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I was thinking it might be the actual TB itself. Back in the thread you said that somehow you managed to get the idle down to 950 RPM by fiddling with the TPS. That sort of implies that the TPS was holding the throttle open somehow which of course would be consistant with having a high idle speed, which the ISV cannot control as it needs a more or less fully shut throttle plate. There is just the fainest bit of light through the bottom of the plate when shut!
So either when adjusting the TPS you are moving the throttle plate. The further you turn it the more likely that is. Or there is a basic misadjustment of the linkage that means the throttle plate is not shut when the linkage is against the throttle stop screw. I think I remember that you had to tighten the linkage up for some reason.
The TP linkage is a bit odd as it uses one part to activate the other (at least on the ABY one I am loking at!). So effectively the part with the throttle cam for the cable moves against the other more substantially sprung bit. There is a bit of slack before it actually moves the throttle plate. The stop for this part is a non adjustable pin. The main part of the linkage has an adjustable throttle stop screw which has a tamperproof cap on the rear. The linkage for the TP sits against this at idle.
Not sure how we can verify this other than with a swop with a know good one.Comment
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Robin I have a throttle body in front of me and I can see what you mean about the cam moving before the main one.It apears to be slack on the linkage that fits on the main shaft.It is the same on all three of the ones I have.
I am looking at one with a spare TPS placed on it, with out the screw,.and if I turn it to much it starts to open the throttle,which is one of the reasons I took the throttle body of.
I set the tps up of the car as it is easier to access the screws,and see if you are moving the throttle plate or not.
I am convinced it is now set in the optimum position,ie it clicks on and of without moving the throttle plate untill it clicks.
This is the second throttle body I have fitted on the car, and the anti tamper devise is missing,its the one of the doner car.The first one was the one of my original engine,which has the devise intact.I changed that just to eliminate it.
There are yellow alignment dots to show the original position,soI may try and adjust it and see what happens,I can move it back if it dos'nt work.Comment
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Lou,
Probably asked before, but what was the car idling at when you had it mapped originally?Comment
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I cannot be absolutely sure but it was below 1000,more like 900, and it did not hunt as it does nowN.or did it have any issues with the drone,and its the sane exhaust.
I have just had a go at adjusting the throttle stop,and it makes very little differance,if any.Comment
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I Have had another go at getting the idle down on my car today.checked all the vac connections with propain with the engine running.but still could not find any leaks..took it for a run and its boosting now to 1.5 with no misfires,but the car still has the same problems what ever I do.
There must be something I am missing hear,what else could cause these problems and still allow the car to boost to 1.5 other than the things I have tested or replaced.cant be timming
or it would not boost right.what about fuel pressure,I have not tested that yet.or the wastegate,but again if it was any of those two then surely the car would not boost,am I right in assuming this.
I realy need to get someone to look at the car,but I have no idea who,MRC do not seem to know,and I think they are no longer interested in these cars,plus they are 170miles a way.
Has anyone any idea who I could get to look at the car as i realy think it is beyond my capabilities now,dispite all the determined efforts put in by newsh and twoqu,for which I am very greatful.
Any advise would be much appreciated.Comment
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Its really frustrating!
Especially as whatever it is must be something on the car as the behaviour appears to be the same with the two different ecu/injector/fpr setups. That still does leave that funky N75 pipework, although re-plumbing that did not seem to improve things!
We are hamstrung as we have limited capability for diagnostics through the ecu. I doubt whether we can gather anything through the measuring blocks as they will be out of range due to the high idle speed. As far as we can tell the idle speed circuit is functional although if we could monitor the duty on the ISV (affordably) that might tell us something.
One thing we haven't eliminated is the A/C idle speed boost signal. Need to see what pin thats on and what input it is. I have read somewhere it could be as much as a 120rpm boost but adding that to the max idle speed only gives us 950rpm. Its unlikely but might as well eliminate it if we can.
To me it sounds like there is extra air rather than fuel and its pulled in under vac. When you leak test, are you including the turbo? Its possible that air could be sucked in from the compressor seal O ring but then you would expect it to lose pressure. The 1.5 bar sounds healthy enough assuming thats what it was mapped for although 0.4 bar down on what others run on high boost. I know the turbo was rebuilt but its not impossible to nick that O ring seal when reassembling it. It might also explain why MRC resorted to that N75 pipework mod as I recall they couldn't get the car to make boost. It is also something we have left on the car during the ecu/inj/fpr swops!
Now I am only thinking aloud so don't rush off and replace the turbo ***** nilly!Comment
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Robin on the contrary Mrc did get it to boost at around 1.7. what they could not do was get the car to convert this into enough power.thats why they suspected the cams.
Mineha said it has more boost than an rs2 and enough fuel and flow.to make more power,but it just was not making it.He also said he had only ever tuned one other s2 that would not make power,but could not remember why.Comment
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I see!
What cams are in now then?
Still not entirely convinced about the expanation as others get more boost with a std N75 with std plumbing. I thought they consulted on that N75 mod to get more boost.
We know its possible to get more than 2 bar with the std N75 don't we!
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7a exhaust and 3b inlet from the doner car.and yes we do no we can get 2.2bar at geat exspense
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I remember seing this:
But whether its your problem or not, I cannot say!Comment
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Thanks for that Robin,I have read through it a couple of times,and I did not think theI remember seing this:
But whether its your problem or not, I cannot say!
symtoms where quite the same,in as much as I don't get the stalling issue on lift of,and I dont run a cone filter,I have an RS2 airbox,but yes I do have high idle and a 7a exhaust cam,so it is definatly something to consider
The idle on my car is high hot or cold,but it runs better cold than hot, as far as the exhaust rezonance is concerned.it also hunts at 1450 hot or cold.
Its a shame the thread did not draw to a conclussion.Comment
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Lou, what kind of diverter valve are you running? If it's a stock black plastic one, maybe the diaphram has split.Comment
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