Alfa Romeo Forum banner

Lamda Question

Tags
lamda
1K views 21 replies 5 participants last post by  Ralf S. 
G
#1 ·
What would you expect to happen if the lamda sensor was disconnected
 
#10 ·
Assuming the lambda heater is working as it should, it takes about 10 - 20 seconds to reach working temperature. If it fails (blown fuse etc), you get some odd results. It'll work OK if you are pressing on, but as soon as you lift or run on light throttle/idle, it cools down and stops working so the ECU just guesses (usually too rich) and will start putting the warning light on and logging an error code 1 2 2 4.

Lots of things poison lambda probes and make them slower to respond to mixture changes even assuming the heater is OK. This is why they should ideally be replaced at 50k miles or so.

My own V6 runs OKish with the probe disconnected. Just get the odd hesitation when pulling away or accelerating gently. Wouldn't recommend doing it for too long - risk of bore-washing and cat poisoning as well as wallet-emptying fuel consumption. Once got 36mpg out of it when it all worked properly. Almost smiled... :rolleyes:
 
#11 ·
AAGGGHHHHH!!! eek! What are you guys thinking of?? DO NOT DISCONNECT THE LAMBDA. The management system will pick up the fault codes and will revert to maximum enrichment setting. Fuel consumption will be very poor- no better than 30mpg (when it should be 40 or higher) and there will be NO performance increase. :( The mixture will be richer than the 12 to 1 at which maximum power is produced. The catalytic converter may also overheat due to overfuelling which may wreck it. eek!

I would advise you not to buy a cheap sensor. You get what you pay for. Both in terms of fuel economy and performance. :( Another minus point is that the wiring may not be very good. It may require an extra wiring part or the wires will be four times as long as they should be.

Advice: Go to a motor factor eg Partco and get an OE quality sensor. NTK sensors will probably cost about £50 + vat- I've already fitted them to 145/146s and they work and last. :D Its really not worth getting a crap part and risking driveability problems. It may also make diagnosing future management problems much harder. :confused:

One final point is that as I am a hands on partner in a garage business, I find that a standard well maintained car will almost always out-perform a not so well maintained modified car! :cool:
The moral of the story is if you fit a cheap lambda sensor and have a chipped, cammed and flowed engine with manifolds and filter, the fortysomething school teacher in a hurry home will still burn you off at the lights if it aint all done right. Believe me, I see more wrongs than rights on young lads cars. Before you wonder, I'm not some old git. I'm a proper petrolhead whose past/present cars have had the aforementioned mods.... and they were/are 'kin quick.

Ally.
:cool:
 
#12 ·
Ally if your a hands on partner (i take it you mean mechanic)then you will know that a quick and easy way to check the Lambda sensor is to unplug it briefly and see if the engine running is better or worse thus identifying wheteher the sensor is goosed or not :rolleyes: as not everybody has access to garage testing equipment

Also the cheap sensors we refer to are on e bay and are the same sensors you buy from Partco etc just at a better price

Also i think i speak for all on this site when i say that our cars are all well maintained and wheteher a cheap Lambda Sensor is fitted or not it will still work and do what an expensive sensor does and won`t affect the performance of the car Unless it`s faulty :D
 
G
#15 ·
"Fuel consumption will be very poor- no better than 30mpg (when it should be 40 or higher)"

Sorry m80, but you're having a laugh aren't you? Only ever got 29mpg from my 1.8 16v with mixed driving. Longer distances perhaps 35-36.

.....and I'm not alone, fuel consumption has come up on here lots of times and we seem to be getting about the same.

Tell us how you do it :D

wrinx
 
#17 ·
Mmm, perhaps 40mpg was a bit high- :rolleyes: bit I meant it figuritively; as a guide only. Must check fuel consumption- or maybe now I don't want to! :(

I wasn't having a pop at forum members car maintenence- sorry Spead Freak. I think that there are a lot of clued up people on the forum. I hope to learn a lot about 155s as there are many problems I haven't encountered. eek!

I was just talking from bitter experience if spurious parts have been fitted. :(

Ally
 
#18 ·
The other night I took my dad on a 125mile round trip for him to buy another 164, I put £20 of optimax in at 81.9p per L. 120 miles of the journey was motorway at about 80MPH, used most of the fuel and by my workings I got only 23MPG, is my car running ok because for a motorway run this sounds very very low, even for an alfa :confused:
im sure his old cloverleaf does better than that!
It all seems fine, goes like I would expect!
is this just normal? :rolleyes:
Cheers
 
G
#22 ·
You should get to 90 degrees very quickly. If you only see 70 when the car's moving on the open road, even after miles of driving then that sounds like a duff thermostat.

The ECU will be fuelling it as it would a cold start, so you will get poorer mpg figures than you should.

The 'stat is quite cheap (£10) and will pay for itself after a few tank fulls.

Ralf S.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top