Fuel mix is too rich

workaccount

Hi,
I have been checking out the spark plugs on my car in the last few minutes. After checking the plugs which are only about four months old and comparing them against photographs in a haynes manual I have come to the conclusion that the fuel system is too rich.

After checking the haynes manual to adjust the mixture it appears that it cannot be modified at all.

It states if the fuel mixture is incorrect it's probably something wrong with the ECCS system.
I don't know what eccs stands for but I am assuming it's the computer control system.

Could it be possible though that the exhaust sensor is problematic? The haynes manual states to check many other things including crankcase breather hose, coompression etc. but I think it is referring to idle speed problems with these as as fuel mixture and idle speed problems are bundled under one heading in the book.

I'm sure I could pick up a cheap ECU if this is the problem in a scrapyard (nissan sunny 94 injected) but could it be the exhaust sensor?

Thanks.

Seth Brundle

Have you had the car diagnosed for emissions etc? Don't go paying money for parts until you know what is at fault!

workaccount

kbannon wrote: »

Have you had the car diagnosed for emissions etc? Don't go paying money for parts until you know what is at fault!

I would not have just gone and adjusted the mixture at the blink of an eye at all. I was just looking to see if and how it could be done.

I might look into getting my own tacho and co meter though. Depending on price of course.

By the way if I was paying for parts I'd be talking about peanuts for parts from a scrapyard or ebay.

Seth Brundle

It doesn't matter how much you pay for them. You don't know the fault so why bother replacing things that are more than likely fine. Find out who can diagnose these cars *properly* and then work from their recommendations

workaccount

kbannon wrote: »

It doesn't matter how much you pay for them. You don't know the fault so why bother replacing things that are more than likely fine. Find out who can diagnose these cars *properly* and then work from their recommendations

Jeeez man. Every hear of abit of DIY? Saving a few bob? Learning abit in the process?

It's an old car. I just thought I might give fixing it a go myself.

kbannon wrote: »

You don't know the fault so why bother replacing things that are more than likely fine.

I think I do know the fault actually. And it seems that there could only be one of two things wrong. Not that many variables!!!

RICARDO1982

My mate had a 94 Sunny 1.4 and the oxygen sensor in the exhaust failed. It would not pass emissions for the NCT. I presume the air filter is not blocked???

workaccount

RICARDO1982 wrote: »

My mate had a 94 Sunny 1.4 and the oxygen sensor in the exhaust failed. It would not pass emissions for the NCT. I presume the air filter is not blocked???

It's a new air filter but I never actually checked the whole pipe for blockages.

So it's an oxygen sensor and of course that's going to affect the fuel mixture. Thanks for that. Did your mate get it fixed and then pass the NCT or what?

Cheers.

RICARDO1982

Yeah it worked grand for him but that just means it is quite possibly your problem not defo. Do you mave any mates with the same car to swap and try out for a couple of weeks? save yourself possibily wasting 150 euro?

workaccount

RICARDO1982 wrote: »

Yeah it worked grand for him but that just means it is quite possibly your problem not defo. Do you mave any mates with the same car to swap and try out for a couple of weeks? save yourself possibily wasting 150 euro?

Does the sensor really cost that much???

I'll try and get one in a scrapyard if so.

RICARDO1982

I think the scrapyard is great for some things but an oxygen sensor you buy there could be as bad as the one coming out of the car... any way if it was only 20 or 30 euro it might be worth a gamble... totally up to yourself.....
Might be worth trying to get a diagnostic on it.

Seth Brundle

RICARDO1982 wrote: »

Might be worth trying to get a diagnostic on it.

Which brings us back to a point some wise poster made earlier.

workaccount

RICARDO1982 wrote: »

I think the scrapyard is great for some things but an oxygen sensor you buy there could be as bad as the one coming out of the car... any way if it was only 20 or 30 euro it might be worth a gamble... totally up to yourself.....
Might be worth trying to get a diagnostic on it.

Hmmm I'm just after remembering there that sometimes you can see a little fuel dripping out of the exhaust. I suppose that's just another reason to suspect theres too much fuel going in.

