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  #1  
Old 06-27-2018, 04:40 PM
Canadian_JOY Canadian_JOY is offline
 
Join Date: Aug 2007
Location: Ontario, Canada
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Default Feedback Request: GRT-Supplied VDO Oil & Fuel Pressure Sensors

I'm currently considering removing our existing engine monitor, an AF2500, and replacing it with a GRT EIS system which will more easily interface with the rest of the GRT gear in the panel.

Over the years I've read several threads here indicating the VDO pressure sensors favored by GRT are less-than-reliable.
1) Is this still the case?
2) What other pressure sensors have been used to good effect?
3) If using other pressure sensors, is the GRT EIS capable of calibration to provide accurate indications?
4) Has anybody re-used in their GRT EIS installation the very sleek 3-wire pressure sensors provided as original equipment with the AF2500?
5) If yes to 4, how did you implement them? (Suspect using 4.8V instrument power to energize the sensor, as well as the existing Common connection, with the "middle" signal wire going straight into the EIS pin should work, but don't want to incur additional down-time of the aircraft should this not work.)

Thanks in advance for your well-considered replies.
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  #2  
Old 06-27-2018, 04:59 PM
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Skid Skid is offline
 
Join Date: Jun 2006
Location: Walworth, WI
Posts: 106
Default VDO sending Units

I have had the GRT EIS system since day one on my RV. The only issue I ever had was due to a grounding issue. I had (dare I say it) put Teflon tape on the threads of the sending unit. The unit grounds through the case. This caused an occasional wild swings in oil pressure.
An easy fix is simply add a ground wire to the unit, I believe I may have read about that fix here on VAF.
No problems since.
I have the EIS connected to my GRT Sport SX, works great.
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  #3  
Old 06-27-2018, 07:16 PM
sjhurlbut sjhurlbut is offline
 
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Posts: 578
Default GRT EIS 4000

I've used EIS4000 on all my RVs. I've used 3 other brands and always go back to grt for reliability and accuracy. Only recommendation is to use the stainless steel fuel press sendor. All other sensors I've never had a single issue. I do rear mount my EIS since I customize the face a bit but I say go for it - it's awesome. One smaller recommendation is to use a sunlight readable LED warning light which may then require a 10k ohm parallel resistor.
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  #4  
Old 06-27-2018, 09:17 PM
Canadian_JOY Canadian_JOY is offline
 
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Thanks for the feedback. Several previous posts here gave the impression the VDO senders would produce erratic high oil pressure readings, indicating the wiper arm of the sender had lost contact with the resistive element, producing a full-scale signal output to the EIS. I'm glad to hear positive news on this front, too.
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  #5  
Old 06-27-2018, 10:00 PM
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Veetail88 Veetail88 is offline
 
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Had VDO senders in my plane for fuel and oil pressure. Both whigged out around 400 hours. Yhey wear out. Common problem. I switched over to Kavlico. Nice to see my pressures rock steady.
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  #6  
Old 06-28-2018, 05:55 AM
Deweyclawson Deweyclawson is offline
 
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Default paressure senders

When updating my RV6 with GRT, I was told that most of the probs with the pressure senders is caused by the ground going thru the case. I soldered a tab to the case of each and ran a ground wire from that tab.

3 years and no problems.
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  #7  
Old 06-28-2018, 08:51 AM
Canadian_JOY Canadian_JOY is offline
 
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Jesse - would you care to share what steps you had to take in order to get the Kavlico sensors to work with the GRT EIS, please?
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  #8  
Old 06-28-2018, 09:01 AM
Lars Lars is offline
 
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Worth noting is that VDO makes their sensors both with grounds through the case (what GRT sells) and with a separate ground stud. Summit Racing carries the latter and they can likely be found elsewhere as well. I've had both oil and fuel pressure VDO sensors fail in 600+ hours of service, the oil pressure sensor twice.
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  #9  
Old 06-28-2018, 10:09 AM
Canadian_JOY Canadian_JOY is offline
 
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Thanks for that feedback, Lars - this kind of confirms my concerns about VDO sensor reliability.

I'm not at all concerned about grounding the VDO sensors as I have had plenty of experience in the use of a gear clamp to bond a ground wire to the case of the pressure sensor. I AM concerned about the long-term reliability of the sensors, hence my wondering whether the Kavlico is ultimately the better sender to use, if they can be made to work for oil pressure and fuel pressure with the GRT EIS.

I appreciate the Summit Racing suggestion - after snooping around their electronic catalog I learned a bit as I didn't know these VDO sensors were also available with built-in low oil pressure warning switch. Using one of these would allow me to eliminate the separate oil pressure switch currently in place.
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  #10  
Old 06-28-2018, 11:58 AM
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Veetail88 Veetail88 is offline
 
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Quote:
Originally Posted by Canadian_JOY View Post
Jesse - would you care to share what steps you had to take in order to get the Kavlico sensors to work with the GRT EIS, please?
Sorry, I have an AFS 4500 so not an exact match. I was commenting on the senders, not the EFIS.

That said, the VDO senders provide a varying resistance, whereas the the Kavlico's, needing 5 volts in, I think provide a varying voltage. To make them work with the AFS unit, I had to get help from Advanced Flight. They said either I could send it in, or do the mod myself. They sent me a sheet on how to do it. Pretty simple mod, but I had to take the unit apart and scratch away 2 circuit pathways on the engine monitor printed circuit board. Easy peasy. Took way more time to remove, disassemble, re-assemble and re-install the EFIS than to actually do the mod. The original design of the board had different senders in mind.

Of course, I then had to wire up the new senders and provide the 5 volts from the unit. That was easy though as the manifold pressure sender (which is already on the front side of the firewall) has 5 volts run to it from the monitor board.
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Last edited by Veetail88 : 06-28-2018 at 12:07 PM.
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