TPS readings??
Turbo Mini Forums

I think Ill take the throttle bodies off tomorrow and have a look and see, after I check out the butterfly problem mentioned above. Nothing ever goes to plan on minis does it!

Basic rule with EFI - the ECU measures the airflow and adds the fuel.

The ECU does not control the airflow apart from at idle, but only then if an IACV is installed.

Without an IACV, the ECU can't do anything about air flow, it just measures it and adds the fuel.

Butterflys being dragged open is unusual as the spindle is usually on the centreline so half the air is trying to open it and half the air is trying to close it....

Schrödinger's cat - so which one am I ???

Maybe this might be a daft suggestion?

http://www.vemssupport.com/forum/index.php...37&topic=1451.0

Spent a few hours today searching for this mystery leak. The butterflys stay seated when the engine firesm so thats ruled out. So I still havnt found it, so I did what I always do when something is broken and I cant figure it out, I take it all apart and re-assemble it.

So I took the TB off the car and have disassemble them, I have noticed some things. I used some soapy water on the joints earlier and turned the engine over, but no bubbles. But,

There was moisture on the rubber boots, at both the flat mating face with the manifold, and the front where the throttle bodies clamp.

Holding the steel manifolds together I can see light through the joint, so the mating face with the head isnt flat, Ill get some feelers on them and see how far out they are. Is there an acceptable limit?

Im going to reassemble them, but was thinking of using some silicone gasket stuff, now, whats the story with this and heat and petrol, It states that max temp is 200 degC , considering its sandwiched between the exhaust manifods, Id imagine I could see over 200 DegC here? also does petrol break it down?

Edited by ciaran on 11th Jun, 2011.

I don't see how you were ever going to see any bubbles with soapy water and turning the engine over when that creates a vacuum.

when you were a kid, did you suck on the stick from the bubble bottle or blow at it?

I had a very bad childhood :/ , but no your correct :) , It was in desperation as I was at a loss. But they are off now and ill try to blow through them and soak the joints in soapy water.

Edited by Rod S on 12th Jun, 2011.

Schrödinger's cat - so which one am I ???

Schrödinger's cat - so which one am I ???

The end of the GP was crazy, it was some drive from button.
No need to post a photo I understand what you mean from your description :)

Yes, forcing Vettel into that mistake on the last lap was superb.

If you haven't got access to a milling machine you can make a stepped washer by cutting a thin washer in half and tack welding it to a thick one.

Schrödinger's cat - so which one am I ???

Right, after all my tightening the manifold studs aint in too good a shape, they aint wrung but I can kind of get the feeling through them that they are going to, what threads are these, Ive seen 5/16 UNC and 3/8 UNC being mentioned.

Back to the problem at hand, I found a leak at the thermostat where I had the head welded due to a crack (Its a non critical area, just right at the corner of where the bolts go for the housing) which gave me a kind of lightbulb moment.

I took off the manifold again and sprayed GT85 around the welds, and who would have thought it, the welds are porous. So with me both not knowing how to weld and not owning a welder, this is a pain in the ass. But they aint porous to the extent of supplying a 1380 with enough air to rev to as high as it wants. SO I must have another leak, Im doubling up the Gaskets too and using the stepped washer technique as mentioned.

Edited by ciaran on 14th Jun, 2011.

5/16" UNF IIRC (not UNC) and unusual as they have fine threads both ends rather than coarse into the casting and fine for the nut.

Re-assemble and try my other old skool trick of spraying something mildly flammable at all the joints with it running. If you haven't got a plumbers butane/propane torch, just use a can of WD40 (but don't overdo it as it will burn on hot surfaces) and listen for a change in engine sound/speed.

Schrödinger's cat - so which one am I ???

the nuts on the stud fitted both ends :/ , does it matter once the Thread on the Head is matched?

Ill spray some GT85 on the manifold when I get the parts, might be waiting awhile for them though, as they have to be posted.

Re the studs, no it doesn't matter but if you buy the genuine ones they usually have a longer threaded part on the nut end than the casting end. It's just unusual for the threads to both be fine - look at any other stud on the engine/gearbox and they are coarse thread into the casting (especially into aluminium) and fine thread for the nut.

Sorry, I didn't realise GT85 is the same as WD40 etc...... (I've never heard that brand name before but I Googled it). It should point you in the right direction.

Schrödinger's cat - so which one am I ???

Yea I noticed that, on closer inspection, I reckon the stud I took out started like as a 3/8 UNC bolt and had the Hex head cut off. Is there a reason for the end not in the head to be UNF? seems like it would be a inefficient way of manufacturing.(then again it is BMC)

I also noticed that there was a ever so slight bend in it. Im going to check the others to make sure they are spot on too. Hopefully this sorts it all out, although I have calculated to flow enough air to run the 1380 at full tilt I need a 64mm hole so I have no Idea how that much air is getting in.

