High Fuel Rate

[HANK1948]

On my 95 I am experiencing a high fuel rate at idle and I am not sure what to attribute it to. At idle in park the fuel rate is 20-25mm3 and in drive with brake is 30-35. I believe while cruising it indicates a "normal" fuel rate but that I am not sure of as well. Cruising at 60mph it is 30-35 and at 70 it's about 40. I am suspecting modified injectors that have shims to try and create a high "pop" injector. Since these are unproven and untested I feel that this is my only uncertainty. Is there any thing else I should be looking at or should I pull the injectors to rework them to stock configuration before anything else?

On another note... I love the new forum! Good job.

[BobND]

Well, if the engine IS idling down, and you are not spewing raw fuel out somewhere, the fuel rate is not really high, as if it were, the engine would rev up on the extra fuel.

[HANK1948]

It starts and goes right to a steady idle with no revving. It idles a steady and perfect 675...

[JohnC]

What's your indicated fuel rate at WOT at 2000 RPM?

[HANK1948]

What's your indicated fuel rate at WOT at 2000 RPM?

I do not know... I have to give it the business of WOT. :eek: I'll do that when I get outta work on the way home and see what's indicated.

[gmctd]

Hank, you never did mention what scanner you are using.............

[HANK1948]

The scanner is a Snap-On brand code reader that can display real time sensor inputs. It doesn't have the capability of much else...

[gmctd]

I think I would divide the displayed fuel rates by 3, for a more normal indication.

Cold = 11 - 12mm (fast idle in Texas)

Extremely cold = 12 - 14mm (fast idle north of the 'it don't snow much down here' line)

Warm = 8 - 9mm

Tweaked IP = 6 - 7mm

Severely tweaked IP = 4 - 5mm

IP @ 65 - 70 mph = 29 - 35mm

Stock eprom to Bill's v2.0 gives same idle rpm, cold or warm

Max WOT fuel rate - well, that's what I paid for............

[HANK1948]

Well I held it wide open for the first time since rebuilding the engine and the indicated fuel rate was 81.6mm3.

After a investigating all items related to fuel I finally took the time to pull and rework the injectors to stock configuration this weekend. I drove it home last night and into work this morning and all the driving issues I had are all but gone...! :D The fuel rate isn't exactly in the range gmctd laid out but it is very close. It's at an indicated 11 - 12 at warm idle and not at the 7-9 as expected. I did notice a leak at the #7 and #4 injectors this morning so I'll have to fix them and possibly that'll lower the fuel rate when repaired.

So this has been a learning experience that you cannot simply place a shim behind the spring of the nozzle to create a high pop injector as we were told by someone supposedly experienced with building injectors.

I had issues with:
1. Holding idle and stalling during high mph decel.
2. Smoking and surging idle for minutes at cold start.
3. It wouldn't start when hot.
4. Very poor MPG.
5. Poor performance.
6. Irregular indicated fuel rate.
7. High indicated throttle percentage.

Because of the rework being completed so recently I have yet to see an improvement of MPG but it is only expected seeing the improvent in performance and fuel rate across the spectrum. All of these issues have been all but eliminated after reworking the injectors.

So a word to all wanting to try to create a high pop injector do not try the same method...

[olddieselboy]

Hello Hank1948: Right on with that injector advice. The only way to get a high pop injector is to build with appropriate nozzle. I notice in your signature that you have a 3.5" down pipe, where is this available? Gord.

[HANK1948]

As far as I know there not available. I made mine out of stainless dyno flex pipe, I welded the old DP flange on to the flex(turbo side) and welded a 4.5" stainless marmon flange onto the other end.