I have just rebuilt my LS VTEC and I am trying to break it in. I am having problems with it bogging under part throttle, then it catches up and runs fine at WOT (this is hot or cold). Also, after it warms up, I stall often on decelleration before a stop or at a stop. It idles fine (although I have set the idle a bit high). But at a stop it wants to die all of a sudden. It does not choak or slowly die, it just dies. Sometimes I can catch it with the throttle but it happens quickly. I am also running a rich. The stupid narrow band meter pretty much reads all the way to the right at rich and leans out a little bit after it warms up but generally stays in the rich area.
I have searched and I am going to check my O2 (the four wires fall out easily and I could have switched the two black wires) and I am also going to double check my dizzy timming. The plugs look fine... just on the rich side. Plug wires look good and there are no leaks.

One other thing... the boost gauge is reading a relativley low inhg... like around 25 at idle. I am not sure if that is related or what is causing that.

Thanks for the help!

 

How old is your cat?

 

No cat, straight pipe.

 

Mee too. Having the same problem with my GSR...

 

It is gotta be the A/F. You may have to buy a simulator.

 

My next steps are to double check the O2, lean it out a little and double check the timming.

The car did overheat a little a week ago but the headgasket looks ok and exaust (albeit a little black) looks OK.

The only thing I did since then is refill the radiator and fixed my downpipe (O2 came unplugged again). That's why I am thinking O2.

 

I have a chipped P06 with uberdata and I used the base GSR fuel map. I think it is a little too rich with the lower 9.0 compression ratio combined with the stock map being rich in the first place. I did lean it out about 10% though. Still too rich. You think being too rich could have these symptoms?

I have only driven the car 2 days. The first day it ran OK, then I overheated it and it ran OK after I refilled the radiator that same day... not stalling or bogging.

I had to fix my downpipe (get it rewelded) then this started happening. For some reason I was not quite as rich the first day as I was the second day when the bogging and stalling started.

 

For sure. I think running rich could definately produce symptoms like that. I changed damn near everything basic and it ended up being my cat (which I hollowed out because it is hella old and was plugged up.) Now my A/F is totally jacked up because I'm obd2 the primary o2 sensor is reading wrong and is noticable when my car warms up.

 

That reminds me. I need to try to restet the ECU. Did you try that so that it could remap the fuel tables?

 

Yes, In fact I have never fixed the problem.. Just alleviated it. I reset the Ecu and let my car idle for about 20 min. It ran great for about 4-5 days then my CEL came on. (Primary o2 sensor) I haven't reset the ecu since because the car still runs.

 

Did you make any mods before this started happening?

 

Intake/Header only.

 

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