Please help

Mick Knowles · Feb 22, 2023

Hi people’s. I’m new to the site so not exactly sure how things work on here but I’ll give it a go and see what happens.
I have a l322 4.4v8 petrol on an 2002 plate with 100,000 on the clock. I do most of the work myself and I absolutely love this car. It’s recently developed a problem that has me baffled and I was hoping someone could help. The v8 isn’t firing on cylinders 3 and 4. I have good comprehension, good fuel supply and good spark so I’m obviously confused to why 3 and 4 won’t fire.

I also have a spare engine so I’ve changed the coil packs, the spark plugs and the injectors and nothing seams to make any difference

I’ve started to look in to the vanos system as a possible culprit but I don’t think the issue I’m suffering meets the requirements of a typical vanos issue.
Any help will be greatly appreciate. Thanks in advance

Shippers · Feb 22, 2023

Are number 3 and 4 plugs wet after cranking as sounds like no fuel...

marjon · Feb 22, 2023

I would ask how do you know it is specifically 3 & 4?

J

kermit_rr · Feb 22, 2023

by wont fire, no spark at all at the plug, or no combustion? assuming its coilover plug.. is the coil getting power?

Western Slope Rover · Feb 22, 2023

Fuel, spark or air. It's all there is to it. Start trying to narrow it down. Checking for wet plugs is the easist place to start.
Also, is the spark bright white ?

pwood999 · Feb 22, 2023

compression test ? . .. or is that Comprehension ?

Mick Knowles · Feb 22, 2023

marjon said:
I would ask how do you know it is specifically 3 & 4?

J

I have the “i car soft” for diagnostic

Also if I disconnect the coil packs on both 3 and 4 there is no difference to the running engine.

Mick Knowles · Feb 22, 2023

Shippers said:
Are number 3 and 4 plugs wet after cranking as sounds like no fuel...[/QUOTE

yes there’s fuel getting through. I can even smell fuel from the exhaust that hasn’t been ignited.

Mick Knowles · Feb 22, 2023

pwood999 said:
compression test ? . .. or is that Comprehension ?

Yes I’ve done one. It’s fine.

Mick Knowles · Feb 22, 2023

Western Slope Rover said:
Fuel, spark or air. It's all there is to it. Start trying to narrow it down. Checking for wet plugs is the easist place to start.
Also, is the spark bright white ?

Checked spark fuel and compression. All are fine.

kermit_rr · Feb 22, 2023

Have you switched the plug/coil to a working cylinder?
My understanding of vanos isn't great but i thought it changed a bank, not one cylinder?

Mick Knowles · Feb 22, 2023

kermit_rr said:
by wont fire, no spark at all at the plug, or no combustion? assuming its coilover plug.. is the coil getting power?

Spark is fine fuel and compression are fine.

Shippers · Feb 22, 2023

How have you checked for spark?...

kermit_rr · Feb 22, 2023

If you have air, compression, fuel and spark, then you have bang. The timing can't change for one cylinder on a bank.
Can you see injector timings?
The inlet cams could be worn, meaning not enough air for combustion, that wouldn't impact the compression values

dubbleRR · Feb 22, 2023

Mick Knowles said:
also have a spare engine so I’ve changed the coil packs, the spark plugs and the injectors and nothing seams to make any difference

What about ht leads ,are they tight on the top of the plugs,or arcing to earth .

..

Shippers · Feb 22, 2023

dubbleRR said:
What about ht leads ,are they tight on the top of the plugs,or arcing to earth ...

Thats why I asked how has he checked spark...also smell of unburnt fuel at exhaust means something is not firing...cant remember which side of inlet manifold supplys which cylinder but I know each does 2 on each bank...also does OP mean 3&4 as in firing order?...

Shippers · Feb 22, 2023

Another thought is over fueling killing spark...

dubbleRR · Feb 22, 2023

Bent push rods would stop valves working right,seen it in over revved motors,,take rocker covers off n see whats moving ....,if its moving,,

O are the ht leads on the right plugs ,just a thought....

Mark Piercy · Feb 23, 2023

Mick Knowles said:
Checked spark fuel and compression. All are fine.

Welcome. What were the results for the compression test on each cylinder?

Grrrrrr · Feb 23, 2023

@Saint.V8 is pretty good with the bimmer engines. @stustrong too.

Anyone got a wiring diagram for the injectors? Is there an internal break in a wire or dodgy connector somewhere common to 3 and 4? Would noid lights help?

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