No signal to the fuel injectors.
Discussion
1999 5li chim, No signal to the fuel injectors. The car was running fine, parked up for a couple of weeks now will not start, the engine spins over fine, I have sparks, fuel pressure but the plugs are dry and there does not seem to be a signal to the injectors. I have unplugged and replugged in the ecu in case I had dirty pins but they look ok. So suggestions please.
LenChim said:
1999 5li chim, No signal to the fuel injectors. The car was running fine, parked up for a couple of weeks now will not start, the engine spins over fine, I have sparks, fuel pressure but the plugs are dry and there does not seem to be a signal to the injectors. I have unplugged and replugged in the ecu in case I had dirty pins but they look ok. So suggestions please.
Do you have a good 12V on the injectors when the ignition is on?The injectors should have a 12v feed on one side of the connector with the ignition on. The other side gets grounded by the ECU on each bank to open 4 injectors at a time. The two circuits are independent, so it would be very unlikely that both sides fail at the same time. So check for 12 volts to start with. The injectors are fired by the ECU once it gets a signal from the distributor to show the engine is rotating. You can check to see if this trigger signal is there by checking the fuel pump- it will run for a few seconds with ignition on if you don't start, but then run again one the engine is cranked, and keep running as long as the engine keeps turning so worth getting someone to listen to the pump as you crank the engine.
Penelope Stopit said:
That's that then, AA will have connected a noid light injector signal tester into an injector plug
Yes as above, check relay and supplies before getting in too deep
This is not my car by the way not that it matters.Yes as above, check relay and supplies before getting in too deep
I have checked the the power to the injectors and I get 12v to earth on both pins of the injector lead to earth with the ignition on. Is that correct or is it a symptom of something else?
I have swapped the relays around it seems to make on difference, also tided some spare one that I had.
I have ordered a new set of plug leads as one came apart when I pulled the lead off the plug. They come tomorrow. Wednesday.
If car is running on 14CUX ECU
Due to the injectors being wired as 4 in parallel for LH bank and 4 in parallel for RH bank, injectors need disconnecting before checking for what polarity is at any particular injector plug terminals
Measuring voltages of circuits not under load will also fool you
Check for positive supply @ injectors with a 21 watt bulb, voltage can be measured while the 21 watt bulb is connected, at least there's then a touch under 2 amps of a load on the circuit being measured for what voltage is present
Disconnect ECU before attempting any testing similar to the above, you can always bridge any relays out that rely on the ECU to activate them
Due to the injectors being wired as 4 in parallel for LH bank and 4 in parallel for RH bank, injectors need disconnecting before checking for what polarity is at any particular injector plug terminals
Measuring voltages of circuits not under load will also fool you
Check for positive supply @ injectors with a 21 watt bulb, voltage can be measured while the 21 watt bulb is connected, at least there's then a touch under 2 amps of a load on the circuit being measured for what voltage is present
Disconnect ECU before attempting any testing similar to the above, you can always bridge any relays out that rely on the ECU to activate them
LenChim said:
Penelope Stopit said:
That's that then, AA will have connected a noid light injector signal tester into an injector plug
Yes as above, check relay and supplies before getting in too deep
This is not my car by the way not that it matters.Yes as above, check relay and supplies before getting in too deep
I have checked the the power to the injectors and I get 12v to earth on both pins of the injector lead to earth with the ignition on. Is that correct or is it a symptom of something else?
I have swapped the relays around it seems to make on difference, also tided some spare one that I had.
I have ordered a new set of plug leads as one came apart when I pulled the lead off the plug. They come tomorrow. Wednesday.
Edited by Zener on Tuesday 12th January 16:11
So we know we have the 12v supply, and its very unlikely both banks would have failed to switch to ground as there are two independent circuits / switching transistors in the ECU. So 2 steps backwards- is the fuel pump running when the engine is cranked to show the ECU is getting the trigger signal from the dizzy? I believe you have RoverGauge (?) - this will show you the fuel pump status, RPM and injector pulse width, so lots to go on.
