Is my cheap optispark the reason my z loses power at 4000 rpm? It's only for a second and then it's back to normal. Could it be coming loose from the engine?

 

"cheap" & "optispark" in the same sentence typically means no good. The optical sensors in those are a complete crap shoot

a scan tool would show if you are throwing any opti codes (high or low resolution)

One very common problem is the rotor screws back out which can cause your problem. That is why loc-tite on those small screws is always recommended

 

Yea I know it was a mistake to not research the optispark market before replacing my old one.

I do get the high resolution code every time I start the car. I replaced the Crankshaft position sensor, but the code returns each time I start the ignition after I've cleared stored data.

 

The high resolution code (P0372) has nothing to do with the crankshaft position sensor. It is for a signal that comes from the Opti - the optical cam position sensor. But that code will not shut down the engine. The low resolution code (P1371) is also for the Opti optical cam position sensor, and that codes does shut down the engine.

Crankshaft position sensor codes are P0335 and P0336

Never heard of an Opti coming loose from the engine.

 

So is it safe to say the optispark is behind my high resolution pulse code and the drop in power at 4k rpm?

 

P0372 sets when the PCM detects low resolution pulses with no high resolution pulses. But loss of the high res pulse does not prevent the engine from running. The PCM can run the engine with only the low res pulse. There will be a small loss of ignition and injector timing accuracy, but not enough that you would likely notice it.

Loss of high res pulse could be due to a either the PCM not supplying the required 5 volt reference pulse, or a faulty Opti harness connector. Or it could be a problem with the optical cam position sensor in the Opti.

If the low res pulse is lost, the PCM can’t run the engine. Normally, loss of low res pulse would set P1371. But it relies on seeing high res pulses without seeing low res pulses. If there are no high res pulses, P1371 can’t be set.. So…. there is no evidence to say with certainty that the low res pulse is causing the shutdown. Other question is why is there a very brief loss, and why does it happen only at 4,000 RPM?

50/50 chance at this point the Opti is the problem. But I can’t think of what the other possible causes could be.

 

I'm just gonna "chime in" here on the question (see above) that Injuneer has raised, because ....... I got "hosed", (for want of a better term?), by a "professional" tuner on this too.
In the CATS tuning tables there is a "handoff", (again, for want of a better term?), right at 4,000 RPM between the Main ignition timing table and the Advanced ignition timing table. Both of these timing tables have rows at 4,000 RPM and ....... they must be identical across all entries!

If not, the ECM gets conflicting input/programming about what to set the 4,000 RPM ignition timing at, and your ignition timing can go "wonky", (still looking for a better term here too), right at 4,000 RPM. At any RPM other than 4,000 ...... there is no conflict presented to the ECM.

Hope this helps?

 

I had that same BS happen on my 94. It would go away after I cleaned the maf but it would always come back. So I bought a new maf and realized it when I removed it from the box, MY maf was ported. When it wasn't "4k-ing" it ran awesome. I swapped out the maf anyways and it wasn't as strong. Ported mafs are cool, but I read are a tuning nightmare. Love my 93.

Not saying its not the opti, but check out your maf, maybe its dirty or ported. Use a q-tip and some maf cleaner and VERY CAREFULLY brush the wires clean. I broke mine cleaning it the last time.