Mi16 Firing On 3 Help ! Tried Everything I Can Think.

[returnofjim 0]

Ok ive got a 1992 205 with a MI engine running on A citroen BX wiring loom and ecu, it was running fine until it developed a misfire whilst driving it. It is a constant misfire on idle and through the rev range.

 

I have managed to narrow it down to no 4 cylinder (cam timing end) is not firing, i have pulled the plug leads of one by one and the injector plugs one by one and the engine didint run any worse when i pulled the ones off at cylinder no 4. So i guess this is the problem.

 

I have changed the following parts for known good or new parts but still no change:

 

New parts tried:

 

Dizzy cap and rotar

Plugs

Leads

Coil

New timing belt correctly fitted and tensioned

 

Know working parts tried:

 

Ignition amp (tried 3 different one)

Air Flow Sensor

Crank Sensor

Throttle posittion sensor

ECU coolant temp sensor

Idle valve

ECU

All 4 Injectors

Fuel pressure regulator

 

I have checked and tried other things also but ive tried that many now ive forgot. Im getting close to calling out a mobile diagnostics bloke now as am running out of ideas.

 

Hopefully someone can think of something ive missed.

 

P.s all the cylinder compressions are spot on and so is the cam timing.

[Anthony 1,000]

Have you checked the injector plug on that cylinder, as sometimes the pins can push through and make poor contact. If it all looks OK. try that injector plug on a different cylinder, and see if the problem follows the wire or not to isolate the issue.

[Richie-Van-GTi 70 2 Cars]

have you checked its sparking on pot 4 with the plug out? If it is then it must be fuel or timing related. Was it previously running right or is it possible the leads are on in wrong order.

[returnofjim 0]

Have you checked the injector plug on that cylinder, as sometimes the pins can push through and make poor contact. If it all looks OK. try that injector plug on a different cylinder, and see if the problem follows the wire or not to isolate the issue.

 

Yeh ive already tried that, I have swaped the injector plug with one off the nearest cylinder and the problem stayed at cylinder no 4 so it cant be a problem with that bit of wiring.

 

have you checked its sparking on pot 4 with the plug out? If it is then it must be fuel or timing related. Was it previously running right or is it possible the leads are on in wrong order.

 

I took the plug out with the lead on and tested its spark, it was running fine then decided to misfire, ive since had all the leads off and replaced them and checked the lead order with haynes 405 manual.

 

Anymore suggestions??

[jonnie205 1]

Low compresiion on number 4? if plug is firing and injector is pulsing a good injector then it must be low on compression on number 4

[returnofjim 0]

Low compresiion on number 4? if plug is firing and injector is pulsing a good injector then it must be low on compression on number 4

 

The engione was brand new a month ago, I cant see it having low compression. Does anyone disagree?

[smckeown 1]

The engione was brand new a month ago, I cant see it having low compression. Does anyone disagree?

 

Always worth checking, could it also be a sticking valve ? Was the bottom and hed new ? or just bottom ?

[returnofjim 0]

Always worth checking, could it also be a sticking valve ? Was the bottom and hed new ? or just bottom ?

 

Ill try and do a compression test tomorrow, the complete engine was brand new from a citroen dealer about a month ago.

[Jim miami blue gti 0]

how much did that cost?

[returnofjim 0]

how much did that cost?

 

too much

[alex205mi16 1]

water in the spark plug hole? sounds silly but i had this a few times, especially after filling up coolant expansion tank. Always caused it to run on 3..

[returnofjim 0]

water in the spark plug hole? sounds silly but i had this a few times, especially after filling up coolant expansion tank. Always caused it to run on 3..

 

ive check and dried out any damp in the spark plug holes but no change, I have called a engine dianostics bloke hes coming Monday or Tuesday, hopefully he will sort it.

[Guest Bishop]

returnofjim,

 

I know how you feel cause I have the same problem. It's annoying as Hell. I changed the whole ignition system, tried other Injectors, changed the piston rings (compression), but to no avail.

 

I started experimenting with a couple of different spark plugs. Up to now the problem still exists but it's getting a whole lot better.

I'm not saying that you shoulg go out and buy 10 sets of spark plugs to see which ones better.

If it helps, maybe you might have a mechanic friend, (as in my case) who can lend you a couple of used ones to try out.

 

I'll let you know if I have something.

[returnofjim 0]

Ok so we now know this misfire is downt to zero compression on cylinder 4. Its been checked on 2 different expensive compression testers and both have given zero reading on cylinder 4, both testers showed all other cylinders had perfect compression.

 

So where should I go from here, I was thinking wip the head off and see what the problem is, ive not had the cam cover off yet, if it was a sticking valve would I be able to see if I just took the cam cover off??

 

 

James

[PumaRacing 1]

Not sure why your first post said all cylinders had perfect compression if they didn't. However.

 

If there's absolutely zero compression then it's either a bent or stuck valve or a faulty hydraulic lifter holding a valve open.

[pugrallye 0]

if its down to zero compression, should not be taking it apart as you will invalidate any warranty availiable on the block, or whatever you purchased from citroen, if you want to check valves on number four pull piston up til its on supposed compression stroke / tdc and make up a pressurised airline feed into spark plug hole, and listen to where its coming out from

Edited April 6, 2006 by pugrallye

[d-9 0]

If you bought it brandnew id be on the phone to citroen demanding a new engine and re-imbursement for the labour for fitting it.

[returnofjim 0]

Not sure why your first post said all cylinders had perfect compression if they didn't. However.

 

If there's absolutely zero compression then it's either a bent or stuck valve or a faulty hydraulic lifter holding a valve open.

 

when the engine was first fitted and started the compression was checked and was correct on all 4 cylinders, it ran for a about a week or so without any problems

 

If you bought it brandnew id be on the phone to citroen demanding a new engine and re-imbursement for the labour for fitting it.

 

The engine was bought as new but it was bought through ebay. it was listed on ebay as new by a citroen dealership. Due to it being though ebay there probably isnt really any warranty with it only any refund ebay might offer.

[PumaRacing 1]

If it was recently running fine and you haven't over revved it then it's very unlikely to be a sticking valve and can't be a bent one. That means it's probably a stuck lifter which you can replace without taking the head off. A leakdown test would isolate whether it's inlet or exhaust side but as you'll have to remove both cams anyway that's probably academic.

[returnofjim 0]

If it was recently running fine and you haven't over revved it then it's very unlikely to be a sticking valve and can't be a bent one. That means it's probably a stuck lifter which you can replace without taking the head off. A leakdown test would isolate whether it's inlet or exhaust side but as you'll have to remove both cams anyway that's probably academic.

 

yeh the engine was running fine for about a week or so, the missfire started whilst driving it but it was never took above 3500 rpm so it wasnt over revved. Ill have a look at it today and see if I can find a stuck lifter.