You can actually get them here cheap http://cgi.ebay.ie/BRAND-NEW-Universal-NISSAN-1-Wire-Oxygen-Lambda-sensor_W0QQitemZ250083590461QQihZ015QQcategoryZ10402QQrdZ1QQssPageNameZWD1VQQ_trksidZp1638.m118.l1247QQcmdZViewItem
Probably rubbish though.


And in America you seem to be able to get good brands for €50 or so.

RICARDO1982

workaccount wrote: »

Hmmm I'm just after remembering there that sometimes you can see a little fuel dripping out of the exhaust. I suppose that's just another reason to suspect theres too much fuel going in.

You can actually get them here cheap http://cgi.ebay.ie/BRAND-NEW-Universal-NISSAN-1-Wire-Oxygen-Lambda-sensor_W0QQitemZ250083590461QQihZ015QQcategoryZ10402QQrdZ1QQssPageNameZWD1VQQ_trksidZp1638.m118.l1247QQcmdZViewItem
Probably rubbish though.


And in America you seem to be able to get good brands for €50 or so.

Thats more than likely water coming out of the exhaust really
its a natural by-product of the combustion process.

RICARDO1982

kbannon wrote: »

Which brings us back to a point some wise poster made earlier.

None of us here know everything, thats part of the reason why
we bother to even do this. If we can bang our heads together
and come up with the right answer all the better...

RICARDO1982

workaccount wrote: »

Hmmm I'm just after remembering there that sometimes you can see a little fuel dripping out of the exhaust. I suppose that's just another reason to suspect theres too much fuel going in.

You can actually get them here cheap http://cgi.ebay.ie/BRAND-NEW-Universal-NISSAN-1-Wire-Oxygen-Lambda-sensor_W0QQitemZ250083590461QQihZ015QQcategoryZ10402QQrdZ1QQssPageNameZWD1VQQ_trksidZp1638.m118.l1247QQcmdZViewItem
Probably rubbish though.


And in America you seem to be able to get good brands for €50 or so.[/quote]

I find it is hard to get some american companies to post to Ireland though

workaccount

RICARDO1982 wrote: »

Thats more than likely water coming out of the exhaust really
its a natural by-product of the combustion process.

Theres a stink of fuel coming out of there too.

workaccount

kbannon wrote: »

Which brings us back to a point some wise poster made earlier.

People have fixed their own cars and learned lots about cars this way as long as cars have been around.

There is not really that much to them....I mean you don't exactly need a doctorate degree to become a mechanic.

Just because you may not be capable of diagnosing and fixing problems with your own car does not mean other people can't or shouldn't either.

And even if I did know nothing about cars theres plenty of rubbish mechanics out there which might just say "not worth fixing" "buy and new car"...."too old" etc. etc.

JHMEG

I think you might be over diagnosing the problem, in that there might not be one.

If the car is running well I would do nothing, as there's probably nothing wrong.

When's the NCT next due?

BTW, the O2 sensor is an overly simplistic diagnosis. It could be a temperature sensor, throttle position sensor, the engine timing might be off, or it could be the way you drive, the petrol you use...

Is there actually a problem?

ford jedi

think i have to agree with jhmeg think your looking for a problem,but on the other hand it is good to get familar with your car . afriend of mine bought a compression tester recently and everytime the car does a slight hicup the compression tester is out .a bit over the top.but he wants to try it out at every opportiounity instead of looking at the obvious


if you think the car is running rich a emissions test is the only way to test it .other than that you are only guessing and that costs money:)

workaccount

JHMEG wrote: »

I think you might be over diagnosing the problem, in that there might not be one.

If the car is running well I would do nothing, as there's probably nothing wrong.

When's the NCT next due?

BTW, the O2 sensor is an overly simplistic diagnosis. It could be a temperature sensor, throttle position sensor, the engine timing might be off, or it could be the way you drive, the petrol you use...

