Dirt inside air intake manifold, engine rough - Alfa Romeo Forum
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(Post Link) post #1 of 7 Old 15-09-16 Thread Starter
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Hmmm Dirt inside air intake manifold, engine rough

I need some collective wisdom to help get my 2006 GT 3.2 back to health please!

I bought it about 10 months ago from a guy who had 4 Alfas so was sure he'd looked after them like a proper Alfisti. Not the case unfortunately!

Over winter here in SA the car suddenly needed to be turned over twice every time before it would start the engine when the engine is cold. Always twice. Even on warm afternoons, if the engine is cold it needs two tries. Out of curiosity I checked over the air inlet system and found a gaping hole on the underside of the flexi hose to the throttle body that had previously just been glued up! Needless to say I replaced it asap and also cleaned the throttle body and manually moved the butterfly valve to clean.

Now in retrospect I have learnt that what I did was dumb, but will that have affected the revving and idling? If so, will the "soft" ecu reset help on a 2006 GT V6 or will it need a full reset?

Having removed one of the 6 inlet pipes to inspect the damage, I've also just noticed a fair amount of oil in the intake manifold, along with gritty black deposits undoubtedly from essentially running with no air filter for god knows how long (and South Africa is a dirty, dusty place!). Images attached. or https://dl.dropboxusercontent.com/u/...0/IMG_1076.JPG https://dl.dropboxusercontent.com/u/...0/IMG_1074.JPG

Other than strange things happening at low revs (which may also be because the positive battery terminal was lose and fixed just now) the engine runs well and doesn't use much oil at all.

What damage might this have done and how can I go about fixing it all?

Thanks!
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throttle body should be fine, just do the reset to re-initialise idle.
Oil in the inlet is unfortunately normal, due to the carter/crankcase ventilation system.....

Last edited by jwq; 15-09-16 at 15:45.
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(Post Link) post #3 of 7 Old 15-09-16 Thread Starter
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Originally Posted by jwq View Post
throttle body should be fine, just do the reset to re-initialise idle.
Oil in the inlet is unfortunately normal, due to the carter ventilation system.....
But is that amount normal? I read about thin films of oil, not pooling like in the photo.
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I just pulled my chrome runners off to tidy them up, and they looked like yours. I just gave them a wipe and a de-grease. The plenum was a bit black too. It's just because of the crankcase ventilation. I didn't notice any difference after I cleaned them up so it's probably not your issue.
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Did the reset tonight and seemed to make the car run smoother and well but engine was still warm. Will see how it starts from cold in the morning!

This is the procedure I followed to reset the ecu (from the ausalfa forum) which all went OK, except it seems to have buggered up the windows which are now misbehaving. Something else to fix...

1. Disconnect the negative lead from the battery for a minimum of 45 minutes. Some people recommend overnight
2. Reconnect the battery negative lead
3. Put key in ignition, turn to MAR and leave for 90 secs
4. Turn off the ignition, but not remove the key and leave for 90 secs
5. Start the engine but do not touch the throttle and let the car idle for 15 mins otherwise the car will not rev freely afterwards (as V6 owners know at their peril)
6. Turn the car off and leave for 10 mins (leave key in)
7. Start the car and take her for a blast
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(Post Link) post #6 of 7 Old 16-09-16 Thread Starter
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So after doing the reset yesterday afternoon the car is definitely running smoother and started first time this morning when cold for the first time in 4-5 months! The "soft" reset is definitely worth doing for any minor engine grumbles.

I'm going to change the spark plugs over the weekend, is there anything else I should look to do while I'm in there?
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A year ago i decided to clean the intake system on my 156 V6, as the previous owner had some Simota?! ricer open filter on the car connected directly to the MAF which was connected directly to the flexi hose. Appart from the fact that these open filters do nothing but make noise and suck up power robbing hot air, few people realise what detrimental effect shortening the intake on these V6 cars have. The intakes on these cars were torque tuned front to back, removing or changing parts of it will in most cases make it sound nice, but reduce torque. I have since sourced a standard airbox and snorkel, as well as top intake plastic pipe, and the car feels much much torqier. As the boy racer filter also was just resting on the top rad hose/oil cap, a hole was formed in the filtering material due to vibration, letting in crap. Upon inspection inside the intake tubes/plenum i found alot of oil (as mentioned previously, this is quite normal) and signs of dirt in the oil inside the intake. Luckily it seems the oil trapped most of the entering dirt inside the plenum, and there was no signs of damage or dirt further down. I cleaned everything, and sprayed down the TB with carb cleaner without moving the butterfly. The car runs great now. I also cleaned the MAF with electrical cleaner, this seemed to have had a positive effect on fuel consumption and throttle response. To conclude, even though the oil from the breather system causes a mess inside the plenum, it also traps dirt that might find its way into the intake that would otherwise end up in the engine. My advice then, do not clean out the oil in th intake more than once yearly, regularly inspect your entire intake tract for leaks and damage, keep the intake system standard for best performance/smooth running, and regularly replace/clean the air filter and do regular oil changes.
On a sidenote, i replaced the corrugated flexi hose on my car with a nice red silicone unit made for these cars by Autolusso, as the standard hoses always tear at the corrugations, and i fitted a K&N filter inside the stock airbox. The car runs like a dream. For those spreading the rumour that K&N filters kills MAF's, please go do some research on youtube, or directly write to K&N about the matter. They spend alot of time/money conducting tests on this myth, and could not find traces of filter oil on any of the MAF's in the tests. Our MAF's fail at random because of dirt (leaky airboxes) and in many cases due to poor quality materials used in the manufacturing process being subjected to heat and vibration.
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