Register Login
Save up to 15% with Adrian Flux insurance!
Reply
 
Thread Tools
Old 24-05-2007   #1
Join Date: Jan 2006
Location: Silkeborg
Posts: 140
Thanks: 3
Trader Rating: 0
Denmark 
To low rpm at warm idle, RPM sensor?

Hi.

These idle problems drives me nuts .
First the engine idles like scrap all the time (To low charging voltage)
Then the idle is low all the time followed by too high Co readings (Lambda probe)
Now it idles fine at cold start and during warm up, but when engine reaches working temp, the idle speed is below 500 rpm, but steady.
I read some where that the ECU uses coolant temp for setting idle speed during cold start and warm up, when the engine is warm it uses the RPM signal from the TOD sensor.
So in my case it could be a defective TOD sensor, or could it?
The RPM reading on the dashboard is OK, doesn't is use the same sensor?
How does a engine run without the TOD sensor? My guess it would have problems with ignition timing causing missfires.

Any advise would be great, i'm lost in this bad idle problem...
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides


Last edited by Migaard; 24-05-2007 at 20:53.
Migaard is offline Reply With Quote Quote 
Old 24-05-2007   #2
Forum Moderator
 
T14086's Avatar
Join Date: Sep 2004
Location: Preston
Posts: 29,985
Thanks: 1063
Trader Rating: 0
T14086 has donated!
United Kingdom 
Re: To low rpm at warm idle, RPM sensor?

Tod?
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

T14086 is offline Reply With Quote Quote 
Old 24-05-2007   #3
Bravo 155 HGT
Join Date: Aug 2006
Location: Ayr, Scotland
Posts: 3,115
Thanks: 10
Blog Entries: 3
Trader Rating: 1
mountainmachine has donated!
Beach Bobbing Bob Champion, War on Iraq Champion
United Kingdom 
Re: To low rpm at warm idle, RPM sensor?

Hi mate what engine?
__________________
mountainmachine is offline Reply With Quote Quote 
Old 24-05-2007   #4
bairns, not bombs.
 
Venters's Avatar
Join Date: Jun 2006
Location: Hades by the River Styx
Posts: 8,701
Thanks: 377
Trader Rating: 0
Venters has donated!
United Kingdom 
Re: To low rpm at warm idle, RPM sensor?

Quote Originally Posted by mountainmachine View Post
Hi mate what engine?
1.6
__________________
Venters is offline Reply With Quote Quote 
Old 24-05-2007   #5
Bravo 155 HGT
Join Date: Aug 2006
Location: Ayr, Scotland
Posts: 3,115
Thanks: 10
Blog Entries: 3
Trader Rating: 1
mountainmachine has donated!
Beach Bobbing Bob Champion, War on Iraq Champion
United Kingdom 
Re: To low rpm at warm idle, RPM sensor?

Cool now we just need to find out what this TOD sensor is, even google doesnt know!
__________________
mountainmachine is offline Reply With Quote Quote 
Old 24-05-2007   #6
bairns, not bombs.
 
Venters's Avatar
Join Date: Jun 2006
Location: Hades by the River Styx
Posts: 8,701
Thanks: 377
Trader Rating: 0
Venters has donated!
United Kingdom 
Re: To low rpm at warm idle, RPM sensor?

It's proberly a sensor we all know but abbreviated in Danish!
__________________
Venters is offline Reply With Quote Quote 
Old 24-05-2007   #7
Forum Moderator
 
T14086's Avatar
Join Date: Sep 2004
Location: Preston
Posts: 29,985
Thanks: 1063
Trader Rating: 0
T14086 has donated!
United Kingdom 
Re: To low rpm at warm idle, RPM sensor?

I reckon he means camshaft sensor.




Or crankshaft sensor
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

T14086 is offline Reply With Quote Quote 
Old 25-05-2007   #8
Join Date: Jan 2006
Location: Silkeborg
Posts: 140
Thanks: 3
Trader Rating: 0
Denmark 
Re: To low rpm at warm idle, RPM sensor?

Sorry guys, i missspelled it, it's the TDC Sensor.
(The crankshaft position reference).
The engine is a 1,6 16V.
Michael
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides


Last edited by Migaard; 25-05-2007 at 19:30.
Migaard is offline Reply With Quote Quote 
Old 25-05-2007   #9
Forum Moderator
 
T14086's Avatar
Join Date: Sep 2004
Location: Preston
Posts: 29,985
Thanks: 1063
Trader Rating: 0
T14086 has donated!
United Kingdom 
Re: To low rpm at warm idle, RPM sensor?

