Kjet stalling

My engine keeps stalling when the revs get low. It was very rare at first but has been getting more regular recently to a point where I can't really drive in traffic anymore.

The engine seems to being the "pop and gurgle" thing a lot more too - you know when you slow with the gears and the engine makes all those cool sports-car sort of noises. Now it does that unless the revs are 1500 upwards.

The ISU seems to be working, but somehow the revs just get too low, and the engine stops. It always starts again.

There was a time when it started with any gas, but now it needs a few pushes of the  accelerator to get going.

So I had a look for this breather thing, but I couldn't find it. Not here:



I thought it could be that because the is a lot of suction when I take the fuel cap off.

I was going to check the air filter, but there's a world of craap on top of that now. Anyway, it's only been in 8 months.

I've had a thought… The times it cuts out I've had the roof down. Only reason I have the roof down is if the weather's hot.

Any ideas of what heat related issue could cause that?

Right, it still happens when the weather is not hot.

I've noticed that it idles at 900 instead of 1000. Could that be it? Do I just adjust the screw?

Could be the o ring on the idle screw is letting in air or lose.
Try getting the engine to normal temperature and adjust the idle screw so the revs are about 1200 rpm, rev it a few times then lower the idle speed to 1000 rpm. Doing this should make sure the car is not running on the anti stall device.

See if that's any better?

Thanks, I'll give that a try  

Okay. I was just about to do that, but I noticed the ISV is not buzzing with ignition on (engine not running).

I cleaned it before, and tested it to see it responded to voltage (which it did).

Hmmm.

Well although it doesn't buzz, it is getting 0.5v when the ignition is on.

When the engine is cold it idles at about 1200. As the engine warms up it gradually reduces until the engine reaches temp where it settles at 950.

I'm starting to wonder if the problem isn't related to the vacuum building up in the tank as I drive.

No idea where I would unblock whatever is blocking it.

the_whip said

Well although it doesn't buzz, it is getting 0.5v when the ignition is on.

When the engine is cold it idles at about 1200. As the engine warms up it gradually reduces until the engine reaches temp where it settles at 950.

I'm starting to wonder if the problem isn't related to the vacuum building up in the tank as I drive.

No idea where I would unblock whatever is blocking it.

Which engine are you running mate

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9A with jet from mk2 16V.

the_whip said

9A with jet from mk2 16V.

KR using k jet?

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9A using KJet from KR. So basically a 2L KR.

the_whip said

When the engine is cold it idles at about 1200. As the engine warms up it gradually reduces until the engine reaches temp where it settles at 950.

When does it stall?

The isv should buzz with ignition on. How is it wired in?. Do the revs drop too fast when you put the clutch in as my kr would do that with the mk1 aav instead of isv. With the isv the revs drop slowly from 2000rpm

paul_c said

When does it stall?

Only after it has warmed up. When I brake to stop at a light or give way, then depress the clutch, the revs drop quite low (maybe 500rpm) and it stops. It always starts again afterwards. I do have to pump the gas a bit, but I also have to do that starting from cold. There was a time when it started without having to do that.

sporttrucker said

The isv should buzz with ignition on. How is it wired in?. Do the revs drop too fast when you put the clutch in as my kr would do that with the mk1 aav instead of isv. With the isv the revs drop slowly from 2000rpm

It does seem odd that the ISV doesn't buzz. I didn't wire it in myself. All I know is that it receives about 0.5V when the ignition is on (engine not running).

It seems like the revs are being controlled by something. When cold they sit at 1200, and wouldn't go much below that when dropping from 2000. Once warm the revs would drop a little faster, and dip much lower before returning to 950 (if it hadn't stalled before getting back up).

 

There should be a separate control unit for the isv somewhere.

Sounds like its running lean. Tweak the mixture at the metering head.

sporttrucker said

There should be a separate control unit for the isv somewhere.

There is.

paul_c said

Sounds like its running lean. Tweak the mixture at the metering head.

Will look into how to doing that, though it was adjusted a few months ago because it was too rich.

mark1gls said

Could be the o ring on the idle screw is letting in air or lose.
Try getting the engine to normal temperature and adjust the idle screw so the revs are about 1200 rpm, rev it a few times then lower the idle speed to 1000 rpm. Doing this should make sure the car is not running on the anti stall device.

See if that's any better?

Note to self: Always do what Mark1 says.

So that seems to have worked. The ISV doesn't buzz, and only gets 0.5V but if I unplug it the car won't start. I guess it must be working.

I unplugged the wire to coil and the revs dropped to 900. I loosened the screw until they were up to about 1000 (and did the reving thing).
The revs don't dip so low when slowing now, and thus far, it hasn't stalled. It also starts with out needing gas which is great.


There is a strange noise it use to make which has returned…
When I stop after a longish drive, it sounds like Chewbacca is in boot.
It's a vacuum building up in the fuel tank. It's really difficult to remove the fuel cap as the vacuum is so strong.
Is that normal?

 

In this hot weather I also get more build up of pressure in the tank but if yours is a lot of pressure it could be the vent underneath the wheel arch is getting blocked.
The valve/vent is hidden underneath the plastic wheel arch liner so you do need to remove that to see the valve.

Cool. I will take a look. I thought it might be hiding away in there.

When you say build up of pressure due to hot weather, is  that not the opposite of what I am getting?