Misfiring Mi

[hman205 1]

may also be worth checking the continuity between the block and your earth point to make sure there is nothing insulating it as i noticed you have painted you engine etc.. just wondering it that is possibbly insulating your earth

[Guest Michael MRK]

No harm in swapping it out to prove it, but I really can't see that a dying relay would cause a regular misfire in a very specific rev range

 

same opinion here, relays can misfir ebut not at certain rpm, and also same for the groud connections, if there is anything in them, it'll totally misfire the cylinder, nt just at certain rpm.

i'm thinkin about the ECU but u said u changed it before so i guess its not what cause that probelm, but still its very likely possibility (used to have the same problem in my other car, mitsubishi Lancer 1991 with a 4g15 engine)

 

aslo check for the timing advance actuators, they might got screwed or something..!! (just another suggestion)

Edited January 26, 2006 by Michael MRK

[hman205 1]

an earth problem is quite possibble if the earth is there but not making a Good connection it could cause all kind of irratice problems such as rpm dependant misfire

 

 

is the Ecu earthed correctly?

Edited January 26, 2006 by hman205

[Guest abdiesel]

Tried the fuel pressure regulator on the end of the fuel rail?? has the fuel pressure been checked with a gauge in the car when the problem happens?

[hman205 1]

Michael Have you had any luck with this ? fingers crossed he hasen't replied as hes to busy driving the thing!!

Edited January 27, 2006 by hman205

[pacey205 2]

Not replied for a while as have been really busy at work, plus the car is at my parents house so Its had nothing done on it either.

 

Earths: All the earths have been checked first of all by me, and secondly by AB motorsport so its very unlikely its that. Can check the continuity again I suppose but Ill have to get my old man to have a look at that.

 

Ign Amp: Using the original 8v backing plate (same as the BX one) with the correct heat paste as well, mountings have also been checked by me and AB again.

 

Plugs: Standard NGK plugs for the Mi, cant remember the code off the top of my head but they are th right ones.

 

Compression: Standard, compresion test showed 190/200 across all 4 cylinders.

 

Fuel pressure: Havent got a guage to check it but AB said it was fine when they had it, might be worth another look I suppose.

 

Michael

[C_W 3 1 Cars]

I finally found the problem to my misfire; it was the rotor arm! The old one wasn't that old and "looked" ok to me. At oulton park my hot low speed misfire turned into a hot "everywhere" misfire so it became undriveable. Luckily Dino has a ignition spares "kit" and after trying a different coil tried the rotor arm and it ran perfectly after that!

 

Was strange how it started from cold fine, ran ok(ish) with the rotor arm faulty with just a low speed misfire but as it got hotter the misfire got worse for some reason.

[hman205 1]

At the point of misfire is it over fueling? or is it just cutting the fuel

[pacey205 2]

No idea, I may be home next weekend though so I could double check then. From memory though Id say it was overfuelling as the plugs were pretty black (I seem to remember).

 

Michael

[pacey205 2]

Any more ideas ?

 

I can only think its got to be something electrical but I cannot think what. 2 seperate auto electricians have said the signal from the CAS was dirty BUT the sensor has been replaced and so has the flywheel now.

 

Tempted to take it to Owen Developments as Jonnie suggested but theyve not replied to ahy of my correspondance so far (phone and email) so not sure I can be arsed.

 

Will have to have a check through of everything next time Im home I guess but no idea when that will be unfortunately.

 

Michael

[tidypug 5 2 Cars]

Just a thought but could you be having the same kinda problem that jonmurgue had? He ended up putting a new shielded wire in which solved the problem.

[pacey205 2]

Its something to check but this is the second loom Ive tried (although the first one was shortend). Maybe next time Im back Ill try shielding the whole wire or something.

 

Michael

[pacey205 2]

Right about time I updated this post although its been a while since I checked it.

 

Original fault was that after sticking an Mi in my car it misfired between 3.5-4.5K but was fine both above and below this i.e it idled and started fine and revved outside 3.5-4.5K with no issues.

 

Parts that were replaced to try and fix the fault

 

Leads

Plugs

Distributor + rotor arm

Coil

Ign Amp

CAS

Injectors

TS

ECU

AFM

Loom

Flywheel

 

Other things that were checked

 

Fuel Pressure - fine

Compression - 195-200psi on all cylinders, nice spread also

All earths

Switched Live

Fuel pump wiring

 

Basically everything was checked and no progress was made, so in the end I took it to Owen Developments near Oxford to look at and after a days worth of looking they found the fault.

 

They noted that the rev counter jumped about upon the misfire (as I had) so concluded that it must be electrical and probably coil related. So after checking all the stuff Id done before they got a scope at and looked at the signals.

 

It turns out that although the Ignition amplifier was amplifying the saprk sufficiently the signal it was sending to the ECU was complete s*ite, whole peaks missing and the rest of them degraded (bearing in mind this was a brand new part).

 

So they swapped for a new Bosch part and it runs fine, absolutely spot on.

 

Ive just spent the weekend finally running it in and sorting out a couple of minor teething issues and its now back on the road

 

Michael

[Anthony 1,000]

So you had two ignition amps with an identical oddball fault? That's pretty damned unlucky...

 

Glad its finally sorted out now though - you've got the patience of a saint for putting up with that as long as you have!

[jonnie205 1]

Good old owens. I didnt think the ig amp sent a signal to the ecu though i thought the ecu sent a signal to the ig amp, i must be wrong

[hexhamstu 9]

So you had two ignition amps with an identical oddball fault? That's pretty damned unlucky...

 

Glad its finally sorted out now though - you've got the patience of a saint for putting up with that as long as you have!

 

i had a misfire, first thing i did was replace the ign amp then a whole bunch of other things after that. then jeram came down plugged in yet another ign amp and all was fine. weird.