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Mixsynth

Saluton, alfistoj!

Got me 16V running OK (driven it all over the place) and it's due for MOT on Friday. Just needs a rack gaiter and rear brake hoses replacing.

It has a niggly problem though that I hope is nothing serious and easily fixed.

The engine starts fine and immediately idles at 1k. It also revs OK when I punch the throttle and seems smooth enough. BUT... when I lightly touch the throttle, even just put my foot on it, the revs drop below 1k and it comes close to stalling out. Take foot off, it goes back to 1k.

What could be causing this? Any ideas?
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Hugh B
'98 145 QV
'89 33 1.7 16V Veloce SportWagon (in hibernation)
16V conversion pics/videos - now updated with extra pictures and explanations

johnboy

[quote="Mixsynth"]Saluton, alfistoj!

Hi hugh,
when mine was running it did the same @ about 1000 to 1500 rev's.if i took my foot off the gas it would sort it's self out.i think it's a flat spot.you will need to get the fueling sorted out i think,this is what i will do.cos i have an omp system which they say i will need to adjust the fueling.i saw this in the deman tweek's mag hope this help's. p.s will be taking the head off tomorrow,just got the six head bolt's to do and it's off.hope there's not too meny bent valve's finger's crossed Sad

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WODA WE NEED? MORE POWER!!

Alfa gt jtdm blackline
1990 S2 16v veloce sleeping!
2002 ts gtv the wifes now
1997 seadoo gsx 800
1999 freestyle superjet

burgo90 · Alfa Sprint Joined: 29 May 2003 Posts: 118

possible to much air gettin in u fitted an induction kit??
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ChrisC · Alfa Sprint Joined: 13 Mar 2003 Posts: 152 Location: Frome

Sounds like a twitchy throttle position sensor, but then again all 16vs have those so it may just be one of those things.. maybe yours is actually on the way out.
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Alfa Sprint QV - Gone to a better home and in happier health for it
Silver Lancia Beta HPE Volumex - under restoration

Mixsynth · Posted: Tue Jul 29, 2003 9:51 am Post subject:

Burgo - sort of, I've got a K+N panel filter. But it shouldn't let much more air in than standard as the exhaust is still standard.

Chris - I thought the throttle position sensor was just "off/on/max"? No positions in between? I've noticed now that when I move the throttle linkage from under the bonnet, the engine doesn't drop revs as it does when using the pedal. Maybe it is just a dodgy switch?

Would a bit of cleaning with contact cleaner help?
_________________
Hugh B
'98 145 QV
'89 33 1.7 16V Veloce SportWagon (in hibernation)
16V conversion pics/videos - now updated with extra pictures and explanations

ChrisC · Alfa Sprint Joined: 13 Mar 2003 Posts: 152 Location: Frome

certainly couldnt hurt, and if it works its a cheap fix!
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Alfa Sprint QV - Gone to a better home and in happier health for it
Silver Lancia Beta HPE Volumex - under restoration

Serpent33

P4 Paul · Posted: Sat Aug 02, 2003 1:43 pm Post subject:

I've just had a mobile tune up chap look at mine for the very same problem,and its the air flow meter that was the problem!!

Mixsynth · Posted: Sat Aug 02, 2003 2:11 pm Post subject:

Air flow meter? As in the whole thing was duff or it required repair/tweaking?
_________________
Hugh B
'98 145 QV
'89 33 1.7 16V Veloce SportWagon (in hibernation)
16V conversion pics/videos - now updated with extra pictures and explanations

P4 Paul · Posted: Sat Aug 02, 2003 2:17 pm Post subject: air flow meter

i dont think they can be repaired?,maybe i'm wrong?but either way im after one

Mixsynth · Posted: Sat Aug 02, 2003 2:21 pm Post subject:

Keith once said you need to clean off the circuit board under the black plastic cover to fix such AFM problems. I wonder if that's the solution in both our cases?
_________________
Hugh B
'98 145 QV
'89 33 1.7 16V Veloce SportWagon (in hibernation)
16V conversion pics/videos - now updated with extra pictures and explanations

P4 Paul · Posted: Sat Aug 02, 2003 3:44 pm Post subject: air flow meter

i've just cleaned it all,put it back on,and its still the same!!!!

Mixsynth · Posted: Sat Aug 02, 2003 4:37 pm Post subject:

How about what was said above - the throttle position sensor?

If you touch the throttle and the sensor moves off the 'min' position, the idle circuit should be cut off - if it does this too soon and the butterflies aren't opened enough to let some air through, I would imagine the revs would go too low to start with. Maybe this must be it?
_________________
Hugh B
'98 145 QV
'89 33 1.7 16V Veloce SportWagon (in hibernation)
16V conversion pics/videos - now updated with extra pictures and explanations

Serpent33 · Posted: Thu Aug 07, 2003 2:56 am Post subject: Re: air flow meter

Sergio

Admin · Posted: Sat Aug 09, 2003 8:44 pm Post subject:

Hi

Could be the throttle position switch. I presume that as you touch the throttle it will richen the mixture slightly. If the TPS doesn't detect that you have pushed the throttle down then the mixture would not richen.

You balance the throttle bodies the same way you balance a set of twin choke carbs with some vacuum gauges.

I would check the linkage between the throttle bodies. What yours is doing is the same as my P4 does if you operate one of the throttles directly and rely on the linkage to operate the other. Due to the free play in the system doing this the throttle body you do not touch lags behind.

All the best

Keith