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CA18DET Tuning question?

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Hi guys, I'm new to the tuning world and new to the entire street car scene. I have an old school 1965 Datsun Fairlady that I have swapped a ca18det into and wired it up to a stinger v4 ecu. The car runs and drives (I had it dyno tuned by a guy that knew things I didn't) but I recently found out how to do a data-log off my ecu and the results were quite scary in my opinion. The engine is standard internals good compression, 40psi fuel pressure with a surge tank and twin pumps, Has a T28 turbo on a high mount manifold makeing 8psi and an aftermarket intake plenum, Bosch wideband 4 wire and all other sensors are standard. My issues are the TPS sensor not working properly and the fact that in the settings of the ecu it has a target of 14.7:1. After learning some things from these courses I am worried this is dangerously lean at 8psi @6500rpm and in the AFR targets for rpm none of the table has been filled out. What I would like someone to confirm is this is actually wrong before I try and adjust the targets and go through the AFR course.

Attached Files

Just to be clear, that is actual AFR reading from a wideband in the exhaust without obvious leaks?

I'd be double checking the calibration data is correct, is it a scaled voltage input or serial data? Check for leaks too. I imagine you want to be low 12s or 11s AFR wise in boost for both power and thermal management.

Can you still contact the tuner? I'd ask what they were targeting.

If you have a consistent missfire on one cylinder it might put you about there, can you check each manifold runner for temperature with a non contact after a pull? Dies it feel smooth?

I much prefer absolute pressure scale, the mixed units fake "gauge pressure" scale of mercury vacuum and PSI bothers me more than it probably should.

Yes it has the wideband in the exhaust dump pipe, the sensor is a bosch 4 wire wideband that the ecm specs the specific part # as one of its settings but you only have limited settings due to the age [predates the dinosaurs]. Therefore I don't think you can change that scaled voltage input, you do however have a setting for target afr at RPM\PSI-HG but like I said this is all left blank at 0 so He may have pulled a fast one and not done the ground work of the tune.

As for contacting the place, I don't really want to as they did some other work as well and it has all since come undone and I've had to redo it (wheel studs, fuel reg etc). I am in Sydney so if you know of any good tuning shops or roll tuners I would be willing to investigate a start over method. In the wideband setting the only target that was set is 14.7:1 and a 30% lenience.

I don't have a constant miss-fire although I do have an intermittent miss at idle (13-1400rpm) this has been going on since we got it running hence why I am looking into the tune itself. It idles find while cold but once warm it surges and miss-fires. Under load the car runs fine and pulls well with minimal smoke.

Unfortunately I don't have the option of an Absolute pressure scale as there are not many modern comforts in the ecu.

Ric Shaw is the only person I have had work done with, there are a lot of good workshops. If they are happy to discuss their tuning methods and setup I would have more confidence.


You'd have to log a wideband sensor to see what the actual AFR is, and your log doesn't appear to include that.

I only tuned one of those ECUs many years ago, but I recall altering the AFR target table from 14.7 to 10.0 and getting no change. It appeared to only be for closed loop trimming, which did not work.

Before getting concerned, I'd get a log of the car with a known good wideband, and hopefully everything will look great since you've said the car drives well.

If it turns out the engine is actually running lean in boost, I wouldn't assume the tune is bad based on the values in the AFR target table. I'd check fuel pressure, make sure a hose didn't pop off the FPR or manifold, go over the car as usual, then ask the tuner for suggestions on next steps.

Please keep us posted.

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