Register Login
Shop4Parts - UK's largest online superstore for FIAT and Alfa Romeo parts
Reply
 
Thread Tools Search this Thread
Old 2 Weeks Ago   #1
Join Date: May 2020
Posts: 10
Thanks: 0
Trader Rating: 0
Finland 
First take off jerky on cold starts, no fault codes

Hi

My Linea 2008 with 137k km on clock, has jerky take off on cold starts, especially during summer and is less pronounced on cold weather or with preheated engine. It feels just as if someone was pumping on the gas pedal and it disappears shortly after changing to 2nd gear.


So far i've changed following:
  • spark plugs, spark plug wires, ignition coil pack
  • both lambdas
  • map sensor (which had faulty iat, and now has more power on lower gears)
I've also cleaned the throttle body and the bigger pcv breather pipe which was clogged with mayo (quite normal after winter). I haven't touched that smaller vacuum tube yet. Service history suggests that it had been changed some years ago.


So far no fault codes set, but obd data suggests that it has fuel trim issue with long term and short term trims variating between -100% to 100%. I believe that data to be incorrect though. Fuel consumption is quite normal, 6.5 - 7.0 l /100 km.


Some have suggested it to be a timing problem due to an incorrectly changed timing belt. Also, a burnt valve has been mentioned. I'd think these would cause more trouble.


So has anyone had similar issues with their GrandePunto or Bravo which are almost the same under the hood? How did you get it resolved?
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

eeeno is offline Reply With Quote Quote 
Old 2 Weeks Ago   #2
Join Date: Apr 2011
Location: Near the M4
Posts: 23,102
Thanks: 812
Trader Rating: 0
varesecrazy has donated!
United Kingdom 
Re: First take off jerky on cold starts, no fault codes

Hi.

Which engine?

( we dont get Linea in the UK)

IS IT..
1.2 / 1.4 .. or something more exotic??

I would clear that small hose... at least you can rule it out...

could be clear..could be choked with mayo
Likes jackwhoo liked this post
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

varesecrazy is offline Reply With Quote Quote 
Old 2 Weeks Ago   #3
Join Date: Apr 2018
Posts: 219
Thanks: 42
Trader Rating: 0
Vatican City 
Post Re: First take off jerky on cold starts, no fault codes

Which engine?
0. Read GUIDES section(s) before posting new thread/s.
Plus SEARCH for similar topics (they are out there - for example scroll this page all the way down, you have "Similar Threads" bar/section).
1. Clean small breather hose. It is (not throttle) responsible for idle rpm air. PCV system must be cleaned every year (especially in cold climate).
2. EVAP system solenoid (it's close to the small breather hose intake manifold port), clogged, leaky. It can spoil the idle. Vacuum leak.
3. Valve clearances (by swapping shims in 8-valve engines). Probably never ever done in your car (it can misbehave with no errors).
4. Invest in diagnostic interface + MES program. Check errors and readings from other sensors (temperatures, pressures, positions, lambdas etc.).
Not clear if you already own one or codes were read by "mechanic"?
5. Then timing belt. Small differences will affect the car significantly, but no errors (until it's really bad, skip 1 full tooth or two).
6. Fuel pressure and/or injectors.
7. Other things? Exhaust leak? Auxiliary belt load (AC, alternator) "choking" the engine? Electrical (power, "earthing points" corrosion)?

PS
Why swapping "lambdas"? What about catalytic converter - is it alive?
Why new coils? Who have "diagnosed" this?
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides


Last edited by GrandePunto PL; 2 Weeks Ago at 09:21. Reason: ...SEARCH BEFORE POSTING NEW THREAD !
GrandePunto PL is offline Reply With Quote Quote 
Old 2 Weeks Ago   #4
Join Date: May 2020
Posts: 10
Thanks: 0
Trader Rating: 0
Finland 
Re: First take off jerky on cold starts, no fault codes

It's 1.4 Fire engine without the turbo. I'm sorry for not searching the forums first but not too many threads exist for this issue on this Linea forum. It's a bigger sedan version of GP or Bravo, same stuff inside. I've never had a Fiat before and i'm not familiar with the common faults with these models.


Well you know, DIY guys just change things even when not necessary. The lambdas were responding slower and i could get them 40 each, original Bosch. Sure, it was unnecessary to do at that point. I suspected possible catalyst failure because the previous owner had run the car with quite poor spark plugs. Also the last year's MOT test showed rich mixture within acceptable limits probably due to spark plugs.

Also service history shows that the car had a misfire issue on some cylinders and the fault code was removed. I'd like to think that it's due to leaked oil from valve cover gasket or poor plug at the time. I'd expect to get misfire fault codes if it was still present.


I have been able to check diagnostic data for sensors. I'm not sure about the throttle & pedal position data. Sometimes when the engine's hot, the rpm does not correlate with the gas pedal position, rpms go too high. Even a slight press on the pedal can do that but that's very intermittent. No faults registered yet.


Otherwise idle is very smooth on hot engine. I'll check those when the weather's warmer and can change the valve cover gasket at the same time. Surely the ECU can compensate for many faults and minor vacuum leaks so proper diagnostic equiptment is necessary.


