This is a nightmare!

If I gently press the accelerator the engine misfires terribly upto about 2500rpm when either it clears or it's revving fast enough you can't notice it.

When driving along below 2500 rpm it's a nightmare, missing all over the place!

I have fitted new plugs and new PCV valves and pipes but it is still there, anyone got any ideas please?

 

I had the same and it was one of the injector plugs(no. 1)that was a bit dodgy. Try cleaning them and wiggling the wires.

 

When you do a ECU-diagnosis, do any codes come up ?

 

It might be a faulty injector or bad PTU.

 

-Eric

 

 

I had the same problem, check the plastic cap that goes to the plugs, mine had cracked and was coming loose.

 

Stu,

 

Check you ignition leads. They break inside somehow apparently.

 

John

 

It could also be your mass airflow sensor if its happening under 2500 revs. Do ECU diag and check for error codes.

 

I can get the engine to miss constantly by placing a small screw driver under the throttle linkage.

I have disconnected all the coil connections in turn and engine note changes as normal so it's not the coils.

I was reading one of the other posts and it said something about the AAC valve, where is this located so I can check it?

Thanks for the help I need it.

 

The AAC valve wont cause that.

 

If all cylinders misfire, not just the one then maybe it's down to something like the power transistor playing up, which is common.

 

Have your TPS voltage checked.

 

It should read 0.44v at idle.

 

It could be the problem of your hesitation

 

Steve

 

I have checked the TPS and it's fine.

I don't know what to do the misfire is there at exatly 1200rpm and the car coughs and splutters like mad but if you keep accelerating it's fine.

It's getting serious as there is a delay when you press the throttle so when you go to pull across traffic it doesn't go the second you press the throttle (not good on the underwear!).

Does anyone know any really good specialistr I could ask or have any other thoughts.

Thanks

 

Stu

 

Where abouts are you again??

 

If your not too far from me in Rochester, then I know just the person you need to resolve your problem!

 

Give Darren a ring on 0797 1193867.

 

He has all the necessary diagnostics equipment to help you.

 

Steve

 

Steve

 

I am based in St.Ives Cambs.

I spoke to Luke last night at the Z centre who is a really nice guy. Apparently the next stage is to swap coils and see if that makes any difference.

It's a really weird problem this one!

 

but which one though Stu ?

 

you posted before that you have already unplugged each in turn and not found a faulty one...

 

did you rev up to 1200 on each test ?

 

Yes I had it sat at 1200rpm when I tried disconnecting each coil and injector lead. Luke thought it would be easier to swap plugs and coils with another Z just to totally eliminate them. Someone yesterday suggested an air leak around one of the injectors?

I just wish there was a simple answer, what seems to have everyone stuck is that the idle is perfect, it only misfires at 1200rpm.

 

have u tryed the air filter that can make them run like a pig at low reves

 

I have looked at the air filters and they were pretty messy so I have cleaned them but it ran the same with them removed so it must be something else. New ones are on order.

I am running out of ideas!

 

Well I have fitted new plugs and new air filters and guess what? The misfire is still there, although I did notice the engine hunting on idle which might give someone some ideas but overall it has got me stumped, I've spent nearly a grand and i'm no nearer the solution. Boo hoo, boo hoo

 

Well I have finally found a site that made some sense of my misfire.

A guy in NZ had a similar problem with his and it turned out someone had fitted the timing belt one cog out on one of the sprockets thus giving a misfire within a certain rev range.

I don't know if my 300 has had a new timing belt but that is certainly a pretty logical explanation.

Anyone got any thoughts or experiences on this?

 

Check the CAS! It should be about centered in

its slot.

If the timing belt is off at the crank then the CAS would be turned almost all the way in either

direction to get 15 degr. timing.

 

Bought my car this way...

 

Maciej

 

 

Maciej,

 

My CAS is adjusted a fair bit to the left with about 10% spare to go (@15 degrees), so its nowhere near centre. Could there be any other explaination other than the timimg belt not aligned correctly?

 

Andy

 

Andy,

I'm afraid I don't see any other explanation.

To check this, you have to at least remove the left timing

belt cover (where the CAS is)

and the crank pulley.

Make marks on the timing belt with a pen and count the number

of tooths between the mark on the crank sprocket

and the mark on the cam sprocket.

If you have the manual, check the procedure there,

it's pretty well illustrated.

 

If I remember correctly, you have detonation problems.

This can be the cause of the detonation so check it ASAP.

 

Maciej

 

 

Cheers Maciej,

 

I'm getting it checked out.

 

Andy

 

My 300 has gone to the shop today to get the timing checked, fortunately John who runs the garage has one and there is a guy at the company next door that has one which is great for swapping parts to find faults so he is going to swap the coils out first to make sure it's not that.

I'm off to Switzerland in it tomorrow which should be an interesting weekend. Can't wait to give it a blast from Calais.