OK the first pic should show the RG with the ignition ON
The second pic is the RG with the engine cranking.
Still waiting for the new plug leads to arrive and there are no plugs in at present, took them out to look at and to save the battery when cranking have not put them back in.
From the pic it says that the there is a duty cycle on the injectors so presumably they are working, is that correct? Or does that just mean that the ECU has told them to work and there is some communication breakdown elsewhere?
So the ECU is trying to switch the injectors, although RoverGauge is not showing the physical voltages to the injectors, just the timing signals to the switching transistors. I still have trouble believing you have lost both banks, so I'd be putting a noid lamp on the injectors to see if they are switching or not for sure. The pulse width is very small at idle, so I don't know if it's enough to heat a filament lamp as suggested.(?) LED Noid lights are not a lot on Ebay.
You could try a squirt of easy start into the air intake to check the engine will actually fire.
You could try a squirt of easy start into the air intake to check the engine will actually fire.
blitzracing said:
The pulse width is very small at idle, so I don't know if it's enough to heat a filament lamp as suggested.(?)
Yes, whoever suggested using a filament bulb for checking the ECU injector negative switching needs to think againDon't get annoyed, use a noid
AA will surely have used a noid
LenChim said:
OK the first pic should show the RG with the ignition ON
The second pic is the RG with the engine cranking.
Still waiting for the new plug leads to arrive and there are no plugs in at present, took them out to look at and to save the battery when cranking have not put them back in.
From the pic it says that the there is a duty cycle on the injectors so presumably they are working, is that correct? Or does that just mean that the ECU has told them to work and there is some communication breakdown elsewhere?
The top screen, Ignition On and 0 RPM, shows an incorrect fuel map cell selection and a Pulse width of 21.46 mS??? The ECU can only issue injector pulses and perform cell selection when it receives the spark/RPM signal from the Ignition Amplifier when the distributor is rotating. At Ignition On the Pulse width should show 0 mS.
The bottom screen, Cranking and 123 RPM, now shows the fuel map cell selection reset for Ignition On, a Duty Cycle of 4 % and the same Pulse width of 21.46 mS.
With a pulse width of 21.46 mS if the injectors are firing there should be a strong smell of fuel especially with the plugs missing.
I'd try swapping out the ECU for a known good one (needs a TVR 500 tune) and go from there.
Incidently, the fuel map RPM Limit (column range) for a TVR 500 tune should be 6188 RPM.
Edited by davep on Thursday 14th January 11:09
Penelope Stopit said:
Steve_D said:
Penelope Stopit said:
Yes, whoever suggested using a filament bulb for checking the ECU injector negative switching needs to think again........................
Yes that was you.Steve
Penelope Stopit said:
If car is running on 14CUX ECU
Due to the injectors being wired as 4 in parallel for LH bank and 4 in parallel for RH bank, injectors need disconnecting before checking for what polarity is at any particular injector plug terminals
Measuring voltages of circuits not under load will also fool you
Check for positive supply @ injectors with a 21 watt bulb, voltage can be measured while the 21 watt bulb is connected, at least there's then a touch under 2 amps of a load on the circuit being measured for what voltage is present
Disconnect ECU before attempting any testing similar to the above, you can always bridge any relays out that rely on the ECU to activate them
Anyway they are lamps, bulbs are what you plant in the garden.Due to the injectors being wired as 4 in parallel for LH bank and 4 in parallel for RH bank, injectors need disconnecting before checking for what polarity is at any particular injector plug terminals
Measuring voltages of circuits not under load will also fool you
Check for positive supply @ injectors with a 21 watt bulb, voltage can be measured while the 21 watt bulb is connected, at least there's then a touch under 2 amps of a load on the circuit being measured for what voltage is present
Disconnect ECU before attempting any testing similar to the above, you can always bridge any relays out that rely on the ECU to activate them
Message Board | Chimaera | Top of Page | What's New | My Stuff