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Overfuelling/EGT issues

Discussion in 'Diesel Tech / 24 volts' started by CptJR, May 15, 2018 at 12:18 PM.

  1. CptJR

    CptJR

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    Hey all,

    I've been trying to research and search the forum before posting but I'm honestly stumped. Here's the situation.

    1992 FJ80 1HD-T 12V motor with stock turbo, been over fueling since I bought the rig- previous owner said he wanted it tuned to "roll coal" aka over fuel. Running 8 psi and I find when boost kicks in around 1800 rpm the EGTs rise aggressively with not much power to show for it. I'm up to 1400F pre turbo before I even hit 100 kph. This would be at I'd say 3/4 throttle. I'm slowing to 60 on hills to even keep it below 1200. Here is my setup, and all the things I have tried as per the awesome info I've gotten on the forum.

    Safari Snorkel intake, brand new air filter changed with less than 50 kms on it. Stock turbo, HPD top mount intercooler with electric fan, 3" custom exhaust. Boost comes in at around 1800 rpm, holds 8 psi steady. So far I have done the following:

    Intercooler/hood scoop installed, I've dialed back the fuel 1/8 a turn, installed a manual boost controller, upped the boost to 14 psi.

    So now, the EGT's are slightly slower to rise and cooler (maybe a couple hundred degrees), and at 80 kph I'm sitting at around 900, but when I really accelerate and the boost comes in, I'm up to 14 psi, and the EGTs are still rising quickly. As my gearbox shifts (Automatic) into 3rd I get the over boost light come on, and again the EGTs are up to 1400F. I can't even get to 110. After I adjusted the fuel mixture it seems all it did was lower my idle to around 600. Which is low, I know stock on an automatic needs to be around 850. Big black smoke clouds at initial acceleration as well.

    So I'm stumped! my next ideas are to clean the injectors, adjust the fuel rod and the boost compensation spring, but I'm somewhat at a loss. Any input or help would be really appreciated.
     
  2. Lumpskie

    Lumpskie

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    Have you pulled the boost compensator apart and looked at the pin? (and star wheel, for that matter) I wonder if you have an aftermarket aneroid. I also wonder if your boost compensator is tuned properly.
     
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  3. dan1554

    dan1554

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    x2 on the aneroid. Or buy a new turbo and crank it to 18+ :smokin:
     
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  4. IanB

    IanB

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    When you adjust the main fuel screw on the injection pump, you will need to adjust your idle accordingly, FYI.

    I'd dig into the boost compensator as well, you're looking for pin travel at your target boost level (mark aneroid pin with a paint pen and test via a drive, or applying 14psi to the compensator reference line so the pin travels, remove and look at the marks from the follower pin on the fuel aneroid pin. You can try backing off the "smoke screw" on the boost compensator lid so the off-boost fuel is reduced and see if that clears up the black cloud on initial acceleration.

    If your issues persist, try disconnecting the snorkel and see if it's possibly a restriction that is choking the engine for air.

    If that doesn't work you may need to back off the main fuel screw further and retune the boost compensator from there.
     
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  5. CptJR

    CptJR

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    Awesome thanks so much for the input guys, I really appreciate it. I'm wondering myself if I have an aftermarket aneroid too, pulling the pin and star wheel/boost compensator was next on my list, but for some reason I was feeling a bit intimidated by it- I'll read into it more.

    As for the Snorkel, I *did* drive with the top off, however the main pipe from the intake up the side of the body was still there, so would still be restrictive potentially if it is an issue.

    Will be a good project in a few days when I'm off dayshift. I'll see how it goes!
     
  6. dan1554

    dan1554

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    Good luck! I would just rotate it so the pin rides on the shallowest profile. You'll know immediately if that was the problem. You can mess with tuning it later. Should take 5-10 minutes.

    Oh don't try to put the aneroid back in without nudging the follower pin back a bit first. Glad I realized this before trying the 200lb press-fit.
     
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  7. IanB

    IanB

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    Read through the official fuel pump tuning thread The Official 1HD-T/FT Fuel Pump Mod Tuning Thread, there's some videos showing the boost compensator and how it all works, make sure to mark things as you take it apart so you can get it back together with the same settings (should you wish to). It's a lot less scary once you've been in there! If the fuel pin is OEM stock (unlikely), you'll need to grind the head so it can be reinserted past the follower pin.
     
  8. CptJR

    CptJR

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    Sounds good, I've bookmarked that page awhile ago and have been chipping away at it- I'm obviously eager to get in there now and figure this issue out. Thanks everyone for your input and help. Really awesome support on the forum.
     
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  9. IanB

    IanB

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    FYI, I treat sustained 1250F as my safe ceiling for pre-turbo EGT's, 1400F is hotter than I'm comfortable with.
     
  10. CptJR

    CptJR

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    Yeah as soon as I hit 1200 sustained I get anxious, previous owner said 1400 transient for a few seconds max, but I get really uncomfortable at 1200 even, so no worries I don't run that hot- it's off throttle as soon as it spikes.
     
