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Post Info TOPIC: Vitara overfuelling


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RE: Vitara overfuelling
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I agree a cracked exhaust manifold would be a possibility if the HO2 sensor was reporting lean (<200mV), but in this case the HO2 sensor is reporting full rich at 990mV and it is still over fuelling.

BTW, G13BB Jimny engines were also very prone to cracking exhaust manifolds. When I replaced mine some years (and ~200,000Kms) ago, I cut through the new manifold mounting flange between cylinders 2 & 3. This allows the casting to move a bit more with normal heating/cooling cycles and no signs of cracking since. I'm not familiar with the Vitara manifold, but it should work on similar style castings on other engines. Just be sure to keep the stud pattern balanced across the cut. See photos.

Feel free to repost these pictures elsewhere if you think they could be of help to others. It worked for me, but I can not take any responsibility for others workmanship.

Cheers...Bob

 



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Another cause of overfuelling with rthe O2 showing lean is a cracked or leaking exhaust manifold. Not uncommon on Vitaras

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1984 Suzuki SJ413K pick up, 1.6 16V Baleno engine
2000 Suzuki Vitara 1.6 8V, many mods
2004 Suzuki Ignis 1.5VVT 4Grip
2006 Suzuki Jimny 1.3VVT JLX+
and many more.



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Just some observations.

The scan tool is indicating the HO2 sensor is reporting full rich at +990mV (for a zirconia O2 sensor) which is consistent with your observation of overfueling. The ECU should be desperately trying to pull the injector duty cycle back to correct this.

Somehow the ECU thinks the engine is running lean despite the HO2 sensor input. This would be consistent with an abnormally high MAF input (apparent high air flow volume). If the MAF checks out OK, it could be a faulty ECU. Could be shorted injector drivers, faulty MAF interface circuit or faulty HO2 interface circuit.

It could also be the ECU is seeing a wide throttle demand, some ECUs ignore O2 and MAF sensors under heavy acceleration and go full rich, so it would be worth checking the TPS circuit. I don't think this is the case as your scan tool is reporting 1.9 degrees which one would think is low throttle setting, but it is worth checking.

Or faulty (leaking) injectors or faulty fuel pressure regulator.

There is an interesting treatise on O2 sensors here: http://en.wikipedia.org/wiki/Oxygen_sensor

Good Luck...Bob



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Yes, check it at idle with the engine warmed up.



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1984 Suzuki SJ413K pick up, 1.6 16V Baleno engine
2000 Suzuki Vitara 1.6 8V, many mods
2004 Suzuki Ignis 1.5VVT 4Grip
2006 Suzuki Jimny 1.3VVT JLX+
and many more.



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Hi

I'll check the voltage and let you know. Should I check it while its running?



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I don't have any links for a supplier. Can you check the voltage at the MAF?



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1984 Suzuki SJ413K pick up, 1.6 16V Baleno engine
2000 Suzuki Vitara 1.6 8V, many mods
2004 Suzuki Ignis 1.5VVT 4Grip
2006 Suzuki Jimny 1.3VVT JLX+
and many more.



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Do you have any links as to where I can obtain a replacement air flow meter

Part number - 13800-58B00



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Hi

The carmnan scan will use the units only provided by the manufacture. There is an option to change the units read to different units, but its will still always give figures in the units from the manufacture. i.e TPS can be changed to % from degrees but it still only gives the figure in degrees. I would say the maf is measured in the Suzuki style but i'm not sure what that is. I take it on your experience of normally being in Grammes per stroke



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Does the Carman state what units it uses? I would have to check but I think that the Suzuki figures are grammes/stroke rather than grammes/second.



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1984 Suzuki SJ413K pick up, 1.6 16V Baleno engine
2000 Suzuki Vitara 1.6 8V, many mods
2004 Suzuki Ignis 1.5VVT 4Grip
2006 Suzuki Jimny 1.3VVT JLX+
and many more.



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60 g/s at 697 rpm?  Based on Rhino's figures that should/would be around 3 g/s.



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Just realised I missed out the reading from the MAF, what donut no

MAF - 60.60 g/s

Thanks



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Hi Rihnoman, thanks for taking the time to reply.

I have checked your figures and can give you some figures from our diagnostic check. We are using carman scan VCi but some of the figures/values are no available from our kit

Engine speed - 697 rpm

ECT - 75.22 c

IAT - not available

TP Angle -  your measurement is in % ours is in degrees. I feel we do not have the TPS set up right and some help on this would be good. Our reading is 1.95 degrees

H02s Sensor 1 991 mv

Spark - 6.25 BTDC

The MAF readings concern me, we have put a new after market MAF on from a guy in Spain but we have been caught on other makes of cars when a cheapo MAF has been used, we now try to fit branded units if poss but this was not an option as they are difficult to find. Some help with setting the TPS would be good. Also the black plastic posidrive idle screw in the inlet manifold, should this be screwed all the way in tight?

Thanks for your time, it is very much appreciated, this has been an ongoing problem with this vehicle for a while and it would be good to get it sorted.



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Have you checked that you are getting the correct reading from the airflow meter? Fully warmed up at ide the airflow should be approx. 3.1g/s and the O2S should be activated:

Vit_16_16V_MAF.jpg

 



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1984 Suzuki SJ413K pick up, 1.6 16V Baleno engine
2000 Suzuki Vitara 1.6 8V, many mods
2004 Suzuki Ignis 1.5VVT 4Grip
2006 Suzuki Jimny 1.3VVT JLX+
and many more.



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Hi.

We have a 1997 Suzuki Vitara 16v. It overfuels badly when the air flow meter is connected. If we disconnect it it runs well, although the fuel consumption is slightly high. We have replaced the airflow meter with a new new unit, not gen Suzuki, aftermarket but the results are the same. I have checked coolant temp sensor and it appears to be reading ok. No fault codes to go on when all connected up. Could we have an ecu fault? Anyone come across anyhting similar. Any help gratefully appreciated.



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