it dont run to good...

[zen]

hi..brief history..2nd gen 1995 uz into range rover..(engine low millage,ebay not heard running but belived good..)

wiring double checked..only fault codes relate to secondary o2 sensors(see other post)

it starts lovely,but there is a large flat spot from about 2k-3k? (no tacho)and a miss ..

the engine appears to be running rich from colour and smell from exhaust..

the miss can appear after revving engine, or made to dissappear by revving the engine..this suggests to me along with apperent running rich (smell and exhaust fumes colour) that it is not injectors but sparks...



so..anything on these engines other than the obvious to check for.(plugs leads)? do the dizzy caps/rotors go intermitent? coils play up?ignitors go intermitent??

is it ok (must be as tacho comes from here) to tap into black/yellow wire on ignitor that has this wire (should feed tacho) to feed into lpg injection ecu? or will this cause trouble,(i reckon this is ok to do)..(before you say switch to gas and see if problem sorts itself, the car is not road legal yet and has empty gas tanks,thus i cant fill them up as i cant get it to filling station)

running rich..do i need the secondary o2 sensors??i do not have them installed (please see post in fuel/afm/wiring section titled secondary o2 sensor...)

without sensors will it go to limp home mode?if so would this light the engine warning light?(mine is not )

flat spot...now whats causing this??it has aftermarket air filter, but i dont see that doing it very hestient at around 2k (no tacho yet) but will pull through it..not sure if i have the correct afm as engine came without,though the one fitted comes from same year engine..
the flat spot is of most concern to me, as i hope miss is just going to be something like iffy plugs..

thanks

 

[Zuffen]

All the symptoms suggest one side of the ignition isn't working.

The miss is usually from running on 4 cylinders.

The rich fuel load is unburnt fuel going down the exhaust.

I'd do a full check on the ignition system.

First ascertain which distributor doesn't have (or has intermittent) spark.

Then try swapping the leads on the igniters as this will prove if one of them is dead.

Then I would move back down the system. Check wiring is all intact between the igniters and coils.

Then check if you have spark from both coils.

Just work through it systematicaly and you will find it.

The rotors etc are very reliable and rarely give trouble.

The missing 2nd set of o2 sensors won't cause it to run badly.

Once plugs are fouled they may need replacing.

 

[zen]

well ..the misfire cleared itself today...hmmmm...but there is still a large flat spot where it seems to pulse untill you clear that rev range..maybe lead/plug breaking down??its really quite a large flat spot that comes on at a certain point (off load) and you can hold it on it, it wont clear untill you drop the rpm or go though it (thou then maybe then there is a misfire i am not able to disern properly as am not used to v8's)

it is firing on both coils as i get a spark on both banks of distributer..though i have seen a stronger spark than what was there (both banks seemed to be weak??) your thoughts on this, maybe they look weak is normal?

its not the afm as when unplugged runs really really rough..

are you sure it dont need the secondary o2's to work properly?2nd gen engine..