Alfa 156 1.8 TS rough idle and misfire at low revs - Alfa Romeo Forum
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(Post Link) post #1 of 40 Old 25-07-16 Thread Starter
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Alfa 156 1.8 TS rough idle and misfire at low revs

Hello!

A past few weeks I have been doing some work on my Alfa. Changed the spark plugs, cleaned the throttle body, "taped" the air intake after the MAF, etc.

The engine was very rough before the change of spark plugs and I thought that will make things better, it did but now i have misfire in the rev range 900 - 2000 and the idle is rough. https://www.youtube.com/watch?v=zjf7zqXPjfE I found this video and it sounds just like mine! Sprayed WD40 over intake manifold with no change in idling, thought that there are air leaks. The only change for better is when I take the air filter off of the MAF and make the intake hole on the MAF smaller with my hands thinking that there is to much air going into the engine if there is an air leak. But also thought that maybe MAF is bad. Can you help me with this, maybe somebody had a similar problem? The diagnostics doesn't show any errors. Thank you!
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also check this hose.
http://forum.alfa145.com/uploads/pos...1164498136.jpg
has be really tight, no movement whatsoever. if it is loose, non metered air might be getting in from there.
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MAF won't show an error until it is completely dead. Also a non-Bosch MAF is a waste of money (as is a Lambda sensor).

the way to test it is to disconnect it and take the car for a run .. it will rev cleanly without, so if you car is running out of steam with it on, that's the MAF.

Have you rest the idle actuator? If you have been opening and closing the throttle manually, you have probably got it out of sync with the ECU now.
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(Post Link) post #4 of 40 Old 25-07-16 Thread Starter
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I have checked the pipe that goes to brake servo, should be OK but I noticed that my brake pedal is very hard to press, maybe the brake servo is gone? i have tried to run the engine without MAF but it ran poorly, haven't tried driving it like that, maybe it will learn that there is no MAF and driv better? My Alfa is not fly by wire, it has a throttle cable from pedal to throttle body. Can it be that throttle body is defective? Maybe there is to much air on lower revs that passes around throttle valve?

P.S. I had fluctuating idle but changed that valve with the spring that goes from engine head and after the throttle body, fixed it, but maybe now is messing with these low revs....
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ti's ok for idle to be weak without maf. but should drive ok.
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(Post Link) post #6 of 40 Old 25-07-16 Thread Starter
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Tested with MAF disconnected, very hard to turn on the car and when I do I have to put my foot on the pedal not to stall the car. I noticed that when I put my foot down to accelerate it almost stalls but when it gets to maybe 2700-3000 rpm it drives ok, below the 2500 rpm it sounds like a misfire the same as with MAF connected. So maybe it is not the MAF...
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try an ECU reset and then a throttle reset.
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Quote:
Originally Posted by alfizta View Post
try an ECU reset and then a throttle reset.
Ditto!

Try the throttle 30-sec trick first .. I'm not going to type it all again .. search or click through to my greenserpent website ..

OK .. my signature has gone .. thanks to the team running this service now, first hacked, now features disappearing?.


Gazza82's 1998 Alfa Romeo 156 TSpark 2.0
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(Post Link) post #9 of 40 Old 27-07-16 Thread Starter
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Did the ecu reset via delphi diagnostics and may Alfa is not fly by wire, throttle reset works only on fly by wire, right???
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Did the ecu reset via delphi diagnostics and may Alfa is not fly by wire, throttle reset works only on fly by wire, right???
I did it on mine, and is not fly by wire.
It's the ignition key procedure thing...
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You might be able to reset the throttle with the 90-second on/off sequence as that works on my throttle-cabled car.

