Bigger injectors - car starting issues.

[Tripz]

I've recently had 6 new 660cc injectors put into my RB25DET, right after the injectors were in, the car has problems trying to start. I got it tuned right after the injectors were in and thought that hopefully the tune will help out with the starting issue, but it didn't. So I'm not to sure what could cause this rough starting (takes a good 8-10 seconds to actually start it).

There's also another issue I'm having with the car. Whenever I drive it and approaching a stop, I shift to neutral and the car will drop to around 100 - 200 rpm and would want to die (which it did twice), then bounce back up to 800 rpm. Sorry for being so broad, but just need some inputs on what I should be looking for so I can make it run perfectly like it did before. Thanks!

[Joe]

what are you using to tune it, and have you brought the issues up with your tuner?

[all4sho]

do you have enough fuel pump and regulator to run 660 inj ?

[Tripz]

Karmin: My tuner is notify of the issue and told me that the tune might help, but he's not to savvy on mechancial issues. PowerFC for standalone

all4sho: I'm running a Walbro 255 and Nismo adjustible FPR

[Darius]

You need to change your injector correction factor if you or your tuner hasn't done so yet. Since the stock injectors are 370 cc and you put in 660s, you need to reduce the correction factor by the direct proportion of the two. 370/660=0.56 So, if you don't see that number somewhere, something was set improperly.

[Tripz]

Thanks. I'll double check that later on today to see if he made the corrections yet (which I'm sure he did). If the corrections were made properly, what other things should I look at?

[gawdzilla]

You need to change your injector correction factor if you or your tuner hasn't done so yet. Since the stock injectors are 370 cc and you put in 660s, you need to reduce the correction factor by the direct proportion of the two. 370/660=0.56 So, if you don't see that number somewhere, something was set improperly.

actually you might not see that. depending on how your tuner changed the map he could've divided all the injector cells by the factor. sometimes i keep the correction at 1.000 and just multiply the entire injector map down a percentage.

[Darius]

See now that would take an extra 30 seconds to do.

But in that case, your map will have values that are around 0.56-0.58 or so.
Modified by Darius at 10:02 AM 9/14/2007

[al_v]

You will need to change the Cranking values ( Cold Start Cranking Table ), according to your new size injectors.....

[Tripz]

Thanks. How would I go about doing that and what value to put it at? The car is starting to backfire and is misfiring at WOT. This happen'd before at the dyno shop, then we changed out the spark plugs and it made a clean run. Now it's happening again and I know its the spark plugs and probably weak coilpack, any input?

[al_v]

Thanks. How would I go about doing that and what value to put it at??

You need to change the value to a 56% of the actual value, in all the table.

The car is starting to backfire and is misfiring at WOT. This happen'd before at the dyno shop, then we changed out the spark plugs and it made a clean run. Now it's happening again and I know its the spark plugs and probably weak coilpack, any input?

Your plugs are probably fouling ,caused by a very rich AFR , or the gap is too much, the gap would be around 0.6-0.7 mm , specially if you have the stock ignition parts.
Modified by al_v at 9:04 AM 9/16/2007

[Tripz]

Do I change the table values in the inj map? Or what menu under setting do I have to go to adjust this valve so it'll be more easier to start?

[al_v]

Do I change the table values in the inj map? Or what menu under setting do I have to go to adjust this valve so it'll be more easier to start?

You need to go to "cranking" , this are the start cranking inj pulse, if you have bigger injectors you need to change this value , otherwise you will have starting issues, specially when the engine is warm.