Rb20 Runs On 5 Cylinders

[daisu]

A bit of history before we start.

Car is originally an RB20E auto Cefiro.

2 years ago the engine and gearbox was swapped with a manual RB20DET from an R32 skyline. We used the loom and ECU from the skyline so all engine parts etc are skyline parts (not cefiro/laurel bits).

Besides the occasional leaking cooler pipe and dodgy coil pack it hasn't missed a beat for the last 2 years.

Recently I got a Z32 ECU that had been socketed and remapped (to suit a VG30) and I bought a nistune kit for the Z32 ECU.

I put the nistune gear in the Z32 ECU and loaded in factory RB20 maps.

After comparing the pinouts for the Z32 and the R32 ECUs, the only wires that needed to be swapped was injector 2 and 5, so I did that at the ECU connector.

So the RB20 was running fine on the Z32 ECU for a few weeks until one morning it started running on 5 cylinders. Thinking it was probably the spark plugs I bought a set of 6 NGK coppers and did that and an oil change. Still running on 5 cylinders (cylinder no 5 is not firing).

So then I pulled out the nistune, swapped injector 2 and 5 again (back to normal) and put the standard R32 skyline ECU back in. Still missing on 5.

Pulled the coilpack and swapped with cylinder 2, no change. So I borrowed from my mates working R32 his coilpack loom and ignitor still no luck.

I borrowed a tester and checked that cylinder 140psi, a bit low but still within specs according the the R32 engine manual.

I got a couple of spare RB20 injectors (but they haven't been confirmed as working) I pulled the rail out, removed injector 5, replaced it with the injector from cylinder 1 (known working) and put one of the unknown spare injectors into cylinder 1. Still missing on cylinder 5, cylinder 1 was working with the untested injector.

The RB20 injectors are batch fired (1, 3 and 5 injectors fire at the same time, their respective ECU pins are joined inside the ECU). So I swapped the wires at the ECU for injector 1 and injector 5 (pin 101 and 110).

Now cylinder 5 is working, but cylinder 1 is not.

So having thought that the problem was identified to the ECU I returned the wires for injectors 1 and 5, but cylinder 5 continued to run and cylinder 1 continues to not fire.

Tried wiggling the wires at the ECU connector and it is definitely bolted down straight and correctly.

So now I was trying to identify why cylinder 1 won't fire, I've swapped coilpacks, coilpack looms, ignitors, sparkplugs, I plugged an LED into the injector loom plug to see that there is a signal getting there from the ECU.

TLDR - Cylinder 5 wasn't working, checked coilpacks, coilpack loom, ignitor, sparkplugs, swapped injectors, no luck. Swapped wires for injector 1 and 5, cylinder 5 works but cylinder 1 stops. Returned wires, cylinder 5 continues to work but cylinder 1 now not working. Can't find the cause of the problem.

So now I've run out of ideas.

Going to try a spare standard R32 ECU tomorrow.

[GTScotT]

you have well and truly established the problem is wiring. make sure youve pinned it right again, try swapping them again ETC. then check for continuity to earth, there might be a cut in the harness somewhere.. find it.. kill it.. kill it with fire (read solder and tape)

dont stress, you have done well so far and are close to the fix.

[daisu]

Won't be able to look at it again until thursday probably. We'll see how it goes then?

Edited February 8, 2010 by daisu

[femno]

or save yourself some trouble and source another ECU loom.

[Sheriff Wan]

Sounds like a cut wire 110 to me - as when you swapped them the problem was still there...

Are you getting any signal at the wire?

[daisu]

Anyone familiar with a noid light? You plug it into the injector loom plug and it lights up with every injector pulse.

I did plug an LED into the injector plug corresponding with the missing cylinder and it was lighting up....

But I read somewhere that you could get false results using a high impedance device (like a volt meter or an LED).

Just had a thought though, I have spare injectors in the garage, I could just plug that into the loom and I'd be able to feel/hear it clicking straight away.

[TRB-001]

that will work.....

it may well be a coincidence that the no 1 injector u put in (spare) has now packed up....

i would say keep looking in the injector/wiring side of things....

[daisu]

UPDATE!

This arvo I unplugged all the injectors and put my LED into the plug for injector 2, lights up okay.

