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Missfire after Revlimit or on high boost, Plugs and Coils already changed VG30dett

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I built a VG30dett some time ago and unfortunately haven't solved a misfire problem until today. I already spent days and unfortunately haven't found a solution. Maybe somone has a good idea what I should do next.

The Problem is the follow: If I go above 1.2bar of boost, the engine begins to missfire a little bit and power are falling a bit too. Back on idle the engine missfires for a few seconds before it returns to normal operation. Same happens if i hit the rev limiter. I found a video from a guy who had the same problem.

https://www.youtube.com/watch?v=BKLEOqaAmaYt 300zx

I already changed the whole ignition system including spark plugs, coils, Igniter and CAS and CAS PIN. Nothing helped. Differential Fuel pressure is okay. I tried also much higher fuel pressure, to verified, that the side feed injectors are sealing well. Think there could be also a mechanical problem, like lifters are pumping up on high boost and rpm . Camshaft and valvetrain are stock. i tested also with turning VTC off, same result.

Only thing that I have noticed is, there is still alot of noise on the RPM Signal. I already tried three different CAS (unfortunately no new one) and replaced the CAS Pin inside the Camshaft. Have a look on the picture in the attachment.

Have you ever had a similary problem? Any ideas?

Car is running on a G4+ Plugin and has the follow specs:

- well tuned up to 1.2bar of boost

- Revlimiter is very soft fuel cut.

- 740cc

- gt2860 turbos

- built shortblock

- rebuilt stock heads.

Attached Files
  • VG30det-missfire-after-reving-wihtout-load-engine-ROC.png
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  • VG30det-missfire-after-WOT-engine-ROC.png
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What spark plugs are you using? Are you getting triggering errors on the ecu?

Would you be willing to post a copy of the map and the 2 logs for people to look over?

I have seen a similar issue when not running the correct Resistor type Spark plug. Are you using a Resistor type Spark Plug?

Hi Guys

I'm still own you an answer. The misfire a finally gone!

I changed to a 36-1 Crank trigger and a one slot disc in the CAS. Now the timing is much more stable and the misfires are gone.

Something more I learnd the hard way. I always thought i can't be the CAS, because I hade no trigger errors on the LINK ECU yet on the OEM ECU and the problem was boost dependent.

Good to see you take the plunge and do it against your beleives. The Link ecus are particulary prone to this problem probably because of how it work with the trigger. But the main problem as you have seen is that it is on the cam instead of the crank...

Can you give me some detalis about what trigger wheel design have you used and what sensor? Thanks!

Sure I used a 36 minus 1 trigger wheel with a cherry hall sensor. I spin the crank pulley on the AC belt groove and spot welded the trigger disc to the pulley.

I chanched the CAS disc to a AEM one. Use trigger 1 Output which has just one signal every 720deg. Aem has a manual how to do this Job. It's really not easy to pull the bearing, without damaging anything.

Most aftermarket ECU's should be capable to use the 36-1 trigger.

Unfortunately i have not done any pictures.

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