EJ25 running rough

[mad max]

Thats an interesting theory Graham. I have been involved with a sparrow hawk and the engine used to stop when I transmitted on the VHF and only when we were flying which was very confusing for a while. It turned out to be an earth problem. I"ll follow it up.

[chook]

Graham, one more thought, check each connector at the injector to earth - use the highest resistance range and compare with one of the other injectors both forward and reverse polarity.It"s sounding like either the injector or the cable between the injector and the box since a new box has no effect. Also check the connector connections for corrosion and arcover between that pin and something else (you might want to use bright sunlight as the pins will be fairly fine). And remember it may be on the wire entry side as opposed to the pin side. While you have the main connector disconnected from the box try some readings back towards the box from the injector connector (high ohms range and forward and reverse polarity).If you want to talk it through them PM me - my email is attached to my profile and I"ll give you

[mad max]

This is Mad Max"s new creation.

[gbw]

Looks fantastic. Who cares if it runs rough, you can just leave it sitting around.Graham

[Disco]

Chook gives some good advice, sounds like he has chased this trouble before.

[mad max]

I seemed to be getting a lot of prop swirl and required a lot of left rudder with full throttle so added the " brahman ears."

[chook]

Max, how are you going with this problem?Were you able to sort out the CRO operation?This one has really got me interested! Much better than a game of cards trying to outwit the failure.Chooky

[mad max]

Just ran a jump lead from the ecu to no. 4 inj. (disconnecting old loom) -- made no difference. Checked signals to all injectors. Oscilloscope has a frequency meter. No 1 - 2 and 3 is 17 hz. and no. 4 is 35 hz. at 2000 rpm.

[mad max]

As a matter of interest the gyro weighs approx 360 kg cruises (when engine was purring) at 63 knots. Has centre pillar dash allowing lots of front storage. Has uhf vhf and hf transcievers. Inflight am fm and shortwave receivers. Horrison gyro with usual instruments. ( you may survive zero vis. with training) Push pull rod rudder control. No cables on gyro except throttle. 80 ltrs useable. Fuel behind firewall (only alloy f/w) C/Fibre kruza cabin. Built for missus and I to fly around the country. Bloody highways too dangerous.

[chook]

Ok Max this puts it in the injector itself or some weird condition of the ECU where some inputs cause it to specifically double feed injector#4. (for what possible reason?)Last option is to physically swap the #4 injector with the next easiest one to get at. Then back with the CRO and see if the fault stays with the position or moves with the injector.Was there any resistive connection between the injector and earth? (on any injectors?)Chooky

[mad max]

The injectors have been swapped left side to right side. the problem remains on no.4

[Darrell Jones]

G;day Max, you seem to have checked the electronics, Have you done a compression test of the engine, It is always a possibility of a sticky hydraulic tappet

[chook]

AHHH jees Max - ya really making this hard!Ok I"m thinking out loud here.4 stroke engine doing 2000 revs per minute.So each piston is also doing 2000rpmSo each piston (and injector) has 500 inlet events per minute. (1 in 4 strokes)You have seen 17Hz on the good injectors. This is 17 pulses per second which is 17pps x 60secs = 1020 pulses per minute.This equates to around 2 pulses (1020pps /500) of fuel per inlet phase per cylinder. Ok that is reasonable.So it is all getting back to the ECU - I know you have swapped it out with another and get the same result.Some input is causing the thing to do this. Have you been able to test your ECU in another engine successfully?Do you have access to an auto lekky who can diagnose any error messages coming from the ECU as this is definitely not normal operation.It may be that you have to take the ECU to a dealer (they will baulk at the fact that it is an aircraft! don"t tellem) One of my mates recently had a failure in his Land rover which could not be identified by his "local" guy but had to go back to the dealer who had the genuine ECU access computer.Chook.

[mad max]

I"ve done 3 compression tests and all cylinders are the same. Half my brain was wondering if a stone or wasp nest had got onto a cam pulley and flicked a tooth as i have no cam belt cover. However I always preflight check for such events and I assume if one cam slips a tooth that side compression would be down a little. The engine has only done 24,000 km so should be in good condition. I think my next step is to find a 95 or 96 subaru and plug in the computer.

[AirWolf]

Hi max,I may as well offer my two bobs worth, a compression test may not necessarily show up a faulty hydraulic lifter as they can pump up as oil pressure builds up reducing the clearance to hold the valve open.Just a thought. Ray