It was losing coolant from thermostat gasket due to faulty pressure cap on coolant reservoir. It hasn't needed any top up for a long time now so i don't think it's the head gasket either.


I was thinking of having the valve clearances adjusted on the next timing belt change after few years.
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

eeeno is offline Reply With Quote Quote 
Old 2 Weeks Ago   #5
Join Date: Apr 2011
Location: Near the M4
Posts: 23,102
Thanks: 812
Trader Rating: 0
varesecrazy has donated!
United Kingdom 
Quote Originally Posted by eeeno View Post
It's 1.4 Fire engine without the turbo. I'm sorry for not searching the forums first but not too many threads exist for this issue on this Linea forum. It's a bigger sedan version of GP or Bravo

Well you know, DIY guys just change things even when not necessary. The lambdas were responding slower and i could get them 40 each, original Bosch.


I was thinking of having the valve clearances adjusted on the next timing belt change after few years.
Your new sensors.. did they have ANY effect?

Resetting valve clearances is pretty involved.. but Checking them is not too bad.. dont wait a long time
Likes jackwhoo liked this post
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

varesecrazy is offline Reply With Quote Quote 
Old 2 Weeks Ago   #6
Join Date: Apr 2018
Posts: 219
Thanks: 42
Trader Rating: 0
Vatican City 
Re: First take off jerky on cold starts, no fault codes

With 12 years and 137000 km, you need to check it first. "Now" (this year). Some valves may need adjusting.

Car was (like most of the cars in the world) neglected/abused by previous owner ("let's just drive until something breaks" strategy).
But it's still salvageable with some maintenance. Fight. Don't quit.
As for electronics troubleshooting, check this guy out: https://www.youtube.com/user/ScannerDanner/videos
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides


Last edited by GrandePunto PL; 2 Weeks Ago at 10:04. Reason: Go. Fight for it.
GrandePunto PL is offline Reply With Quote Quote 
Old 2 Weeks Ago   #7
Join Date: May 2020
Posts: 10
Thanks: 0
Trader Rating: 0
Finland 
Re: First take off jerky on cold starts, no fault codes

Wouldn't valve clearance issues like power loss be present at all times, not just with cold engine? Idle is very smooth, although when engine is cold it has a slight knock and sounds like diesel engine. Some suggest that slight knock on cold engine is common to Fire engines. Cold engine idles well starts a bit elevated 1600 rpm, then drops to 1100 rpm, hot engine at about 800 rpm. All smooth. Map sensor change made the cold idle more quiet.


This problem is only momentary, only for a short distance like 100 metres after first take off and then throttle is responsive, no power loss.


It was very difficult to see much change after changing the lambdas. They were just old and sluggish and had deposits on them. Catalyst is probably fine. I will know after the next MOT.

Maybe I should have the valves adjusted then. It would be doing about 10 k km a year anyway so, I was not thinking of taking it to the garage for the valve adjustmet yet. Maybe that just needs to be done before I change every part in the car without getting it fixed.
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

eeeno is offline Reply With Quote Quote 
Old 2 Weeks Ago   #8
Join Date: Apr 2017
Posts: 2,307
Thanks: 158
Trader Rating: 0
United Kingdom 
Resetting valve clearances is pretty involved.. but Checking them is not too bad.. dont wait a long time [/QUOTE]

It is quite cheap and straightforward to check your valve clearances yourself. Then you will know if they need adjustment or not, they may well be fine and not require adjustment. Checking yourself could save you some money.
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

jackwhoo is offline Reply With Quote Quote 
Old 2 Weeks Ago   #9
Join Date: Apr 2017
Posts: 2,307
Thanks: 158
Trader Rating: 0
United Kingdom 
Re: First take off jerky on cold starts, no fault codes

When engine cold before first start in the morning please use your obd reader and post what the ecu reads as the coolant temperature. Plus tell us roughly what the ambient temperature is where you are.
Is the car inside overnight or outside?
Do You live in Finland?
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides


Last edited by jackwhoo; 2 Weeks Ago at 10:41.
jackwhoo is offline Reply With Quote Quote 
Old 2 Weeks Ago   #10
Join Date: Apr 2018
Posts: 219
Thanks: 42
Trader Rating: 0
Vatican City 
Re: First take off jerky on cold starts, no fault codes

Valve clearances have different impact in different temperatures (it is not equal when cold and hot). Plus, transition (clearances) from cold to hot is not linear.

"Deposits" on the lambdas? How about sparkplugs? Google (pictures): "sparkplugs wear chart" or similar entry. You judge engine by the plugs look.
This engine could be another victim of the "long-life" oil change strategy (marketing slogan). Full of sludge, tar inside, black goo.

