02 sensor contaminated?

I removed my o2 sensor for the first time when upgrading my exhaust. It was my first time seeing an o2 sensor, I meant to be careful but the tip of ceramic kissed some grease in the engine bay. Car drives but has multiple issues. During idle it seems to have an intermittent problem. Sometimes it idles fine with pretty normal afrs, then it will start running lean then rich, surging and going back and forth. Then it may act normal for a little, then go wack again.

Would the little bit grease contact damage the sensor? I also changed injectors at this same time but under load afrs read 11ish at 10 psi so I?m guessing they?re working properly. It does seem to lean spike in boost but then levels out. Should I be concerned about this too? Before any of this I still had an issue with the car shutting off when shifted into neutral over about ~3.5k or in any amount of boost. This is still occuring.

I apologize for the long post but I need help diagnosis these issues and my project thread isn?t getting much attention. Im grateful for any guidance, thanks. Car is a 1990 740 b230ft with a 3 inch amm and 36lb/hr white injectors.

Have you tried going back to using an 016 mass air sensor? I don't know your list of mods but an 016 can support quite a bit of power before needing an upgrade. As far as the O2 sensor, yes grease can contaminate the sensor and I'm sure it would cause strange readings. If you have a voltmeter put it on the 2v scale and check out the sensor operation with the engine fully warmed up. See if it's oscillating properly. If not then it's bad.

Usually the actual sensing part of the O2 sensor is protected by the metal shield. Just a contact with grease is not likely to contaminate it.

Only engine mods are IPD turbo cam, 012 amm and 36lb/hr white injectors. I have another 012 I will swap in and see if that solves the issue, however Im skeptical thats the issue because the problem only started after I upgraded the exhaust and contaminated the o2 sensor. It was idling normal although rich when I had green giant injectors, but no idle surging or anything. The car would still die when put into neutral at high rpms though, but it idled completely fine.

My understanding was if I upgrade injector size a larger amm is a necessity? I guess I don?t fully understand what I?m doing. My goal with this car is to maximize the performance of the 15g and stay on lh2.4.

I should have mentioned this detail in the initial post. When the car dies when shifted into neutral above 3.5k or in boost, it goes really rich before it shuts off. Im just trying to add as many details I can so you guys can help me out!

The issue must be the amm, injectors, or o2 sensor correct?

dl242gt said:

Have you tried going back to using an 016 mass air sensor? I don't know your list of mods but an 016 can support quite a bit of power before needing an upgrade. As far as the O2 sensor, yes grease can contaminate the sensor and I'm sure it would cause strange readings. If you have a voltmeter put it on the 2v scale and check out the sensor operation with the engine fully warmed up. See if it's oscillating properly. If not then it's bad.

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Anyone? I tried to make my post more concise. Any tips on fixing the issue with the car dying and weird idle? I just want to maximize performance on my setup with a 15g with turbo cam and lh2.4. My time to work on this car is running out.

I replaced the O2 sensor and swapped in another AMM. Neither of these solved the stalling issue and funky idle. So it must be the 3-inch exhaust, eBay 36lb/hr injectors, or the fact I have a 3-inch AMM in the first place.

Put it back to stock and recheck.

I'm ordering hoses to reinstall stock AMM and I need another resistor pack to reinstall stock injectors. If anyone has a resistor pack for cheap give me a PM.

ZVOLV said:

Put it back to stock and recheck.

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