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Discussion Starter #1
Hi,

Having spent a fortune getting an aircon leak fixed I now have another issue.:mad:

I'm finding the car responding oddly at low throttle openings, almost as if the throttle butterfly is acting independently of the pedal....I know it is nothing to do with the pedal though because it also happens on cruise control.

Ii is noticable most when trying to maintain steady speed on the motorway, the power comes and goes by large amounts with minor throttle adjustments, making for very jerky progress. It smooths out when you floor it and idle seems OK. It also seems OK if I'm doing a lot of stop/start driving, it starts to go wrong when I'm going a reasonable distance at a decent speed....

What actually may be happening I suppose is it is dropping to three cylinders at a certain throttle positions and then kicking in again.

I've also noticed that when driven gently the mpg doesn't pick up like it used to.

I'm going to check plugs, coil packs etc but no errors are showing. My other thought is there could be an injector on the way out. Are they a pig/ expensive to change?

Any other things to check would be welcome - could this sort of thing be the MAF?

Cheers

Mike
 

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check the corrugated air intake pipe,near the thottle body for cracks
 

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What mileage is the car?
When and what was the last service?
Try disconnecting the MAF just to rule it out..
Also could be an air leak between MAF and Throttle body, if its been removed to sort AC out might be a place to start...

Does it sound like its missing???

My MPG is poor at the moment but i havent changed the Air filter for a bit so i'm going to pull it all out next month when i change my Rad...
 

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Discussion Starter #4
Thanks for the suggestions. I'll have poke about tomorrow. I did think of a air leak and had a quick look, but I'll check again. Is there an idle control valve which could stick?

115,000 miles, almost all motorway miles.

Its got a full service history (alfa or black&white), I've had it since new. I did the plugs myself not so long ago.

The symptoms started before the a/c work was done.

Its hard to tell if its missing, the power drops and rises intermittently, but this tends to be at higher revs so i'm not sure if I'd be able to tell if one cylinder was misfiring. It does occasionally feel lumpy (probably missing) shortly after a cold start (could be a clue?)
 

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remove the top cover & remove the 4 coil packs, look down the plug wells for oil or water

also check or cracked HT packs or spark plugs
 

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injectors are located at the UNDER sid eof the inlet manifold & are a 'pig' to get at & remove.

I was talking to an alfa mechanic who says that the injector of cyl 4 is a common failure causing misfiring.... massive job to get at & replace.
 

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Discussion Starter #7
I was afraid so.

Suddenly jts seems like a bad idea....

What really annoys me is my fiat coupe 20V turbo has done 150,000 miles and gets much more abuse, is utterly reliable and costs a fraction of the alfa to keep going. Much,much quicker too...
 

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at the back of the inlet manifold are TWO large black conenctors with approx 20 wires in each.

dsconnect the battery & then disconnect these connectors & spray the contacts with cleaner.... might help.
 

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What is happening peeps? sudden heatwave and MAF`s going down everywhere,just got over the shock of paying for mine:eek:.............and jack still thinks he`s skippy the bush kangeroo!:mad:
 

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^^^^ did you replace the maf yet? ^^^&

if not try sending Steve from Alternative Autos an e-mail:

[email protected]

with the last 8 digits of your car so a she can be certain that the ma fis the correct one.
 

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Discussion Starter #13
Why is nothing ever simple.

Trying anf failing to get the connector to the MAF sensor off. Just left it soaking inWD40 'cause it won't budge..

Is it a simple as pushing in the tab on one side and pulling, or am I missing somthing?
 

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Discussion Starter #14 (Edited)
Well, the connector came off with a bit more persuasion.

The car runs exactly the same without the MAF, no better no worse. I took the plugs out, they all look a nice health colour, the only thing I notice was a bit more whith Checked leaks/cracks in the air pipes and found nothing. Cleaned up the connector blocks behind the engine.

Still running the same.

What I have noticed in all my fiddling is if I rev the engine on the drive to about 1500 rpm there is a misfire going on. It misfires for a 2 or 3 seconds or so and the revs drop, it then stops misfiring for another 2 or three seconds or so before misfiring again. Quite a regular on-off thing going on, which may be the source of the running problems. I have a spare coil pack somewhere so I'll try swapping things around - does anyone know what the pins on the coil pack should measure?

I could also try getting someone else to rev the engine while I disconnect a cylinder at a time to try and see which one is at fault.
 

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Are you sure its a misfire? Misfires will usually cause MSCF, most likely its just drop in revs due to lack of fuel/air mixture which would most likely be throttle, MAF or lambda. If its running the same with MAF off then something is not right because it should idle like a dog and go like a rocket with the MAF off.
 

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Discussion Starter #17
I'm not sure of anything. It does feel like a misfire, you can feel the off balance vibration of the engine in the car, but no errors. If I was sure it was the MAF I'd quite happily change it but I need to eliminate the other stuff first.

I wonder if the MAF on my Fiat coupe is the same and I could try a swap Hmmmm.
 

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The MAF for mine was some astonishing price. I think some ducting was replaced as well - can't remember TBH!

Maybe you have a dodgy engine mount as well. But if you think it's the injectors, then maybe it is! Might as well replace the plugs anyway. I think on Volkswagens, it is usually the coil packs. Those bloody MAFs seem to be a service item on so many different car brands!

Can you read/get read the codes?
 
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