It can be little bit of everything: valve clearances a bit off (2-3 valves maybe, not all of them), little deposits here or there (on the pistons and rings too), some sensor is still misbehaving, a little vacuum and/or exhaust leak (or restriction), timing up to 1-2 degrees out (it will not flash CheckEngine).
Likes varesecrazy, Bernievarian liked this post
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides


Last edited by GrandePunto PL; 2 Weeks Ago at 11:16. Reason: GOOGLE sparkplugs look, wear.
GrandePunto PL is offline Reply With Quote Quote 
Old 2 Weeks Ago   #11
Join Date: May 2020
Posts: 10
Thanks: 0
Trader Rating: 0
Finland 
Re: First take off jerky on cold starts, no fault codes

Thank you everyone for your invaluable ideas. The car's service history suggests that it had regular oil changes done between 10k-15k km each year. It doesn't require any fancy oil, just any cheap regular 5w-40 synthetic will do just fine.


Driveablity is actually good. I'm actually going to change the whole thermostat housing with the new temperature sensor because i couldn't find the gasket anywhere. The idea of incorrect enrichment due to misbehaving temp sensor is a good one. The data from previous diagnostics shows that the sensor was giving correct readings when engine was already warmed up but i never got the car to misbehave while using the scanner. But i'm going to do just that. I've not suspected this sensor because the car starts fine always.


I have cheap elm327 bluetooth thing with "Car scanner" android app. It can't access can bus data but the things that i can read with it can be useful. Surely MES- license and proper equipment could save me some money too.


If one would have done everything by the book, it says valve clearance checks every 30k - 60k km. But who does that? Nobody. It's actually a nice car and i'm going to keep it for several years unless it breaks completely. Yes I'm in Finland.
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

eeeno is offline Reply With Quote Quote 
Old 2 Weeks Ago   #12
Join Date: Apr 2017
Posts: 2,307
Thanks: 158
Trader Rating: 0
United Kingdom 
Quote Originally Posted by jackwhoo View Post
When engine cold before first start in the morning please use your obd reader and post what the ecu reads as the coolant temperature. Plus tell us roughly what the ambient temperature is where you are.
Is the car inside overnight or outside?
Do You live in Finland?
Cool do temp checks and report back
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

jackwhoo is offline Reply With Quote Quote 
Old 2 Weeks Ago   #13
Join Date: May 2020
Posts: 10
Thanks: 0
Trader Rating: 0
Finland 
Re: First take off jerky on cold starts, no fault codes

I didn't get the car to jerk noticeably and the coolant sensor reading appeared to be very consistent, starts from the ambient temperature 4 c and rises (see the attachment).

Some have said that Fiats develop intermittent jerks due to crankshaft position sensor without any fault codes and only until it fails it sets a code and car won't start.

Also sometimes when engine is not yet completely heated, it knocks a little when accelerating. Some have needed to change the knock sensor but it's not on the top of my list.
Attached Thumbnails
Click image for larger version

Name:	Screenshot_2020-05-17-13-17-07-153.jpeg
Views:	5
Size:	66.3 KB
ID:	209136  
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

eeeno is offline Reply With Quote Quote 
Old 2 Weeks Ago   #14
Join Date: Apr 2017
Posts: 2,307
Thanks: 158
Trader Rating: 0
United Kingdom 
Quote Originally Posted by eeeno View Post
I didn't get the car to jerk noticeably and the coolant sensor reading appeared to be very consistent, starts from the ambient temperature 4 c and rises (see the attachment).

Some have said that Fiats develop intermittent jerks due to crankshaft position sensor without any fault codes and only until it fails it sets a code and car won't start.

Also sometimes when engine is not yet completely heated, it knocks a little when accelerating. Some have needed to change the knock sensor but it's not on the top of my list.
Very nice graph posted, thank you.
Coolant temp sensor looks to be behaving correctly.

Next time you go for a longer drive graph the coolant temp again and make sure coolant gets up to correct running temperature.
I wouldn't worry about knock sensor at this point but would try super unleaded fuel and see if knock goes away.
Knock from combustion of fuel is a very different knock sound to other mechanical knocks. It is more of a rattle than a know to my ears.
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides


Last edited by jackwhoo; 2 Weeks Ago at 12:12.
jackwhoo is offline Reply With Quote Quote 
Old 2 Weeks Ago   #15
Join Date: May 2020
Posts: 10
Thanks: 0
Trader Rating: 0
Finland 
Re: First take off jerky on cold starts, no fault codes

I tried injector cleaner and the car didn't misbehave at all but soon after second full tank the behaviour returned. It may be related to 95E10 fuel. I'll try 98E5 next time.

It's a mystery. What about timing advance data? How was it supposed to change?
__________________
FIAT Forum Useful Links:
Donate to FF | Buy FF Merchandise | Classifieds | FF Insurance | How-to Guides

eeeno is offline Reply With Quote Quote 
Reply
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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) Jerky in 2nd gear when cold? typecastboy 500 12 09-11-2016 12:48
(T) Cold jerky engine matty23 Panda 12 18-04-2016 11:53
(T) Jerky cold engine start ruinin Panda 0 25-06-2014 02:54
(T) Snatchy and jerky from cold... Owyerbin Panda 8 27-06-2013 15:12
(T) Engine fault on cold starts Mino Stilo 7 22-12-2009 20:00