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Discussion Starter #1
Just happened now. I was driving then slowed down for a corner and when I accelerated in 2nd, nothing. The car idles, but revs slowly and doesn't pull at all...:(

It's the GTV again...:cry: Anyone know what it could be? Hopefully not another MAF?:rant:
 

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Could also be the plug on the throttle itself... Happened to me on the way to port Alfred... luckily I had my mechanic on-hand..:lol:
 

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Throttle Potentiometer

Had the same issue on my 156 Sportwagan, turned out to be the throttle potentiometer. It had to be replaced...well that is what I was told. Not sure if it was or if maybe just a plug was loose.
 

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Discussion Starter #7
Ok she started up fine and drove well for the rest of the day but the management light is still on. The two suggestions I got were also throttle pot and maf so I'll have to get it diagnosed. Giorgio says they've never replaced a throttle pot yet, always managed to clean the connectors and get it going again. No one has a 3.2 MAF in stock!
 

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Almost 90 % of the time like Cuzz said. The agents and other diag junkies replace everything since they can read but not diagnose
 

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Discussion Starter #10
Richard it's been sorted since the Q2. I love the feel of the new clutch that was fitted at the same time as well, but I've been told 3.2's don't go through MAF's like the 3.0's do, for me this means 3 new mafs in 3.5 years of GTV ownership since I already replaced two on my blue GTV :cheese: I'll just have to laugh it off.

TN as you say. They also couldn't pick up a loose earth caused by them not tightening a bolt that they loosened at my last cambelt service!:mad: I made them plug the diagnostic computer in and it showed 4 cases of "no earth connection" on 4 different systems, and still I had to trace and fix it myself for fear of my car spending another 3 weeks there! :rant:
 

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Discussion Starter #13
This morning: No engine light, performance is good but throttle response is deffinitely not what it should be so I think it's the MAF not performing correctly and the car is running closed loop.

Will this affect the engine's performance if it's been remapped? i mean when a car is remapped, the fueling, spark advance and other parameters are changed from standard values but performance still depends on sensor inputs. If the car runs closed loop, it runs off a pre-calculated program and ignores sensor values?
 

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If the car runs closed loop, it runs off a pre-calculated program and ignores sensor values?
In closed loop the ECU do not use the predetermined map. It uses the Lambda to determine fuel mixture and advance the spark until the knock sensor cry stop. The map is being used as soon as you open the throttle above a certain amount and it goes to open loop.
 

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Discussion Starter #15
Corrie, perhaps I got my open and closed loops confused. Which is which? Lets say a lambda fails. Does it run in open, or closed loop?

Secondly, will a car ignore the chip if it is running in this "failsafe" mode? The reason why I ask is because my GTV pulls strongly, but the throttle response is deffinitely not what it was. It easily pulled to 220km/h in a quick check yesterday but in light throttle driving I have to provide more throttle input than I used to give before. It therefore feels a little deader, and when I put my foot down it doesn;t pull as immidistely as it used to, it's like it takes a second for the throttle to open fully?
 

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Closed loop functions with small throttle openings and then the lambda and knock sensor controls everything. As soon as you open the throttle larger the ECU start running off the predetermined 'performance' map. In the same way the ECU will switch to the limp-mode map when certain malfunctions occur. See this as several different maps on top of each other. There are also different maps selected from the factory for different conditions from cold Scandinavia to hot Africa.

On a turbo car there are many more maps, because a map is 3D (rpm, air-flow and timing) When a 4th parameter is needed (boost pressure) it jump to a different map every 0.2bar (see Lancia Integrale manual) But this is useless info only interesting in a mathematical sense.

To grasp this easier, with a Unichip in the car, the closed loop part can not be adjusted, or it can be adjusted, but the ECU will immediate overwrite this with the help from the Lambda, when you start driving. With a radical turbo car we unplugged the lambda permanently, to force the ECU to use the reprogrammed map.

The 'performance' map is used with 1/2 to full throttle openings and this part can be adjusted by a Unichip. That is a problem on my 916, it is very thirsty when I cat-foot around. The ECU is programmed for a 3 ltr MAF and I am running a 3.2 ltr's MAF, causing my engine to run rich in closed loop. When the car work hard the consumption is good because the mixture is corrected by the Unichip on the 'performance' map.

The car will not perform at all in limp mode, the timing is pulled back and the mixture will be very rich to protect the engine.

I hope this help
 

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In closed loop if the lambda is working as it should the management will lean out or enrich the fueling accordingly.
Open loop the fueling is managed by the maf. If the Lambdas faulty it will default to permanent open loop which will not necessarily influence power to much but consumption will suffer.

No need to remove a the lambdas when you ad a turbo since it will keep the mixture perfect while driving normally and when you start adding fuel it will be in open loop anyway.

You only get faults when you start adding fuel while the motors running without boost 0 bar or lower.

The knock sensors always work and will adjust timing accordingly.

Ian your fault sounds like it’s either the potentiometer in the car or the butterfly.
Make sure that all the connections are clean and properly connected. You can also clean the butterfly to see if that helps.
If you are sure that alls fine do a reset and let the butterfly learn all its parameters again.
 

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Discussion Starter #18
TN I think a throttle reset would be in order. This morning all was well, the car feeling it's normal self! On Saturday I took it for a drive, basically took it through the mountains and twisty beach roads for some fun and it deffinitely was not revving as it should but after starting it this morning, she felt back to her normal self.

I think I'll ask Giorgio to clean the throttle pot connections for me because he says it fails in two ways: Either you only have half throttle (felt like that to me) or you only have idle (how will I get my car to him if it only has idle?:confused: ) :cheese: But for now I'm glad she is over her hiccups and performing well again.

Thanks for the advice and responses, it's much appreciated :thumbs:
 

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Ian my GTV had hick-ups as well, until Cuzz discovered that the way the cables were strapped, make them hang on the throttle plug. It caused a bad connection every now and then on rough roads.
 
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