Is there actually a problem?

ford jedi wrote: »

think i have to agree with jhmeg think your looking for a problem,but on the other hand it is good to get familar with your car . afriend of mine bought a compression tester recently and everytime the car does a slight hicup the compression tester is out .a bit over the top.but he wants to try it out at every opportiounity instead of looking at the obvious


if you think the car is running rich a emissions test is the only way to test it .other than that you are only guessing and that costs money:)

Well in fairness guys I didn't just decide that my car had a rich fuel mix out of the blue.

The plugs are black and sooty and there relatively new. Theres only 3000 miles on them. Black and sooty is an indication of too much fuel. There is also a fairly strong smell coming out the exhaust. I have also read though not verified by a "trustworthy" source that the 02 sensor needs to be changed either every 60k or 100k!

She seems to run fine but I have always felt that it could be just a little better and perhaps this is where "extra bit better land" lies.

How much would it cost to go to a garage and just get an emissions test?

I think ppl may be having a go at me because I came across in my first post as a complete newbie diagnosing such a large problem....but I ain't stupid and work in a technical field 5 days a week and am well able to understand mechanics and car systems.

At least I'm willing to go out and try to learn....guys are you all elitist mechanics that hate the thought of a "non-mechanic" being able to fix such a problem.

Mr.Diagnostic

workaccount wrote: »

I think ppl may be having a go at me because I came across in my first post as a complete newbie diagnosing such a large problem....but I ain't stupid and work in a technical field 5 days a week and am well able to understand mechanics and car systems.

In fairness, if you you go back to the top of the thread and read it again you were the first to have a go.

The advice you got was valid. It makes sense to go and diagnose a problem rather than just start bolting on parts. This would be even more true in your case since you dont know there actually is a problem.



either way, if you can cure the condensation coming out of the exhaust you will win fame and fortune

workaccount

workaccount wrote: »

I would not have just gone and adjusted the mixture at the blink of an eye at all. I was just looking to see if and how it could be done.

I might look into getting my own tacho and co meter though. Depending on price of course.

By the way if I was paying for parts I'd be talking about peanuts for parts from a scrapyard or ebay.

Mr.Diagnostic wrote: »

In fairness, if you you go back to the top of the thread and read it again you were the first to have a go.

The advice you got was valid. It makes sense to go and diagnose a problem rather than just start bolting on parts. This would be even more true in your case since you dont know there actually is a problem.



either way, if you can cure the condensation coming out of the exhaust you will win fame and fortune

Ok I see how my post above could have been interpreted that way. It really was not meant this way though at all.

I think I felt it in post 4 tbh. "properly"

Mr.Diagnostic: What do you conclude when you see a spark plug with that is black and sooty? Are they meant to be this way?

crosstownk

workaccount wrote: »

What do you conclude when you see a spark plug with that is black and sooty? Are they meant to be this way?

No they are not meant to be this way.

A black, sooty plug is usually an indication of too much fuel or too much oil in the combustion chamber. How much mileage is on the engine......?

kona

running too hot maybe?? whats the fuel consumption like, it could be a fault with a sticking choke for example.

crosstownk

kona wrote: »

running too hot maybe??

Would that not tend to burn off any deposits? Usually hot running results in a very dry plug.

kona

deposits are good for the engine(up to a certain point) they help stop the engine burning oil.

if the plugs are covered in crap id give the car a good service, also time frames on cars are jack****, its all mileage, and where you do the mileage.
when did you last change the air filter??

some plugs (bosch) ive found to be ****! i took a new set out after about 2k and put ngk back in. no hassle.


id go and do:
oil
plugs
leads
filters.

then drive it for a few days, then cane it on the motorway.

check the plugs again.

when i tune my yoke, i used gunsons colour tune, best invention as regards air/fuel mix apart from carb balancer.

ive a carb so i can adjust the fuel/air mix.

you cant but it will tell you if you are running rich or lean. blue=good, orange =bad.

as regards to the condesation coming out the exhaust, this is a by-product of the cat, if there is a smell of fuel id check for leaks. if petrol was pouring out the exhaust id be changing the car, as 1)valves could be ****ed, 2)cam could be ****ed, 3)timing, 4)all of the above. and when the exhaust heats up, that much fuel will ignite easy.

