Lrp additives effect on O2 sensors
paulf - 14/1/06 at 09:01 PM
I have just thought of a potential problem with my Megasquirt conversion on my crossflow engine.
I havent had the head converted for unleaded and so run with castrol valve master as a lead replacement and am concerned that the 0xygen sensor may
not like it.
I therefore have a few options either convert the head to unleaded, but dont really want to if i can avoid it, run with the sensor and hope it is ok
, or either dont use an oxygen sensor which I think will make setting up and data logging harder , or run with a sensor and use unleaded to set up and
then remove the sensor once i have a running map.
Has any one any suggestions on what to do?
Paul.
MkIndy7 - 14/1/06 at 10:28 PM
I thought the major problem with Leaded petrol on injected cars that it pollouted the Catalytic converter rather than the sencors, although I may and
probably will be proved wrong.
As the cats were introduced to reduce emissions therefore injection was forced upon the manufactrers at the same time.
Some of the old Triumps etc were injected long before cats and Unleaded I would have thought, so they either didn't have Oxygen censors, or the
leaded fuel didn't cause a problem.
(infact we had a 1992 (J) twin cam Sierra with injection that could run on both as it was just before Cats came in)
paulf - 14/1/06 at 10:51 PM
The cat is the main problem but i also think oxygen sensors can be damaged by some fuel additives, the older triumphs etc didnt have an O2 sensor but
they are essential with a cat to alow it to work correctly.
I dont have a cat ,but the addition of an O2 sensor to megasquirt allows data logging and auto tuning of mixture, so i would like to be able to use
one.
I will most likely end up swapping the engine for a zetec or vauxhall but want to get it operational with the crossflow first, as i am running out of
time this winter for the project if I want to be on the road for the spring again.
Paul.
quote:
Originally posted by MkIndy7
I thought the major problem with Leaded petrol on injected cars that it pollouted the Catalytic converter rather than the sencors, although I may and
probably will be proved wrong.
As the cats were introduced to reduce emissions therefore injection was forced upon the manufactrers at the same time.
Some of the old Triumps etc were injected long before cats and Unleaded I would have thought, so they either didn't have Oxygen censors, or the
leaded fuel didn't cause a problem.
(infact we had a 1992 (J) twin cam Sierra with injection that could run on both as it was just before Cats came in)
MkIndy7 - 15/1/06 at 12:06 AM
Could always try the every 4th tank full trick, think ford even recomended that for the later pre injection Sierras
That way there shouldn't be too many build ups of deposits etc whilst maintaining enough lead to lubricate the valves.
Could you not re-coup the cost of converting the head if you sold it on afterwards as an unleaded head?
MkIndy7 - 16/1/06 at 11:35 PM
Not sure how relevent this is but:
I've just realised I removed a Red Top vauxhall engine (believed to be from a Calibra originally) yeaterday and it doesn't have a Cat or a
Lambda sencor (I'm presuming that is the 02 sencor) yet it has sequential injection, the hardest to control I belive.
So there must be some other way of controling it or setting it up.
I'd be interested to know how they manage because were in the process of going to throttle bodies and megasquirt and a Lambda sencor where all 4
pipes join would be hard to disguise, unless you can get away with it on just 1 branch inside the engine bay.
MikeRJ - 17/1/06 at 08:50 AM
quote:
Originally posted by MkIndy7
Not sure how relevent this is but:
I've just realised I removed a Red Top vauxhall engine (believed to be from a Calibra originally) yeaterday and it doesn't have a Cat or a
Lambda sencor (I'm presuming that is the 02 sencor) yet it has sequential injection, the hardest to control I belive.
So there must be some other way of controling it or setting it up.
I'd be interested to know how they manage because were in the process of going to throttle bodies and megasquirt and a Lambda sencor where all 4
pipes join would be hard to disguise, unless you can get away with it on just 1 branch inside the engine bay.
I'm doing the same, C20XE with bike throttle bodies and Megasquirt.
