G4X not revving past 5500rpm

[FavourK]

Hi guys,

Just recently put my daily back together and started the process of road tuning. Slowly getting the hang of things but I am struggling with diagnosing this issue. The car will rev to ~5500 rpm and hit what feels like a rev limiter. However, in the logs the RPM Limit is not activated. Also, the trigger error counter does not register any errors. 

This is a PanicMade AltezzaLink G4x running on a Lexus IS300 with the factory 2JZ-GE and all factory crank/cam sensors. Attached are my config and a log file in which I was able to reproduce the issue.

Thanks!

IS300ConfigFile.pclx 3rdgear limiter pull.llgx

[Adamw]

A couple of suggestions:

1. If you are using the stock ignition system then the 'JZ ignitors dont like much dwell, they will go into over current protect mode and stop charging the coils.  Typically they dont like any more than about 1.8ms when battery voltage is normal.  
2. Your alternator isnt charging, this means you are running in cells in the dwell table that have quite large values ~3.6ms average in your log.  Potentially making suggestion #1 more likely.
3. You are very close to hitting the MAP limit.  The default MAP limit has a control range of 10Kpa, this means it will start limiting 10Kpa lower than what it is set to.  In that log yours is set to 163Kpa and you are reaching about 147kpa.  This means you are only 6kpa away from touching the limit.  There are no signs that it did limit, but you will only need a slight change in air temp or something and you potentially will be - which could make diagnosis of the real misfire more confusing.

[FavourK]

Thanks for the response.

 

I recently tested the alt and it was ~13.4V at idle which seemed quite a bit on the low side. I will replace it and go from there.

Besides that, would you suggest reducing the max dwell to 1.8-2.0ms? This is one parameter I haven’t adjusted at all from the base calibration.

[Adamw]

Bat voltage is only showing 12.4V in the log.  For the dwell - yes, put 1.8ms in the 14V row and maybe 2.0 in the 13V row.  

[FavourK]

12.5v from the link software and 13.5v at the battery is a pretty big voltage drop no?
 

I suppose I should also mention the battery was relocated to the trunk. I have the + 0 gauge wire running from the front of the car and the - grounded to bare metal/chassis in the trunk. Could this be part of the problem? 
 

Thanks

[Adamw]

If the ecu is seeing lower voltage than the rest of the engine then you really want to fix that.  Injector dead times and dwell etc will be wrong unless the ecu is has an accurate indication of the voltage powering these items.  

[FavourK]

tested w/ the dwell set to 2ms and it stopped breaking up at 5500. Now just need to fix my charging/voltage drop issues. 
 

thanks again

[Bsalinaz]

I think we’re having the same issue as I drive my battery voltage is dropping at the ecu but my battery is still charging around 13.8v? Let me know if you figure out your issue I’ll be digging into mine this weekend as well! Also I wouldn’t say 13.4v is low for charging to me it doesn’t sound like an alternator issue. 

[FavourK]

I’m going to try running a ground wire from battery negative directly to the block. Looking at my logs from before I did the relocation, logged battery voltage was very close to measured voltage at the battery.