Loss of power Air intake and MAF - Page 2 - Alfa Romeo Forum
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(Post Link) post #26 of 28 Old 12-06-11 Thread Starter
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I have emailed them, and see what happens.

there is so much on this car to fix!! got to check pullys and bearings next. Then get the inner wheel arches welded. This things rusted worse than my 20yr old MR2
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Originally Posted by VelocityVinnie View Post
Right well ive stuck the OEM hose back on apart from the the concertina bit which i had to cut out as it was screwed, and ive bodged it with a bit of alloy pipe and some rubber hose adapters.

The car is still idling a little lumpy and the exhaust still jumps around, although some of the power has returned, but i still think it should be faster, although having not driven this car when it was perfect or driven any other im not quite sure on what the power should be like. I did get taken out in this car a long time ago when i mate owned it, and it seemed more agressive from memory. Maybe because im used to driving a fast car this car now feels underpowered, and im exspecting to much from it.

I have driven it without the MAF plugged in today and the idle was the same but there was now power at all in driving it took an age to get even to 30mph, the injector light also comes on with it unplugged, so im guessing this forces the car into limp mode.

checked all pipes for leaks, inlets ect and all A OK.

this is defo looking towards exhaust and lambda, and maybe a little thermastat thrown in.

Good news is the ABS light has stayed off since i fixed it, whooop!

trying to track once of these flexi pipes from breakers is prooving hard! and why is everything for the V6 exspensive, i thought Mazda were exspensive, but alfa take the pee!
get your codes read (make note of them and clear then read them again)when you sorted pipe out as your hay stack is getting larger
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Really the only way to know for sure is to read the error codes. The Bosch Motronic system relies on the values presented by an array of sensors (MAF, Throttle Postion Sensor, Crankshaft Position Sensor, camshaft position sensor, lambda(s), etc) to not only determine mixture, but also injection point and ignition timing; any of which if incorrect will cause the engine to run ratsh*t. The codes will point you in the right direction otherwise your in the expensive realm of replacing things until you fix finally the fault.

The intake plumbing has to be leakfree to ensure that the MAF (if it is indeed working properly) gives a correct signal value. It is quite possible for a dud MAF to give a false value that is within the parameters acceptible to the ECU, so no 'injector light' but an incorrect MAF signal is likely to show up as a fuel trim error code. Cracks in the concertina are often cause problems and with all respect, 'bodging' may create similar problems.

Breather hoses also have to be connected and leak free. The V6 as with most engines uses a PCV (positive crankcase ventilation) system that relies on manifold vacuum to operate. Removing a hose effectively creates an air leak that invalidates the MAF signal - engine runs lean.

Given that disconnecting the MAF hasn't given an improvement it is likely (assuming the other sensors are OK) that the lamdba is dead (and the MAF could be too). Faulty MAFs and lambda often give similar symptoms as both sensor are involved with adjusting fuel trim in closed loop (normal) mode. When you get your cable, connect up using FiatECUScan, KWP2000 (Sanders Alfa version) or Alfadiag and read the fault codes. A dead lambda is easy to spot if you graph its output using this function on the above software, the voltage should ocillate between almost zero volts and 1 volt. If it occillates very slowly or gives an irregular pattern, or is a flatline, it is stuffed and requires replacement. A disconnected MAF sends the ECU into open loop and the ECU runs off the injection/ignition map programmed into the ECU using the TPS and lambda to calculate/adjust the the fuel mix and spark timing.

The MAF in my twinnie died on Friday -injector light on, stalling at the lights, etc- after playing up fo the last month or so. I connected up and saw the error codes, which once cleared reappeared as soon as the engine was started. Checked the MAF output which was constant regardless of rpm. So shes f00ked. I reset the ECU using KWP2000 and this fixed the idle problem and the car is actually now running better than previously as I wait for my new MAF to turn up from EB Spares. The reset cleared the fuel trim settings that were trying to compensate for the dodgy MAF signals. It is running in open loop, the lambda which is 6 months old providing correction for the mix (although it will be a bit richer than when in closed loop). If the lambda was poked I'd expect the sort of symptoms you describe.

Darryl in New Zealand
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air , intake , loss , maf , power

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