Unlikely to be crank sensor,more likely HT misfire or air flow problem/leak.Have you changed timing belt recently?
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

T14086 is offline Reply With Quote Quote 
Old 25-05-2007   #10
Join Date: Jan 2006
Location: Silkeborg
Posts: 140
Thanks: 3
Trader Rating: 0
Denmark 
Re: To low rpm at warm idle, RPM sensor?

Hi T14086.
The timing belt was chaged last year by a Fiat garage.
But it has run OK a periode after the change.
Do you know if the TDC sensor is used for displaying the RMP on the dashboard?
If it's a HT problem or a airflow problem wouldn't it be present during cold start and warm up?

Michael
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

Migaard is offline Reply With Quote Quote 
Old 25-05-2007   #11
Forum Moderator
 
T14086's Avatar
Join Date: Sep 2004
Location: Preston
Posts: 29,985
Thanks: 1063
Trader Rating: 0
T14086 has donated!
United Kingdom 
Re: To low rpm at warm idle, RPM sensor?

At start up the auto choke is on,does the engine light come on(has been on)?

Is there a misfire or just poor idle(motorised throttle fault probably/map sensor/air leak)
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

T14086 is offline Reply With Quote Quote 
Old 25-05-2007   #12
Join Date: May 2007
Location: Dublin
Posts: 51
Thanks: 0
Trader Rating: 0
Ireland 
Re: To low rpm at warm idle, RPM sensor?

if its noisy while idleing it is possibly pinking which is an ignition problem. 2 possible causes are 1) problem with the octane level of the fuel and 2)if the engine is running hotter than usual.
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

MickDev is offline Reply With Quote Quote 
Old 26-05-2007   #13
Join Date: Jan 2006
Location: Silkeborg
Posts: 140
Thanks: 3
Trader Rating: 0
Denmark 
Re: To low rpm at warm idle, RPM sensor?

Hi.

No, the engine symbol hasn't been on since the lambda probe was replaced a month ago.
The engine doesn't misfire...
Everything is normal except from this one problem.
The Fiat workshop manual (by Fiat) states the idle speed is set by the ECU using the TDC sensor when the engine is warm.
But it looks like it's the same sensor that the ECU uses to display RMP at the dashbord... So it seems like it's not the problem.
The ISCV motor was tested a few months ago, working fine.
I guess it's also the ISCV motor that raises the idle speed when the engine is cold, and that works OK.
Is there an easy way to determine if the engine is taking false air somewhere in the intake?

Michael
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

Migaard is offline Reply With Quote Quote 
Old 29-05-2007   #14
jug
blessed are the apostates
 
jug's Avatar
Join Date: Nov 2005
Location: Durham
Posts: 13,806
Thanks: 554
Trader Rating: 1
jug has donated!
United Kingdom 
Re: To low rpm at warm idle, RPM sensor?

Quote Originally Posted by Migaard View Post
Is there an easy way to determine if the engine is taking false air somewhere in the intake?
that cant be happening, a vacuum leak would cause high idle.

have you tried cleaning out the throttle body?

when cold the iscv will bleed air in, allowing a decent idle rpm to be achieved, but once the coolant temp sensor tells the ecu that warm condition has occured, the iscv goes to normal position, which is then not allowing enough air in with butterfly valve in closed position. give the throttle body a good clean out, you'd be very surprised how often this is the cause of low idle rpm on fuel injected cars.
Likes Mamdouh liked this post
__________________
2.0 twinspark veloce

Last edited by jug; 29-05-2007 at 15:50.
jug is offline Reply With Quote Quote 
Reply
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump
Similar Threads
Thread Thread Starter Forum Replies Last Post
(T) X1/9 stalls low rpm - runs fine high rpm erisajd X1/9 6 18-01-2005 03:06
(T) sensor fault low fuel slight return andy thrill Stilo 6 28-10-2004 10:28
(T) [Tipo 1.6 ie 94] Injection light and idle Malex Tipo (Classic) 1 28-07-2004 21:18
(T) low idle? mackett Cinquecento / Seicento 1 18-02-2004 19:46
(T) 1975 Fiat Spider- Stammers at low rpm under load stahara 124 Spider (Classic) 2 05-11-2003 17:57