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Individual cylinder control

Discussion in 'FAST Support Forum' started by wabco40, Dec 11, 2017.

  1. wabco40

    wabco40 New Member

    Joined:
    Nov 13, 2015
    Location:
    Perth, Australia
    Hi, I'm having issues with the rear cylinders running rich on my 427 sbc. I'm using a front mounted throttle body on a fabricated manifold, the front cylinders are ok but each cylinder gets progressively richer towards the rear. Below is a picture of the plugs. The engine started to develop a miss, I'm guessing because of the rear carbon fouled plugs.
    I'm using XFI 2.05 in sequential mode and was thinking maybe I could progressively reduce the fuel to the rear using individual cylinder control to try even things out.
    Has anyone had a similar problem? I'm open to any ideas or suggestions. Thanks.
    Brad

    [​IMG]

    [​IMG]
     
  2. Fastmanefi

    Fastmanefi Active Member

    Joined:
    Jun 4, 2011
    Location:
    Sonora, CA
    Three things:
    1) Looks like an MSD dizzy. Where are you getting the cam signal?
    2) Assuming your Crank Ref Angle is set to 50 degrees - set your injector retard to 70 degrees.
    3) I'd have the injectors flow matched first, and if they are close then go ahead and lean out the rears.
     
  3. wabco40

    wabco40 New Member

    Joined:
    Nov 13, 2015
    Location:
    Perth, Australia
    I'm using a crank trigger for the crank ref angle which is set at 50 degrees btdc. The MSD dizzy has only one reluctor tab which is used for the cam signal, this is set at 75 degrees btdc.
    The injectors where flow matched when I purchased them but I will send them out and get them checked again.
    Thanks for the reply.
     
  4. wabco40

    wabco40 New Member

    Joined:
    Nov 13, 2015
    Location:
    Perth, Australia
    Fastman, a question about the injector retard? Wouldn't setting it at 70 degrees (with a crank ref of 50 degrees) put the injectors opening 20 degrees past top dead centre on the intake stroke.
    At the moment I have the injector retard set to 0. As I understand this would put them opening 50 degrees btdc on the exhaust stroke.
     
  5. Fastmanefi

    Fastmanefi Active Member

    Joined:
    Jun 4, 2011
    Location:
    Sonora, CA
    Yes - Your WANT to start the injection AFTER TDC which is after the camshaft reversion pulse is gone and just as the piston starts the downward intake stroke. This only effects idle but every little bit helps.

    If you leave it at ZERO then the injection pulse STARTS at 50 degrees BTDC of the upcoming intake stroke and it is affected by the camshaft reversion. This has nothing to do with the exhaust stroke. The attached picture shows the event with ZERO as the injector retard.
     

    Attached Files:

  6. wabco40

    wabco40 New Member

    Joined:
    Nov 13, 2015
    Location:
    Perth, Australia
    Ok, thanks. I will give it a try.

    I have taken the injectors out and getting them flow checked at the moment. I'm away working until next week, so will sort it out then.

    Thanks for the advice.
     
  7. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    How did things work out here?
     
  8. wabco40

    wabco40 New Member

    Joined:
    Nov 13, 2015
    Location:
    Perth, Australia
    I picked up my injectors from being flow checked this afternoon. There was a 9 percent difference in flow between them (so much for my flow matched set!!!).
    I had a engine miss on the left cylinders. When I pulled the spark plugs, #5 plug was wet and fouled. I marked this injector prior to flow checking and sure enough this injector was flowing the most.
    I didn't take note of the position of the other injectors, so I'm unsure if it's the injector flow difference or the manifold air flow that's causing the rich rear cylinders. I suspect it's both.
    I plan on placing the higher flowing injectors to the front and the lower ones to the rear just to see what difference it makes.

    Either way it looks like I'm going to be in the market for a new matched set of 42lb injectors. Any recommendations.
     
  9. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Other than what Richard already recommended, I was looking at your plugs and the gaps looked wide. It made me wonder if you had opened the gaps and had a weak spark. Gaps should remain as set by sparkplug manufacturers. Your plugs look new and appear to be running cold for a stock heat range. You may want to check for an open thermostat also. Be sure to check out the engine temp sensor and TPS calibration, as this will affect fueling as well.
     