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  11. CptJR

    CptJR

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    So bit of an update, I feel like I'm on the right path, I pulled the aneroid and dialed it back to about halfway, the pin is riding right on the shallowest profile- EGTs are still rising but not at the terrifyingly quick rate they did before. I maxed out at 1200F, 13 psi at 80 kph. Now the one thing I'm still trying to figure out is the star wheel, anti clockwise increases spring pressure meaning more boost is required to push the diaphragm down, and therefore injecting more fuel? the issue I'm dealing with now is the fine tuning. I'm very slow to accelerate and not really making any power above 80 kph, 100 is possible but he chugs hard and that's when the temps really climb. So just to make sure I'm on the right page here are my next steps:

    Decrease star wheel spring tension (turning clockwise) *maybe* increase the aneroid fueling, and after that I'm planning on readjusting the idle screw since I'm still idling around 650 rpm.

    I'm not looking for massive power, I just want to get to 110 without temping out so I can comfortably cruise the highway to get to some great off road areas. Is there a set amount of clicks on the wheel that is "stock" or minimum/maximum? I read of guys going to 10 clicks or 65 clicks?


    I should also note that there were two washers on the aneroid pin, and surprisingly it was a stock pin as well. I haven't heard of those washers mentioned in other posts, they must be stock I'd assume?

    Thanks again guys.
     
  12. IanB

    IanB

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    You should set your star wheel so you get full travel of the aneroid pin at your target boost level, without getting into the fuel cut portion of the grind. With that set if you're EGT's are too high then you need to remove some fuel via the main fuel screw. If it's a dog off boost with main fuel reduced you can use the "smoke screw" adjustment to bring in more fuel before boost causes the aneroid pin to start moving.

    1200F at 13psi and 80km/h is way too hot. Make sure your air filter is clean and there are no intake restrictions causing you issues. Check the turbo for shaft play that might indicate it's not working properly.
     
  13. CptJR

    CptJR

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    So with full travel I should see a mark along the pin the whole ramp, and obviously not up onto the cut off. Off boost he's good- it's on boost above 80 there is very little acceleration. Air filter is brand new and I've unhooked the snorkel for these runs. I guess it's back to adjusting and trialing the different settings for now..
     
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  14. IanB

    IanB

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    That's correct on the pin marking. From there, to bring EGT's down you need to remove fuel, or add air.
     
  15. CptJR

    CptJR

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    Well I'm at a bit of a loss- I have the star wheel set perfectly, when I go to adjust the fuel it seems it's either the same problem as before, or at one point I wasn't even getting above 900 rpm when WOT and obviously I was crawling along. Will have to do more troubleshooting tomorrow, gotta get to work for the night.
     
  16. mudgudgeon

    mudgudgeon

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    The tricky part is having a IP that someone else has screwed with is that to start with you are guessing at where settings are. You have no baseline.
    Often, if you adjust one setting, you need to re-adjust all of them (main fuel screw, idle screw, aneroid position, star wheel spring preload, off idle fuel/smoke screw). It takes time, especially figuring out a baseline. I wouldn't expect to get it right in one or two goes, it's a process that might take numerous adjustments over a couple of weeks and you¿feel like you're going in circles for most of those adjustments.

    I'd strongly suggest read some of the official tuning thread linked above.
    Start at about page 29.
    Around the same time there was a handful of guys trying to baseline new to them rigs, so there was some good combined troubleshooting happening from pg29 onwards
    Look for posts by @Lumpskie @DancesWithMutts @vwluv10338
     
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  17. CptJR

    CptJR

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    Thanks for that- ironically I just got to page 29- I was starting to wonder how much info was buried there as it started to go a bit into other things. I'll keep browsing- motivated to get it figured out of course, just annoyed that I had to quit for the day! as you said, it could be a process over a few weeks.
     
  18. Lumpskie

    Lumpskie

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    Did you already adjust your transmission kickdown cable? If you are running high throttle at a low RPM, you'll get really high EGTs. @IanB gave me a heads up on that and it helped my rig a lot.
     
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  19. CptJR

    CptJR

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    I have not- I'm going to research how to do that now, after reading the entire 67 page thread, I'm a bit more confident- however still feel like I don't know what I'm doing! I was thinking of doing what @IanB did and take one of the washers out to allow for the aneroid pin to travel further, and then maybe dial the star wheel all the way down, and work my way back from there. There are just so many different ways to get caught up in this and trial it. However perhaps first I should adjust the kickdown cable. I'm wondering about it because I do find there is a "sticky" spot on the skinny pedal I have to step through, and there seems to always be an abrupt acceleration once I push through it, and the gearing especially 3 to 4 always seems sort of like it's hanging up, I have to let off the pedal and modulate it quite a bit to get the shift to happen. Hopefully I'll be able to get at it in a few hours!
     
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