Zetec Puzzler

[Bob Tucker]

We tried a separate coil, HT leads & different plugs & got identical symptoms.

The fault is consistent.

Paul Dunnel has tested the ECU on a test rig, & passed it as OK.

but the odd thing is that although we dont get a spark on the 2nd cranking, we do get the same reading at the coil connector.

Ignition on shows 12V, then when cranking it drops to 9V..but Im thinking that may be the result of the ECU switching on/off??

 

My gut feel is that the ECU is failing when installed on the car.

Just need to find a way to prove it.

[sj-bradley]

Sounds like you may have a crank sensor going faulty.

 

These work when you move metal in front of them, I.e. they are NOT a simple switch but produce an AC signal only when metal is moved towards and away from them.

 

You can test this off the car by checking for a voltage change when someone is moving something like a spanner past the sensor end.

 

It could be that the sensor IS sending an intermittent signal so that fools the ECU into thinking the engine is running.

 

Check wiring around there as it is subject to a lot of vibration and possible heat from the exhaust nearby. Check resistance readings for the wire (disconnect both ends and check end to end) while j-j-jiggling it a bit.

 

If you have another CPS, I would consider replacing that.

 

Simon.

Edited February 27, 2015 by Simon B

[stevedohc2b]

Bob / John ask for a replacement ecu to try on the car then send one back if it corrects problem.

 

May be they could send a tecee with it ( offer a small fee if needed )

 

if i brought mine along we could try my omex to run spark if parked cars next to each other ie side by side if room and wires reach

 

Stephen

Edited February 27, 2015 by stevedohc2b

[Guest 2b cruising]

Careful Steve. The can easily be damaged if johns is getting spiked by another part of his circuits.

Only my opinion.

[Bob Tucker]

We have used two CPS & various `wiring options.

I have also checked both of them off the car moving a metal bar across the face & got a signal each time.

Seriously I'm not knocking any ideas....keep em coming.

 

I think John will call Dunnell on Monday & see if they can send someone down with a spare ECU.

Even paying travel costs & a days wages is cheaper/easier than trailering the car to Suffolk.

1 Extra problem is they dont make the ECU that John has anymore.

[steve in stockport]

Is the shielding on the CPS correct? Some ecus like it earthed and some like it open.

Also does the ecu need to see the fuel pump work or could you wire the pump separately from an ignition controlled supply thereby giving the ecu one less thing to worry about controlling?

[tractor]

I would still try the edis its cheap and simples

[Guest 2b cruising]

The standard of workmanship on Johns car is the best I have ever seen by a self build. I would go by contacting Dunnell and seeing if they will travel and sort there own equipment. Test bed is ok but live firing can't be beaten.

[Guest zerorace]

My first job now would be 12v straight to the ecu from the battery just wrap the battery end round the terminal same for the fuel pump to get the ignition switch out of the equation and give you the option to cut the power to both then Is not unheard of for the ignition switch to drop the aux power when cranking.

Edited February 27, 2015 by zerorace

[sj-bradley]

If any wiring is shielded, don't make the mistake of grounding BOTH ends as this can create current flow in the shield which is something you are trying to avoid and can cause all sorts of problems.

 

If you can, ground all shielded wires at one star point (usually the ECU)

 

Simon.

[Guest lotusPaul]

Ok.

lets start thinking. Are you aware your position indicator needs the correct gapping...an air gap between it and the puckup point..if its to big it wont even read it so ecu says no spark required. Yes I had this on my car.a pain to diagnose.

 

Old school thinking now. Your on carbs so ecu only needs a 3d ignition map. MAP or TPS ? Personally I think its a waste if an Ecu but lets look at what it reading and doing.

 

You have new parts and same symptoms. Clearly this leads to a failing in whats left. Id go full hog, strip it all out and rebuild. Check EVERY component is installed correctly before moving to the next.

 

Earths are an ecu's worst enemy. Make sure these are solid.Also try linking engine to gearbox to chassis/ battery. Just to ensure good returns.

 

Point was raised before. Fuel pump should be controlled via a relay.this gives the ecu the ability to switch it on and off without interference.

 

Do not be afraid to rewire while rebuilding.Dont trust anything without checking.

 

if all else fails. And possibly to confirm ecu fault.fit the edis ignition with your components. If it works you may well have a better grounding, no pun intended, to speak to Dunnell about a faulty ecu.

[Bob Tucker]

Hi Steve, John had conflicting advice.

Redline tuning said fit a shielded wire, earthed one end. John tried that. no difference.

Dunnell insisted on a twisted pair, 8 twists per inch. Tried that no difference, its what is fitted now.

I'm not sure how the pump or the ECU is wired.

Hi brother in law is a top notch electrician who wired the car for him..

Thats something John can check & confirm.

It may be time to try an EDIS unit, & set up a test loom off the car.

[stevedohc2b]

Bob

John

I have a Ford brakes at the other end of industrial estate Called all Ford,

If e bay links have no joy in an eds bits.

Did you check compression?

 

Stephen

[Bob Tucker]

Hi Stephen,

not directly, but we had removed random plugs to test when we turned it over.

It was easy to hear the starter labour when it reached a cylinder with a plug.

We also had a 110 amp battery jumped to John's on board battery.

[sj-bradley]

If you really have a weak spark, that implies to me that the coil pack is not being switched quickly enough or possible capacitive effect between the ECU and coil pack.

 

Is this (3 wire) a shielded one? It's not really needed there as that is a fairly high current. If you have got a shielded wire, disconnect the shield from one or both ends.

 

The output to the coil pack should be a clean, sharp transition and any capacitive effect from shielded cable could slow this sufficiently to produce a weak spark.

 

I still think the ECU is getting confused over whether the engine is running or not, so I still would have a real CLOSE look at the CPS and wiring.

 

Simon.