Disco 2003 118 k Misfire on 6, 4, 8
 

2003 Disco II. 118k

I start having problems 3k ago. Misfire on 6 & 3, knock sensor, air balance problems. I did complete tune up. Spark plugs (Tried Bosch & Champion Iridium) , 8mm ignition wires (kingsborne), replaced all gaskets, replaced knock sensors, checked compression (150 -160). Car worked great for 3k and one by one start to show up codes for misfire on 6 , 4 and then 8 cilinder. Changed ignition coils (Beck/Arnley) and nothing helped. Accelerate good if you keep it above 2200 rpm but try to keep it in 1700-2100 and got no power and engine is choking.
If you drive down the hill check engine does not flash but try tu put any stress on engin and it starts blinking.

Please help.

Have you ever replaced your o2s? What are your codes?

PO306, PO308, PO 304. No I did not replace my O2 sensors but I thought that something can be wrong with them and swapped them when was doing tune up (first time). I did't noticed any change in codes so I just assumed they are ok. They looked ok to me (clean). I didn't try to clean them cause I read it can damage it.

If you have codes, then we can assume you have a scan tool. Check O2 sensor values with the engine running. If you got values that don't change or are incorrect, check your wiring then possibly replace the O2. If the numbers are ok, then you should look at your maf.

Hi

I checked one more time today and there is total misfire on 6-th cylinder.
Completely no spark. Is it possible that spark wire on 6-th went bed after 3k miles and how this is correlated with 4 & 8 cylinder?

If not the o2 sensor, I would check if the cat is clogged or bad. Any funny exhaust smell? I suppose I would not rule out a bad wire... I have had 2 bad brand new parts in the last 6 months! But, there could be damage to the cat or 02 if you have been dumping fuel into it with a plug that is not firing.

No funny smell at all. I think it is time to invest in good (not only codes) scanner. It seems like without that it is only guest work with a codes. I contacted Kingsborne and they sending me replacement cables. Any suggestions what scanner? i know that people say that Hawkeye is really good but price is a little steep. Any experience with Autel MS509?

You confirmed you have zero spark on that plug but spark on the others?

Yes. No spark on 6-th but sparks on 8-th & 4-th. How explain that?

You can't run around with no spark on #6.
You are putting raw fuel into your CAT and you'll toast your CAT eventually.

1) Put in new plug. See if spark. Old plug could be fouled and shorted.
2) Replace the spark plug wire with a GENERIC wire from an autoparts store. See if spark.
3) No spark - your coil pack is probably bad. One cylinder in the pack can quit. Make Beck Arnley honor the warranty and send you a new coil pack.
4) Your mass air sensor could be giving wrong fueling. Try to clean it with that CRC sensor cleaning spray. This is probably true if the plugs have shiny black coating on them. (Which may be shorting out the plugs).
5) Check for vacuum leaks. Make sure the brake vacuum line is not sucking air. Check all the purge lines for PVC to the valve covers. Check the SAI vacuum line. Check that your air intake plenum manifold is torqued correctly - those 6 10mm bolts on top are all tight.
6) With your scan tool - go to dynamic scan mode.
WATCH the O2 sensors - they should cycle between 0 and 1 volt.
7) report back on dynamic readings from SCAN tool.
Best,
J