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Car Forum / UK Car Forums / Car Maintenance (UK group) / August 2007Injector problems after cleaning?
I decided to treat my Daewoo Lanos injectors to a professional service & ultrasonic clean. It ran very well before having them serviced but with over 116k miles I thought it would do it good - Big mistake. Fitted the serviced injectors and it ran like a bag of shite! Idles lumpy, judders when you lightly touch throttle and down on power. Got hold of some injectors from a low mileage Lanos and put them in and the car drives better but was still not as good as it was before I had the original injectors serviced. Trying various things (which made no difference) I then unplug the O2 sensor and with it disconnected there is a big improvement. The engine sounds better, idles smooth & loads more torque (although lights up the CEL). Now the car drove good before having the injectors cleaned and I've since read that the injectors fitted to these cars don't perform well to being serviced. As it now runs better with the O2 disconnected, is it likely the serviced injectors have also ruined the O2? Running the car without the O2 sensor will make the ECU run in 'open circuit' mode, using standard fuelling maps for your engine. The fact that everything is ok when doing this indicates that the injectors are fine. It is possible that the ECU is still expecting knackered injectors, and trying to compensate for that. Have you given the ECU time to adjust, or tried resetting it? I've just removed and cleaned the injectors on my car, and the car now runs like a dream. Andy. >I decided to treat my Daewoo Lanos injectors to a professional service & > ultrasonic clean. It ran very well before having them serviced but with [quoted text clipped - 13 lines] > to being serviced. As it now runs better with the O2 disconnected, is it > likely the serviced injectors have also ruined the O2? > Running the car without the O2 sensor will make the ECU run in 'open > circuit' mode, using standard fuelling maps for your engine. The fact that > everything is ok when doing this indicates that the injectors are fine. duh, of course I mean 'open loop' mode. Thinking about something else when I wrote it. > Running the car without the O2 sensor will make the ECU run in 'open > circuit' mode, using standard fuelling maps for your engine. The fact that > everything is ok when doing this indicates that the injectors are fine. These are the known good injectors that I fitted from another Lanos. I suppose what I should do to determine if having the original injectors serviced has harmed them is to try them again but with the O2 disconnected and compare how it runs. > It is possible that the ECU is still expecting knackered injectors, and > trying to compensate for that. Have you given the ECU time to adjust, or > tried resetting it? It's ran crap for over 2 weeks since having them serviced. I also disconnected the battery to force it through a learn phase but no joy. They told me they replaced the filters & seals and that 2 of the injectors were low and not squirting as good as the other 2 so kept flushing them through the machine until they were all even. It ran great before having the injectors serviced and now looks like the O2 is shot! Sounds a bit much of a coincidence? >> Running the car without the O2 sensor will make the ECU run in 'open >> circuit' mode, using standard fuelling maps for your engine. The fact [quoted text clipped - 22 lines] > of > a coincidence? Sounds like a coincidence, have you pulled the O2 sensor to see if it's covered in soot? "Duncan Wood" <newsto@dmx512.co.uk> wrote in message > Sounds like a coincidence, have you pulled the O2 sensor to see if it's > covered in soot? The damn thing is solid and those special O2 sockets are crap! If it's going to come out I think I'll need to snip the wire to get a proper socket on and then hope it doesn't also bring the manifold thread with it! To be honest, given the cars age and value and that it's running very well with the O2 disconnected I'm tempted to just leave it at that. Apart from possible cat damage is there any other consequences of running with the O2 disconnected? > "Duncan Wood" <newsto@dmx512.co.uk> wrote in message > > Sounds like a coincidence, have you pulled the O2 sensor to see if [quoted text clipped - 7 lines] > leave it at that. Apart from possible cat damage is there any other > consequences of running with the O2 disconnected? risk engine damage over a long period of time , certain mot failure on emmisions and cat I presume you have tried warming the exhaust up first? To be quite honest I don't know how on earth you are going to assess the condition of the sensor by looking at it - if you really think it has gone then you'll only find out by replacing it. Have you considered you might be barking up the wrong tree as to the cause of your problems? Just because removing the sensor makes the car run better does not necessarily mean that the sensor has gone. And I very much doubt that the injector change could have buggered up your O2 sensor. Are you sure the injectors you were sent back were yours? Are you also sure that the company didn't damage them, or reassemble them incorrectly? Have you called them to see what they think the problem might be? Andy. > Are you sure the injectors you were sent back were yours? Are you also > sure that the company didn't damage them, or reassemble them incorrectly? > Have you called them to see what they think the problem might be? Yes that did occur to me but if you read my earlier