Workshop Couldn't Figure It Out... Engine Beeing Jerky And Using Alot Of Fuel

[Norlig 1]

Good day, got suggested this site from a forum member on Alfaowner.com, I have been having problems with my engine for maybe 5-6 months now, Car is an Alfa Romeo 156 1,6TS 2000mod CF2, throttle is controlled by a wire.

 

These threads sum the issue up pretty much:

Sketchy Throttle when cruising

Car been at workshop for 4 weeks

Should have bought a new car

 

 

TLDR: The issue with the car is that when I Cruise down the road, the throttle is jerking me at random times, it can go from fine, to suddenly jerking quite hard. Although it appears to only happen when the gas pedal is only slightly engaged, if I am accelerating hard with the pedal pushed down, it goes fine.

 

When the engine is idling, the RPM can drop to as low as 450 RPM, then rise back to 1000 then drop down again to 450, up down up down.

, but this was when playing with the throttle, gently pushing it, but the same happens at idle, but then it can stop and idle normally again, its usually after I have driven and come to an intersection and have to push the clutch pedal.

 

Sometimes, when I want to accelerate howevere, the engine will sort of die out, I then have to first let go of the gas pedal so it will go back to idle, hit the clutch and then gas up the RPM to have enough power to get moving.

 

The engine is using alot of fuel, and I have looked for air leaks, and so did the workshop, but we did not find any, The MAF I have recently cleaned, and I have also gone as far as swapping out the ECU,

 

I have gone out of my mind trying to figure this out, I Love the car and to drive it, but this engine is so disheartening at the moment.

 

Any help would be highly appreciative, thanks!

Edited October 19, 2013 by Norlig

[flyblo5 17]

Don't panic, just wait for smaky to apear and all will be well.

[Gibot123 16]

Are you getting any fault codes at all for injectors or anything else.

What have you done so far .

Have you checked the air by pass valve on the plenum chamber. It has a spring return valve in side if the spring is week it won't function properly and this could be part of the problem . It's a small black plastic housing with an air flow pipe attached . You need to pop it off and inside there should be a plastic valve with a spring sometimes the spring gets weak and the valve won't stay where it needs to to allow the engine to idle properly.

You can but a repair kit from the dealer at about £7 I think .

Hope this helps.

I'm sure Smaky will have some other thoughts on this too.

Have you checked the injectors for condition and leaks .

[Norlig 1]

Are you getting any fault codes at all for injectors or anything else.

What have you done so far .

Have you checked the air by pass valve on the plenum chamber. It has a spring return valve in side if the spring is week it won't function properly and this could be part of the problem . It's a small black plastic housing with an air flow pipe attached . You need to pop it off and inside there should be a plastic valve with a spring sometimes the spring gets weak and the valve won't stay where it needs to to allow the engine to idle properly.

You can but a repair kit from the dealer at about £7 I think .

Hope this helps.

I'm sure Smaky will have some other thoughts on this too.

Have you checked the injectors for condition and leaks .

 

The only day fault code I get is for the lambda sensor, but that is because of problems earlier in the cycle I think. The sensor is only a year old. It reports a lean status almost constantly though and values stop to below 200mV for a split second sometimes. So I'm not sure about it actually.

 

The valve with the spring you speak of, is this the oil seperator valve next to the throttle body? If so the workshop checked it and didn't find any faults with it. If not, where is this located? (Plenum chamber?)

 

this Smaky guy sounds nice

Edited October 19, 2013 by Norlig

[alfizta 6]

HI Norlig! the valve Gibot is refering to is the one on this Gazza's article, the oil separator valve or crankcase breather valve, shown on the first 3 pictures.

http://greenserpent..../idle_saga.html

 

the coil should be at least 1 cm long. I also checked mine, gave it a cleaning, and streched it a bit, about 2 mm longer, just enough to make sure valve closes completely. be carefull not to lose any valve parts. they are small and easy to fall into the engine bay.

 

you don't need to take off the hose clip to do this check, just unclip the end of the valve from the intake manifold.

Edited October 20, 2013 by alfizta

[alfizta 6]

top Smaky guide here too

http://www.alfadriver.com/forum/index.php/topic/1510-guide-breather-valve-replacement/

[Norlig 1]

That is indeed the part that the workshop said that they had looked into, and did not find any issues with. I linked them Gazza's post to make sure as well.

[Smaky 73]

But this fault is more likely to be a split air intake duct, MAF , oil at the plugs or Lambda, if you have no fault codes and you can garentee the ducting has ABSOLOUTELY no splits or gaps, inspect the spark plug wells for oil, if that is all good and clean then replace the MAF..

[Norlig 1]

But this fault is more likely to be a split air intake duct, MAF , oil at the plugs or Lambda, if you have no fault codes and you can garentee the ducting has ABSOLOUTELY no splits or gaps, inspect the spark plug wells for oil, if that is all good and clean then replace the MAF..

 

I do get an error code for the lambda, but took it as an issue from earlier in the engine. I'll post the error code tomorrow. Both the MAF and lambda is just over a year old, but I see how it could be the lambda as I don't think it's original. The MAF is bosch though.

 

I thoroughly looked through the pipe between the MAF and throttle body for tears, I found none.

