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        General >> Problems >> Another opportunity to get ripped off
        
(Message started by: Paulus on Apr 20^th, 2006, 7:07am)

Title: Another opportunity to get ripped off
Post by Paulus on Apr 20^th, 2006, 7:07am

http://cgi.ebay.co.uk/20HP-O2-SENSOR-PERFORMANCE-CHIP-FORD-SIERRA-SCORPIO_W0QQitemZ8056248127QQcategoryZ38786QQrdZ1QQcmdZViewItem

Title: Re: Another opportunity to get ripped off
Post by martin_rowe on Apr 20^th, 2006, 8:32am

excess fuel will cause a drop in power, if it was that easy Im sure all the manufacurers would have thought of it first.

Title: Re: Another opportunity to get ripped off
Post by david_molloy on Apr 20^th, 2006, 11:19pm

Don't know on this one.... logically manufacturers will "lean out" as far as possible as better for emissions results.
If the chip fools ecu into more fuel = richer mixture & it is near or at optimun fuel mix ratio - then more power and worse emissions
From look of it not an interactive component so assume that alters signal to give fixed %age fuel increase
There again I may be talking b*llocks
I'm sceptical most of the time but to me worth a further look
Appears that fitted to post cat sensor so 2 needed for 24V
But I'm sure that I read on site somewhere that it was the pre cat sensors which were the most important ones.
However signal from post cat sensor must have some effect or why fit it
Hopefully someone more knowledgable will be able to comment
david

Title: Re: Another opportunity to get ripped off
Post by sector-9 on Apr 21^st, 2006, 12:09am

Until cats were commonplace, manufacturers did try to weaken the mixture as much as possible to save fuel. Ford already had a 'lean-burn' HCS kent engine in the Escort/Fiesta. Unfortunately cats don't work very well with such a mixutre so they enriched the mixture to provide what is known as "stoichomeric" (spelling suspect!) ratio which works out at something like 14.7:1 air/fuel and is what cats operate best with. This is the purpose of the HEGO sensor - it sends a signal which varies sharply at around lambda 1 (i.e. that stoicho thing) so the ECU is forever see-sawing the mixture one way then the other to maintain the ideal.

The pre-cat HEGO sensor is what controls the mixture; I'm not too sure on how much effect the post-cat sensor has but the ECU uses it to tell if the cat is working. Over time the sensors slow down and no longer switch back and forth as fast. However the ECU ignores the sensor(s) whilst the engine is cold, or at full throttle.

I'm not sure what the device does to the signal from the HEGO sensor, but I imagine it holds the 'too lean' signal longer so increasing the average amount of fuel injected overall. If that guess is right (and it's a pretty wild guess), then the device may be nothing more than a reservoir capacitor. ::)

Darren