Mx5 eunos 1.8 mk1 compression

[Riko360]

So today Ive Compression tested my eunos 1.8 as its been having hesitation issues since I have owned it... Although the hesitation has been random and only happen occasionally, as of Friday it got to the point where it basically wouldn't accelerate- was misfiring and hesitating all over the place. I have been under the illusion that it is probably the cooilpack as its common to go on there cars, but today a friend recommended we compression test it...

so we compression it today where I got the following readings (I'm basing cylinder 1 on the nearest to the cross member)

Cylinder 1: 12.5
Cylinder 2: 12.75
Cylinder 3: 10.75
Cylinder 4: 12.75

All of the above are in bar obviously. I'm assuming from here the valve seats are gone on cylinder 3 as the engine is using no oil.

Can anyone comment if this has happened to them? Am I on the right lines of the problem?

Many thanks!

[stevieturbo]

Whilst there is a marked drop in compression, I'd struggle to believe that is the cause of such bad running that the car wont actually accelerate etc

A vacuum gauge might show poor valve sealing if that was the cause of the reduced compression.

[Rhino]

I'd have a look at the crank pulley. I had a mk2 1.8 that developed a slight misfire at a certain rpm, turned out the pulley had come slightly loose and the cam sensor wasn't picking up the timing wheel attached to the pulley

[DVandrews]

I doubt that degree of compression loss would show up at all in the running of the engine. If it did, it would be a steady slight off beat feel rather than the symptoms you describe. Most misfires are electrical, I would look elsewhere.

Dave

[fatjon]

Number 1:Coil Packs
Number 2: MAF

[Pumaracing]

Riko360 said:

Am I on the right lines of the problem?

No.

Only 30 psi down on one cylinder wouldn't make a scrap of difference to general running other than being a miniscule amount down on power which you'd never notice. You have an intermittent electrical problem but that could be just about anything from a dodgy connection to a failing component in the fuel or ignition system.

[Riko360]

thanks all for replies... been away so only just caught up on here.

a friend has also said the compression shouldnt be a issue and that the engines are generally bomb proof. im going to see if i can get a coil pack off ebay which may be a pain as mines a early 4 pin coil :-/ then will look at the MAF.

ill update if i solve the problem!

[appletonn]

Also worth replacing the temp sensor at the rear of the cylinder head that tells ECU whether car is hot or not. If it fails, car thinks it is cold and dumps loads of fuel in leading to a choked feeling and lots of popping and banging

[appletonn]

Also worth replacing the temp sensor at the rear of the cylinder head that tells ECU whether car is hot or not. If it fails, car thinks it is cold and dumps loads of fuel in leading to a choked feeling and lots of popping and banging