge cam that required bigger injectors then as the the fuel requirements wouldn't be much different at idle so opening time on a bigger injector would be similar.
    What's a stock injector idle pw time for comparison?


    Advance changes never seemed to make any difference.
    Running pig rich does which is why i still possibly suspect the manifold, if it's not the injectors.
    I'm 99% certain there is NO _usual_ vacuum leak anywhere. Everything has been gone over many times.
    Even knock sensor has been replaced twice.

    As to the manifold, I'll log again and pump propane into the rocker cover with the PCV valve blocked off just to see.


    Thanks again
    Mitch
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  7. #22
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    Do you have the part number on bosch injectors.
    Low pulse adder is to compensate for non linear behaviour at very short opening.

    You need to inrease cylinder volume, because pcm cant see over 100% ve. That way you keep ve resolution.
    The value I gave you is appoximate and may need corrections.

    Investigate any mechanical issues that may arise and affect the tune.
    Felpro intake gasket are really cheap. Might worth a try if you suspect a problem.
    Double check for anything that may produce a knock at the engine, exhaust pipes or body.

  8. #23
    Fuel Injected! Terminal_Crazy's Avatar
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    Quote Originally Posted by kur4o View Post
    Do you have the part number on bosch injectors.
    Low pulse adder is to compensate for non linear behaviour at very short opening.

    You need to inrease cylinder volume, because pcm cant see over 100% ve. That way you keep ve resolution.
    The value I gave you is appoximate and may need corrections.

    Investigate any mechanical issues that may arise and affect the tune.
    Felpro intake gasket are really cheap. Might worth a try if you suspect a problem.
    Double check for anything that may produce a knock at the engine, exhaust pipes or body.
    Hi
    Injectors are from FIC - www.FuelInjectorConnection.com
    Ordered 30lb Modified Bosch 3 Injectors ( Stainless later core )
    Later ones were 42lb @ 3 Bar Modified Bosch Blue Demon 3 Fuel Injectors

    No info on either of these. I've scoured the web - nada.

    OK on the other info.
    Just been looking at the Gaskets. The felpro's LT4 ports aren't as big as the AFR (or Edelbrock's) so far as i've found.
    Also looking at plugs & O2 sensors.
    I got squeeks, not anything knocking.

    I'll pull plugs, do vac check, PCV check & propane this weekend

    ps @ Scott Pfautsch: Did you ever get info from FIC on the Bosch injectors?

    Thanks
    Mitch
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  9. #24
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by kur4o View Post
    Double check for anything that may produce a knock at the engine, exhaust pipes or body.
    I'm running nearly identical roller rockers and have a far worse amount of what I believe is false knock that bands heavily around 1700 rpm. I've been all over the car looking for exhaust system interference and came up with nothing. I don't understand why it's better in hot and humid conditions and worse when the air temp and humidity drops. Reducing timing seems to make it worse. I've been wondering lately if it might be noise from my dual mass flywheel. But I think Mitch has a single mass setup.

    One thing that might be worth looking at is the possibility that a lifter may be sticking intermittently and holding a valve open slightly.
    Last edited by spfautsch; 3 Weeks Ago at 05:04 PM.
    '95 C4 LT-1 ZF-6, Polo Green
    Comp 467 / XFI 280, UltraProMag RRs, LE1 Heads, Lunati 73925 Springs

    Somebody stole the spark plugs out of my other car, yet it still runs???

  10. #25
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by Terminal_Crazy View Post
    Did you ever get info from FIC on the Bosch injectors
    Nope, but mine are grey bodied LS injectors that I managed to find a partial offset table for. I may be giving you the wrong #s but I believe the PN that was left on the injector body was GM 12561462 which crosses to Bosch 0280155931. Nothing along the lines of low pulsewidth compensation though. My table at 0x129f5 is also zeroed. I did however reduce my "minimal injector pulsewidth" constants at 0x126d5 and 0x126d7 to 0.56ms (0x25).
    Last edited by spfautsch; 3 Weeks Ago at 05:01 PM.
    '95 C4 LT-1 ZF-6, Polo Green
    Comp 467 / XFI 280, UltraProMag RRs, LE1 Heads, Lunati 73925 Springs

    Somebody stole the spark plugs out of my other car, yet it still runs???