    Last edited: Dec 19, 2017
  10. wabco40

    wabco40 New Member

    Joined:
    Nov 13, 2015
    Location:
    Perth, Australia
    Thanks, I've got a fresh set of plugs and have set the gap to 38 thou. The previous plugs where set at 44 thou, I think I may have had the mistaken belief that the gap needed to be wider using an MSD ignition. If these plugs foul I will look at going one heat range hotter.
    I'm using a 180 degree thermostat and according to the Fast e-dash the engine temp runs between 185 - 190 degrees. This is also confirmed with a mechanical gauge. I have recalibrated the TPS as well.

    I did what Richard recommended and set the injector retard to 70 degrees. I will see what these latest changes make before replacing the injectors and looking at individual cylinder flow rate.
     
  11. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    The new plugs should be fine so long as you don't open the gap from that set by the plug manufacturer for this plug. You are already using the factory heat range and should not need to go hotter. Setting the injector retard as Richard recommended should help get things back on track with the new plugs.

    The wider the gap, with higher compression, and too much fuel, the poorer ignition will be. Wider gaps than the plug was set for by the manufacturer affect advertised plug temps.
     
  12. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    You should also check the cap and rotor condition, and phasing. MSD distributors using a locked out advance need the MSD Phasing Rotor. The phasing rotor screws loosen easily if no Loctite was used - even if you are using one.
     
  13. wabco40

    wabco40 New Member

    Joined:
    Nov 13, 2015
    Location:
    Perth, Australia
    Cool, thanks for the advice. I previously read on other forums to open the gap up, but since then I have learnt that this is a mistake with higher compression engines and you have confirmed this.
    The cap is new and I'm using a phasing rotor, this is phased at 25 btdc (confirmed with a spare cap with a window cut into it). What I didn't do was put loctite on the rotor screws but definitely will do this.

    Will keep you posted on the results. Thanks.
     
  14. wabco40

    wabco40 New Member

    Joined:
    Nov 13, 2015
    Location:
    Perth, Australia
    I have finally solved the problem.

    I fitted new spark plugs (NGK BKR6E, one range colder then the Autolites I was previously using) and went for a 10 mile test drive. This engine has never run as good, much better idle and a lot less slow speed surging. I had previously put the slow speed surging down to the size of the cam but now it's much better. I'm guessing this is due to the 70 degrees injector retard. Thanks Richard.

    When I returned I took the plugs out, but # 5,7 and 8 where black while the others where ok. What I did notice was they where wet indicating it could be oil. I had previously suspected this so disconnected the PCV and fitted breathers. When I had the intake manifold off I checked how it seated on the heads and also the old gaskets showed a constant compression around the ports with no leakage.
    The engine is a fresh build with less then 150 miles on it. I did a compression test and this showed everything was ok and all cylinders consistent. Number 5 cylinder seemed to be main problem so I suspected #5 intake valve guide. What I found was there was no thread sealer on the intake rocker stud. These are tapped all the way through to the intake runner. When I unscrewed this stud there was oil on all the threads and oil could be seen on the bottom of the intake port. I checked all the other rocker studs and they had thread sealer on them. Looks like the builder forgot to put sealer on this stud.
    This would explain why #5 spark plug fouled first, being right in the line of fire from where the oil was getting sucked in. The oil was then being distributed around the plenum to the other cylinders with the rear getting the most of it.
    I re-sealed the studs and fitted NGK BKR5E11 spark plugs (same heat range as 3924 Autolites!!!) and then did another 10 mile test drive. The engine performed well however I feel it liked the colder plugs better. I'm not sure if it's because of the smaller 38 thou gap of the BKR6E compared to the 43 thou gap of the hotter BKR5E or if it just likes the colder plug.
    With the sparks plugs removed they looked much cleaner. The rear plugs still looked a bit darker then the front but I think this is due to left over oil in the intake, this should clear up. With the amount of oil being sucked in I would have thought it would be blowing blue smoke but I didn't notice any.
    What I did notice when starting after sealing the rocker stud was it ran very lean at about 15:1 until it warmed up and went into closed loop. With the vacuum leak sealed I guess I will have to do after start enrichment again.
    I still have the 9 percent difference in injector flow but will sort this out after Christmas.

