Jump to content

Fuel map inquiry


Kanjo`

Recommended Posts

I am having a really weird issue with tuning a Link PNP Honda OBD1 ecu . The car is fairly stock and in the cruise area its requesting more fuel that it does at wot . It is really weird and do not know how to properly explain it so I have attched the tune after all the adjustments have been done (have not tested it yet) I can not upload the logs that I have only the tune  but you should be able to see what I mean

Tune mods : B18C with shorter custom gears completely stock besides intake manifold , cai and 68mm tb , -8 feed line , -6 return line , fpr stock injectors , 320 aem fuel pump . 

P.S Have played around with the dead time and have similar results .

TIA

 

old tune test.pclr

Link to comment
Share on other sites

It doesnt look too unusual to me.  At low RPM many engines will have a better VE at smaller throttle openings than WOT.  It looks like it has only been tuned to about 4600RPM so your not even on the high cam yet.  

Link to comment
Share on other sites

Thank you Adam , see the thing is that as I increase and go to the high cam I have a dip . I have uploaded some hits and you might be able to see what I mean . Like the end result is anything but sooth . Now could the exhaust being stock headers and cat still on be any reason ? I have around 170 psi at all 4 cylinders if that is anything to take under consideration .

vtec.llg test1.llg

Link to comment
Share on other sites

Provided you are sure the injectors are stock, then that engine is not making any power.  In your dyno ramp log the injectors are only at 44% duty cycle at 6300RPM and WOT.  That is only enough fuel for about 90HP.  B18C are usually around double that and the injector DC is usually around 80% at WOT on a stock engine.

Are you sure the high cam is actually working?  

Link to comment
Share on other sites

I can feel the difference of the vtec engaging (besides the noise chnage) . I have tried to turn it off and test it and it's a pretty obvious difference .unfortunately for the time being I found not have access to a dyno and everything is on the road . That is the reason that I am sceptical of the injectors . Except if they are externally OEM but they have done some mods to them . 

Are there any suggestions to look at ? Will swapping over injectors be any benefit as I have a set of rdx injectors that I might try and see how they perform .

Link to comment
Share on other sites

No.  As I mentioned earlier you appear to have an airflow issue.  You have the same injector pulse width and same fuel pressure at 3700RPM as you do at 6500RPM.  So, if you are putting in the same amount of fuel and are measuring the same AFR, then that means the airflow/VE is the same at both RPM's.   The shape of your fuel table reflects the amount of air that the engine is flowing.  If it is dropping off at high RPM, that means your VE is dropping off at high RPM.  This would suggest an air flow problem, not a tune problem.

Link to comment
Share on other sites

Thank you Adam . I know that the intake should be ok as I believe that I have good vaccum at idle and if I put my hand in front of the TB to block it the engine stalls .

So that might mean a cam maybe ? Also (maybe dump question) but stock headers and OEM cat wouldn't cause these issues ? Like I have a 68mm tb with an Edelbrock Victor X manifold on it . 

Link to comment
Share on other sites

Thank you Adam . I believe in terms of timing I am correct as I used the locking tools and also on ignition timing I should be good as I have locked the timing to 286 deg (using coils) . So I will double check the intake/tb just in case and then move on .  

Link to comment
Share on other sites

So I did a quick 2nd gear pull with vtec off and on . I cant upload the logs but some info is the following :

NO VTEC @6751 0mgp Target lambda 0.85 I have 0.575 , Injector DC 54.6%

VTEC @6783 -1 mgp Target Lambda 0.85 I have 0.767 , Injector DC 53.7% . 

So I believe that the cam is working (regardless of the adjustments that are needed) .Also if I remove the vacuum line from the fpr without blocking it will that help eliminate if it's the intake or the fpr causing issues ?

Could this be a result of the fuel upgrade ? Like I am -8AN Feed and -6AN return . If not will have to see what will happen with the exhaust.

Link to comment
Share on other sites

Why dont you just tune it to give it the correct amount of fuel?  You can see in the log your differential fuel pressure is well controlled so there are no problems with the fuel system. 

 

10 hours ago, Kanjo` said:

Target lambda 0.85 I have 0.575 , Injector DC 54.6%

Do you actually trust your wideband?  There are not many widebands that can read down to 0.575 lambda and the are not many engines that would actually run at that.  I would be quite suspicious of that.

 

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.

Guest
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...