Toyota Sera - Trouble Starting and Then Struggling Engine

Hiya,

Just wondering if anyone could give any suggestions to the problem I'm
having with my car.

Took three or four trys to start the car up the other night and when it
does it has some strange behavoir.

If I press lightly on the accelerator the car revs fine builds up quite
high until i let go and it returns to about 700.

If I press quickly to about halfway down, the car struggles to do
anything at all.

If I then press to almost full it will struggle a bit but then catch on
and give some high revs.

So far I have replaced the spark plugs, Distributor Cap, Rotor Arm and
HT Leads but with no luck.

Anyone have any ideas what could be the problem?

Steg

Forgot to mention it's a manual and if you need more information about
the engine because it's quite a rare car, try going to

[url]http://www.omicron.uk.com/sera/aboutsera.html[/url]

That will probably be able to answer any question better than I can.

Any further info need though I should be able to answer.

Thanks again

Steg

"steggy" <steven.clark4@ntlworld.com> wrote in message
news:1140193313.609494.230720@o13g2000cwo.googlegroups.com...[color=blue]
> Hiya,
>
> Just wondering if anyone could give any suggestions to the problem I'm
> having with my car.
>
> Took three or four trys to start the car up the other night and when it
> does it has some strange behavoir.
>
> If I press lightly on the accelerator the car revs fine builds up quite
> high until i let go and it returns to about 700.
>
> If I press quickly to about halfway down, the car struggles to do
> anything at all.
>
> If I then press to almost full it will struggle a bit but then catch on
> and give some high revs.
>
> So far I have replaced the spark plugs, Distributor Cap, Rotor Arm and
> HT Leads but with no luck.
>
> Anyone have any ideas what could be the problem?
>
> Steg
>[/color]

If the vehicle is fuel injected, check the engine coolant temp sensor and
cold start enrichment system, whether it is an enrichment system for the
injectors or a cold start injector. Check for vacuum leaks and for a leak
in the intake tube between the air filter and throttle body. Also check
base ignition timing.
--

Ray O
(correct punctuation to reply)

There was a gap between the fuel injection system and the air filter
where the pipe hadnt been secured properly. I have fixed it but the car
is still the same.

I wouldnt know where to find the "engine coolant temp sensor" sorry I
don't know a hell of a lot about cars. And if I did I wouldnt know what
to look for to see if it was broken or not. If you can give me any
advice about this, possible location and what to look for if it's
broken.

The radiator has a small leak in it, but I didnt think that this could
lead to a problem like I'm having. But your mention of coolant made me
think I better mention it.

I've had the car for almost a year now and never had a problem like
this before, it's just come on all of a sudden.

If I cant find a problem on my own I'm going to have to get it to a
garage and I really can't afford that sort of expense at the moment.
Any help would be very much appriciated.

Thanks

Steg

"steggy" <steven.clark4@ntlworld.com> wrote in message
news:1140518111.545753.229600@o13g2000cwo.googlegroups.com...[color=blue]
> There was a gap between the fuel injection system and the air filter
> where the pipe hadnt been secured properly. I have fixed it but the car
> is still the same.
>[/color]

I forget what the original symptoms are but a leak in the intake will cause
driveability and hard starting problems. Check the intake hose carefully
for other cracks, especially on the underside or back side where it would be
difficult to spot.
[color=blue]
> I wouldnt know where to find the "engine coolant temp sensor" sorry I
> don't know a hell of a lot about cars. And if I did I wouldnt know what
> to look for to see if it was broken or not. If you can give me any
> advice about this, possible location and what to look for if it's
> broken.[/color]

The coolant temperature sensor is generally on or near the thermostat
housing. Follow the top hose of the radiator back to the engine - there is
usually a bulge where the hose connects to the engine, and the thermostat is
in the bulge and the coolant temperature sensor will be somewhere near the
bulge. It will be a threaded cylindrical piece with one or two wires coming
out.[color=blue]
>
> The radiator has a small leak in it, but I didnt think that this could
> lead to a problem like I'm having. But your mention of coolant made me
> think I better mention it.[/color]

I forget what the orignial symptoms are, but if the coolant level is low and
there is an air pocket in the system, the coolant temperature sensor might
not be able to sense cooclant temperature.
[color=blue]
> I've had the car for almost a year now and never had a problem like
> this before, it's just come on all of a sudden.
>
> If I cant find a problem on my own I'm going to have to get it to a
> garage and I really can't afford that sort of expense at the moment.
> Any help would be very much appriciated.
>
> Thanks
>
> Steg
>[/color]

On an engine with a carburetor, the carburetor mixes air and fuel for the
engine to burn. When the engine is cold, the choke restricts air flow so
more fuel enters the engine for a given amount of air, which raises idle
speed. This is known as an enriched mixture. Once the engine warms up and
the choke comes off, then ratio or air to fuel is adjusted for optimum
performance.

On an engine with fuel injection, the coolant temperature sensor tells the
computer whether the engine is cold or warm, and if it is cold, then the
computer will enrich the fuel mixture until the engine warms up. There are
basically 2 ways to enrich the mixture in a fuel-injected engine. One way
is to have an extra fuel injector known as a cold start injector, which
sprays extra fuel while the engine is cranking. The other way is for the
computer to tell the regular injectors to spray extra fuel. To be honest, I
have no idea which system the Sera has, but if the enrichment system is not
working, then the engine will struggle until it warms up.

Another possibility is that there is a vacuum leak that seals itself up as
the engine warms and the connections expand.
--

Ray O
(correct punctuation to reply)

Thanks for your help Ray, but I think you may be under the impression
that the problem only happens when the engine is cold. It happens
regardless of engine temperature. Don't know if this will have any
effect on your prognosis. :-)