Mr.Diagnostic

workaccount wrote: »

Mr.Diagnostic: What do you conclude when you see a spark plug with that is black and sooty? Are they meant to be this way?

Its not quite that simple. That colour of the plug will change to reflect the combustion conditions in the chamber during the time immediately leading up to the ignition being switched off. The colour of the plug that you saw is likely to be totally different to the colour is is normally, while driving. The colour will change on a regular basis.

Plug colour was never very acurate, even with old systems. Your system is modern enough to be capable of much more accurate fuel control than an old carburettor. This in itself renders the plug colour diagnosis inacurate.

Unless you want to spend a lot of time doing what we used to call "plug chops" then you are unlikely to get any useful info from looking at the plugs.

workaccount

crosstownk wrote: »

No they are not meant to be this way.

A black, sooty plug is usually an indication of too much fuel or too much oil in the combustion chamber. How much mileage is on the engine......?

110,500.

Mr.Diagnostic wrote: »

Its not quite that simple. That colour of the plug will change to reflect the combustion conditions in the chamber during the time immediately leading up to the ignition being switched off. The colour of the plug that you saw is likely to be totally different to the colour is is normally, while driving. The colour will change on a regular basis.

Plug colour was never very acurate, even with old systems. Your system is modern enough to be capable of much more accurate fuel control than an old carburettor. This in itself renders the plug colour diagnosis inacurate.

Unless you want to spend a lot of time doing what we used to call "plug chops" then you are unlikely to get any useful info from looking at the plugs.

So is the only way to tell if the mixture is too rich or lean by checking exhaust emmisions?

Mr.Diagnostic

workaccount wrote: »

So is the only way to tell if the mixture is too rich or lean by checking exhaust emmisions?

Emissions are normally checked at idle and also at fast idle. If you had a fault at these engine speeds then it woud show up. A lot of faults occur under different load conditions so unless the car is on a rolling road this will not be tested.
Simple answer, an emission test will normally tell quite a lot.

As an aside, how much time does any car spend at idle? I would think its a smallish percentage of its total running time.
How much time would it spend at high idle with no load? Very little, if at all.
It kinda makes a nonsense of the NCT testing procedure.

kona

Mr.Diagnostic wrote: »

Emissions are normally checked at idle and also at fast idle. If you had a fault at these engine speeds then it woud show up. A lot of faults occur under different load conditions so unless the car is on a rolling road this will not be tested.
Simple answer, an emission test will normally tell quite a lot.

As an aside, how much time does any car spend at idle? I would think its a smallish percentage of its total running time.
How much time would it spend at high idle with no load? Very little, if at all.
It kinda makes a nonsense of the NCT testing procedure.

+1

nct is just a money spinner, the testers are muppets, and then since they cant speak english cant tell you the story, i was told id lower suspension arm wear, my car doesnt have lower suspension arms. thats among the other bull**** he said:mad:

workaccount

Mr.Diagnostic wrote: »

Emissions are normally checked at idle and also at fast idle. If you had a fault at these engine speeds then it woud show up. A lot of faults occur under different load conditions so unless the car is on a rolling road this will not be tested.
Simple answer, an emission test will normally tell quite a lot.

As an aside, how much time does any car spend at idle? I would think its a smallish percentage of its total running time.
How much time would it spend at high idle with no load? Very little, if at all.
It kinda makes a nonsense of the NCT testing procedure.

Do many garages have rolling roads? I know that one in my town has one and there a big ford dealer. There rolling road is for the test for commercial vehicles....Can't remember what that test is called.

So you think the emmisions test will give a good indication of problems when moving without load? What other problems apart from rich fuel mix can you find with this test?

How much does this equipment usually cost?
I have a car automotive sales brochure at home with loads of servicing equipment including computers etc. for decent prices....didn't see an emmisions testers though.

Thanks for all info. I'm really learning alot here.