Electronics/ECU experts, help needed please

Okay so some people may have seen my previous thread about my car intermittently starting after fitting a single and a AEM V2. I have checked nearly everything and cant find the issue. All sensors working, fitted new fuel pump etc etc. Also having trouble getting the AEM software connecting up and also cant get the car to my garage as my mechanic is away. Its looking more like a fault with the ECU but to confirm I need to know a couple of things.

1 - When the ignition is turned to on, does the ecu send a signal to the fuel ecu to prime the fuel pump before it receives the signal from the cam and crank sensors?

The reason i ask, is that the first issue I had was fuel pump not priming, which i believed to be the fuel ecu, however swapped it out and nothing, so to get it started I had to do the 12v mod. However I think that only masked the problem as the car still only starts intermittently. So my plan was to fit the fuel ecu back in with a relay as I need a 12v supply for the walbro 450. Then if the fuel pump primes intermittent but the car fires each time that happens it a sure fire issue with the ecu and not any of the sensors/timing star. Also I have checked all 3 power sources to ECU with multi meter and all getting power. Last thing I could think of is that one of the grounds is bad from the ecu which I will check later.

Sorry for the long winded post but wanted to give all details.

Many thanks in advance for any replies.

Anyone?

Only asking as I plumbed the fuel ecu back in with the 12v mod and relay and suspicions confirmed the fuel ecu is fine. The main ecu is working intermittently. Just need confirmation on the question in my first post.

Cheers

Sounds like a dodgy ground tbh. If you were messing around over at the turbo side is the loom all properly plugged back in round the alternator etc. If not check grounds around the engine block to chassis and the inlet manifold as well as the ground at the firewall.

P.s I am no expert lol #disclaimer

Are you trying to diagnose this without connecting to the ECU?

Has it ever run / been mapped, if not how do you know what calibration is on there?

The ECU is going to be the best diagnoses tool for this issue

Sounds like a dodgy ground tbh. If you were messing around over at the turbo side is the loom all properly plugged back in round the alternator etc. If not check grounds around the engine block to chassis and the inlet manifold as well as the ground at the firewall.

 

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Did cross my mind but the car does start intermittently and when running has no issues what so ever. Would I not need a constant ground?

Did cross my mind but the car does start intermittently and when running has no issues what so ever. Would I not need a constant ground?

Yea but if its dodgy it would start sometimes and sometimes not. Otherwise it would be a good ground lol or at least thats my thoughts on it!

Are you trying to diagnose this without connecting to the ECU?

 

Has it ever run / been mapped, if not how do you know what calibration is on there?

 

The ECU is going to be the best diagnoses tool for this issue

The car has run since the turbo and ecu was installed ad mapped by Romian at Syvecs, and has no issues what so ever whilst running. Have managed to connect to the ecu when it's running but can't see any issues on the software but I'm not an expert with the Aem software. The car starts randomly and I know when it's going to happen as the fuel pump primes. It's like the ecu has suddenly woken up. Ecu has 12v's on all pins that power is meant to run through. Basically I sit there turning the key back and forth to the on position until the pump suddenly primes to which it always starts.

The car has run since the turbo and ecu was installed ad mapped by Romian at Syvecs, and has no issues what so ever whilst running. Have managed to connect to the ecu when it's running but can't see any issues on the software but I'm not an expert with the Aem software. The car starts randomly and I know when it's going to happen as the fuel pump primes. It's like the ecu has suddenly woken up. Ecu has 12v's on all pins that power is meant to run through. Basically I sit there turning the key back and forth to the on position until the pump suddenly primes to which it always starts.

Dodgy EFI relay?

Yea but if its dodgy it would start sometimes and sometimes not. Otherwise it would be a good ground lol or at least thats my thoughts on it!

 

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I would agree but how does the car continue to run. Also I can think how the ground would suddenly connect if the car is stationary and all I'm doing is turning the key back and forward

I would agree but how does the car continue to run. Also I can think how the ground would suddenly connect if the car is stationary and all I'm doing is turning the key back and forward

Id be looking at the relay then

Check the EFI relays and the immobiliser if there is one fitted. When you turn the key and the pump doesn't prime, do you get any other electronics come on (dash etc)?

Check the EFI relays and the immobiliser if there is one fitted. When you turn the key and the pump doesn't prime, do you get any other electronics come on (dash etc)?

 

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Yeah all dash lights come on, relays click, and I also tested the 12v feed from the relays to the ecu and its live. Not sure how to check immobiliser but there was no issues at all before the turbo/ecu was changed. Also when I click the immobiliser to start the car the crank turns like normal, however I know it won't fire as the pump has not primed.

 

I also ran a constant 12v feed to the pump so I new the engine was getting fuel but the just masks the problem.

Just a thought. I need to test if the ecu is turning on. I know its getting 12v, and I can get that off one of the ground wires, just trying the other (pin 79 and 80). However If I took the ecu out and hooked it up to a 12v source and ground (jumper pack). Would it do any harm. I ask as that way I could hook the laptop up to it and see if it can pick it up. That would help isolate the issue away from the ecu as every time the car works when I have the laptop plugged in, it picks the ecu up on the software.