Alfa Romeo Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
Hello!

car details:
Alfaromeo 156 1997
2.0 TS


So just couple of hours ago got my car fail the emissions test.

I have replaced the lambda sensor about one year ago, and the cat yesterday. Before the cat replacement the lambda sended really garbage data (voltages between 300 - 500mV) and now (more like pwm) -100mV - 1000mV.
Also now it idles much more smoother at around 850rpm, (before it was shifting between 700 - 1100rpm). I can't feel any problems regarding to performance, so the car accelerates normaly, doesn't seems like it might stall, and so on.

only errror code that shows up (before the cat replacement there was always 3 codes, regarding to lamda sensor (integrator over upper limit, intermittent, lambdasond intermittent) but now I only get the "integrator over upper limit, intermittent"

the guy who tested the mot, said that there might be issue with ignition. I have changed the sparkplugs year ago. the idle sounds like that might be the case because its not steady, but more like (
) (the first part, and not my video or car) but not as bad as on the video...

waiting if someone knows more about this...
 

·
Registered
Joined
·
17 Posts
Hi, have the same issue with a jts at the moment. Fault codes for lambdas, so I replaced sensors and cat, but still failed the test. It looks now as if there is an issue with the MAF - just check the connection, clean sensor carefully with contact cleaner and try again. Might be a faulty wire or connection on the way to the ECU, though. H
 

·
Registered
Joined
·
235 Posts
I've written about this before - check your MAF sensor - Ideally try one that you know is working OK. When I had my TS I had a 'lumpy engine', the fault code pointed to lambdas not performing. But as I had it explained by a wiser person that I, if the MAF is not good and throwing garbage data/mixture into the engine management, the lambdas will never cope with incorrect balance as it comes out so shows the error.
 

·
Registered
Joined
·
410 Posts
Wow, 1997 that is older than my 1998 2.0TS. I read/maybe it was just a dream that MAF sensors do age badly, and so all cars with a MAF have some way to compensate for an elderly MAF. This means you need to reset the learned calibration values, and let the ECU figure out new values based on the lamda. Of course this only works if there are absolutley no air leaks upstream of the lambda, and of course no air leaks downstream of the MAF. The CF3 has a pair of lambdas close the engine before the primary cats which helps a lot, but our older CF2 engines only have one lambda, far away, so much more possibiliy of oxygen ingress, you only need a tiny, tiny split in the exhaust to let air in, and 1% air in will upset the learning. So try reseting the cal. values and take the car for an italian tune-up. The Idle position will be reset too, so you might need a bit of accelerator to start it the first time after a ECU reset. The ECU should be able to fix itself given enough time, but the reset will get thing moving considerably faster. Let us know how you get on, and of course if the MAF is really old, it may be outside the calibration range of the ECU altogether, but it sounds to me like you just had a failed sensor, and the ECU needs a bit of learnin'
 

·
Registered
Joined
·
3,358 Posts
How much did it fail by? Do you have the numbers from the part of the test it failed. Was it miles over (indicating a problem to be fixed) or was it only just out.....indicating that a dam good thrashing is needed before the next test!....which is exactly what was needed to get my 159 through the test. Went from being miles over the limit to miles under after a 5 mile thrashing on the A27!
 

·
Registered
Joined
·
9,178 Posts
What make is the lambda? If it's an NTK one .. bin it! Fit a Bosch even the LS615 universal is better that the NTK rubbish (wrong ohm rating to start!).
 

·
Registered
Joined
·
100 Posts
700-1100 rpm is what my brother referred to as "hunting" he had a heavily tuned subaru impreza and the exact same issue occurred, 100% the MAF sensor, once replaced the car idled and fuelled correctly (they only lasted about 5 weeks, but still) so get that replaced, as above.
 

·
Registered
Joined
·
2 Posts
Discussion Starter #8
Okay, thanks for the answers, now I'm going to test the maf values, amd then try to clean it, and measure the values again

The lambda is bosch original.

The values that were wrong were at 2000rpm

CO measured 1.2, accepted 0.2
HC ppm measured 615, accepted 100

I have no clue what the units are...

And how I can reset the ECU?
 

·
Registered
Joined
·
410 Posts
High CO and HC means you are running rich, its usually the other way with intake air leaks. Have you tried to remove the pipe from the air cleaner to the MAF, just to be sure the filter isn't blocked?

The CO is usually by % partial pressure (volume).

I just watched your video again, and it sounds a lot like you are missing on one cylinder. While the car is running you can try disconnecting one of the PRIMARY control plugs to a single spark module. Obviously don't try with the secondary or you'll get a nasty high voltage shock. The CF2 is different to the CF3 since the coil packs are wired up for redundancy, I think 1,4 and 2,3 . Anyway when you remove one of the coil packs from the equation the engine idle should fall by 100 rpm for a bit, but the important thing is that all the coilpacks do the same, If not you have a bad coil pack or spark plug or plug lead or plug resistor. I had a few issues with mine, and carefully removed all the packs and resistors and cleaned them with WD-40. Top tip when you are removing a connector from a live coil pack do it with one hand, keep the other one behind your back, then if you get a shock it does not go accross your chest, you don't want that, it hurts a lot.
 
1 - 9 of 9 Posts
Top