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Discussion Starter #1
Hi guys, Exhaust advice needed..

It seems the cat of my car has been completely removed by previous owner. No regulations here, no problem..

But the engine is very growly, "gargle" noise, when pressing at low revs, and seems slow to respond. This is most noticeable at stop start, in which I can't make the wheels spin at all. Higher than 3k, engine seems to respond actively and normally.

I could get a new cat, if that really is the issue, but maybe there are other ways? I've been looking for a 2nd hand one for a year now and still no results - getting tired of this!

Calling on your expertise.. I wish to have a more snappy engine and maybe save on petrol by making my exhaust proper.
 

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Do you have the CF2 AR32301 engine of the CF3 AR32310 engine?
 

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Discussion Starter #4
High end power seems good, same as original according to my comparison test with other local 156's.. It sounds louder than the original.. I would describe it as untamed. But don't think I have more power than the original... Low end clearly has less power as the wheels don't spin.

I can't remember my engine model. here we refer to what I got as "outside" engines. I can't trust the engine bay tag because seems the engine was replaced on mine.. But based on this website, I have the CF3 type exhaust system: http://www.vito03.com/media/exhausts/9b4166e3.jpg that fits AR32310. I'll check for sure later..
 

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Discussion Starter #5 (Edited)
Why do you ask David C?

Im not sure how to determine the engine model except with the exhaust. I see many alfas at my friend's shop. Some have the mesh thing in their exhaust but I don't. I know I have the CF3 exhaust. Unless it is possible I have an exhaust manifold that converts between models...

Bottom line is I know racers remove the cat to get more flow and more power. So what's wrong with my car then? Or maybe the power is actually lower and low rpms?
 

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best way to tell is have a look from underneath.

you see on that pic you posted the left most part that would connect to the manifold has two large round chambers on it, these are two small cat converters. you will then note on that picture that it then feeds into another larger cat converter.

so if you car has 3 cats, like that picture, you have a CF3 car. if your car just has 1 converter, you have a CF2 car.
 

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Take and post a picture of your exhaust system from underneath car and also one for manifolds.
Also send ecu number from sticker of ecu that starts 0 261 xxx xxx :)
 

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Discussion Starter #8
As I said, I got the CF3 exhaust system. The injection ECU is Bosch Motronic Me7.3.1 (Outside EU version) but that is used on a wide range of cars I suppose.

I'm wondering if I can diagnose the problem by reading the O2 sensors from the 1st cat (using fiatecuscan). There are many sensors I could use. And I can compare on other 156's at the shop too. But I am running blind and need your insight!
 

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As I said, I got the CF3 exhaust system. The injection ECU is Bosch Motronic Me7.3.1 (Outside EU version) but that is used on a wide range of cars I suppose.

I'm wondering if I can diagnose the problem by reading the O2 sensors from the 1st cat (using fiatecuscan). There are many sensors I could use. And I can compare on other 156's at the shop too. But I am running blind and need your insight!
if you got FES why not just read fault codes in ecu:rolleyes:
 

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Discussion Starter #11
Okay..

I just read the errors and I got Warning: Low engine power. Switch off engine do not proceed. Go to the dealer.

:p There are no errors for my problem, silly! But it's a good point, I should have mentioned I have 2 warnings even though they are not related: Canister Purge Valve and Knock Sensor*. Are you saying if I had invalid values at the 02 sensors, something would pop up? If that's the case, my 02 sensors are fine.

Even though it is a selespeed, other 156's I tested can spin their wheels. Mine can't (well except when the wheel is turned at a high angle, if you can picture what I mean). Maybe exhaust has no performance impact? Maybe it is another factor? Clutch position? Checked, adjusted, replaced sensor.

*OffTopic: The valve is not too important anyway and the knock sensor is not exactly easy of access.. the risk of breaking something outweighs the possible benefit of fixing it. I opened a thread about it a year ago, still not sure what is that sensor or error. It is deep in my todo list.
 

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Okay..

I just read the errors and I got Warning: Low engine power. Switch off engine do not proceed. Go to the dealer.

:p There are no errors for my problem, silly! But it's a good point, I should have mentioned I have 2 warnings even though they are not related: Canister Purge Valve and Knock Sensor*. Are you saying if I had invalid values at the 02 sensors, something would pop up? If that's the case, my 02 sensors are fine.

Even though it is a selespeed, other 156's I tested can spin their wheels. Mine can't (well except when the wheel is turned at a high angle, if you can picture what I mean). Maybe exhaust has no performance impact? Maybe it is another factor? Clutch position? Checked, adjusted, replaced sensor.

*OffTopic: The valve is not too important anyway and the knock sensor is not exactly easy of access.. the risk of breaking something outweighs the possible benefit of fixing it. I opened a thread about it a year ago, still not sure what is that sensor or error. It is deep in my todo list.
what are error codes that are showing on FES? i got a feeling you may have an ecu problem
 

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Discussion Starter #13
I was joking! :eek:

Please check my post again carefully. I have 2 warnings but not related to engine performance.. I think.

If you have an idea, please elaborate. I'm quite dumb, I didn't get your point...
 

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Discussion Starter #14
Ok, looks like I'll have to fix this the hard way.

I'll compare fuel, airflow, lambda, etc with a normal car. Make sure all cats are good. I'll fix knock sensor and canister purge valve too.

I should be done in 1-2 years.
 

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Discussion Starter #16
I never found any info on knock sensor. Please give me any info you have; I think knock sensor fault indicates engine knocking and possibly a spark issue, which triggers the ecu to maybe change timing and increase the electricity sent to the sparks?

What I got is a sensor no signal, not an actual error. I would notice engine noise, I suppose.

For my low power/gargling noise issue, without any leads I'll check temp/fuel/air sensors and get back to you.
 

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If the ECU knows the knock sensor is not working it is quite likely that it will automatically use a default and very conservative ignition timing to protect the engine. That will affect performance so I suggest that you fix the knock sensor before proceeding.

This may be bull but a defective sensor needs replacing before any other fault finding.

Someone here may also know if a new knock sensor will need ECU reset procedure to be instantly effective.
 

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Modern cars will advance the ignition timing until the knock sensor does it's job. Once a "knock" is sensed the timing is automatically retarded slightly. This allows cars to run optimum timing regardless of what fuel is used or other loads are on the engine.

So, as above, if the ECU knows the knock sensor is defective I suspect it will use a very conservative ignition map that would protect the engine regardless how poor the fuel quality is. Remember there is far worse fuel in the world than we buy so the map would have be very conservative.

However, I am not an ECU expert and do not know that this is what it would do if the knock sensor was defective but I would be surprised if it didn't.
 

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I was joking! :eek:

Please check my post again carefully. I have 2 warnings but not related to engine performance.. I think.

If you have an idea, please elaborate. I'm quite dumb, I didn't get your point...
what are your codes read by fiatscanecu:rolleyes:
 
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