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High idle selespeed update

2167 Views 15 Replies 6 Participants Last post by  robf781, 
G
Hi guys,

Update on the idling problem I've been having with the selespeed. Got some free time today, so removed the throttle body to inspect it better.

All inner workings appear to be fine and no sign of any damage, no teeth missing off any of the cogs etc. The rear of the throttle was quite grubby as you can't get to it from the front without removing it, also the area around the edges of the butterfly was a bit grubby looking so I gave the whole lot a nice clean with some carb cleaner and a rag. Also removed some crud from inside the inlet manifold behind the throttle and gave it a clean too.

Finally reset the throttle by disconnecting the battery and touching the connections together to clear the memory. Then doing the 90sec reset on the throttle pedal.

Left idling for a while and initially seemed ok, but once nicely warm started playing up again with the revs going from 1200 to 2500 and bouncing between the two. Then the injector light came on :confused: so connected it up to AlfaDiag and read the fault code as MAF sensor out of range.

Disconnected the MAF, reset the throttle again and went for a spin. the high revs are now gone, idle stays steady at about 950RPM (thats not to say it's fun to drive, very jerky and nearly stalling at times) but this tells me it may have been the MAF all along. Strangely though, there's no obvious lack of power, and no problems getting to high rev's.

In summary, anyone having this problem with the electronic throttle, try changing the MAF early on, it could be a hidden fault. I suspect that cleaning the throttle has just made it more obvious (why I don't know), or else I somehow knackered it by removing it. I'll let you know when I get a new one if it's fully cured.
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fastboyslim

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#2 ·
How many miles on that MAF? I have always heard these things always stop working but when talking to a guy from Autodelta was told that they are very robust and only get blamed for a lot of things. mine looks **** on the outside, scared to think whats going on inside. might need a replace soon.
 
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G

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Discussion Starter · #4 ·
What makes you think that? I think I will try a new MAF first then see what effect that has. Seems extreme to suggest it's the ECU just like that.

Oh, and the car has done 74k and no mention of MAF being changed before so I assume it's the original (well overdue I think)
 
G

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Discussion Starter · #7 ·
makker said:
seems extreme but its the likely cause..
have your ecu scanned first and all basic checks carried out before replacing your ecu.
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Well I'm off to get new MAF later today and we'll see if that helps. I'll let you know.
 
Chris

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#8 ·
It sounds like the MAF to me. Its a bit extreme to be suspecting the ECU at this stage.

However, before going nuts and spending the money, have you gone for a good drive since cleaning and resetting? It can take a fair few miles before it all settles down again. Mine sometimes takes a 30-40 mile run to get settled after a clean.

Anyway, its just a comment, MAF seems like the likely culprit. 74K is a bit early maybe but they do tend to 'wear out'. I should know, I'm on my 4th if you count the one the car shipped with. I did manage to break one of them myself tho ;)
 
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Discussion Starter · #9 ·
Well, fitted the MAF today. Running a lot better, but still has the fault light lit up on the dash, reset it using AlfaDiag and it just comes back straight away. Same fault, air flow meter out of lower limit. I'm going to do another ecu reset tomorrow and see if that helps me clear it, but I'm beginning to think there may be something wrong with the ECU (apologies Makker looks like you were right).

One question, I'm assuming the ecu is on top of the throttle body yes? I have had this disconnected recently, so it may be that some crud has got into the connections (or alternatively I've managed to ruin it) Sick of the problems I'm having with this car.
 
marko

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#10 ·
i had a carry on similar with mine... turned out to be air/fuel ratio was out due to a shot engine temp sensor... was telling the car to adjust A/F ratio to cool it down even when cold... just a thought for ya :)

what error codes are you reading?
 
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Discussion Starter · #11 ·
think it was P0100 something like that, it says air flow meter out of range, below lower limit something like that. I'm actually getting a new temp sensor anyway as the one I bought with the thermostat was the 4pin type, I needed the 3pin so the old one's still on there.

We'll see if that makes any difference when it gets done.
 
G

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Discussion Starter · #12 ·
Well, idling problems now sorted (thank god). Got the new temperature sender and fitted it today (2min job if that) and straight away the car feels much better, fault code light has gone out and all seems well.

I also disconnected the multi-connectors on the top of the ecu before I went to get the part (in the other car... doh) and cleaned the contacts with air spray. left it disconnected for a couple of hours and then reconnected after fitting the new temp sender. Idle is much smoother even at cold start and driveability is better (although it's still ever so slightly ropey as the ecu is learning my driving style again).

All in all, happy days. Just the airbag ecu, lower wishbones, and cracked rear bumper to sort out now. (groan)
 
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Discussion Starter · #13 ·
Well it's back, the idling problem is just as bad as before. Convinced now it is a problem with the throttle body.

Just a quick question, should there be a slight gap between the throttle butterfly and the body when it's spung closed? or is this my problem.

Just seems confusing that it only does it when warm. when it's cold it idles nearly normally (just a slight spluttering) but as soon as it warms up, revs are bouncing all over the place. worse bit is that if you sit at a junction and just tap the accelerator a tiny bit, it will then drive off on it's own at about 1700revs (with it being selespeed). Makes it hard to control in traffic, and a nightmare to park. It's off for a cambelt change next monday so hopefully Wyn Lear will be able to sort it out.
 
G

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#14 ·
Good luck m8,im having a prob with my sele when cold its ticking over fine for a minute then starts bouncing and nearly stalling then when its warm the revs can go up to 2000 idle and aint it a biaatch not having the clutch control for once!Cleaned the throttle body worked for about 4 days so now having MAF changed and temp sensor on Thursday along with the belts and all,anyway good luck hope ya get it sorted ;)
 
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