But in many cases you need to do the full idle actuator reset on AlfaDiag/MES followed by the 90-sec reset (clearly shows this as part of the process). And sometimes more than once! (reset, 90-secs, try, repeat reset, 90-secs, try .. repeat .. )

I have no idea if Delphi diagnostics will work .. it depends a lot on the age of the car and functions in the diagnostic software and what protocol the Delphi works on. As you have a cable I would think it's the earlier model and you'll need an Alfa-specific diagnostic as the code is so customised it doesn't really look like anything standard it's pre-EOBD and not even OBD-II compatible: more like OBD-I with VAG-COM specifics!

cheers, Gary

HIS: ex-1998 156 2.0 TSpark with Sport Pack 2, sunroof and hi-level spoiler in Alfa Rosso. V6 intake mod, clear side repeaters and Zeatek undertray. 10th Sep 1998 to 12th Jan 2017

HERS: 2009 MiTo 1.4 95bhp Turismo arrived 21st November in Techno Grey with colour-coded headlight surrounds.

My Alfa156 Web Site - how-to's, piccies, links, useful stuff, etc.

Last edited by gazza82; 27-07-16 at 14:31.
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(Post Link) post #12 of 40 Old 30-07-16 Thread Starter
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Tried everything with no solution. Today I drove it to LPG installation and I hope it will e OK and that maybe one injector is the problem and lpg will override it.
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good luck with the lpg conversion. post us some feedback when you are done.
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(Post Link) post #14 of 40 Old 30-07-16 Thread Starter
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good luck with the lpg conversion. post us some feedback when you are done.
Of course! Should be finished by the middle of the next week. Will make pictures and post it.
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(Post Link) post #15 of 40 Old 04-08-16 Thread Starter
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LPG conversion update

I don't know what to do with my car...now it is ten times worse! No power, rough idle, the RPMs stay at 3000 and won't go down, on LPG and on petrol. Now I cannot drive the car at all! Idle is at 1100 rpm, if I put my foot on the pedal i just stays at 4000, 3000, 5000 rpms and sometimes it goes up all by itself! It is driving me mad! Done the ECU reset, nothing. The LPG guy couldn't connect the diagnostics to the car but I can and it showed me injectors fault and lambda. Cleared the errors and it is worse now!
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try unplugging the lambda sensor
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(Post Link) post #17 of 40 Old 04-08-16 Thread Starter
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Originally Posted by alfizta View Post
try unplugging the lambda sensor
Unplugged it, nothing! Two months ago changed the camshaft sensor, unplugged it too, the same, car runs the same without lambda, camshaft position sensor and MAF, only rough idle but over 1500 rpm goes OK. But when MAF connected it now goes to 3200 rpm and that it would be my new idle
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what about disconnecting the injectors one by one?...
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Originally Posted by alfizta View Post
what about disconnecting the injectors one by one?...
If it is on petrol, if I disconnect first one there is noticeable difference, also with other three but there is also change in revs when it is running on LPG, which got me thinking, maybe the lpg and petrol runs together???
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I think LPG engines run on petrol at least on start up and maybe until engine warms up.
do you remember which injector was causing the error code in the ecu?
I would get injectors examined. I think is not expensive.
some people here have LPG converted 156 and 147s. maybe you get some help from them.
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also that taped intake sleeve after the maf... are you sure it isn't leaking? I would get a new one.
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(Post Link) post #22 of 40 Old 05-08-16 Thread Starter
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Yes, when it gets warm it goes to LPG. All injectors showed errors. Will check for air leakage.
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yes, check that intake first, then...
i find it too much coincidence for all the 4 injectors to be faulty. maybe you have a fuel pressure,delivery issue. fuel pump or fuel vapour recovery valve...
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and then relays and connections related to injectors, fuel pump,...
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(Post Link) post #25 of 40 Old 05-08-16 Thread Starter
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I have managed to reset the ECU, now it is back to square one, rough idle and hesitation. I have made a video that shows what is currently happening to my 156.

https://youtu.be/N-kOwE6jQi8

Very similar to the video I posted in the first post. Maybe there is an air leak in the inlet manifold?
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