Engine/Transmission (1994 - 1998) #5 Fuel Plate

[moparguy]

Thinking of changing fuel plates, I've been running a 5 plate since about '01. Of late it seems it's hard to start building boost (afc issues I suspect) with my homemade HX35/40 Hybrid (has HTT Stage 2 turbo kit which included a 8 blade 60cm HX40 compressor wheel and compressor housing) and 215 injectors. Timing is at 16.5 degs. Air filter is a BHAF, exhaust is 4" with a Walker straight through muffler.

The old truck occasionally pulls a 11,000 lb hunting trailer through the Rockies as well as a John Deere backhoe in the flat lands at home. Getting started with no boost is a pain. Then when in the mountains having to constantly watch egt's is another aggravation.

I "may" have a #8 plate stuck back in a drawer, really don't recall if I did the trade-in deal with TST for the 5 or not.

*****All the above said, anyone gone from a 5 plate to a 8, or 10? If I can find the old 8 I'll try it. If no find, then either grind or trade the 5 to TST for a 10.*****

IF, anyone has stepped down from a #5, any observations to driveability/smoke/spool-up or power you can share is appreciated.

According to Dr. Joe D some years ago the 10 fuels more down low than an 5 and less up high, reducing egt's. I like reduced egt's these days better than more power (that I can't use due to egt's anyway).

Thanks, Ron

 

[Bob4x4]

The 10 starts fueling earlier and cuts fuel where the 5 is still fueling.If your truck has changed from years past I would diag that first

 

[moparguy]

Totally agree. I'm about to pull the truck in the shop and dive into the afc and check things out. My thinking is with time running short to get ready for the Colorado trip I'd try and have a different fuel plate on hand to install in an effort to lower egts.

The only other major projects are fix the wench and replace the 250,000 mile control arm bushings, then an alignment.

 

[Joseph Donnelly]

As Bob said, diagnose the fueling problem--could be the filter, pre-filter, or lift pump. Otherwise, the turbo could be going out.

 

[JMcCoy]

I would also look at the fuel return line for a suction leak and throttle linkage for stretching.

 

[moparguy]

Thanks all for the suggestions. I failed to mention that once underway with rpm up and boost available power is still good, it's just that of late it's slow to build boost. Once 10 lbs or so of boost it's off to the races.

Today among other things I pulled the afc and checked the diaphragm and short tubing that supplies boost to the afc and all was good. I really expected to find a problem.

I also found the old #8 plate, having second thoughts on going back to it and may try grinding a 10.

 

[moparguy]

Mod's please delete this duplicate.

RR

 

[moparguy]

Yesterday I put things back together after; adjusting the pre-boost screw on the back of the afc housing to contact the afc control rod, then adding 3 turns of preload. Hope being this would provide sufficient fuel to eliminate the huge lag I'd experienced prior to the 5lbs of boost needed to start the real fueling process. I installed the afc housing in the center position. I also loosened (turned to the engine) the star-wheel 30 clicks.

On the fuel plate, after much deliberation I decided to try grinding one of my stockers to a #10 profile. I'll post images under a separate post. The jury is still out on whether or not this was a good move.

I will say that I don't think there's any way a home ground plate can duplicate the results of the real thing from TST. They put a lot of effort into getting it right, best we can hope for is a pale imitation with our bootleg copys.

Test Drive: Results were mixed, the lag was helped a bit but is still unacceptable and I still have tuning to do. I'm not getting sufficient fuel until boost is up for the truck to get out of it's own way.

Next step is to slide the afc housing full forward. My knowledge base is admittedly weak and I'm not sure if loosing the star wheel more will help or if I need to add more turns to the pre-boost screw, perhaps both. I'll see later today if the afe housing full forward helps.

I'm still not getting any smoke on initial take off so fuel is needed.

The home brewed #10 plate does come on strong in the mid-range in 3rd gear and up, makes smoke and pulls hard. Max unloaded egt with a pre turbo mounted egt probe was 900 degrees. I installed it about .10" forward of center.

That's the report this morning, if anyone has advice I'm all ears.

Ron

 

[moparguy]

Update, being a tad on the lazy side I didn't want to pull the intake in order to get at the front engine side afe housing screw. Would have been necessary in order to loosen the screw (along with 3 more) allowing the housing to be slid full forward. So, with the help of a shorty flat blade screw driver and a 3mm allen wrench I removed the preboost screw cover and tightened it 2 1/2 more turns. This makes a total 5 1/2 turns of preload.

EUREKA!!! I now have instant fuel and power. Also an unacceptable amount of smoke. So after lunch I'll take about 15 clicks out of the starwheel. If still too smokey it'll be pull out a full turn on the preboost and see where things are.

 

[JMcCoy]

Glad to hear your getting closer. I'm just a little concerned that this may be a bandaid for the real problem that had developed.

 

[moparguy]

JM, point taken. I really haven't been driving the old truck much the past several years. Less than 5k miles per year on average. A couple of years when working pipeline projects and not taking off for elk season it might have only been a 1,000 miles (or less). Reason for mentioning this is I'm not sure when the preboost fuel issue cropped up, but it's been noticeable for the past very few years. I really can't imagine what the root cause was.

The above said, the solution appears to be adjusting the preboost (or smoke screw as some call it).

This afternoon I checked the star wheel and afc spring with intentions of tightening it up a few clicks thinking I'd backed it off too much and the spring was loose. However when I inserted a screw driver into the spring it was still under tension, no slack at all.

I then moved to the preboost screw and backed it off 1 turn, too much. Slow to build boost, zero smoke. I added a 1/2 turn back. Much better, still noticeable smoke. Took out a 1/4 turn, good power, reasonably quick boost and only the very slightest (as in had to look very close to see anything) haze. Another 1/8th turn in might have been perfection. But not today. If my thinking is right, 4 3/4 turns of preload is what it took.

I suspect I could mess with the preboost and star wheel all day to dial things in to perfection. But I'm extremely OK with how the truck moves out at the moment, particularity considering where things were a couple days ago.

The real test will be in just over two weeks in the Rockies between 5,000' and 11,000' dragging an 11,000 lb. trailer. That's where things will likely get smokey and hot. It's hard to tune for the mountains when one lives at 300'.

 

[surfbeetle]

I have the #5 plate on my '95 and it's been great. I had an issue where I was not getting enough boost early on when taking off. I replaced the intercooler hoses and clamps. That solved my problems. Also you'll want to diagnose the waste gate control hose off the turbo. I had one that got a hole in it. Lastly, there are threads here where you can build a pressure test tool from common plumbing parts and use an air compressor with 10 to 15 psi of pressure to pressurize the system and check for leaks with engine off. I'm not discounting that you may have AFC fuel issues, but if you aren't 100% sure of the rest of your system, you'll just be chasing your tail trying to resolve your issues. Good Luck!