It was nice to meet some of you at the Cotswold wildlife park - in particular Ajay.
My car seems to have developed the above symptoms. The plugs are new, as is oil, coolant etc so I'm confident that's all fine.
I've never checked my fuel pump so will start there and I know my maf would benefit from a clean so will do this too.
Had anyone else got any explanation for a low down mis fire? How does the 260 regulate its idle? Does it have a control valve?
Thanks
Ed
How does the 260 regulate its idle? Does it have a control valve?
A combination of ign/spark timing and IAC valve located on the air intake plenum.
You need a scanner to check the ign timing thro reading the live data usually around 12 to 16 deg @idle doubt if there is a problem there,
and your fuel pressure.
Clean your Maf with carb cleaner first and check for any obvious air leaks, plenty of how to on youtube if your unsure.
LUMPY MISFIRE HEARD THRO EXHAUST, mine does that and always has done without a misfire.!!!
mine does this when we have hot days and stuck in traffic for a while just evaporation in the fuel rail?
If it's lumpy at idle it's easy to check for a failed coil. Pull the electrical connector off one coil at a time with the engine running to listen for a change in the engine note. If one doesn't result in a change to the engine note, then that cylinder is misfiring (likely to be the coil but could also be the injector).
i had a misfire under light load recently and it turned out to be dampness on coil #8.
Rich
Ok great will check all of the above. Are there any daft vacuum pipes on the 260 inlet that can cause problems? I know my old V6 Vectra was a nightmare for this.Quote:
Originally Posted by WNJ516
Where abouts is the IAC valve? This may need cleaning out... again an issue on the Vauxhall V6 that could cause an uneven idle.
Yes it was a hot day when I mainly noticed it but I must admit, mine always seems to creep up from 0 revs to idle when you start the engine, regardless of temperature, the engine doesn't spring into action like every other car I've ever driven.Quote:
Originally Posted by gignwah11
Cool Rich thanks for the advice. I did mention damp coils to Austin Garages but he seemed to think it was mainly down to people removing the sound deadening on the bonnet - which mine still has! Either way i'll check the coils next time it feels lumpy.Quote:
Originally Posted by Richb
Strange really, on full throttle it's great - just starting, idling and slow manoeuvres it seems to struggle occasionally.
Not sure if mine has had the fuel pump clip done, does this solve many problems? I also have the Viton seal - whatever that means!!
WIt's on the plenum chamber, held on by 2 allen headed screws, has a pipe and small black plastic resonator box which connects back to the intake air hose.Quote:
here abouts is the IAC valve? This may need cleaning out
Or see it on page 36 of the 260 training manual, found under the index of the forum
Check all hoses that connect to the plenum chamber, Clean your Maf sensor
When mine was misfiring, it was fine at idle and on heavy throttle. I pulled the back coil and it had water tracks running down into the plug well. I've read the issue is due to leaking washer jets and the under bonnet sound proofing hides the issue, so that's why people remove them. No signs of leaks on mine though :confused:
The IAC is bolted onto the front side of the throttle body plenum, look for the valve with the diamond shaped mounting surface.
My car does spring into life with minimal cranking or fuss, then settles to a nice solid idle. Check all hoses that that connect to the air intake pipe as anything that's come adrift will cause an air leak downstream of your maf and effect all running apart from WOT.
I understand the orange clip (if that's what you mean by pump clip?) is purely to stop the fuel filter falling apart as they can do. It's on passenger side of tank under the rear seat. It won't cure any other problems... and you would know if you needed it as you'd be stuck at the side of the road.
Not sure where the viton seal goes, maybe this is the seal between the two halves of the filter. I'm still learning about these engines so others will probably have more definitive answers!
Rich.
Quote:
Originally Posted by WNJ516
Thanks again for the help guys.Quote:
Originally Posted by Richb
Mine has always been a little slow at building up from engine off to engine switched on / idling. I assumed that the ten year old spark plugs were to blame for this and the low down mis fire. The mis fire had mostly stopped but seems to have reappeared. Also fitting a new battery helped the starter motor throw over more confidently but it's almost like the fuel pressure is weak to start with or indeed an air leak or similar?
