D-Jet Fuel Injection Help, Loss of Power with Warm Engine Options

[914_teener]

Ok so I took a closer look at the plugs and decided it was running lean. Made a few adjustments and now have a much nicer plug color. Runs much better but I will have to seek out someone with a AF meter to get it exact.

Ordered a TPS board and I think that will solve the hesitation as currently the injectors do not fire when the throttle is moved as they should.

And just for fun I hooked up the temp sensor on the throttle body. For some strange reason it runs fine now with it attached.

So what is your fuel pressure?

(IMG:style_emoticons/default/popcorn[1].gif)

31 PSI.

You can rent an AFM is you don't want to buy it.

Check it as Rich suggests under WOT, part load ,and idle and check back.

31 should be okay if your CO checks out and you have the 2.0 injectors that have been flow checked.

[Mblizzard]

Ok so I finally bit the bullet and ordered a wideband AF meter. Going to replace the TPS board, add electronic ignition, and try to adjust the MPS.

Anyone know what I should be looking for at idle, crushing and WOT?

[cary]

Search the word "stoic".

I have mine set at 12.5. Once you bring in down under 14 you'll know you're on the right track.

[Mblizzard]

Search the word "stoic".

I have mine set at 12.5. Once you bring in down under 14 you'll know you're on the right track.

Found this from Chris:
Using a wideband O2 meter that reads in A:F ratio, you want to see:

13.5-12.9 on the gauge while accelerating or climbing,

12.8-12.5 at WOT,

and 16-17 while cruising, going downhill or decelerating.

What about idle?

Based on what Chris has 12.5 would be pretty rich.

So because a lower AFR means a "richer" mixture, you want rich mixtures on acceleration and leaner on deacceleration.

[r_towle]

Rich on accel, lean on DECEL....

Idle will be what it is.
If you setup the TPS properly ( look closely at the new board) there is a special circuit for the idle mixture.

The MPS settings are for part load, and WOT...

Those two settings are what matters with the MPS...the rest of it works based upon those two screws...

[Mblizzard]

Oh so I got the AF Guage (IMG:style_emoticons/default/smile.gif) installed.

So under acceleration I am at 13.4 to 14.7.

WOT I am at 14 to 15 plus.

So that tells me I am running lean. With the additional displacement that seems to make sense.

What is the best way to overcome the lean condition? I am assuming MPS adjustment?

Is there a tool for holding the outer screw that will allow you to adjust the inner screw out to richer up the mixture?

[r_towle]

is it lean all over the place?

If so, I have had good luck getting a 1000 ohm potentiometer (volume knob) from radio shack and placing that inline in the CHT wire.

turn it up until you AFM reads correct in all ranges, then measure the POT with an ohm meter to see where it is set.

From there, got back to radio shack and buy a resistor that is the same as you measured the POT...and replace the POT with the inline resistor.

This works on the whole range..so if you are only lean in one spot or another, it may not be a good solution and adjusting the MPS is really what you need to do.

rich

[914_teener]

In another thread you posted the location of the welded bung. Why did you pick that location?

[Mblizzard]

In another thread you posted the location of the welded bung. Why did you pick that location?

Well it was easy to get to and it met the installion guidance of placing it in a location and angle that would not collect water.

[Dave_Darling]

What is the bust way to overcome the lean condition?

Best? Any way that works.

Try bumping the fuel pressure a few PSI. It looks like you're already over the stock spec by a bit, but you can go a bit further IMHO.

You can add resistance to the CHT circuit. That will make the FI think the engine is always cold, so it will add extra fuel. It can be a bit fussy.

You can unplug the intake air temp sensor. That will richen the mixture across the board slightly.

You can adjust the MPS. It is definitely fussy--you can make large mixture changes with little tiny physical adjustments. You'll have to hold things in the right place as best you can when you go to adjust stuff.

--DD

[ChrisFoley]

Is there a tool for holding the outer screw that will allow you to adjust the inner screw out to richer up the mixture?

(IMG:style_emoticons/default/bye1.gif)

[Java2570]

You may be able to get away with just adding some extra resistance to the CHT circuit like Rich mentioned.
Obviously, there's a line where it would create a problem if it's too much but you could try that and
experiment with various resistors or try the potentiometer idea.

