serious but weird problem, garages are stumped

[spit]

Yes, it is showing some of the hallmarks of spurrious O2 bank feedback isn't it. Been there in the extreme with mine after the C2 install. Different kind of fault but the same result.

i dont think I'm near chesterfield........

sooooo...... do you know where you are?   s:wink: :wink: s:wink:  You will find help local to you in SYorks but you'll have to give us a clue!

If you haven't yet tracked one down, I have a spare ICV or two that you're welcome to try. If swapping out makes no difference, you can just send yours back to me rather than go through another swap. I've also got some manifold O2 sensors that you can swap out - they've got blown heater circuits so are worth diddly but they'll give you a few free runs before an engine light and enough time to establish if there's anything in Aaron's theory before splashing out on new sensors.

Aaron is a bright button.  s8) s8)

[aaronjb]

Aaron is a bright button.  s8) s8)

Ta Ste  s;) s;)  It's not my first trip around the fuel-injected block, so to speak  s:) s:)

[robbie33]

Wow thanks aaron, that could explain alot. The car is not an import, thank god. Ill mention that to the garage on monday. Could removing the precats have caused it, i just thought the garage damaged the manifold when replacing an o2 sensor, the wrong one, i was where the sensor screws in, they had to cut it off and weld another nut on ? ? I just cant remember back if it started after that. Does icv need replacing or can it be cleaned/fixed. Would this still remedy when warm ?  Like i said the perfoms normal when hot or the accelerater is pushed all the way, hot or cold ?

[aaronjb]

An air leak into the exhaust manifold (especially around the O2 sensor) could cause interesting running problems just like you're experiencing (though the engine would be doing the opposite of what I said earlier, sorry - it'd be reading lean and adding fuel until you get rough running.. that would be worse when cold as the engine is already richer than normal on the 'choke' and better at full throttle as you've got plenty of air going in).

You really need to get it away from the garage and to someone who really knows these cars and how to read diagnostic equipment - a local member with a full diagnostic scanner or laptop based 'code reader' would be a good bet  s:) s:)

[robbie33]

You know what aaron, that sounds right on the money ! I bet you are right ! As thinking back it was fine before the pre cats were gutted, this would also explain the slightly higher fuel consumption. Perhaps the heat expansion is sealing the leak when hot aswell. Not sure why it would run fine at full throttle though ? Cutting bits off the manifold and welding another back on cant be good for it. If this is it, can you reccomend a good manifold. And where id get it from ? Thanks again

[Anonymous]

Could removing the precats have caused it, i just thought the garage damaged the manifold when replacing an o2 sensor, the wrong one, i was where the sensor screws in, they had to cut it off and weld another nut on ? ?

You should have let us have this little gem of info in your 1st post,this cant be good for the sensor and if they are willing to bodge this what else have they bodged?

[K T M Rider]

You really need to get it away from the garage and to someone who really knows these cars and how to read diagnostic equipment - a local member with a full diagnostic scanner or laptop based 'code reader' would be a good bet  s:) s:)

or if there are no members near to you so equipped you could buy your own ELM 327  (ebay for around £12 - you will need a laptop)

 m http://www.ebay.co.uk/itm/ELM327-OBD2-1 ... 220wt_1154 m

record some relevant data with screen capture software:

 l viewtopic.php?f=11&t=31029 l

upload the screen capture video to youtube and then post the youtube link back in this thread.

here's (a very boring) one I made earlier   s:) s:)  :

 m http://www.youtube.com/watch?v=Mu8ZclMR1qg m

EDIT - on the other hand, now that I've read the thread properly you could just bung on another manifold first  s:) s:)

[robbie33]

yes i should have remembered this little doozy, but im a little naive and if a proffesional mechanic tells me its a sound job, i tend to believe them.  i remembered that when i had the precats gutted the garage, when completely unnesacarily changing the wrong o2 sensor b1s1,shoulda been b1s2 they broke it off in the manifold and had to cut it out and re weld the nut back on, this fits all the symptoms. thinking back the car was fine except for an annoying rattle from the precat chamber. since they changed the wrong o2 sensor i put it down to that fact.
massive thanks to aaron, id never have ever would have looked at the manifold.
so it looks like a new manifold, can anyone reccomend a replacement, i have the tte twin exit exhaust on.

[Anonymous]

Where about in Yorkshire are you Robbie?

I have two manifolds in my garage, the both have perfect pre-cats still in so can be knocked out if you want, also one of the bottom three studs has snapped off and needs replacing.

Les

[robbie33]

thats a very generous offer les, i may just take you up on it, but im looking at this baby

 m http://www.carbenfibrecreations.co.uk/m ... 00-07.html m

which i was after in the first place to avoid the precat problem, but i cheaped out, and its ended up costing me £££s more in the long run

does anyone know if this will fit my tte ? and it looks lovely doesnt it ? will it give any increase in power ?

