14CUX ECU Problems with injectors on Chim 450

[Troemmelche]

Hello all,

I have some problems with my chim 450. After consulting the bible and checking with rovergauge with no faults the following situation occurs when i switch on the ignition:

Fuel pump primes, engine turns but no start. After 1 min of leaving ignition on, there comes fuel out of the plenum. This lead to filled up cylinders, a mix of fuel and oil in the oiltank and a blocked engine because compression of liquid is not possible. I hace emptied everything and changed oil.
I have also checked the resitance of of the injectors which are all ok. But i measure 6 to8 Volts at pin 11 and 13 with ignition on which causes the injectors to open and filling the plenum with fuel? They should be powered only two times per stroke. Or do i not understand the function of it correctly?

So as i wrote, no faults by rovergauge and all the sensors work fine. Also the supply power to the ecu is equal to battery current.
I want to make sure that the fuel system works before starting it again.

Any guess or idea is highly appreciated
Best regards from cologne
Mario

[Troemmelche]

Just wanted to add, that ignition works, checked for sparks on each cylinder...

[Belle427]

I would guess an injector or two has mechanically stuck open for that amount of fuel to come out.

[pmc_3]

Check the injector wiring around the coil it can rub through on the coil bracket and short causing the injectors to be permanently open.

Noid lights would be useful to help with your diagnosis.

[Troemmelche]

I checked the ECU. I unscrewed it yesterday evening and also measured the transistors, the resistance is maximum.

The resistance between ignition coil and ECU PIN 39: It is there, but the wiring was not in OK. I rewired everything and now have a 6.8kOhm connection between the negative terminal of the ignition coil and ECU pin 39. The ECU should now receive a signal.

In addition, the fuel pump was connected to the main relay via a separate cable! As a result, the pump ran permanently with ignition. This shouldn't really be a problem, as the fuel circuit has a pressure relief valve and a return line. However, the pump is now reconnected to the fuel pump relay which is also controlled by the ECU. Here the 1-2 sec signal comes on at ignition, then presumably as required by interpretation of the measured parameters by the ECU.

I will see in the next few days whether replacing the relays with diodes, wiring the ignition signal and correct pump wiring will help. But first I will remove the injectors and check them. I don't want to flood the engine with gasoline again and have to change the oil again (2 weeks ago I drained 8 liters of oil/gasoline mixture). Maybe one of them is mechanically stuck.

[sixor8]

When I did a bit of restoration work on a Chimaera in 2017, I had the fuel rail powder coated. When the injectors were out, I had them cleaned professionally. If you can apply 12V across them you can hear them click open and shut, so you may be able to check if one of them is stuck open.

[PabloGee]

One day, I hope to gather the cash to buy a replacement set of injectors - I've got the original Lucas ones, and I have read enough reports of them being a poor design and therefore a model that was only used for a short time.

The ones I'd love to replace them with are Bosch 0 280 156 045

Apparently plug and play replacement, much finer spray pattern, though I want verification on the flow rate being same/similar.

Anyway, good luck with it, would be interested to hear how you get on

[Polly Grigora]

Troemmelche said:

But i measure 6 to8 Volts at pin 11 and 13 with ignition on which causes the injectors to open

There shouldn't be a voltage at the injectors with ignition on


With ignition off disconnect ECU and injectors, check loom with voltmeter between battery positive and ECU plug terminal 11 and then 13....Should be open circuit, no voltage

[Paulprior]

I don’t think that’s correct, with ignition on you should have 12v to the injector coils, the negative side of the injector is switched to earth via the ecu, if you have 6 to 8 volts across the injector you either have a partial short to earth or a faulty ecu, try measuring the voltage on both sides of the injector to a good earth

[blitzracing]

Paul is correct. The injectors have 12 volts on one side on the brown orange wire and the other side is then grounded through the ECU to fire them in blocks of 4 for each bank. The grounding / switching wires are yellow white and and yellow blue. As suggested the reason to flood the engine BUT on one bank is a short to ground on the switching wire that goes back to the ECU.