post I had changed those injectors for a known good set and although a noticed improvement it still ran crap. Unhooking the O2 made a huge improvement to the running and smooth idle. I know I really need a scope to test the O2 but using a DVM there didn't seem to be much fluctuation around 0.6v and very little change even if I introduced an air leak by pulling a vac pipe. If I touch the ecu end of the wire with one hand and the batt + with the other the engine will then splutter to a stall. > >> Running the car without the O2 sensor will make the ECU run in 'open > >> circuit' mode, using standard fuelling maps for your engine. The fact [quoted text clipped - 25 lines] > Sounds like a coincidence, have you pulled the O2 sensor to see if it's > covered in soot? My 02 sensor is always covered in soot, and I know its working just fine lol. >>> Running the car without the O2 sensor will make the ECU run in 'open >>> circuit' mode, using standard fuelling maps for your engine. The fact [quoted text clipped - 25 lines] > Sounds like a coincidence, have you pulled the O2 sensor to see if it's > covered in soot? Well I managed to remove the O2 and took some pics below. Anyone know from the pics if this is normal or not? The flash makes the tip look lighter than it actually is but one side of the sensor tip is a lot darker than the other side. While it was out I used a blow torch and measured the voltage. It quickly reaches about 0.8v with heat applied and very quickly drops to 0 when removed. After refitting the sensor and connected the wire I gave it another try and the car ran sh.t again and lacked power, but unplug the sensor and a big improvement. http://i222.photobucket.com/albums/dd74/panther4674/O24.jpg http://i222.photobucket.com/albums/dd74/panther4674/O23.jpg http://i222.photobucket.com/albums/dd74/panther4674/O22.jpg http://i222.photobucket.com/albums/dd74/panther4674/O21.jpg > Well I managed to remove the O2 and took some pics below. > Anyone know from the pics if this is normal or not? The flash [quoted text clipped - 11 lines] > http://i222.photobucket.com/albums/dd74/panther4674/O22.jpg > http://i222.photobucket.com/albums/dd74/panther4674/O21.jpg It's not impossible that a problem with one or more injectors was concealing an O2 sensor problem. O2 sensors are a service item. The removed sensor doesn't look too bad to me, except that the extent of corrosion on the outside says it might be due for a replacement. See http://www.picotech.com/auto/lambda_sensor.html John >> Well I managed to remove the O2 and took some pics below. >> Anyone know from the pics if this is normal or not? The flash [quoted text clipped - 19 lines] > outside says it might be due for a replacement. See > http://www.picotech.com/auto/lambda_sensor.html Cheers John, I've ordered a new O2 from SparkPlugsRus. £28 includes vat & del for a NGK oem direct fit which is not a bad price compared to other places who wanted around the same or more for universal and you had to splice on your old connector. > Cheers John, I've ordered a new O2 from SparkPlugsRus. 28 > includes vat & del for a NGK oem direct fit which is not a bad > price compared to other places who wanted around the same or > more for universal and you had to splice on your old > connector. Good luck. Please let us know how it goes. John >> Cheers John, I've ordered a new O2 from SparkPlugsRus. 28 >> includes vat & del for a NGK oem direct fit which is not a bad [quoted text clipped - 5 lines] > > John Right, I've now fitted a new O2 (I can definitely recommend www.sparkplugsrus.com) It would appear that the problem was not the O2 although it did seem to run a bit better but still lacked power, a slight judder and rough idle. Getting a bit pissed off I put on my coat of big pockets and headed for the local breakers. Luckily a lanos was there so I managed to strip some sensors and the results are: Replaced the TPS & ISCV made no difference! Replaced the air intake & MAP sensor and the baby now runs absolutely perfect like a dream :) Now I don't know if it was the AIT or MAP that was faulty as I replaced them both together at the same time but the car now runs brilliant with loads more response to the pedal. The engine sounds better, it pulls better with no judder and I can now change up the gears sooner while still maintaining good torque. What does puzzle me though is the car ran great before I had my original injectors cleaned but why should that have caused a fault in either the AIT or MAP sensor? Still, it's all sorted now and finally running great again so I'm happy. What I have learned though, if it aint broke don't f.cking fix it! :) > What does puzzle me though is the car ran great before I had > my original injectors cleaned but why should that have caused > a fault in either the AIT or MAP sensor? Still, it's all > sorted now and finally running great again so I'm happy. What > I have learned though, if it aint broke don't f.cking fix it! :) Always examine the simplest explanations first. It's one of these that's most likely to be right. Causing a new fault by simply fixing another is not a simple explanation. But perhaps a sensor or its wiring got disturbed/damaged during the work on the injectors. More likely you had two faults, and the combination was bad enough to cause the ECU to continue running in open-loop mode, covering up both problems. This is strongly suggested by the behaviour when you forced open-loop running with good injectors - namely when you disconnected the O2 sensor. Glad it's sorted now. John |
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