    The picture below shows the plugs on the left from the first test drive and the ones on the right after sealing the rocket stud.

    IMG_5787.jpg
     
  15. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    The last set of plugs looks normal for a new engine. But, they are the wider gap plugs. Use the BKR5E - they will have the same gap as the BKR6E. It appears the rest going on is just fuel map changes and timing. Are you using adaptive learning? You may want/need to turn that off. If you are trying to build your own tune, you might want to consider contacting Richard for an online tune.
     
  16. wabco40

    wabco40 New Member

    Joined:
    Nov 13, 2015
    Location:
    Perth, Australia
    I went to purchased the BKR5E (40 thou) but the shop only had the BKR5E11 with a 1.1mm (44 thou) gap. I'm sure if this is the same plug with the gap opened up to 44 thou or a different plug. As you said before changing the gap changes the plug temp.
    Yes, adaptive learning is turned on. I saw Richard did online tuning on his website. I will get in touch with him early in the new year about this.
     
    Last edited: Dec 22, 2017
  17. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    If Richard did the tuning, it is fine. You may need to reload the maps. Those plugs are different - but in the same heat range. BKR5E (7938) uses a .036 gap. BKR6E (6962) has .032 gap. Follow Richards advice on whether use the adaptive learning.


    This may help you with the plugs - http://www.partcat.com/ngk

    The site is acting crazy. I was in error in the previous post concerning gap on BKR5E and BKR6E. The gap is the same for BKR5E and BKR7E.
     
    Last edited: Dec 22, 2017
  18. wabco40

    wabco40 New Member

    Joined:
    Nov 13, 2015
    Location:
    Perth, Australia
    Ok, thanks.
    Richard has not done the tuning, so far it's only been me. I will get in touch with Richard after new year.
     
  19. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Site finally started working well enough to see some of your older posts - for a short time. I now know your approximate compression and the camshaft used. A tune from Richard should be beneficial to you. It should definitely stop all surging.

    I would get a set of plugs with no more than .036 gaps. I can use either of the BKR5E or BKR6E plugs in my 9.5:1 compression 406 small block Chevy with TH400 - in an '85 TA. Both plug versions perform equally as well. Unfortunately, I don't have the option to turn off adaptive learning and manually build mapping, as I have the EZ EFI 2.0 ECU. But, I actually do have it running quite well - with just enough vacuum being made with its XR282HR to play well with my EZ EFI 2.0 ECU. My idle in gear is nice at 750 with the 2500 stall speed.

    Concerning the published .032 gap for the BKR6E, I actually believe that is in error and should be .036. .032 is the gap used on the race plugs that start in heat range 8 in this style of plug. The extended tip styles also perform better in street use.

    If you have a manual transmission, you should definitely have the adaptive learning turned off and use specific mapping. You don't want mapping changing between gears - which often does cause noticeable surging.
     
    Last edited: Dec 25, 2017
  20. wabco40

    wabco40 New Member

    Joined:
    Nov 13, 2015
    Location:
    Perth, Australia
    I thought there must have been a problem at my end with this site.

    The cam used is a 280XFI HR13, 230 - 236@.050, 113 lsa. The compression is about 10.5:1. It is also a manual transmission.

    I previously thought I have a fuel fouling problem as the rear plugs had a black soot appearance. This is why I was asking about individual cylinder tuning. Thankfully this problem is now solved.
    What I don't like is the injectors having a 9 percent difference in flow rate. I have ordered a match set from Five O Motorsport in CA https://www.fiveomotorsport.com/ which will be here next week.
    When I fit the new injectors I will try both the BKR6E and 5E again and keep the gap down to .036. Will see which one the engine likes. I will also turn learning off.
    I work away from home for a week at a time but when I return I will get in touch with Richard about a tune. I have read the details on his website and seems to be a good deal considering what's involved. I guess Richard is reading this post.

    Thanks for the advice. Hope you have a great Christmas.
     

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