Jump to content

rb25 with g4 struggles at cold start sometimes

Jalal Syed

Recommended Posts

I have a r32 with a rb25det in it. I ran the car with the stock 25 ecu for two seasons. And now couple of weeks ago got the g4 put in as well as a tune with pretty descent numbers for a stock rb25(stock turbo). The car ran fine for 4 days, and then one day after the car sat for 5 hours at work, i went to start it and it barely revved up then just died. I tried again and it would try to keep idle, would hunt for couple of seconds then die again. started again and this time added some gas, my rpm was jumping all over the place at this point and the car was very rough. After keeping the car alive manually (adding some gas) after couple of mins it went back to its normal self...it idle was perfect and the car drove like a dream. 

The weird thing is it only happens when I leave the car out in the sun for more than 3 hours or so. When I leave the car parked in the garage in my house and start it the next day its fine. I can only seem to replicate this problem at work...Last time i started it after a 8 hour shift and i had to manually rev it for atleast 15 mins before the car settled down. The rpm gauge jumps everywhere and the car feels like its missing at random spots, my wideband numbers are all over the place too. I will try and make a video next time. I hooked up the laptop to it and only fault code is RPM limit activated, which i believe is caused by the jumping rpm gauge? The car has no vacuum leaks and is running copper plugs bcpr6es changed at last oil change. It runs and pulls fine otherwise. 

Link to comment
Share on other sites

Hi Jalal

Is it hot in the car when this happens (ECU likely to be warm too)?

It sounds like it is having trigger problems. This could be a board issue that is only happening when it is warmer.

Are you NZ based?

Link to comment
Share on other sites

If the ECU temp is getting over 70C then there is a good chance it is purely a temp issue and simply letting the ECU cool will help.

If however the ECU is down around 50C it could indicate there is a hardware issue as the ECU should be happy up to around 60C

Link to comment
Share on other sites

  • 2 weeks later...

So far it hasnt done it any more since I have been cracking my windows and sunroof a bit when I park during a shift at work now. So it must be the ecu overheating. I do have a question though simon regarding a different matter, I will be doing a long 2500 km round trip journey with the car tomorrow. There is a elevation difference of roughly ~900 meters less in Vancouver (where I will be travelling to). Calgary is where I got my car tuned so will that elevation difference have a significant impact on my cars driving ability? As long as it coasts fine Thats all i really care for, I wont be racing anyone or going to the track there. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...