I have a Honda civic LX with a chipped VTEC ECU. The car ran fine and vtec worked good on the mini me and still does. When I accelerate my wideband shows that I run pretty good... not rich or lean about 12:1 but sometimes just randomly it runs really lean when I accelerate.. it runs lean until about 5k rpm then runs rich. The car runs so lean it doesn't pull then it jumps forward at 5k rpm. I have no clue what this could be. It does this once in a while. Other times it runs fine. Help please.

 

you say your chipped are you just running on a base map or a dyno tune ? if its only a map you might want to look into a dyno tune and get your fuel tables adjusted. but the fact that it only does it when it wants to is beyond me i have no clue why it would do that sorry.

 

Its chipped with a base map. I'm note ready to tune it yet. I only have it chipped because I want to do a Type R swap into it sometime soon. It runs fine sometimes and sometimes runs really lean. I was wondering if it had something to do with the injectors or the fuel pump. Maybe shorting fuel pump or something. Or the chip having bad connection in the ZIF socket. I dont know..

 

Maybe the fuel pressure regulator is malfunctioning?

 

I wanted to mention that my map sensor is tapped into the same hose that the fuel pressure regulator goes to in the manifold because the EX manifold doesn't have another port for the map sensor I don't know why.

 

It's not always going to be stoichiometric. It has to do with throttle position and other factors. however, you should not feel the car lurch like that.

where did you get the basemap from?


what "wideband" is this though? if you're not using a wideband O2 sensor in conjunction with the a/f ratio gauge, then all your a/f gauge is doing is giving you a "light show."

 

What year and engine Civic?

 

I have a 1993 with a D16Z6 engine. It had a D15 in there before and a map sensor was connected to the manifold but the D16Z6 engine didn't have a place for a map sensor. It came of a JDM 95 civic EX. And I'm using an AEM wide band. It works fine but goes lean sometimes and it does lurk forward around 5k RPM and runs fine past 5k. Then after a few minutes it runs fine at low RPM too. I don't know

 

Oh and I had a D16Y7 before the D16Z6. I chipped the ECU after I put in the D16Y7 and it always ran perfectly well. Never had a problem like this. Then I just put in the Z6 instead of changing heads for vtec and started to have this problem.

 

The D16Z6 engine doesn't have a hose connection for the MAP sensor because it connects directly to the throttle body (see diagram). I am not sure whether your MAP sensor and fuel pressure regulator can work properly the way you currently have it set up.

 

where did you get the basemap chip from?

and if the chip was for a d16y7, you can't use it for a mini-me...


wait a second... what ECU do you have?

 

I have a P06 with a vtec conversion kit in it. The vtec works fine. I can feel and hear it kick in. When I had the D16Y7 I just disabled vtec in the ROM. I used a base map from the stock maps that came withe crome. (P28 USDM Civic D16Z (304)). I have the vtec set at 4500 and that's about when it kicks in. I don't know why you want to know what maps cause it does this randomly but sometimes it works fine.

I redid my setup with the map sensors. I used the map sensor on the manifold and hooked it up and changed the fuel pressure regulator hose back to normal. I haven't really tested it but maybe it will start to work fine.

 

okay.
the reason i wanted to know what basemap it is is because the way you were saying things kinda led me to believe you bought one of those chips on ebay, which could very well cause these kinds of problems.

 

No I bought a blank chip from moates.net.. The car still runs lean whenever it wants to even after changing the map sensor setup.