General No increase in revs whilst accelerator depressed.

Drammy

New member
Joined
Aug 11, 2008
Messages
30
Hi all,

I am having a prbolem with my Fiat Bravo 1.4 S (S reg).

It started with the car stalling a lot. I changed the throttle body. A garage found the following faults in the ECU and also changed the lower manifold as it was cracked.

Control module diagnosis FIAT Motronic MA 1.7.3 Error Memory
463A - Immobilizer Engine Control Unit - Blocked
0203 - Speed/reference-mark sensor - no signal
FFFF - Control Unit Knock Control Module - Faulty

I changed the Crank Sensor on further advice from this forum.

The car is better (the manifold replacement helped the most) but it still stalls a bit and a further issue has developed...

With the car in my garage I start it up and leave it idling / rev it a bit. Eventually the ECU error light comes on. When the light is on I press the accelerator and the car revs up I then release the accelerator and the engine gently drops in revs, if I press the accelerator again before the revs have reached idle then there is no increase in revs at all.

Eventually the revs drop to idle (foot still on accelerator) and all of a sudden the throttle kicks in and the revs increase again. I can do this repeatedly whilst the ECU light is on.

The accelerator cable is obviously opening the valve but its as if there is no mixture passed through until the revs reach idle.


Has anyone got any ideas what the issue could be as its causing a complete loss of drive whilst out on the roads.

Any help appreciated...

Drammy
 
OP
OP
D

Drammy

New member
Joined
Aug 11, 2008
Messages
30
Thanks for the suggestions Steve.

Can you/anyone provide links to resources to read up on these parts?
 
OP
OP
D

Drammy

New member
Joined
Aug 11, 2008
Messages
30
Is there another name for the MAF sensor?

On shop4parts I can only find an air flow sensor but only for the JTD engine and can't find any equivalend part for the 1.4 engine...
 

Steve H

New member
Joined
Sep 19, 2008
Messages
81
Location
Midlands
Might be MAP sensor on those engines not MAF :eek:

Speed/Reference mark sensor, will look this up asap, thought that was crank sensor? But you changed that?

Jug is pretty good with the electrics side of the fiats, try PM'ing him?
 
OP
OP
D

Drammy

New member
Joined
Aug 11, 2008
Messages
30
Hi Steve,

Yes, I changed the crank sensor.

I have tried PMing Jug but it appears I am not the only one - his message folder is full. I will keep trying.


Thanks again,
Drammy
 

jug

blessed are the apostates
Joined
Nov 28, 2005
Messages
13,807
Location
Durham
light still on means the ecu is still detecting a fault.

we know the immob code cant be the problem, and you've replaced the crank sensor, so that leaves the 3rd code. the "knock control module" (aka knock sensor) may be faulty. the knock sensor is needed to adjust ignition timing. a fault will make the ecu run at default "safe" timing (10degrees retarded), which causes a loss of performance and economy. your lack of throttle response could be explained by that.

try replacing the knock sensor, its fitted to the back of the block between cylinders 3 and 4.

if that fails to fix it and the light remains on then the garage have not obtained all the codes during their diagnosis, or there is a fault in the crank sensor or knock sensor circuits.

I have tried PMing Jug but it appears I am not the only one - his message folder is full. I will keep trying.
whoops. i must have at least 30 email notifications telling me my box is full :eek:

i'll go delete a few now.
 
OP
OP
D

Drammy

New member
Joined
Aug 11, 2008
Messages
30
Thanks jug,

Where can I get a knock sensor from? Shop4parts don't seem to stock them...
 

jug

blessed are the apostates
Joined
Nov 28, 2005
Messages
13,807
Location
Durham
personally i'd go to a scrapyard, it'll be a fiver at most.
 
OP
OP
D

Drammy

New member
Joined
Aug 11, 2008
Messages
30
Oh, OK, so I don't need to get underneath the car to extract it then?
 

jug

blessed are the apostates
Joined
Nov 28, 2005
Messages
13,807
Location
Durham
no, you'll be able to reach down the back of the engine to get it.
 
OP
OP
D

Drammy

New member
Joined
Aug 11, 2008
Messages
30
Just wanted to say thanks to everyone for their help, especially jug.

I changed the knock sensor and the car is now driving well again. I also changed the throttle body again. One of these two fixes resolved the issue.
 
Top