[Oni mkiv]

So I have searched and tried sooo many things. None seem to fix this. I have been recently getting an engine code 52 which means running lean. At first i thought Fuel pump, so i got a walboro and didnt fix it. Next was swapping out my turbos cause they were going bad. Then o2 sensor and sti not fixed. I reseted the ecu every time tk clear codes and still keeps coming up. I dont see how i need to mess with knock sensor because i never messed with anything in that area.

Here are some symptoms:

-- as soon as i hit .9 bar or so, car misfires like its hitting rev limiter (6 month old plugs and wires)
-- only when Im cruising and not even boosting does the cel light come on.
-- car runs sluggish, boosts fine just a lack of power - something is just not right.

Is it possible i have a vacuum leak? How do i check? Where are some possible areas?

 

[EviLo7]

a vacuum leak can only make a difference if it was a maf sensor engine but its not. it may cause a slight power loss under boost but not a lean problem. do you have a wide band to confirm if you are in fact running lean?

 

[Oni mkiv]

I dont but i was thinking about doing that very soon and getting an AEM afr. Is there anything else i can do to diagnose this in the meantime?

 

[supraracer01]

You NEED that a/f gauge so youknow what's going on, it could be a bad ecu, clogged injector, low fuel pressure, clogged fuel line, clogged fuel filter, or a bad map sensor, but until you can tell us what and when yougo lean it's just throwing darts in the dark...

 

[Enslaved87]

Since this is the easiest thing to check for, open up your ecu and look at the capacitors, rule that out first. Assuming all is well with that then you have a lot of troubleshooting to do. What are your plugs gapped to? Remember in extreme rich conditions a o2 sensor will actually show a lean condition. Gap your plugs down and see if it helps any. Also, make sure the vac hose from the manifold is connected to the fuel pressure regulator on the fuel rail.

 

[destrux]

Check your coils for cracks. My car had badly cracked ignition coils and the car would misfire so much that the O2 sensor was reading all the unburnt oxygen in the exhaust as being lean, and the ECU was adding more fuel which made the car run even worse. Then the car threw a lean code when it hit the maximum fuel correction value.

I took my coils out and cleaned them with electronics spray cleaner from the auto parts store ("QD electronics cleaner") and then coated the cracks with CLEAR nail polish. You have to use clean because the colored stuff is colored with metal particles. The clear is non-conductive. Then I wrapped the coil towers with electrical tape just to be safe and the car runs perfect now.

Also, the bad cutoff you're hitting at .9 bar is boost cut. Normal boost cutoff is 1.0 bar, but your gauge could be off by a little bit.

I should also add that my wideband also read false lean while this was happening... so a wideband won't help you figure things out all the time like you'd think it would.

 

[Oni mkiv]

ECU capacitors were changed 2.5 years ago - they should still he fine but i will check again.

Manifold hose to fuel pressure regulator? Can someone show me where thisis?

What should my spark plugs be gapped to? I will also check coils for any cracks. Not sure exactly how to do that but i will check for anything suspicious and buy some cleaner.

Side note: my car is running super rich... it smells like my friends car when he dumps in race gas in his mkiv. Can i still drive my car around? Is it bad for the engine?

 

[supraracer01]

i usually gapped my ngk 6097's to .26-.28

 

[Oni mkiv]

Also forgot to mention that my cars idle bounces between 600-700 RPM or so. I can also hear it in the exhaust when i stand outside. Would that be a vacuum leak?

 

[destrux]

It still sounds EXACTLY like cracked coils.

You're looking for hairline cracks on the part of the coil that sticks down in the sparkplug hole, and up on the coil body near the screws that bolt the coil to the metal brackets. I had cracks in both places.

The bouncing idle is because of misfires, and the super rich smell is the unburnt fuel from the misfires.

You could also buy new coils, you don't have to repair them like I did, but new coils are $$$.

 

[Oni mkiv]

Are these hairline cracks visible?

 

[Oni mkiv]

Well... here is the update. I cleaned my coils and changed my sparkplugs to ngk 4644. Car runs fine; no bogging out in the top end but engine light sti comes on and retards timing =\. Anyone have any thoughts on this?

 

[EviLo7]

im assuming you are using California piss water? have you tried running the car with a higher octane gas or maybe using an octane booster? its a long shot but 1jz stock timing maps were meant for higher grade fuel than 91.

 

[Oni mkiv]

91 octane worked fine for 2 years with this piss water. This is just a recent thing