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Afr going lean.

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Hey guys as the topic says, I'm having lean issues with my build. I have a gtr motor in a 240sx with the haltech platinum plug in pro ecu. Here is the problem, normal driving is ok, but as soon as I apply steady gas during acceleration the car first starts running at the expected target afr then goes leaner until I back off the throttle. I've data logged three runs, increased the fuel in the affected cells but it still happens as if I never corrected those cells, not even an improvement the afr values. I had an in tank dual aem 320 lph setup but the hoses kept backing off either one of the pumps so I've gone back to a single walbro hellcat pump. All the lines have been tightened and the system checked for leaks. I have the tomei type l fpr. In addition, checking the data log, I'm not getting any voltage drop with the battery so I'm not thinking of this being a battery issue. Any thoughts? I'll try to load the log file when I get a chance. Thanks all.

Perhaps injectors supply not enogh !

Forgot to mention, the injectors are ID 1000cc.

Do you have a datalog you can post up bro? Are injectors working correctly? I would check for any vacuum leaks aswel as this would cause you to go lean aswel

Yea, I was thinking about that too. Checked for leaks and I have none, these injectors are about a year old but have not been in use for a that time, if you get what I mean. I'll post the data log in about two hours, I'm away from the laptop now I'll have to grab it thanks.

Here are the logs, I'll describe the sequence. First two runs, lean and lean pt2 I didn't do any fuel map corrections, I simply checked for vacuum leaks. Lean run pt3 was made after I enriched the fuel map in that area that I still saw the lean event. The file called lean run still was made after checking every connection in the fuel line from feed on the fuel tank to the fuel rail and then back on the return to the tank, my only other option before changing any parts is to borrow an aux input, connect it to the electronic fuel pressure sensor output and log another run. I have nylon braided 8an feed and 6an return. Any help is appreciated.

Attached Files

Anyplace you can sent screenshot of the runs bro as only have my phone on me at the moment....also what wieland are you using? Is it also reading lean on the dyno?

I have dual widebands for each bank, they are aem 30-0300 x series. It's only been road tuned. Haven't scheduled dyno time until all bugs are out.

Update, I've sorted out the lean issues I was having. It turns out that my mechanical fuel pressure gauge was faulty so while I thought fuel pressure was ok, it was too high. I changed it and thenI did a test run and it solved most of the problem. I then took apart my inline fuel filter and discovered it was 50% clogged. Washed it, reinstalled it, did several pulls and now no more leaning out. So I'll be going back to trying to tuning the car. Thanks all!

If your filter was 50% clogged on a relatively new installation I'd be a little suspicious of problems in your fuel system. You don't want that happening again and the engine going lean when you're not watching the AFR!

Update to the update, turns out that "somebody" dropped a roll of electrical tape in the gas tank during the build. In the process of draining and cleaning the tank.

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