 

I will check the Wells for oil, when I changed the plugs a year ago, the one furthest left had some in that, but seller said it was because of him spilling when he filed up the oil.

[Norlig 1]

error code:

 

 

The lambda is showing as going very low for a good period of time, and also going very high,

 

 

 

It is mostly when I release the gas pedal, or only slightly move above idle (cruising) it that I notice jutterings and bad behavior.

 

Also when in traffic, when in a queue I want to move forward and I rev the engine to get going, when I have have gotten to a point where I release the clutch fully the car will sort of halt for a small moment and then keep going

Edited October 22, 2013 by Norlig

[alfizta 6]

well, if the lambda is not bosch, unplug it, and try running the car. check if she gets better. it's a very easy task. black connector next to the white one on back of engine bay. that's my last drop

[Norlig 1]

I'll unplug it before I drive home from work and see if there is an improvement

[Norlig 1]

Driving home, I was suprised how smooth it was. It Didn't jutter or feel weird when cruising, rpm's wasn't doing below 800.

 

But then I stopped to get my mail and I heard the engine rpm fall low and the engine shake.

I got in and started to drive the 100m left to the house and it was really juttering and rpm was going low and car shaking.

 

This car...

[alfizta 6]

:\ try it again, you won't loose anything.

[Smaky 73]

Driving home, I was suprised how smooth it was. It Didn't jutter or feel weird when cruising, rpm's wasn't doing below 800.

 

But then I stopped to get my mail and I heard the engine rpm fall low and the engine shake.

I got in and started to drive the 100m left to the house and it was really juttering and rpm was going low and car shaking.

 

This car...

 

I would say it was the Lambda, but did you do a proper ECU reset? Not just the 90 second crap.

[Norlig 1]

 

 

I would say it was the Lambda, but did you do a proper ECU reset? Not just the 90 second crap.

 

Should I reset all self adaptive parameters by connecting my laptop to it, or should I disconnect the battery for 45mins. Let idle 15 then drive it?

 

What defines an ecu reset?

[Smaky 73]

well, if the lambda is not bosch, unplug it, and try running the car. check if she gets better. it's a very easy task. black connector next to the white one on back of engine bay. that's my last drop

 

Bosch Lamdas aren't used on these, ideally they'll be NGK/NTK.

[alfizta 6]

Bosch Lamdas aren't used on these, ideally they'll be NGK/NTK.

I'm shocked! that's new to me!!!always thought they were all bosch and NTK could eventually replace. thanks, thanks!

[Smaky 73]

Should I reset all self adaptive parameters by connecting my laptop to it, or should I disconnect the battery for 45mins. Let idle 15 then drive it?

 

What defines an ecu reset?

 

You need to do this on Multiecuscan, and then run this

[alfizta 6]

Should I reset all self adaptive parameters by connecting my laptop to it, or should I disconnect the battery for 45mins. Let idle 15 then drive it?

 

What defines an ecu reset?

on MES, F7 - Reset self adapt param and idle actuator

just after this TRA and DTV self adapt param should reset to 0, FRA to 1,000. (EDIT: DTV value after reset was wrong)

 

still you have to do the "90 second crap" after, like Smaky says , to recalibrate the idle actiuator.

 

90 second key on MAR position (before ignition)

90 second key off (but key still in)

start the engine and let it idle for 10 min without touching the pedal

 

90 second thing is criticall. repeat procedure if you think it didn't do anything.

 

EDIT: well, like Smaky just posted (embarased)

Edited October 23, 2013 by alfizta

[alfizta 6]

just looked at eLearn manual. it displays 2 possible lambdas for the 1.6 TS feb-2000 to jan-2001.

1) heater resistance 8,5 to 9,5 Ohm, probably bosch

2) heater resistance 3,5 to 4,5 Ohm, probably NTK

you could make sure you got the wrong one by checking both lambdas, old and new, resistances...

 

probably Smaky could explain us which versions are which...

Edited October 23, 2013 by alfizta

[Norlig 1]

thats what I thought, drove to work with no changes from yesterday, it was better than normal, but still not perfect. will also try to reset what you said above before driving home.

 

Thanks!

[Smaky 73]

46750241 is the oem Lambda which was Bosch, it's shared between the 1.8, 2.0 and 2.5 CF2 engines.

 

CF 3 use the later NTK lambda as standard, but either one will work in either engine as the heater test is purely for an open circuit.

[Norlig 1]

The car seems to be behaving when driving now, still want a few more drives to work and home to be sure, but I havent had any major issues like the last 100m home yesterday.

 

I recorded MES while driving home again:

http://www.youtube.com/watch?v=EHFcTP9qfpY

 

When I push in the clutch, this happens:

 

 

From what I can see, the Injection time goes high, then the RPM falls. Then the injection time goes low and the RPM rises. Then injection time rises and RPM falls again.

 

I also checked the Self adaptive values before driving home and when I got home, they did not change at all.

 

 

Also, the desired intake air quantity, and the actual air quantity is really far apart, the desired one really wants to stay way way low for some reason.

Edited October 23, 2013 by Norlig

[alfizta 6]

is lambda sensor disconnected?