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02 voltage and maps 3.5 v8


gav-

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Please bare with me, I have tried the search engines and cant find the answer I am looking for,

I have now installed megasquirt and edis on a rover v8. It does run although not very well. It will start and idle but smells very rich (in fact i almost suffocated myself!!)

The o2 rear bank voltage at idle never gets above 0.06v (yes not 0.6v) if i rev it then the o2 voltage does increase. The sensor is fully inserted into the exhaust, the probe length is in the body of the exhaust flow.

What should the o2 voltage be at idle? I have posted a screenprint of my ve and spark tables. the req fuel is 9.4ms. I have checked the timing with megasquirt disconnected and edis powered up and this is correct, but i am yet to check the timing whilst the engine is at idle.

post-2168-12775860221_thumb.jpg

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First off, assuming your sensor is a normal narrowband one, RTFM and remind yourself how narrowband sensors work and why you can't have an accurate answer for "what voltage should it be at X,Y,Z". If your sensor is not a normal one but, for example, one of the original Range Rover Titania ones, then it won't work directly with Megasquirt.

Second, if it smells really rich then IT'S REALLY RICH - chances are you've chucked so much fuel down the exhaust you've drowned the sensor. It may burn itself clean once you've leaned things out a bit, or it may be dead. You can remove & clean by heating the tip with a blowlamp till it glows, it should also put out a voltage you can read to confirm it's working.

Next - O2 rear bank? How many O2 sensors are you using, where are they, and how have you got them connected? Most people use a single narrowband sensor for MS, located after the Y piece.

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Fridge, Thank you for your reply.

It is a normal narrowband sensor not a titania one. this is the second one I have tried now as i thought the previous one was faulty, i doubt it is now this one is installed.

I only have one lambda installed however on tunerstudio it is just selected to rear bank o2.

I have manually typed in the fuel and spark settings from istruggletogate11 post, and i will try them tomorrow. Instead of using the tables i posted above.

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PM Me me your emial addy and I can then send you mine and can look at your MSQ

Frankly I think you are FAR FAR overcomplicating things, and microexamining what is most likley

a huge flaw(s) in your MSQ matched to your Engine. Is your lambda a 4 wire heated one ?

Where is it / they located / and what settings ?

Looking at your screen dump your Spark is WAY off unless you have a massively hairy cam and advanced the cam timing

(then soft at hug RPM) and your fuel is equally looking rich, though that depends on things as well in req fuel

Where did the full MSQ Come from / spark settings from / why ?

How close to 10 degrees is the tw, how did you set it ?

What tuning have you done, and why now is it so rich ?, is it better or worse than origianl start up ?

I have now a vast range of MSQs for a number of Rover V8s some wild some mad, so if yours

is way off in too many areas, once I know what you have I can ping you a copy to load

These are say 7/10, and then some fine tuning with MLV will get better the more you do

But 1st, get the basiscs right, lastly what code are you using ? 029V ?

Nige

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Looks like you are adding spark advance instead of taking it away under load at one end of the map, and then swapping back to "normal" practice about half way up the rev range.

I'd search for one of the maps from the various MS threads, or take HFH up on his offer.

Bear in mind that if you are copying a Megajolt spark map, then the load axis is reversed as compared to Megasquirt- on MJ the lowest load (0kPa) is at the top of the table, whilst WOT (100kPa)is at the bottom.

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HFH,

Thank you very much for the map, it runs!! Fitted the new starter motor last night and started first time this morning.

However, the lambda is still not working. If i select front O2 voltage gauge and the ignition is on then the o2 voltage reads 0.2v and doesnt change whilst the engine is idling and reving. If i select the rear bank 02 sensor this is still reading 0.02v.

Which one should I select? I have run the earth from the lambda back to the engine block should i run it to the battery instead? I havent had any resets, or any other faults with the system. It is a four wire one.

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i understand its standard practice however all of the infomation I recieved from the supplier of the ECu that the earths go back to the engine block. Oh well another change then!

just so I know, should the gauge read front or rear 02?

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I have now rerouted the earth from the lambda from the engine block directly to the battery, with exactly the same outcome. Still reading 0.2v on the front 02 sensor.

