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Bad Idle/p1311 - Lack Of Upstream Flow, O2 Sensor Indicates Running Le


Falky100

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Having troubles again guys.

For ages now, my car has had a bad idle and a code logged, P1131 - lack of upstream flow, o2 sensor indicates lean on bank 1. This code loggs itself regularly and I clear it each time. But lately it hasnt come up but still have a bad idle. The car shakes a little like it is missing at idle but seems to go ok when I take off, it also surges sometimes at idle and sometimes when I push the clutch in and let the revs die down. I cant remember whether I had this problem before my mech changed the o2 sensor (not genuine). I think it is a HEGO because it has 4 wires. Not sure what else to write and tell u guys, but if I think of more I will let you know. Also one last thing not sure whether it is my TB or my injector rail but something is ticking around there (sounds more like the injectors), whether that is related or not, that is up to you guys to give your input on

Many many thanks in advance.

John.

P.s, what I have done to try and fix this problem so far is clean the throttle body, it helped for a bit but the problem has arisen again.

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Stock injectors tick pretty loud. Especially

On hot days. Without looking I'd be inclined to say there was a build up of sludge/ oil in that inlet donut restricting a bit of flow. My 2c anyway. Best of luck mate

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Ok, quick update. Strangely enough my car had that code come up again as I was driving home. P1131 - Lack of upstream Heated Oxygen Sensor switch, sensor indicates Lean - Bank No. 1... That is exactly what my elm said. So beats me whether it is a faulty sensor and needs the genuine ones... Also, my car is a BF mk1 xr6T 6sp manual if that helps with any of my pain in the A-hole issues.

Thanks for your help Dave, what donut are you talking about? is it in the injector rail? If it is, I just had the injectors cleaned by my mech about a month ago (he said they were putrid. The car has only done 75,000 kms. From what he said, the last owner had some good fun in it *wanker*....

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Sorry mate, I was half asleep for some reason I thought you said rich on no1 so I thought gunk in the inlet donut on that cylinder ( the donut shaped plenum runner thing) restricting flow.

Now I'm properly awake lol. The non genuine sensor may be a shorter length therefore giving a different reading. May also be screwed in too tight or loose. Seeing as it wouldn't cost anything to check that Id check that first. Did this error coincide with the injector clean? He may have accidentally dislodged a pile of sh*t in that injector that clogged it up once running? If you decide to replace them send me a PM, my stockers are floating around in the shed.

Dont stress though. These Barra's seem to be able to take an absolute flogging! :)

Best of luck again

Edited by MX Dave
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Thanks Dave, il keep you in mind if I end up having to replace the injectors. Its hard to remember whether the rough idle came after the mech replaced the o2 sensor (got a strange feeling it did). I also think that he cleaned the injectors in a hope to fix the rough idle (injectors were done after the o2 sensor was put in.). Would it make sense to you that the "running lean on no.1 bank" is related to the o2 sensor? And upstream sensor is the 1 in the dump pipe I assume. I got quoted a genuine one from fraud the other week and it was like $300 round figures. I also have a strong fume smell coming from my exhaust, now whether that is just the premium fuel I use (98 vortex) or whether the car is adjusting the "lean" mixture and making it run rich, could be another thing. I get about 420kms per tank.

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Strong fuel smell from exhaust would be a dodgy or non exisant catalytic converter. That may be a cause for some of your problems. The exhaust flowing more would raise boost and would explain the leaning out.

300 bucks is a hefty price tag. Hopefully that's not the issue.

Give the cat a poke/knock if it sounds hollow or rattles unbolt the sucker and have a look :)

Edited by MX Dave
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I havent had increased boost, I make just over 4psi (is that what it is suppost to make?) How musch does a stock cat cost? I didnt want to put a hi-flo one in since you have to tune after. I hava a stock ba cat here, but I dont think that will bolt up correctly will it? Since there is 2 o2 sensors on my bf?

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Yeah round 5psi is stock. I'm eager to find out what your problem is. Hopefully nothing major. But my check list would involve that new sensor ( for length/tightness sealing etc) the injectors ( for dislodged gunk, incorrect installation or broken o rings when reinstalled) and the cat (for that fuel smell). If they all seem fine I'm not sure what the problem would be :/

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Thanks for your interest Dave, it would make my day to fix this issue. My car is booked in at blacktrack performance (near newcastle) on friday. So after I get it back. Il make sure to fill you in on the results.

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Ok everybody, 6 new coil packs later and my car is running great (4 coils were cracked, apparently a common problem I have been told).

So... Just letting everyone know, if your car has the symptoms mine had, check the coils. Might save yourself alot of money in the long run!

Cheers, John.

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