ecu dumping fuel

[dsmoverboosted]

What would cause an ecu to dump way to much fuel in? Say enough that on stock injectors I would be able to remove 30-35% fuel and not knock. My ecu is not fried and I am not leaking boost. thanks

 

[steve]

What does the Engine Coolant Temp sensor read (via your logger)?

Steve

 

[dsmoverboosted]

196-199. I am thinking of unhooking un o2 to see if limp mode improves it. Could that be it?

 

[steve]

I am thinking of unhooking un o2 to see if limp mode improves it. Could that be it?

Not once the ECU goes open loop.

 

[dsmoverboosted]

right I forgot about that. What else could it be? I did just finish installing my frank 4 turbo, 2g mani, intake and o2 housing. I know I got some exaust leaks in the manifold that i need to get welded (egt hole drilled and I dont have one, i got a bolt with some rtv copper in it now) could that be it?

 

[steve]

Boost leaks will cause the car to run rich. A open hole for an EGT will cause the O2 to read lean and you'll see that in your fuel trims from closed loop but during open loop it's just airflow, airflow corrections, fuel pressure and injector size that control AFR.

Considering how rich the stock maps are you could pull a lot of fuel out if your only tuning for knock. Do you have a wideband to measure your AFR?

Steve

 

[dsmoverboosted]

No i dont. These are still stock injectors, I havent got my 680's in yet. There is something wrong for sure. I guess since it happens in open loop the o2 isnt the problem so the exaust leak souldent be the issue i suppose.

I also rerouted my pvc and breather to a catch can. but My intake doesent have a breather hole and I plugged up my intake mani nipple. I get 20hg vac at 900rpm

 

[Talesin]

Check your fuel pressure if you haven't. It's possible that your rewired walbro 190 could be overrunning it, or the FPR could just be toast.

 

[dsmoverboosted]

If it was the fpr wouldent my o2 see rich and the ecu would try to remove fuel not add tons more? Is it possible that I got 2 different problems? one when i cruise and one when i boost? It doesent make sence to me that the o2 reads lean and adds fuel in closed loop and in open loop im still pig richwithout the ecu's help.

I am going to unplug my o2 and just see what happens. I got nothing else right now I could think of other than maybe its 2 different issues. Maybe my fpr goes funky when boosting from increased pressure and my o2's screwy while driving normal.

Man that would be bad timing.

I am open to any and all suggestions, feel free to throw them out there.

 

[steve]

It doesent make sence to me that the o2 reads lean and adds fuel in closed loop and in open loop im still pig richwithout the ecu's help.

That's classic boost leak. Under vacuum you suck in unmetered air and read lean while under boost you leak metered air and wind up rich.

Steve

 

[dsmoverboosted]

I know what you are saying but i think i worded it wrong. under vac i am still pig rich. The ecu sees super lean in the o2 sensor i am thinking from the exaust leak and dumps fuel in making me pig rich. I am not lean at any time.To get my fuel trims close to 100% i need to take away 10-20% in vac. Or am I mistaken?

But I do know I need to boost test for sure and i gotta fix my exaust leak. I will do it asap, I hope those fix my problem