[K T M Rider]

you may want to look at this one instead.

just as shiney, half the price:

 m http://www.ebay.co.uk/itm/00-07-Toyota- ... 2170wt_827 m

just don't believe the bit about the power increase

[Anonymous]

you may want to look at this one instead.

just as shiney, half the price:

 m http://www.ebay.co.uk/itm/00-07-Toyota- ... 2170wt_827 m

just don't believe the bit about the power increase

That's the one I have fitted.........probably the same as the more expensive one    s:wink: :wink: s:wink:

[K T M Rider]

That's the one I have fitted.........probably the same as the more expensive one    s:wink: :wink: s:wink:

Well as it's not made from CF I guess he gets them from somewhere   s:) s:)  

worth pointing out that i believe the supplied gaskets are deemed to be rubbish, but you'd be needing new ones with a s/h stock manifold anyway

[robbie33]

ok, here is where we are, ordered a new manifold and gaskets which should arrive tomorow, i went down to the garage to book it in for thursday, and explained  about what happened when the precats were removed, ie, b1s1 o2 had to be cut out and a nut welded back on etc and explained aarons theory, which im still 100% on, that there may be a leak around that sensor, the mechanic took a look and said doubtful, as he cant hear it blowing, but agreed it probably was an o2 sensor problem, despite there not being an engine light. hes gonna get a guy to check out all readings on his computer, again i explained to look at the fuel trims and see what that sensor is doing.
he doesnt think the manifold is at fault unless the welding is interfering with the flow over the sensor.
he thinks maybe the precat being removed might have caused the problem, i explained about the precat failure in these cars and he didnt look too convinced to start with as he explained the exhaust blows OUT, not suck IN. i said they had to be removed regardless as they were making a loud rattling noise and it was very annoying.
can anyone tell me what the o2 sensors readings should be ? and if aaron is correct, what would the reading be then ?
as i dont want to be stung for another set of o2 sensors, im already eating in to the new sofa money ! the mrs wont be happy !
the mechanic is already charging £50 for this guy to read all the codes and said it would be £80 to fit the new manifold, but he wont do it unless the guy puts the computer on it first as it could be any number of things.
the car is obviously running rich, mpg is around 36, normal driving, i check the oil once a week, and its always at full on the dipstick, over the year ive had it its gone down a very small amount, but not since the last oil change 4 months ago.
he mentioned it could even be the ecu at fault, moisture in on a morning, but i doubt it. re reading my diaries has confirmed that this problem only started when the precats were removed. its a definate.
im still firmly in agreement with aarons assesment, its the only explanation so far that fits all the symptoms.

[aaronjb]

he explained the exhaust blows OUT, not suck IN

Oh dear .. clearly he's never heard of EGR; which has been a feature on most cars since the 1980s and in our case is performed by the valve timing allowing some exhaust gas to be scavenged out of the exhaust and back in to the cylinder under cruise conditions. EGR, by the way, stands for Exhaust Gas Recirculation and is used to reduce emissions and cylinder temperatures during lean cruise.

As for the O2 sensor readings - they're narrowband sensors so all you should see is that they 'flip' between lean and rich continuously. In terms of voltage then <0.5V to >0.5V. But what you need read is the long & short term fuel trims - it's unlikely you'll see a problem just looking at the O2 sensor readings.

Are there no club members near you willing to go over with a decent diagnostic tool/laptop?  s:( s:(

[Wabbitkilla]

This garage seem to be leading you on a merry trip.

It's possible that it's the manifold, it's also possible the garage didn't use gaskets when putting it back on as we've found some places seem to think it's acceptable to just use exhaust putty ... which dries out and leaks!

Getting a nearby member to help, or maybe visit a nearby member to help could be very useful.

[Steve Green]

I have said elsewhere that we, on this forum are the expert amateurs, and some of the expert professionals.

The vast majority of mechanics see Audi, VW, Pug, Cit, Ford etc. A few see Toyotas but even mainstream Toyota dealers only see cars in their first three years for services and are stumped when it comes to anything older. many would never have seen a MR2.

I was assured by one Toyota dealer that my SMT actuator used standard Hypoy gearbox oil. Wont be going there again.
I am prepared to guess that very few mechanics are aware how a rear caliper really works. They just change parts.

[robbie33]

Just had a call from the garage, he says its the o2 sensor that isnt working properly, the one that the first garage swapped for no reason, also turns out its a cheap generic one to boot. Im still not convinced, surely id have got an engine light ? And im pretty sure a friend checked that sensor with his computer. Oh well we shall see tomorow.

[aaronjb]

The CEL will only light if the ECU detects the heater circuit has totally failed or the sensor is just about stone dead.. It can be 'lazy' and cause massive fuel trims but not throw an O2 sensor CEL.

Once again - have you had the fuel trims checked, and if so, what are they?