Plugged it into the connector for injector 1, lights up okay.

Then, because I was worried about the high impedance of the LED giving a false indication, I got another spare injector and plugged it into the loom for injector 2 and held it in my hand. Turned the CAS by hand and the injector was clicking. Did the same for the loom connector on injector 1, same clicking noise.

So, that proved loom was okay.

Plugged injector 2 and 3 back into the loom and the plug for injector 1 plugged into the spare injector in my hand. Again it was clicking.

This proved that with the ECU was able to drive the 3 injectors without problem (remember they are batch fired).

So then I unplugged all the injectors and reconnected the loom to only injector 1 in the rail. Again, it is clicking.

This proved that the injector is firing.

Next I removed the sparkplugs and coilpacks for cylinders 1 and 2 and checked the spark across the plug while turning the CAS by hand.

There was no difference in the appearance of the spark between the two. Swapped spark plugs and tested again, no difference. Swapped coilpacks, tested again, no difference.

So, now I'm confident that the spark plugs are firing okay.

Put it all back together and still not firing.

Things I hadn't proved.

Compression in this cylinder.

Fuel rail pressure.

Is the injector flowing or clogged.

Cylinder 1 was working fine until.... I installed the untested injector.

And Cylinder 5 (the one that was originally missing) started working as soon as I put in a known working injector.

So the next logical step was to put a known working injector on cylinder 1.

Lifted the rail again, removed the questionable injector from cylinder 1, shifted the know working injector from cylinder 2 to cylinder 1. Installed another spare (untested) injector onto cylinder 2.

Started it and now running on 6 cylinders ! Though after all this I still have doubts about the condition of the untested injector I put in cylinder 2.

Also, I think there is a leak on the inlet piping because it has alot of hesitation and stutter when driving under normal conditions. So I'm going to make up a cap to go in the turbo inlet and pressurize the piping using an air compressor, should be able to find leaks without the engine running then.

[daisu]

Hooked the air compressor up to the inlet this evening and found quite a few leaks.

4 leaks where I had plugged unused vacuum lines with bolts, was able to seal them off by tightening the bolt further into the vacuum line.

Had a leak where the hose clamp wasn't tight enough on a pipe join.

One of the intercooler pipes has a leak where a hole has been welded up.

And there is a leak on the throttle body butterfly shaft seal (air is coming out from behind the throttle position sensor).

That was at a test pressure of 0.5 Bar, keen to see what happens at 1 Bar.

[GTScotT]

Good to see shes running on all 6 now mate! that goes to show that even tho an injector is clicking away it could still be blocked internally.

Props to you for working it out and adding an excellent thread for future reference.

[daisu]

Welded up the leaks on the intercooler pipes but the throttle is leaking quite badly.

Incase anyone wants to know the RB25 throttles don't fit on the RB20 plenum. Can't remember whether it was series 1 or 2, but one has a TPS that is incompatible with the RB20 (unless you were to modify the wiring). I didn't try fitting it. The other one has a TPS with the same style plugs for the TPS and throttle switch but it was physically larger.

Also, any sort of software that interfaces with the ECU via the consult port makes it really easy to adjust your TPS (can see TPS voltage and throttle switch position).

Edited February 13, 2010 by daisu

[daisu]

Fitted a replacement RB20 throttle this arvo, pressure test came up good. It was still loosing a little pressure but very slowly and I couldn't hear it.

Idle is very smooth now. Took it for a drive, still hesitating and bucking a bit but I'm hoping that it's just have to adjust the timing.

[cory b]

Hi i no this is a old az post but im having problems with my no 1 cylender running a wasted spark set up all leads are getting spark but its only running on 5 cylenders if i take no1 plug off nothing changes i pulled plug out it was wet with gas all other cylenders are dry any 1 no wat it could b

[cory b]

Hi i no this is a old az post but im having problems with my no 1 cylender running a wasted spark set up all leads are getting spark but its only running on 5 cylenders if i take no1 plug off nothing changes i pulled plug out it was wet with gas all other cylenders are dry any 1 no wat it could b

[Hadouken]

Maybe. And just maybe it must be the starter motor.

Seriously dude. It's the coilpack

[89CAL]

All leads are getting spark?