have a 95 del sol with a ZC block and a d16z6 head. like tittle says if I rev out to redline the car will enter limp mode and I can't rev past 3.5k rpms. it's only in limp mode for a few minutes then returns to normal. Also, if I cycle the key, the car will exit limp mode immediately until I redline the car again. doesn't matter what gear im in, or if im in neutral it always happens. I've tried running 2 different ECUs doesn't make a difference. only code I have is 21 for vtec solenoid because I don't have it wired up yet but I don't see how that would cause limp mode. did a compression test and it came out good, about 180 in all 4 cylinders. spark plugs look healthy too nothing noticeable that I think would cause the issue. only problem the car has had recently is that the distributor would die out once the car reached operating temp and wouldnt turn on again until I let the engine completely cool down. I ended up replacing the ICM and ignitor from a donor dizzy and it solved the issue, but the limp mode issue remains - it was there before the dizzy died. no idea whats up but I have to short shift around 6.5k rpms otherwise I'll trip the car into limp mode. any help appreciated thanks

 

I'm pretty sure you need your vtec working if you are revving to redline...

Remember the engineers made Limp mode for a reason! and it's to prevent the driver from Fkn something up when all parameters are not met in the ECU when driving and pushing the engine to its limit..

 

I've used this ecu before the z6 head swap and I could rev just fine to 7.2k rpm without entering limp mode afterwards though. I'm not even hitting redline, I'm almost 1k rpm away from it. I do plan on wiring vtec in the future but for now I'm wondering why its entering limp mode and why cycling the key makes it go away

 

"Limp" or "Safe" mode doesn't just cut redline by 1000 RPM... it will cut it down to 3-4000 RPM. It also wouldn't simply "fix" itself and switch back to normal engine operation without a key cycle, so I do not believe that you are experiencing a "Limp" mode scenario. What IS more likely would be the common instrument cluster tachometer function failures that appear as a "slow" tach... it appears to be functioning as normal, but in fact, the higher you rev the engine, the greater the error. Many people who experience this issue can pay close attention to the RPM in which VTEC engages... and when it hits LOWER than expected, one would also see redline at a lower point as well. Since you do not have VTEC functioning at this time, the way I would test this theory is to pay attention to what your speedometer reads at a particular RPM (at or above 5000 RPM if you can) in a specific gear when the tach appears to allow you to rev freely to redline. Once it appears to redline short, see if the speedometer is lower at the same engine speeds that you sampled. If so, then the tach is not your problem. IF however, your speedometer reads higher at the sampled engine RPM, the tach is your problem and your engine is running just fine.