Is there any diy way to check the timing on my car using those timing light gun thing?
My car is running but has rough idle.. After replacing timing belt..

Arlo said:

After replacing timing belt..

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Therein may lie the clue? First off has to be a recheck that all the timing marks line up correctly. Easy enough to be one tooth out. If that doesn't find anything my next move would be to plug in Multiecuscan and look for DTCs. If it hasn't flagged anything up you can then run through the live data sensor outputs. After that it gets mucky. Good luck

Checked timing with cyl 1 in tdc and using the cam locking tools. It is spot on.
There are no dtc's. I unplugged the fuel evaporation hose from the air intake and it started to run better. Plugging it back in and its the same as before.. To me this indicates that its is running way to rich. So I started suspecting o2 sensors.. Tested them both and the work propperly. Multiecu says sensor 1 has closed loop but sensor 2 (after cat) has open loop indicating there is something going on. I turn on graphs and compare the two sensors.. After having the engine run for a while to heat things up sensor one is a 0.5ish volts like its supposed to. But sensor 2 just reads a steady 0.056 volts. Im in no way an expert but this looks like its not ok but i checked the sensor by heating it with a torch and it goes from 0 to 0.93 volts and back again.. Also tested the heating element and burned my finger. Then i tested continuity from the plug to the plug on the ecu and its all good. It seems my ecu just not see the sensor or ignore it.. Again no dtc's. Did my ecu partialy die while i was dong the belt change? I always u plug the battery when i work on anything.. Arghhhhh??

What vehicle..and which engine.

Older .. rubber bung ... FIRE motors will run whilst many degrees out of time.

Charlie

Arlo said:

I turn on graphs and compare the two sensors.. After having the engine run for a while to heat things up sensor one is a 0.5ish volts like its supposed to. But sensor 2 just reads a steady 0.056 volts.

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Just so I understand you've got the engine good and hot? By the way what car/engine is this, not that it'll make much difference to the O2 sensor outputs. Then you've got MES plugged in and you're looking at the graphed pre and post cat voltage outputs?

If this is what you're doing the pre cat sensor should be switching somewhere around 0.8/0.9 volts to 0.1/0.2 volts and back again roughly once a second. I find frequency and exact voltages vary but broadly speaking you should be seeing this. Speed the engine up a bit, say to 2000 rpm and hold till you see the trace alter - the frequency should increase (that is it should switch more quickly). If, as you say, it's holding a constant 0.5 volts that's not right.

The downstream one should hold a steady (or almost steady) reading. Around half a volt would be good. If the CAT is good it will not oscillate.

The precat sensor has quite a marked effect on fueling so if, as you say, it has a steady output and shows no tendency to switch or to only switch slowly with reduced amplitude it may well be your problem. It's worth mentioning that most (the Zirconia type) oxygen sensors are best thought of as little batteries. Although the heater in it is powered from the vehicles battery the signal voltage is produced by the sensor itself. The Japs were very keen on Titania sensors which act like a variable resistor and I believe you can come across them in euro vehicles especially very new ones. I think there is also a new "wide band" type now on the go too which I know nothing about at all. Good reason to stay with older cars say I!

Hope some of that is helpful. Interestingly our little Panda has a precat sensor which is working fine but a post cat sensor which, although giving a straight line output, is right up at the 0.9 volts. This would indicate an absence of oxygen so "rich" mixture which makes no sense if the upstream sensor is working OK and the CAT emissions passed on the MOT not so long ago. I suspect the sensor may be goosed. Going to take it out and test it with a flame just like you. The car is a bit "dull" on the acceleration but I didn't think the post cat sensor had much effect on fueling so I'm a bit puzzled.

PS to the above. Remember the MAP (MAF if it's got one. I say that 'cos Fiat like their MAP sensors) will affect fuelling. Check it out too, their vacuum side can get blocked or contaminated with fuel. Pulling that pipe off will have an effect on vacuum in the manifold which the MAP will pick up on.

Just switched over the os sensors they are both the same and the problem switched with it.. Although i bench tested both o2 sensors the after cat (downstream) is faulty.. I ordered a new one.. Quite weird that it decided to die while i was replacing belts..

Glad you found a problem

interesting outcome. Must try switching mine round and see if that post cat sensor continues to give the weird reading when in the pre cat hole. Thanks for posting your outcome.