Using the maps that HFH supplied, the engine idles at approx 1000 with the pwm enabled and revs ok, however the engine does sound rough with plenty of pops/misfire at idle. The spark position at idle is 13deg BTDC on tunerstudio. As soon as the engine is reved the pops disappear. The pops are very loud, and actually appear to be developed at the position in the exhaust where the lambda sits! When this pops occur the voltage from the lambda sensor increase (jump) to 0.5v and once the pop has finished drops down to 0.2v. Also as soon as the ignition is turned on with tunerstudio connected I can see that the lambda is reading 0.2v without the engine running.

Is it possible that there is an injector stuck open and this is adding alot more fuel? When the fuel hits the hot lambda (4 wire) it ignites and causes a pop. There are no flames from the exhaust just this loud pop.

Any suggestions?

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Turn down your required fuel until it no longer stinks of fuel and pops through the exhaust.

Also, CHECK the map hose, this will give the symptoms you describe, as it thinks the engine is at WOT the whole time.

Do you know the history of the engine?

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Since posting above, I have checked the timing with the ecu disconnected and the edis sparking. rather than the timing being set at 10deg btdc. It 8 BTDC. Do I therefore change the trim angle to +2, or do I change the fixed angle to -8? Surely both have the same outcome??

I will adjust the this and the fueling at idle tomorrow. I have to say this is fun! I have been thinking what other cars I can put this on!!

The engine has been rebuilt a while ago, it does breathe quite a bit.

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OK, first thing goes back to my first post - are you using a normal narrowband sensor or are you using a Land Rover / Range Rover original one which are Titania type and DO NOT WORK DIRECTLY WITH MEGASQUIRT.

Second, fixed timing is what it says - it is to fix the timing at a single value rather than use the ignition map, useful for checking your timing but not for driving. You need to adjust your trim angle.

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ok I am learning and loving this. The engine is running better and better now, only thing is that the lambda still isnt reading. I have checked the wiring back to the ecu by putting a 0.7v battery onto the temporary connector for the lambda sensor, and tunerstudio reads 0.7v correctly.

I have two narrowband sensors which I have tried and they both give the same output. My next move is to move the position of the lambda boss to nearer the y piece. I currently have it located 18inches from the y piece as this was an easy location to put the boss.

I have used the trim angle to adjust the timing. I have adjusted the req fuel down from 20 to 14.6 and it is sounding better. Is there a guide somewhere other than the megasquirt index which discusses tuning theory? I notice that the engine doesnt respond very quickly to quick jabs of acceleration. Slowly pressing down is ok, but quick acceleration and it doesnt like it.

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Last thing to check, which colour wire from the lambda sensor are you using for the signal?

No point moving the sensor, if it is a heated one then you should have no problems even with it in the tail pipe.

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I have two narrowband sensors which I have tried and they both give the same output.

OK, but you still haven't answered my question - are they "normal" Zirconia type or are they Range Rover type Titania sensors. Both are narrowband but only one type will work.

When you say they both give the same output, is that just the 0.2v output when connected to the MS or have you tried heating them with a blowlamp & measuring the output voltage with a multimeter off the car?

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as they say a picture says a thousand words, The lambda is fitted as shown. For reference the lambda is located approx 24inchs from the y section of the exhaust. I am using the black wire for signal and grey wire for earth.

I am proposing moving the probe towards the next to the y section, not only will this speed up the response but will also improve its flow within the exhaust.

post-2168-127845247051_thumb.jpg

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One white wire to earth to battery.

other white wire to fuel pump relay

black - signal wire on ecu

grey - earth wire to battery

With the engine running there is battery voltage on the heater wires. When I measure the voltage on the earth/signal this reads 0.2v from the lambda. If i disconnect the lambda and put a 0.7v battery across the signal and earth then this reads 0.7v on tunerstudio. So it leads me to think that the lambda installation is wrong. either the probe is not in the exhaust stream or its not upto temperature.

also, i have just wired the heater cables to a battery and the heater works ok, probe gets very well. So it must be the actual installation? The fact that the probe is at an angle, and positioned before and after a bend? Its the only thing i can think is the problem now!

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Right, from the top:

Black is USUALLY the signal (but sometimes the signal ground which must be grounded back to the ECU plug)

Grey is USUALLY the signal ground which must be grounded back to the ECU plug (but sometimes the signal)

White are the heater, so one needs to be +12v ignition switched (from the fuel pump relay is fine) and the other needs to be grounded (not critical where).

Note all sensor grounds must be grounded back to the ECU plug, you can quite easily lose half a volt or more going from engine block to chassis to battery to main loom to ECU which will throw sensor readings right off.

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