ECU Diagnostics?

[ToroGTS]

I have a nistune type 2 board. At the start of summer the car wouldn't start and I ended up finding a burnt out track on my ECU. I repaired the issue by jumped with wire between the two related pins and the car started normally and drove, but since then I've had a series of new issues, no starts, misfires ect. Is there a place that can verify that no transistor, capacitors or anything were damaged on the ECU?

[Skym]

Not sure, parts don't fail like that without wiring problems (no resistor when using another models injectors is one example). Or could be earthing problems.

When does the missfiring start, just after warmup???

[ToroGTS]

Car currently will not start, though I have started it two days ago and had it running on all cylinders cleanly at idle (till full warm) until I tried to rev the engine at which point it stalled after letting off throttle. When the engine was running I was able to pull plug wire from each coil (Ls2 coil set up) and observed a strong spark from coil to plug wire on all cylinders. I am going to look at fuel pressure/regulator tonight and possibly pull fuel injectors for cleaning/servicing. When I do get it running, I am showing ~17 AFR at idle on wideband, which I had interpreted as a misfire (I have had coils burn out in the past with similar AFR result and operational symptoms).

**To answer my original question, I contacted Nistune and they will diagnose and repair ECU's if you ship to them (Australia) for $120/hr. I believe the best course of action would be to find another RB20 ecu and simply install my current nistune board into that ECU, retaining my original tune ect.

[Skym]

Running engine lean can make engine stall. It's similar to removing fuel pump fuse and letting engine run lean, stall. Check TPS adjustment as well (could be set at a lower voltage), as can cause engine to stumble, stall. Can check TPS adjustment without turning engine on, but have power to ECU (dash lighting up, etc).

Sometimes it can be a intake manifold or exhaust manifold gasket leak, especially if around 17 AFR.

[ToroGTS]

Can confirm that TPS is brand new, properly calibrated. No leaks after MAF or in exhaust system. Strongly suspecting clogged injectors at this point, fuel pressure seems to check out at 38 psi idle and 45 WOT pre boost (can't really build boost in neutral). Pulled ECU and inspected some components, everything looks good. Also noticed that the ecu pins for injectors 1, 3 & 5 and 2, 4 & 6 share respective common signals on circuit board, are all controlled in those batches simultaneously. I don't suspect there is an ECU signal issue at this point because my issue is not occurring at three cylinders simultaneously, and rather appear to be in the region of cylinder 4 & 5.

[Skym]

Stock injectors usually leak when have done high km (common problem) and causes missfiring. Sometimes it's the injector loom itself that goes hard, brittle over time (coilpack, injector looms cause missing problems and is quite common).

As far as I know, it's sequential at lower rpm and batch at higher rpm with injectors.

Sounds like an exhaust manifold airleak with the lean A/F ratio, as it starts leaking on the last 3 cylinders that are closest to the firewall due to the exhaust swinging (check the exhaust hangers, as some might be missing or have failed and check for loose exhaust manifold studs, turbo to exhaust manifold studs, leak on turbo to outlet pipe flange, etc).

I know you have checked this, but it pays to check again, as sometimes miss things.

[ToroGTS]

I've arranged for an off car injector clean, rebuild and flow test. I will update when and if I find a solution here!

[chitrees]

Update

[ToroGTS]

Injectors were found to be clogged on cyls 4 & 5. Replaced them with new 480cc injectors from a local injection shop (Injector Dynamics, High River AB). Fuel pressure was high enough to sputter out some gas under boost but it would fail to start and idle properly. My belief is that is was still flowing but that the spray pattern was like a dribble so it was not sparking off properly.

[Skym]

Good to hear that you found the problem.

[chitrees]

What was your idle like prior? Could it start with pedal depression or not at all?

[ToroGTS]

It would either no start at all or just start normally. Primarily the issue was that it would eventually just drop cylinder 4 & 5 randomly and then idle like garbage.. but if I pushed it back to boost it seemed to function normally but then maybe stall or sputter once I went back to idle. I had recently done the ls2 conversion with brand new AC delco coils so I knew it wasnt ignition related to begin with.