Technical High tickover speed

[silombts]

Hi there. A bit off help needed. I have recently had to change my old engine for a good used unit. Car is a Seicento 1.1 SPi Sporting 98 - S reg

Runs ok except for idle speed runs at a constant 1500 rpm once warm. I've checked for obvouis air leaks and sensor connection but seem ok.

You can hear the stepper motor correct if you blip the engine i.e. The revs die down then stepper corrects.

I used the coils and crank sensor of the new engine but everything else was of the old engine. I did find the small emmision pipe blocked up with self tapper?? and wondered if this was to correct old engine running problem. Maybe the ECU needs time to re-learn base settings? What kind of mileage do they need to self-learn ?

The engine light is not on by the way and it drives superb.

Any ideas thoughts useful...Thanks

 

[rallycinq]

Its getting a wrong signal somewhere.

I'd still think air leak. Are both air connections on the back of the TB either connected to something or blocked?

Cheers

SPD

 

[silombts]

Cheers rallycinq.

I've had a quick look this lunch and look ok.

I have bought some carb cleaner so i may have a spray to see if it picks anything up. I'll also have a closer look at the pipes to check for splits etc

 

[silombts]

Just an update. Checked all the hoses. As they should be. Brake servo hose is split a little just on join on manifold but a tight fit. Wrapped with duck tape (temp)and clip. Tested hoses and gasket using carb cleaner. Idle stays constant.

I removed and cleaned the idle speed control valve. This temp brought idle speed to 1200 rpm but now back at 1500.

I am tempted to disconnect the valve to see what base idle is ? Would this proove the ISCV ? By the way, it same warm or cold and the idlde does not fluctuate.

 

[craigb244]

i would say its the idle valve. they do wear out. just do scrappy or somewhere and nick one from a punto (a lot of fiats (and other cars) have the same one)

edit: what was the new engine out of? are you using the original throttle body or the one that came with the engine? if all else fails swap the TB back. do check the 2 small connections on the rear of the TB as they can get mixed up (one is restricted and connects to the crank breather/airbox and the other is emission crap iirc)

also check the throttle cable is loose.

 

[silombts]

i would say its the idle valve. they do wear out. just do scrappy or somewhere and nick one from a punto (a lot of fiats (and other cars) have the same one)

edit: what was the new engine out of? are you using the original throttle body or the one that came with the engine? if all else fails swap the TB back. do check the 2 small connections on the rear of the TB as they can get mixed up (one is restricted and connects to the crank breather/airbox and the other is emission crap iirc)

also check the throttle cable is loose.

craigb244 - The engine came without a TB.It's off the original engine. You mentioned the small breather pipe being restricted ? I did remove what looked like a small grub screw/self tapper from the end of the small oil breather pipe that attaches to the manifold. How are these normally restricted ?

I will see if they can swap over although they look in the correct place. I also tried it with the throttle disconnected and same.

Thanks for your reply, much appreciated.

 

[chento]

sounds very like a vaccume pipe in the wrong place or an intake leak

what revs does it run at when cold ?

Do you have any history on the new engine ?

ive experienced a similar problem once before and it turned out the replacement engine had a lightened flywheel so it ran a high tick over

you say the car is driving perfectly except for the high idle , have you tried turning down the tickover screw ?

 

[craigb244]

best way to check is remove what ever is connected to both the two connections at the back. (bit of windscreen washer hose or that size pipe and connect each end to each nipple)

now start the engine and little it run for a bit. give the throttle a couple of jabs and see if it settles.

If not... get a a hair spray bottle full of water and then mist some around the bottom of the throttle body while running.
if the engine tone/speed changes while doing this then you defiantly have a leaky gasket.

 

[silombts]

Thanks for all the help. Now sorted. The small breather pipe and evac pipe were on wron way.

Now, does anybody want a good used TB, complete!!! Never mind will do for spares.

Cheers

 

[rallycinq]

Thanks for all the help. Now sorted. The small breather pipe and evac pipe were on wron way.

Cheers

Yup, fairly common.

Glad you've got it sorted.

Cheers

SPD