Trouble starting engine after conversion

[Griffin]

I've just got the engine in a cefiro running. It's an r34 rb26 head on rb30 bottom end. I'm using the wiring/ ECU from the rb20 that was originally in car. All wiring is converted to suit the 26 intake manifold / r34 cas.

It starts and idles with afm disconnected. Runs pretty good. As soon as afm is plugged in it dies. Fires up on the key for about a second then cuts out. 

Could there be anything I've overlooked to cause this. 

It has adjustable fuel reg to compensate for bigger engine. Once it's running I'll fit a haltech and turbo , injectors etc but just need it going for now for rego inspection.

[Griffin]

It wants to start as usual with afm plugged in but seems like I've missed something. There are no vacuum leaks.

[mick-r34gtt-]

Could just go mafless..

[blind_elk]

Do you know what fuel pressure you have with the adjustable FPR? Have you tried playing with the fuel pressure? Still running standard RB26 injectors?

[Griffin]

Standard injectors. Have a gauge . Set at 38 psi adjusted up and down . More pressure = higer idle. 

Would tps / cas setting cause it?

[Dose Pipe Sutututu]

I'm assuming you're running the RB26 injectors on a RB20 ECU? Are you running the resistor pack?

Also to ghetto it, as the ECU assumes there are RB20 injectors in the car, lower your base fuel pressure to like 2 bar or so. See if that starts 

[Griffin]

I'm pretty sure it's not injector related. 

The afm plugs have a fair bit of green corrosion on them ( male and female) 

How can I test these?

Also when fuel pump primes, as soon as it cuts off the pressure quickly returns to zero. Should the fuel pressure stay in the rail? Hoses are connected correctly.

[Dose Pipe Sutututu]

pressure drop is normal if there isn't a check valve in place.

So let me get this right.

You have:

• RB20DET ECU
• RB20DET sensors & loom
• RB20DET AFM
• RB26DETT Injectors
• No resistor pack installed on the +VE side of the power going to the injectors

[Griffin]

Rb20 injectors with fuel pressure increased. I only need it to run for now. Na mode.

[Dose Pipe Sutututu]

do you have a wideband? see what the AFRs are like when it' idling with the AFM disconnected. Generally it should sit close to low 11s, high 10s as it's in limp mode.

If it's leaner than that, squeeze in more fuel pressure and then try to start it with the AFM plugged in

[Griffin]

I do but not easily accessible. Should I just fit 26 injectors and resistor pack? 

I had a similar problem years ago with a 25 neo in vl. Had to wire in a jumper wire to maf neg or pos. This maf worked 6vmonths ago but now it's pretty corroded.

[GTSBoy]

There is no way that you will get it to run on 20 injectors on a 20 ECU even with the fuel pressure bumped up a bit.  It's a

3 LITRE ENGINE

[Griffin]

Will do.

[Griffin]

Problem solved. Rewired the afm. Runs good on 55psi base pressure. 

[Dose Pipe Sutututu]

Hope there's a wideband on it