Vk Vacuum sensor.

[VK SL 3800]

Hi

Just recently my VK with the EST ignition system has developed a bad ping under light throttle at low to medium revs, I'm guessing either the CAS or the Vacuum sensor on the fuse box would be at fault as it has only started doing this recently and only once at normal operating temperatures. but in saying that on a warmer day last week (about 30 to 35 degrees) the pinging was worse and across almost all revs but still only under light throttle. Give it some and it was right. If you run it on 95 and its barely does it at all, run it on higher octane fuel like its designed to the problem goes away completely. The temperature sensor has been replaced withing 12 months so unless i got a dodgy one its not that. It has not lost any of what performance it had and just makes it a bit annoying to drive. Car has only done 80 odd thousand kms. Can anyone help?

Cheers Ben

 

[ari666]

ok, i am pretty sure they dont have a crank angle sensor, but willing to be corrected.

has the timing been moved at all? is the retaining bolt on the dizzy tight? have you got a timing light to check where initial timing is set? checked that enough fuel is getting through? i.e. filter condition, put a vac guage on it to see what its up to?

also, its good to note that the engine is designed for leaded fuel (super) so you really shouldnt be using anything under 95 RON anyway.

 

[D34N]

I think the EST VK's use a CAS system, remember reading it when i was looking at EFI Distributors etc and the advantages that VH's etc came with

 

[VK SL 3800]

The timing has not moved and the dizzy bolt is done up tight, but i dont have a timing light to check, although ive read Est System isnt effected by small movements of the dizzy because of the way it works so unless its way out you shouldn't have a problem. As for the fuel i have changed the inline filter after the pump but not the inline filter before it, but i didnt think it would be a fuel issue because clogged filters or a faulty pump would effect hard acceleration before light if you get what i mean, i was leaning to a dodgy vacuum sensor because im pretty sure it's the only sensor that directly changes it readings under acceleration, i cant see how any other sensors can tell the computer if the car is accelerating or not.

 

[codfishface]

The Engine Speed Sensor (Crank Angle Sensor) will also be affected as acceleration changes.

Have you checked all your vac lines and PCV system? Even leaks in the rocker cover and side plates can upset your vac readings.

 

[codfishface]

The Engine Speed Sensor (Crank Angle Sensor) will also be affected as acceleration changes.

Have you checked all your vac lines and PCV system? Even leaks in the rocker cover and side plates can upset your vac readings.

 

[ari666]

well pinging is often caused by a overly lean mixture(lean misfire), its not always timing. if there is a CAS, then i am no help to you on the timing side of things as i have never worked on a 202 with one. but even with a cas, you still have a timingmark and a spark plug lead, so you can get an idea. if the system works the same as a skyline, then the cas with re-adjust any changes you make to timing anyway, so changing it is a futile effort, but you can sus it out. having said that, skylines timing is changed via the cas.... so i have no idea how it would work with both a dizzy and cas, but yeah... whatever.

its always good to rotate your harmonic balancer to 0 and using the timing marks on the timing cover as a guide, put 5 degree increment marks on the balancer with liquid paper, from 0 to about 25. then with your light on, rev the engine and see how far it is advancing mechanically.

a timing light is quite cheap and i carry one around with me always, cos' on hot days i have to retard my timing a little to help stop pinging as it is right on the edge. so yeah, just get one. you will find uses for it all the time. even working on your mates cars or your mums.

what i would do in the meantime is take out a spark plug or two and check the colour/condition. this will be a good guide as to your mixtures, and with a decent vac reading we can get a better idea of whats goin on inside the engine. mixtures i can help you with, cas i cant. sorry.

 

[VK SL 3800]

ok, i pulled out a couple of plugs and checked their colour, all looked good, then went over all my vac lines, looked all good, checked over the PCV system and rocker gasket for leaking, all good again. went to the wreckers on Thursday arvo and picked up a second hand sensor to check if it made a difference, and what do you know, good as new! Will have to get myself a timing light though............