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The fluttering I see on that needle appear to be nothing more than that caused by engine vibration. There's very little movement actually. But look at the fuel pressure fluctuations on the graph display. I see more than 30# deviations!!! Your fuel pressure isn't flailing around that much. You've got grounding issues, hence my question about exactly where the fuel pressure sensor and WB are grounded!!
I agree that my fuel pressure shouldn't be fluctating THAT much. Wideband is an LC-1 with all grounds soldered to one lug and grounded at the engine block. Fuel pressure sensor should be getting it's ground from wherever the TPS get's it's ground. It's one of Julio's kits that uses a jumper harness from the TPS. Eric replied on his forum and mentioned the wideband sensor. He brings up a good point. I know wideband sensors generally degrade over time and I've had that same sensor on there for several years now. It could be a start, however that still does not address the original issue.
Gauge taped to the windshield showed a nice 1:1 with no fluttering. That was about three months ago when I last did that (prior to fuel logging).
Pump is a standard Walbro 255lph purchased from Racetronix along with a new hanger assembly and intermediate wiring harness. Yes, hotwired. FWIW, boost does flutter a small amount at WOT but it doesn't correspond with the fuel pressure fluctuations, as those are much more drastic.
From my Google searching, it looks like a the disc style seat, similar to my "old" Accufab unit.
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I know everyone is screaming grounds (and for good reason), so here's my system and what I've checked: Entire wiring harness is a Casper's unit replaced ~3 years ago; positive and negative cables both new(ish) and grounded to clean, metal/metal grounds at block; battery is new(ish) and tests good; newer Powermaster alternator putting out plenty of amps; LC-1 wideband grounds are all soldered and grounded on the intake lug behind injector #6; both sets of system grounds are clean, metal to metal, and grounded to separate locations on the back of the block. Also have two braided grounding straps from block to firewall. I don't think I've overlooked anything. /shrug
GNONYX
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I could be wrong, but your rail fuel gauge should be Liquid or Silicone Filled as the one in Full Throttle site
Your present fuel pressure rail gauge looks like a regular gauge, and no liquid filled.
http://www.fullthrottlespeed.com/customkititems.asp+kc+001GMRAIL+eq+
Your present fuel pressure rail gauge looks like a regular gauge, and no liquid filled.
http://www.fullthrottlespeed.com/customkititems.asp+kc+001GMRAIL+eq+
I thought the same thing too but forgot to mention that! I think a good test would be to disconnect the TPS splice, reconnect the original connector, and go for a run. Although the fuel pressure trasnsducer would be taken out of the equation, if the TPS cleared up, then I'd be on to something. I could then run dedicated wiring to the input board for the Powerlogger (since it already has the ability to run a 5v sensor). Hell, might not be a bad idea to do regardless. I think I'll do that.
Also ordered a new wideband sensor from flea bay. Will see if A/F clears up also. Will report back...
Keep in mind liquid filled gauges aren't accurate in an environment with temperature swings ( like under the hood of a car).
PSIG is relative to atmospheric pressure and with a sealed 'reference' it can't self adjust accordingly.
Just to keep in mind. The logs I looked at from TTA308 were just as jagged and 'impossible'.... when he put his Kirbin regulator back on, it smoothed out. Same grounds, same everything. The scientific method was appeased.
PSIG is relative to atmospheric pressure and with a sealed 'reference' it can't self adjust accordingly.
Just to keep in mind. The logs I looked at from TTA308 were just as jagged and 'impossible'.... when he put his Kirbin regulator back on, it smoothed out. Same grounds, same everything. The scientific method was appeased.
Accept for one frame,the WOT TPS voltage is either 4.66 volts or 4.64. That could just be an adjustment thing. If you rotate the TPS sensor just a touch or move it up or down in either direction,the WOT voltage might stay steady.
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Yes, noticed that as well. I already readjusted TPS last night for that very reason. Just finished wiring up the fuel transducer via the Powerlogger input so it now has it's own dedicated circuit (i.e., 5v ref and ground). TPS is now back to stock configuration. Won't get a chance to test things out until at least tomorrow because it's raining here. If things still look wonky after the next test run, I'll start looking at the FPR and wideband sensor again. Gotta be methodical about these things. Thanks for all the input gentlemen.
I respectfully disagree. Actually, the gauge that's on there now was glycerin filled but I drained it out for the very reason 'earlbrown' mentioned: Liquid filled gauges are notorious for inaccurate readings once they heat up. Either way, I'm satisfied with the explanation that it is engine vibrations and/or a combination of the injectors (as Eric from TurboTweak suggested) causing the disturbance at idle. Again, my main concern here is getting accurate readings under boost and WOT where things really matter.
GNONYX
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The working temperature range for glycerin filled gauges is normally between 30 to 160 degrees. Silicone oil will withstand a wider temperature range (from -50 degrees to 300 degrees), but will also be more expensive.
TurboTdr3.8
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Dave is right Bob says to never hook anything to powerlogger for 5v and gd cause it could cause pl and ecm to get wipped out if something goes crazy with that device .
Am I missing something here guys? By design, the input block is configured to run one 5v sensor if needed. It's right there in the manual. I have the transducer (a 5v sensor) hooked up exactly like is shown in the example given in the manual. Yes, there are warnings about ensuring that care is taken during installation and not to hook it up any other way...but nothing that specifically prohibits this.
Thanks. I may look into this in the future.
TurboTdr3.8
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http://www.vortexbuicks-etc.com/PowerLogger.htm , read last paragraph .
this diagram is correct. you can run one sensor from the analog block.
what you never want to do is connect that +5v terminal to another source of 5v. Also, accidental grounding of that 5v terminal has been proven to kill the ECM and PL.
Note, that the current version of the PL no longer has 5v available at the analog block. (the instructions have been revised also)
Bob
Thanks for that input, Bob. I didn't realize there was a new version of the PL out. I'm confident in my install and don't see any instance where the wiring would get botched up.
For those of you following this thread, Eric is helping out over on his end as well. In summary, once the weather clears up, I will first test the readings and see if they've stabilized. I'm hoping that separating the TPS and the fuel transducer and giving them each their own circuit will eliminate some of the erratic readings. Once my new wideband sensor arrives, I will give that a shot as well. I'm suspecting a possible lazy sensor. In the meantime, I need to check the alky system again just to make sure it's output is up to standard...and then possibly the fuel pump.
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