vvc NO SPARK! where do i start

[stugrip]

engine died (just outside Goodwood Saturday) recovery engineer and a spare spark plug, determined no spark "ECU or cranksensor" he suggested

so does my car have a plugin point for a scanner?

should i just replace the CS sensor?

if its ECU what are my options?

I know Emerald make ECU's but is it a better option if my ECU is fried?

I was brought up in the fag paper and points, condensor, rotar arm era my modern engine electronics knowledge is ltd, any ideas?

 

L7 VVC

Its blue 150 bhp

I like it

[Mark Durrant]

Does the fuel pump run when you turn on the ignition, if not check the ECU fuse

 

Mark D

[stugrip]

All checked,

Fuel pump runs, immobilizer lights function properly, 30 amp ok, but no spark.

[rj]

Throttle pot?

[charlie_pank]

In simple terms, the ECU determines how much fuel and when, and when each spark plug should fire.

 

There are a few variables that determine how much fuel should be injected and when each plug should spark:

Air density/temp/pressure (normally somewhere in the inlet manifold, though not always used)

Coolant temp (thermometer in cooling system)

Engine speed (crank sensor and cam sensor)

Load on engine (throttle position)

Air/Fuel ratio (lambda)

 

 

not all of these are used in all ECUs and there are other things too on fancier ones. To determine each of these things one or more sensors are needed. Depending on which sensor has failed it is sometimes possible for the ECU to substitute in average figures so that it can 'get you home'. When this happens it errs on the side of 'caution' which generally means more fuel, as this will only damage your fuel bills rather than your engine. Other sensors are crucial to the engine running at all for example, if the ECU doesn't know what position the crank is in, it has no idea when to provide the spark. Most of the other sensors giving up or giving false readings will result in the engine running badly, but won't stop the spark being provided all together.

 

I would start by checking his diagnosis - make sure you really are getting no spark when you turn the engine over on the starter. If that's the case and you can't find any loose cables, then you really need to get it to someone who can plug in to the ECU and see what it's upset about, this will very quickly tell you exactly what's wrong and save you guessing and replacing parts one by one.

 

back here because I want to be.

[charlie_pank]

Forgot to say, if it is the ECU, I would recommend an Emerald, as it means you can fully map the engine using your PC as you upgrade bits of it, but it does cost time and money!

 

back here because I want to be.

[Mark Durrant]

If the car is EU2 there are plenty of things to check such as rotor arm, dizzy cap including the centre contact, coil, ignition lead that runs from the coil to the dizzy cap.

 

Mark D

[oilyhands]

Although there are many sensors that can fail, there are very few that will stop the spark, most will simply cause incorrect adjustments to the fuelling or timing. If you are getting no spark then either you have a wiring fault, a faulty CPS or a faulty ECU. A faulty TPS or MAP sensor will not stop the spark, in fact the ECU will still fire the coils with no TPS connected or with a bad MAP signal.

 

I would check the continuity of the loom connections, the loom appears to be quite stretched on VVC cars. Check the CPS wiring particulalry, if you can swap the CPS for a know good one and see what transpires.

 

Oily

[7 wonders of the world]

If you find you need a crank sensor I've a new one for sale here

 

cheers

 

Too young to be old !

[jackb_ms]

I have an EU2 VVC ECU if required

 

Jack

 

Emily, The Very Yellow 21

[stugrip]

Will recheck for spark, the car has 2 coil packs and no traditional dizzy etc. So I guess that makes it EU3...

Thanks for all the posts

 

L7 VVC

Its blue 150 bhp

I like it

[oilyhands]

No, if it has a dual coilpack on the side of the block it is an EU2. EU3 VVCs have plugtopped coils

 

Oily

[stugrip]

Thanks dave it's EU2 then, I bought a 50 mm TB from you 2 years ago. as I previously mentioned I know nothing about my engine , had it been an old lotus twin cam or ford v6 I would know more. The loom all seems intact so I will change the crank sensor first, if I can find it!

[stugrip]

Changed crank sensor still no spark, scanner says "air intake sensor reads minus 275 oC " guess next move is ecu check?