Hi Everyone,

I recently purchased a 1999 3.0 V6 S Type SE petrol, with 74k on the clock.It has a tendency to stall at standstill, idles roughly from time to time. Changed plugs, manifold gaskets, fuel and air filters, air temp sensor and the cracked coolant tank as well as the vacuum elbow at the back of the manifold. Now it is idling a little better, still stalling out occasionally but has developed a powerloss with flashing engine check light when going uphill or hoofing it on open road. Does not happen when using the cruise control at speed, even when using cruise cancel then resume to slow down and speed up. Sounds like it's miss firing.
Any thoughts?

 

Firstly, welcome aboard.

When time permits please do an intro in teh "New Members Area........".

Common itmes AFTER what you have done are:

Ignition coils. I did the 3 under the manifold in both ours whilst in there, it just made sense.

At the rear of the engine, LH side, is a 90deg elbow for the breather vac supple, and it has a habit of collapsing due to age. This is NOT the "known elbow" in the depths of the "V", it is clearly visible by just looking at the rear of the engine.

Could also be the transmission having a hissy fit, and a fluid change has done wonders for both ours. Those exact symptoms were still present in the Silver car after all the "catch up" I did, but the fluid change (6 times in about 4 months) did the trick.

Also, disconnect the battery, wait a few minutes, reconnect, do the radio code etc, and see if anything gets better, it usually does.

Others will chime in with their lists.

 

Flashing MIL means catalyst damage is occurring!!!! Do not drive the vehicle under these conditions.

What DTCs are stored? Do not disconnect the battery until the DTCs are read. Post them for the forum if you want help.

 

Thanks for the reply Grant, I've ordered coils, going to change all six.

 

I have yet to purchase an OBD2 device, never needed one before. Will post codes as I get them. Cheers.

 

Not just codes. Get one with live data and watch fuel trims!

 

Had at the local Jag dealers and an auto elec tech, neither could get live data with their kit

 

Then they're pathetic as tools from as little as £5 can. I would not go back to anyone so utterly hopeless just as I would not use a dentist who didn't know that teeth are to be expected in a mouth.

 

The plot thickens; I took the car on a 100 mile round trip to collect my mum from Manchester airport. Again, using cruise control some of the time to accelerate and slow up. No flashing check engine while using cruise, but got it a couple of times briefly, while using my hoof going uphill or giving it a bit of a boot. Arrived early at the airport so disconnected the battery for ten minutes and on the journey back got no check engine and it ran more smoothly, didn't miss a beat and idled more regularly.
I'm inclined to think that while changing the plugs, and the other shenanigans under the hood, I 'disturbed' the loom, (for want of a better explanation), giving rise to current intermittent problems. Anyone have a better explanation?

 

You're destroying your cats. Battery off means car is relearning so can't throw codes or warnings yet.

Cats cost a LOT MORE than an OBD tool or new coil(s) which are the most likely culprits but the tool is both cheaper and provides evidence.

 

Am I failing to understand the fault/codes mechanisms with this car? If there's a seeming mechanical problem, which goes away after an electrical disconnect/reconnect, then isn't it likely an electrical problem?
I took worrying heed of NBCats post about ******** the catalytic converter, is that the only meaning of a flashing check engine light? Like I said, not had this beauty long and don't want to cack handedly ruin the poor old girl.
Appreciating the input on here.

 

It hasn't gone away. You're failing to understand the implications of battery disconnect. You've forced the car into a state where it has to do a bunch of things. Save yourself pain by reading the details in the workshop manual - free download - or take advice given. Stop doing things you don't understand, like disconnecting the battery! This isn't a 1970s simple car.

 

Ok, you might want to possibly outline the implications of battery disconnect. The 'car has to do a bunch of things' doesn't really cut it. I might be new on here but I'm not a complete fool and would appreciate not being patronised.
My working life is spent at the bottom of the ocean; well heads and pipelines etc, (keeping the oil needed for these vehicles flowing), so I think I've a little sense as I'm still alive & intact after 18 years at it.
I'm just reasonably cautious with an ongoing life to lead as well.
This thread already has conflicting advice, re battery etc so I'm still looking for something approximating an answer.
I do appreciate all the proffered advice and experience from this forum. Cheers.

 

As previously stated, do not operate the vehicle under conditions that cause a misfire and thus flashing MIL. A misfire causes raw petrol to be burned in the catalytic converter overheating it and melting the core.

Do not disconnect the battery until the codes are read through the OBD port. If the battery is disconnected, the vehicle must go through a reset cycle that can take upwards of 50 miles or more. It is important to know what codes are stored to make a proper diagnosis instead of guessing and replacing parts.

 

Time to read the workshop manual and data on this site. On the wider web, too, if you like.

 

I too have an occasional misfire and have read through this thread and others,from this thread I still have a number of things to check.I have changed the 3 coils and plugs on the left under the inlet manifold still have the easy side to do.I have read about an OBD tool this appears to read fault codes is this correct ? Sounds like I should maybe invest where can they be sourced and any idea of the cost.My misfire does not flag up any messages at the moment.

 

jaggernought

My misfires stopped after all 6 were replaced.

As for original poster, my poor idle was the dreaded elbow that sits on the engine block.

 

Have finally got round to changing the last 3 plugs and swapped the coils from the left side to the right ,the misfire has now gone.The plugs removed were set at 40 thous thankyou to the garage that changed them for not bothering to look up the proper gap.