Hesitancy on light throttle - Alfa Romeo Forum
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(Post Link) post #1 of 14 Old 18-07-16 Thread Starter
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Hesitancy on light throttle

Good afternoon!
My 2008 1.9JTDM Lusso has covered 81,000 miles and is serviced by the main dealer at the appropriate mileages. The last service included a second new cam belt and water pump; the EGR valve was replaced in May 2015. The car is almost only used for journeys in excess of 25 miles.
It has recently developed an intermittent problem; on a light throttle, and at about 1500RPM in an intermediate gear, there is some hesitancy. This clears on acceleration and is not evident in top gear.
I'd be grateful for any thoughts that you might have.
Kind regards to all.
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Flatspots could be caused by a misreading MAF sensor.
When driving along, try coasting at various speeds and look at the rev counter, it should drop and stay at the normal idle speed. If it bounces, that may well be another hint the the MAF sensor is misreading.
You can also try unplugging the MAF to see if it makes a different (You'll get a warning, but that should clear when you reconnect the MAF.) if so then it will likely be the cause.

Some people say MAF sensors can be cleaned, but from experience any improvement from cleaning doesn't last. Best to buy a new one - and don't go for a cheapo eBay replacement!
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(Post Link) post #3 of 14 Old 20-07-16 Thread Starter
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Good evening and many thanks for your reply. It's an interesting possibility and I'll check it out on Saturday when I have long run planned - I'll report on the outcome.
With kind regards
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OK, so I've got a 2.2 JTS so a completely different kettle of fish but I had the very same symptoms as you describe.

Last September, after changing the oil and filter, my Brera developed a slight hesitancy under light throttle below 2000 revs. This disappeared under acceleration.

A few days or weeks later, I was never sure which, I noticed the illumination on the information screen (between the main dials) and the tail lights would flicker on tickover.

This said to me, voltage regulator even though it had only done 35,000 miles, so after putting up with it for a few months, my Brera is really only a weekend car, I replaced the alternator.

As expected, this cured the flickering and, surprise surprise, it cured the hesitancy also.

I am not saying this is what is wrong with your car, but it is worth taking a close look at your alternator. You just never know.
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(Post Link) post #5 of 14 Old 21-07-16 Thread Starter
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Originally Posted by R50MEO View Post
OK, so I've got a 2.2 JTS so a completely different kettle of fish but I had the very same symptoms as you describe.

Last September, after changing the oil and filter, my Brera developed a slight hesitancy under light throttle below 2000 revs. This disappeared under acceleration.

A few days or weeks later, I was never sure which, I noticed the illumination on the information screen (between the main dials) and the tail lights would flicker on tickover.

This said to me, voltage regulator even though it had only done 35,000 miles, so after putting up with it for a few months, my Brera is really only a weekend car, I replaced the alternator.

As expected, this cured the flickering and, surprise surprise, it cured the hesitancy also.

I am not saying this is what is wrong with your car, but it is worth taking a close look at your alternator. You just never know.
Good morning and many thanks for your comments, I'll run a check on the alternator at the weekend.
With kind regards
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(Post Link) post #6 of 14 Old 27-07-16 Thread Starter
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Good evening.
I checked the car over the weekend; there was no evidence of uneven tick over when coasting but I will investigate the MAF sensor further. There was no flickering of the display or tail lights so I assume that the voltage regulator is OK.
Thanks for you interest, I'll report back in due course.
Kind regards
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I have the 2.4 and with 130K KM on the clock, I have been seeing the same issues as you - in my case, it has always been the EGR. So the car is currently on its third EGR in 4 years, and next week it will be time for it's fourth.... stupid stuff.

(and no, this is not an invite to the usual EGR blank+delete discussion - some people, like me in Switzerland, get heavily fined if caught so it's out of question).
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Have you tried just cleaning the egr? Not had a 2.4 but on my 1.9 jtd GT it was a very easy job.

Easy to remove, soak it it carb cleaner for a while, brush what you can. Manually activate the moving parts while spraying carb cleaner. Should be able to get all the gunk out this way and have a freely moving egr valve.
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(Post Link) post #9 of 14 Old 04-08-16 Thread Starter
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Good morning and thank you for your message. The EGR valve was replaced just over a year ago and should therefore still be reasonably clean. However, I will have look at it , it's important to eliminate all the possibilities!
With kind regards
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I had something very similar recently, except it felt more like the car was going to stall when lightly accelerating at around 1800-200 rpm. If I put my foot down a bit more it felt fine. For 5 I got a bottle of contact cleaner and blasted the MAF and MAP sensor, no problems since that I've noticed.

There's not much to investigate on the MAF as such, remove it, then spray the platinum mesh inside liberally with electrical contact cleaner and leave to dry for 10 minutes, job done.
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So many people forget the MAP or MAP(T) I believe it is on one of these. Give both a clean as you have nothing to lose.
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Check the power loss guide in the stickies for the most common issues.
Many Alfa garages supply reconditioned EGRs, which are prone to early failures (as has been demonstrated by the number of people refusing to check it as it was recently replaced only to find it at fault many later).
Just unhook the map sensor to check if it is at fault
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(Post Link) post #13 of 14 Old 08-08-16 Thread Starter
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Quote:
Originally Posted by giblets46 View Post
Check the power loss guide in the stickies for the most common issues.
Many Alfa garages supply reconditioned EGRs, which are prone to early failures (as has been demonstrated by the number of people refusing to check it as it was recently replaced only to find it at fault many later).
Just unhook the map sensor to check if it is at fault
Good morning and many thanks for your responses. I'll check with the garage to make sure that the replacement EGR was on OEM part and I'll put the MAP on the work schedule.
I'm grateful to all who have taken the time to read and respond to this thread.
Regards to all.
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Sorry, typo...MAF sensor is unplugged, worth giving the MAP sensor a clean though (the whole of your manifold will be a similar state )
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