Sequential injection isn't hard to control as such, it just means the controlling hardware is more complex. It's only effective at low
engine speeds anyway (at high engine speeds the injection pulses overlap to such an extent that it's effectively batch fired). The primary
reason for it is to reduce emissions at idle and during cold start.
The 20XE's and earlier C20XE's were not fitted with cat's in their original aplication, hence no need for for a lambda sensor. Not
hard to weld in a bung for one though, which means you can use a wideband to help set up the megasquirt, which is what I'll probably do.
Back to topic, LRP is not good for lambda sensors, it degrades the sensor in a simmilar way to 4 star leaded fuel. By far the easiest method is to run
on unleaded for tuning and then remove the sensor if using LRP or fuel additive. However, with LRP being phased out and already getting more
difficult to find, fitting hardened valve seat inserts makes far more sense, especialy whilst the engine is not installed in the car.
paulf - 17/1/06 at 11:07 AM
I thought that was the case with O2 sensors, I will just have to run with a temporary one and unleaded whilst setting up.I dont actually use LRP but
put castrol valvemaster in it , the engine is still in the car but I do have a spare head although hadnt intended spending out on an unleaded
conversion ,as i am sure it will be replaced by somthing more modern next winter.
Paul.
MkIndy7 - 17/1/06 at 05:39 PM
*Thread Hijack sorry*
quote:
Originally posted by MkIndy7
I'd be interested to know how they manage because were in the process of going to throttle bodies and megasquirt and a Lambda sencor where all 4
pipes join would be hard to disguise, unless you can get away with it on just 1 branch inside the engine bay.
Oops mixing 2 projects, Am rebuilding a 2.0 XE Nova as well and leaving the standard injection on, was stating my observations on that install.
Was more pondering how vital a Lambda sencor is to running megasquirt and other managements (its the pinto thats getting the TB's and squirt).
And if it had to be placed where all 4 branches collect together or if a reading off 1 cylinder is enough?
From what I have interpreted from reading a little, is that the enrichment upon acceleration etc are controled by a fixed map, and then there's
an ideal Stoich value map and the lambda just fine tunes this further? but I would expect it can only really work on cruise due to the delay between
imputing fuel and the exhaust mixture value being read. So is it really worth all the hassle of the sencor for what little you might save in fuel, and
emissions.
On the original question, if there's no octane difference with the Valvemaster addative then it should run ok when reverting back from unleaded.
(I still think you could re-coup the cost of having it converted)
Have you tried mapping it yet, is it really so far out and so hard to do without the Lambda sencor?
paulf - 17/1/06 at 06:41 PM
I am using valvemaster plus as it has a comp ratio of about 10.5-1 due to being fitted with 1300 pistons so I do need an octane booster,.I could
probably manage by using super unleaded or optimax and if necessary adding some thinners as an extra octane booster.
I havent got it running yet as I have just finished building the eCU and am presently playing with it on the desk with a simulator, but will have to
map from scratch.
Paul.
quote:
Originally posted by MkIndy7
On the original question, if there's no octane difference with the Valvemaster addative then it should run ok when reverting back from unleaded.
(I still think you could re-coup the cost of having it converted)
Have you tried mapping it yet, is it really so far out and so hard to do without the Lambda sencor?
Syd Bridge - 18/1/06 at 09:37 AM
A couple of cautions regarding Valvemaster and thinner.
Valvemaster....Don't overdose the fuel with this stuff. It creates a yellowish glaze buildup on the plugs. I've been running it in the old
workhorse Sierra(donor in waiting). After 5k miles, plugs were shot.
Thinner....If using the gunwash with 'up to 5% methanol', don't use any more thinner than 1part thinner to 2 parts fuel. (This will
give about 102-103 octane, with 95 unleaded.) The methanol content WILL eat mechanical fuel pump diaphragms. But, I will add that this mix in a well
built blueprint 998 A plus engine is good for 3-4 hp. 
Syd.