My MAF has come away from the poorly designed U bend which leads to the filter housing. I've no doubt that cleaning that will help - plus I plan to reposition the MAF to where it sits on a mustang and get rid of the restrictive housing for a better filter.
My Maf broke away from the input section I glued it back with silicon sealer, I would seek advice on moving the MAF, if that's your intention. I don't why but in the early days there were some reason as not to move it, perhaps Herman, Nich or Brain could give you a reason not to. I have a K&N filter in the cars original housing and that's what is supplied with a S/C conversion so doubt if it creates a restriction. Perhaps other members could give you some advice.
The intake set-up on the 260 is not really a problem. Also the MAF is not in a U-bend but in a straight section, just after the elbow that come from the tube.Quote:
Originally Posted by WNJ516
This set-up works well, even on S/C cars.
With mine I've cut away most of the filter housing and effectively created an open filter with K&N cone. The MAF is still in the same position.
I think the MAF position is not the problem. Anywhere before the throttle body is fine as long as it's not in turbulent air
When starting, just give it a second or 2 to let the fuel pressure build up. If the pump was at fault, you'd notice at full throttle.
Agreed with the pump theory - maybe I'm cranking too soon? Either way, goes like stink at full throttle so must be ok.Quote:
Originally Posted by Herman
RE the intake - I just find the concept of bonded intake pipework ridiculous. It clearly doesn't last as it seems most people's mafs eventually break away from the elbow and it even has a flanged inlet face with four bolt holes as though it should correspond to a flange on the pre-maf pipework. I've never owned another car with bonded pipework, its always sleeved/clamped.
I can't even see why it was moved for the ZT. It sits up top in a mustang, and gains almost nothing by being where It is on a ZT... Apart from potentially being out of engine bay heat soak?
Herman, does yours sound throatier with an open filter? We hired a mustang GT-H in the states and albeit a slightly different engine, the open filter in the engine bay have a serious growl when pushed!!
All I can say is mine sounds fine :)
Welcome to have a listen and a drive (as a passenger)
There is not that much wrong with the standard set-up, MG got it pretty spot-on
I find that a couple of self tappers in the housing that comes adrift works wonders to hold it all together. Far better than silicone.
I glued mine when it came loose with UHU300+ and gave it an oven cure at 60 degrees. Works a treat:)Quote:
Originally Posted by James C
Does the wife know you used her oven for engine parts?:DQuote:
Originally Posted by Herman
Who's oven....................??Quote:
Originally Posted by peterv8
I do all the cooking in the house...............pork, beef, lamb and mg parts :)
I would suspect a leak on the intake side, maybe a split somewhere like the pipe that goes across the top of the engine, or a clamp not done up firmly.
Maybe you can stick your head under the bonnet and listen for air sucking or whistling noises while someone blips the throttle for you.
When I had a problem with an air leak in one of the PVC hoses, it led to running high rpms.Quote:
Originally Posted by stevenw
Erratic idle could be a number of things but start with the simple ones:-
- Is the air filter clean or does it need replacing?
- Does the IAC-valve work (check by pulling the plug and the car should almost stall)
- Is the EGR-valve doing it's job. Difficult to check but you may be able to pull the vacuum hose off.
- How old are the plugs?
- Is there a leaking injector? Pull one by one until you find one where the present condition doesn't change
- Maybe a faulty COP, running 7 cylinders. Same testing procedure as above
- Does the fuel pressure sensor work (OBD scanner)
That's it for starters and of the top of my head. Sure there's more that can be easily tested but it escapes me for now :)
Check your spark plugs are at the correct torque. A common fault with the modular V8 is poor threads in the heads for the sparke plugs.
My 260 has spot two out so far, the Ford repair is to fit an insert called a timesert. Available from Wurth here in the UK.