topiwala

Hi Guys,
Wondering if Im doing something stupid with my brand-new 185 cdi zero. Im using cool power 20% red synthetic and 0% nitro. Out of the box and on the test stand, I had a few challenges to get the engine to run smooth and transition from idle to full. At times, i found myself having the adjust the regulator way in, and then out, and found my self chasing the engine. But, all of a sudden the engine came right and the needle valve and the regulator setting were back to what I would expect (1.5 turns out on the needle and regulator essentially flush with the housing). A few runs on the bench and I was happy to put it into my partnership.

Now in the model, I just fired it up. The engine warmed up but then just coughed, spluttered, and on the verge of back firing. Once again, I found myself chasing the engine settings. I couldn't get it to transition smoothly out of an idle, without it coughing/spluttering.
The most noticeable thing while trying to run in the model, was when I successfully got it idling, it would sometimes start to transition nicely to a higher power setting. I left it running at a mid high setting for a few seconds, but then all of a sudden the engine just went extremely rich, just kept surging and the rpm dropped, with lots of smoke from the exhaust. I then stopped it.

Essentially, if it transitioned normally, it would suddenly/randomly go extremely rich, and surge and cough. It would eventually loose rpm to a point of back firing.

Not sure whats going on here.
I have changed spark plugs, all fuel lines, cleaned needle valve housing. replaced valve o-rings.

Any clues, or assistance would be greatly appreciated. All else failing it will go back to YS for a check up.

Disappointing to go through this on a brand new unit.

I've run 140z's, 140L's, 160 dz's,170 dx's, 175dz's, with no issues This 185 zero is proving a little bit of a devil at this stage.

topiwala

Well I ended up sending the engine back. I got it back two days ago, and guess what. Its still doing exactly the same thing as before!! I have once again, tried needle settings and regulator setttings either side of the the normal/expected setting. changes to the setting make no difference.
Once I got it back and installed in the model, the first run up lasted about a minute before the problem came back.

Any one out there who can help....be greatly appreciated.

At this stage, I am considering returning the engine for either a replacement or refund.

Very unfortunate...i really don't want to go electric

arnstein

I have experience with CDI by not the ZERO, yet! I am assuming there is nothing wrong with the engine itself, since it just was returned from service.
I got similar problems as you described, what I did was to reduce the oil content.
I am aware the manual says 10-20% for the ZERO and 5-25% for the nitro version.
For me a reduced oil content helped.
My 2c worth.

Arnstein

topiwala

Thanks. That's interesting. I've been wondering about that. I've tried various combinations of mixes. Mostly increasing oil level to eliminate over sensitive needle settings.
the thing is that on bench I had it running sweet after a bit of fiddling. Settings with same fuel were kind of what I expected and had with my previous cdi YS.
But then once in the model, something changed.
i have a new backplate rpm sensor coming from YS. let's see what happens.

Then if that doesn't do it, I'm going to try 10% nitro.

topiwala

An update. Engine fixed. A new rpm sensor/back plate. The problem was a dodgy rpm sensor. YS sent a new one to me, and once installed, the engine has never missed a beat. Back to a happy grim on my face every time I run it.
Thanks YS.

Mayur

arnstein

I find this test kit useful, if you suspect something wrong with either the rpm sensor or the wiring: http://www.rcexl.com/news/Accessories/7.html

Arnstein

spaceworm

Please. how did you get from fuel mix issues to sensor breakdown? Thanks

BartekSz

Hello, Could you tell us, what is the real performance diffrence beetwen DZ185 cdi and ZERO?

Maybe some one has both or tested them?

topiwala

Hi. It was never a fuel mix issue. The sensor must have been intermittent and therefore screwing up the CDI timing. And the symptom was an engine getting fuel but not controlled ignition. And hence cough/splutter rich etc. Since the sensor replacement the engine has been perfect. I've even put the old sensor backplate back on to confirm. With the old sensor the problem comes back. So it was a confirmed failure of the sensor.

topiwala

The zero seems to like a prop one size smaller then the non zero. I'm running a 20X10.5. Where was the normal CDI likes a 21x10.5, I think. I'm getting 7000-7100rpm with mine. Still running in. Power wise, I don't have a need for anymore than a 170 in my Comp arf valiant patternship. But the 185 just feels a lot smoother.

topiwala

Also. Before confirming an issue with CDI/ignition system of the engine, I actually ran it with just a glow plug and the problem disappeared. Because with a glow plug, the entire CDI system is out of the circuit. Once the spark plug and CDI went in, the issue would come back. So that way I confirmed that something was wrong with the ignition side of things. So the first step in the troubleshooting was to change the backplate sensor.