Starting point for 1hdt fuel tuning (1 Viewer)

[wagonteeth]

I have read all of the 74 pages of the ihdt fuel pump tuning thread and still have an unanswered question on where to start with fuel tuning.

The basis for my question is this:. My 94 HDJ81 has 200k km on it. I have replaced injectors with oem as part of a baseline, as well as an oem air filter. I will replace the fuel filter this week and will begin tuning the pump afterwards if the heavy smoke isn't resolved.

It is pretty smokey at 6,000 ft asl. Maybe it's the higher altitude. The truck came from coastal California. The smoke didn't change after the injector swap, so I'm guessing that it maybe running rich since it's black smoke at low rpm heavy throttle and doesn't lean out as the turbo spools up. If I'm easy on the throttle there is no smoke and after the injector change there is no smoke at idle.

Is there a baseline setting for the android pin, spring tension and top plate?

i am assuming that the adjustments were fiddled with over the past 25+ years, so is there a setting to start with?

 

[veiloctane]

Here's a good read.

1HDT boost compensator adjust, now no throttle response

Hi All. just tinkering with my new 80 series, I was trying to reduce the smoke at idle so I took the top off the boost compensator to see where the off boost screw was at on the circular ramp. I also did one full revolution 360. of the diaphragm just to feel the tension and gauge where its at. I...

forum.ih8mud.com

also, do you have any gauges? , boost/EGT/AFR lamda Wideband

I say Wideband is nice to have then you can tune more accurately.

each engine is different so I'm not aware of any starting point

I would first start with pump timing and check your fuel pin. mines have always been smokey and I found out that half my pin was ground down and always giving full fuel on boost. it be worth it to see if your fuel pin has been messed with. sine Zeal Power rod was really expensive I have chosen to go with trundles automotive fuel pin and cap for more adjustability. BTW this is in Kiwi Dollhairs not USD

 

[jellis]

Sounds like it's over-fueling. You need a Mightvac and then you can set your aneroid pin @ boost properly. These videos are VERY helpful if you've never played with this before:



Pay attention to this post in the insane thread:

The Official 1HD-T/FT Fuel Pump Mod Tuning Thread

Run rich as in higher egts at low rpms? That's what I would think... but I'm a noob at this stuff. The way I picture it is that, with too soft a spring, very little pressure will move the rod, allowing the rod to administer more fuel earlier, when your RPMs and boost is much below max. Then...

forum.ih8mud.com

IIRC the FSM has some baseline settings for the fuel pump?!? The main thing is overall fueling screw.

Or you could find a diesel shop who can tune an old mechanical pump with an AFR gauge....I still need to do that.

 

[veiloctane]

Any one or shop that can tune a 12v Cummings can tune your VE pump there pretty similar.

 

[jellis]

Note that if the shop is at a significantly different elevation you should notify them so they can tune accordingly

 

[AussieHJCruza]

Within the limits of the turbo, altitude does not make any difference to a turbocharged engine that runs a conventional wastegate. Altitude is not the reason she's overfueling. Maybe a minor difference in idle/off boost fuel, but no difference on boost providing the turbo can move enough air.

 

[mudgudgeon]

The starting point is what ever you got now.

Every pump, every engine is slightly different. There is no single setting you can use as a starting point. Every pump will have been set up on a flow bench at some point, either in the factory, or by a rebuilder. Baseline is set to achieve specified fuel flows, not a defined position of adjusting screws etc

If you think it's smokey, take some fuel out, or increase boost.

You haven't mentioned if you have stock exhaust, stock turbo?

If it's all stock, the main fuel screw will have a security collar on it.

Start by playing with the off boost fuel setting and star wheel/aneroid pin.

You absolutely need gauges to know if you're achieving anything. Otherwise you're just completely guessing

Tuning is baffling at first. It takes a lot of trial and error to get a handle on what the adjustments all do, and how they interact.
It takes a lot of tweaking, testing, re-tweaking, and testing, testing, testing over and over and over.
Find yourself a strip of road with a decent long steep uphill section to push it hard up the hill repeatedly to assess each tweak, and prepare to get real familiar with that strip of road

 

[Tsvigo]

if ur car has high mileage and there is a diesel shop, let them check and run the pump on the test bench. with what u describe. the setting on the pump fueling is off.
during 0 boost, there will be smoke be seen but it is not as dark like a charcoal, mostly is grey.

FYI : none of the other proposed solution will solve ur black smoke, but will increase smoke. you can diy tuning it but how accurate is that in fueling? Also AFR reading varies in all cars and all situations.

 

[Obrokoff]

First step - install pre-turbo EGT gauge.