You don't need a 64mm hole...... my IACV has about a 6mm hole across the pintle (taking into account the taper) and it would quite happily hit the limiter when I had the IACV settings all wrong in the software.

But in my case with MAP, the ECU only matches fuel to leaking air.

You're slightly different in that your ECU isn't actually measuring the air and adding the fuel, instead it's assuming the airflow from a combination of TPS and RPM and then adding the fuel.

Does it sound rich when running, ie is the high running speed coming mainly from excess fuel rather than excess air, which would point back to your TPS signal being wrong as you originally thought (TPS can't do this on a speed/density programme but maybe it could on a TPS only system but, even so, it would still need a fairly large air leak)

Schrödinger's cat - so which one am I ???

I disconnected the TPS and fired the engine, It still went and hit the limiter, however It wasnt nearly as severe, TBH It does kind of remind me of what happens when you yank the choke out when running carbs, however, that tends to have a limit to how high it can rev.
Honestly I have no idea what im looking at on the maps, its just a spreadsheet with numbers, I understand how each is plotted onto the graph, and I can read the graph, but I wouldnt have the abiliy to change the numbers myself if the maps were wrong, Im reading up on it, but there is very little I can find in the college library. Best book I found so far was on Bosch systems by probst.

Well, It now works perfectley, It idles perfectley too, noticabley different to the Carb/dizzy setup.

Its just a temp fix at the minute to make sure that the manifold was the culprit. The new Throttle cable was abit iffy too, so I replaced it with some gear cable from my bike and its now working sweetly.
Im going to get the manifold welded again as the permanent fix. Thanks for all the help, I would have been another 2 weeks messing around without the help so its much appreciated.

As an Aside, I replaced Pistons and rings, I have read that the engine should smoke for abit untill the rings bed in, I dont have any noticable smoke out the exhaust?

Edited by ciaran on 15th Jun, 2011.

If you can post a screen grab of the software I'll explain it to you.

Glad you have got this far.

Somewhere in the software should be the ability to calibrate the TPS for fully shut and fully open - hopefully Joe can explain as I've never touched Canems - but it's usually dead easy.

Re. the new rings and smoke.... some do, some don't.

There are so many different factors that affect this, but if it does smoke during idle/testing, get some load on it ASAP.

Luckily mine doesn't (new bores, rings and pistons) as I've been testing it at low loads for many hours now.....

Schrödinger's cat - so which one am I ???

Ill get some screen shots of the software up soon, Im just really busy at the moment. Got to have another look at the TB today, the Throttle cable is still sticking on say the 1st 40% of the travel, if you go WOT and let off it returns, so I presume the springs aint strong enough. Next time I go EFI I think Ill just do it myself, too much thats not right with these Throttle bodies.

I managed to calibrate the TPS myself and set the static timing, the software is pretty easy to use in that respect, its just the fuel and Ignition maps I dont know!

WOW. I took it out around the block on a little shakedown. The car is transformed and this is just the base maps. There used to be fuck all power down under 3k, now the car is like a spaceship. I have to say even considering the expense, Any non standard mini should really be running an ECU, theres no excuses.

Few problems I noted,

1)theres mayo on the oil cap, possibly just condensation? all the head bolts were torqued to the values in the haynes.

2) Servo, this is worrying, I bled all the brakes, but the brakes are shit, like you have to jump on them. So Im thinking the servo maybe busted or that Im not giving enough vacuum to it to allow it to work 100%. Im taking the vacuum off some fairly small take offs. The OD is probably not far off 3mm on each one, would this be enough to get a decent vacuum, if its not Ill have to get the manifold welded...again :/. The brakes wouldnt stop me in an emergency, so this isnt acceptable.

3) Timing cover is leaking oil from where the plates join, so much for new gaskets lol.

Suppose 3 things aint bad for my first engine rebuild. Its not smoking and theres no back pressure out of the oil filler cap.

Good to hear.

You won't know about the mayo until its had a good long run to evaporate any moisture out of the oil.

Servo won't get as much vacuum from a wild cam anyway but 3mm pipes certainly won't help. To see if the servo is functional, do the MOT test routine on it (engine off, pump pedal a few times to release any stored vacuum, press pedal hard then start engine (at idle) and see if pedal gets pulled down a bit further by the servo seeing vacuum).

Schrödinger's cat - so which one am I ???

Mayo is all gone after a few runs so I think it was condensation thank god.

I got some graphs from the data logging and I will post them when I figure out how. The car is running extremely rich however and I think the timing is a tiny bit out.
I have set the static timing at 5 deg BTDC , its a 1380 with a 286 cam, however I have no figures for what to set it to so I set it to the closest thing, the 1275 cooper from 1990. What have others set theirs to?

Another slightly worrying thing is the plug on number 3 seems to have oil on it, Im hoping this will go away as the engine beds in, however none of the other 3 cylinders have oil on them.