[Mblizzard]

Wow having the AF gauge made all the difference. Adjusted the MPS inner screw out a bit and upped the fuel pressure to 31 and I am running in the high 12s under acceleration and 11 to 12 on WOT. Will have to fine tune it a bit more but what a difference in performance.

Thanks for the info guys. Will keep posting updates.

[Mblizzard]

Is there a tool for holding the outer screw that will allow you to adjust the inner screw out to richer up the mixture?

(IMG:style_emoticons/default/bye1.gif)

As a redneck engineering fix I cut a small slot for a screwdriver in the outer MPS adjuster which with some effort will let you adjust the inner screw while holding the outer in place.

[Java2570]

Right on!!

[Bleyseng]

Oh so I got the AF Guage (IMG:style_emoticons/default/smile.gif) installed.

So under acceleration I am at 13.4 to 14.7.

WOT I am at 14 to 15 plus.

So that tells me I am running lean. With the additional displacement that seems to make sense.

What is the best way to overcome the lean condition? I am assuming MPS adjustment?

Is there a tool for holding the outer screw that will allow you to adjust the inner screw out to richer up the mixture?

yes, the best way is to adjust the MPS to your engine.

[Mblizzard]

Well I am getting closer to the ranges Chris suggested and I just keep findind more power! (IMG:style_emoticons/default/aktion035.gif)

Making small adjustments and driving for a bit then adjusting again as suggested.

I am really impressed with how much cooler and more powerful the car is now that it is not constantly lean. Not sure the AF meter will be a permeant gauge but it will stay for the time being.

I think now I am getting close to getting the performance out of the 2056 build that I wanted.

The thing that I learned is that very small adjustments in the MPS can have a huge impact on the mixture. I was making way too large changes when trying to do it by trial and error.

Still have a small idle hunt issue as the engine goes very lean for a moment and slows but the goes back to rich and runs well. Will have to think about that one.

[ChrisFoley]

Well I am getting closer to the ranges Chris suggested and I just keep findind more power! (IMG:style_emoticons/default/aktion035.gif)

Making small adjustments and driving for a bit then adjusting again as suggested.

I am really impressed with how much cooler and more powerful the car is now that it is not constantly lean. Not sure the AF meter will be a permeant gauge but it will stay for the time being.

I think now I am getting close to getting the performance out of the 2056 build that I wanted.

The thing that I learned is that very small adjustments in the MPS can have a huge impact on the mixture. I was making way too large changes when trying to do it by trial and error.

Still have a small idle hunt issue as the engine goes very lean for a moment and slows but the goes back to rich and runs well. Will have to think about that one.

Do you know that there are 3 adjustment screws?
Do you have a hollow hex tool to hold the outer diaphragm screw from turning while you turn the slotted inner screw?
The plug on the end of the housing is the third adjustment screw. It sets mixture at WOT after the other adjustments are completed.

[Mblizzard]

Well I am getting closer to the ranges Chris suggested and I just keep findind more power! (IMG:style_emoticons/default/aktion035.gif)

Making small adjustments and driving for a bit then adjusting again as suggested.

I am really impressed with how much cooler and more powerful the car is now that it is not constantly lean. Not sure the AF meter will be a permeant gauge but it will stay for the time being.

I think now I am getting close to getting the performance out of the 2056 build that I wanted.

The thing that I learned is that very small adjustments in the MPS can have a huge impact on the mixture. I was making way too large changes when trying to do it by trial and error.

Still have a small idle hunt issue as the engine goes very lean for a moment and slows but the goes back to rich and runs well. Will have to think about that one.

Do you know that there are 3 adjustment screws?
Do you have a hollow hex tool to hold the outer diaphragm screw from turning while you turn the slotted inner screw?
The plug on the end of the housing is the third adjustment screw. It sets mixture at WOT after the other adjustments are completed.

Yes I know about the full load stop. But have been focusing on getting the others set. Don't know if it is right or wrong but I assumed that the ful load stop,would be the last setting after you had the others correct.

[Bleyseng]

Can you turn the WOT stop? On a MPS the first thing I do is remove the epoxy and clean the threads so I can unscrew it. Then I run it without the WOT until the adjustment is correct for part load. Then I install the WOT and set it's adjustment...
Finally I epoxy it so it's not going to move just like oem.

I don't like the drill a hole in it method....