  11. #26
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    Last edited by Stokes1114; 3 Weeks Ago at 07:18 PM.

  12. #27
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    GM 12561462 is ls1 28 lb/hr at 4 bar pressure.
    If they are stock I can get you the correct voltage offset settings.

    The best injectors will be the gm stock production ones or ford SVO.
    Cal data is readily available from stock tunes.
    Ls7.ls9 are really big improvement but alot shorter and needs modification to fit.


    I guess fic don`t provide injector data, because they don`t have one.

    Wrong plugs can get you alot of pinging. If they heat too much.
    Get us a pic of your current ones.
    Maybe try 1-2 points colder splugs.

  13. #28
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by kur4o View Post
    GM 12561462 is ls1 28 lb/hr at 4 bar pressure.
    If they are stock I can get you the correct voltage offset settings.
    None of these are stock - FIC remans / modifies injectors. They remove the pintle cap, clean and replace with caps (and possibly do something else) to give the flow rating the customer orders. Normally they grind off all part numbers and paint the injector bodies light blue, but in my case they only removed the Bosch P/N and left the GM P/N. They advertise these sets as flow matched Bosch D3s and that they will come with a flow test printout, but mine did not. Mitch was able to pester them enough to send offset data for his, but I didn't bother because mine idled well using the SVO offsets and minimum PW I found @ 3 bar.

    This is purely speculation, and I hate to bag on FIC but it's possible Mitch has a mix and match bunch of injectors that may or may not be electromagnetically similar but are minimally flow matched (at some pulsewidth). I ordered mine to flow 42lb/hr, and based on my VE trims they flow closer to 44. But thankfully I know mine at least match electromagnetically. When pull my engine next month I plan on sending mine to a third party to flow test.
    '95 C4 LT-1 ZF-6, Polo Green
    Comp 467 / XFI 280, UltraProMag RRs, LE1 Heads, Lunati 73925 Springs

    Somebody stole the spark plugs out of my other car, yet it still runs???

  14. #29
    Fuel Injected! Terminal_Crazy's Avatar
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    Ok Iíve got a few things to pull apart and check again tommorrow.
    See what I find.

    Most info Iíve found so far on the injectors is to just zero the low pw tables.
    This motor is idling about 1.8ms with the 42lb
    I donít see the voltage offsets having a major effect on the fueling once the motor is running. Voltage is pretty stable by then.

    Thanks
    Mitch
    '95 Z28 M6 -Just the odd mod.
    '80 350 A3 C3 Corvette - recent addition.

  15. #30
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by Terminal_Crazy View Post
    Most info I’ve found so far on the injectors is to just zero the low pw tables.
    As long as what you have are all Bosch type III I think you should be fine zeroing that table. But without any part #s you're taking FIC at their word. If you have one or two that are completely different from the other six or seven except in gross flow rating, all bets are off.

    Quote Originally Posted by Terminal_Crazy View Post
    I don’t see the voltage offsets having a major effect on the fueling once the motor is running. Voltage is pretty stable by then.
    Cooling fans draw a fair amount of power, especially on high. It sounds like you've jettisoned your A/C but the blower and the additional draw of the cooling fans keeping the A/C condenser working make a noticeable difference, especially at idle when the alternator output is fairly limited. You also have an electric water pump right? All this stuff makes an impact on system voltage.

    Long story short, I wouldn't dismiss offsets completely. I pay attention to the ECMVOLTS pid frequently enough I've considered making the "User Parameters" PID selections in eehack remember the last selection.

    Edit: It may be reaching, but are your injectors painted? If so have you considered filing through the paint to see the color of the base plastic?
    Last edited by spfautsch; 2 Weeks Ago at 07:00 PM.
    '95 C4 LT-1 ZF-6, Polo Green
    Comp 467 / XFI 280, UltraProMag RRs, LE1 Heads, Lunati 73925 Springs

    Somebody stole the spark plugs out of my other car, yet it still runs???

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