Hi All,
I have a Wren44 Gold (still on the bench) and I cannot get it to consitently start...I've tried the gas valve in every position from 1/2 turn to 2 turns open...Ocasionally it starts, but mostly I get the following:

Gas ignites, Fuel ramp DOES NOT occur, temp reaches approx 170c then start terminates...the ECU displays "Start Bad"

Temp is around 25degrees c outside.

ECU battery was from between 10.1V and 10.8V



Another issue, once I had it running, when I pulled the stick to idle quickly, the engine quit....sure would not be good in flight!


Any Ideas??

Thanks in advance,
John

Verify all your connections to the Fadec. Especially the thermocouple. You may have it backwards.

Hi Gary,
Everything is connected properly...it starts occasionally, but not consistently....I think one of the settings may be off, but I don't know what any of the settings mean [sm=drowning.gif]

it seems you are not getting a rpm reading could it be you have the rpm connector reversed?
temp sensor sounds good
bad start normaly indicates a none rpm reading.
and dont use to much gas , it will only slow down the start
also make sure your glowplug coil has been pulled out enough
and it should be glowing bright white

did you alter the settings?
they just dont run off.........

Not sure about the start problem.


As for the flame out. What is your Decel delay setting? It may be too low.

is your pump running? whats the PW at when it should be ramping? This does sound like a sticky pump problem.

Jason

John,

There shouldn't be anything much wrong as the engine will have been working perfectly when it left here. We run every engine several times and the ECU settings are set individually for best performance on that particular engine. The screwdown gas restrictor connected to the solenoid is pre-adjusted to do a clean start with full pressure from your supply, so the valve on the top of your canister should be fully open.

We are always here to help and the best thing is to talk to us directly. I have PM'd you asking for a telephone number and I'm sure we will get this sorted out quickly.

Sara Parish
Wren Turbines

As discussed over the phone and PM, the use of 3 cell LiPo is recommended as opposed to the NiMH battery supplied.
I have also PMed you the two setting changes needed to reduce the starter motor voltage and glow plug voltage.
I am sure this will resolve any starting issues.

I have been using 3 cell LiPo on my Gold with no problems at all, in fact the startup procedure is barely 15 seconds.

Regards

Johnny

Stupid question....please confirm you have not reversed the gas and fuel lines.

I have seen this before...

Paul

I think this problem was traced to a faulty battery pack.

Yes, it was all sorted out a couple of days ago. Faulty battery, as Jason said. The customer, John, had received one of the last of the KAN batteries - we have now changed to a LiPo. His starts were OK at first, but then the battery failed. He has tried the engine with another battery and it's fine, so we've sent him one of our new LiPos as a replacement for the failed one and look forward to hearing that he's installed and flown the engine.

Sara Parish
Wren Turbines

Thanks everyone for your help, and especially to Wren for their quick ability to diagnose and solve the problem....thanks also to Peter at Altecare!

Here's what I can't figure: Why not directly contact the dealer/distributor/manufacturer first?! Give them first crack at it...respect them and their expertise...certainly in Wren's case! No missadvice and gotta be the quickest, I 'd guess.

Ray
AMT-USA Field Rep

a well maybe others read this thread to and then call wren first..

John is new to turbines and he was a bit anxious I think to get his turbine running again on the bench. He is all set now and a very happy camper.

Good!

now he will get addicted to it...like me a few years back
darn hobby............
i remember myself a few years back
i had the Wren turboprop as my first turbine
when i started it the first time , i was so impressed by the sound it never got to idle.
i was so scared i turned it off.......