Running problems on boost and cruising

[Greg_S]

Chaps,

Im planning to take a look to find out what the problem is at the weekend and wanted to know if you have any suggestions.

At the moment when cruising along it feels like the engine misses the odd beat very slightly you can feel car hold back for just 1/2 a sec when driving along every now and again.

Then when it comes onto boost it coughs and splutters and generally holds back and wants to kangaroo.

I changed the engine mount on drivers side a month ago so will check the Lamda is connected up properly. MAF connections and the intake pipe are connected properly.

The coils and leads were changes last year and the plugs changed last year and currently running NGK's, but tempted to put some bosch back in to see if it helps.

Any other suggestions?

[S2central.net]

I'd deffo go back to Bosch plugs in the 1st instance...

Then its air leaks maybe, MAF sanity and a check of air and water temp sensors.

Kangaroo'ing is either very bad misfire or intermittent fuel supply - worth checking fuel delivery and health of fuel pump and its relay as well.

[Greg_S]

Hopefully the fuel pump is good since it has the bosch 044 pump fitted but will def check that. Any tips on checking it?

[Flat on my back]

.

Don't forget the knock sensors...

[Greg_S]

Knock sensors are only 2 years old too because I replaced those a while back when checking for a fault

[A80Avant]

wont be the lamda.It wouldnt chuff up on WOT,cause it gets out of the loop.I would lean towards coils and rubber beru inserts as well as the occasional boost leaks etc.

If you ask your car,it will probably reply that the 561 fault is there,but it might catch something else up as well.

[Flat on my back]

Tps...

You'll need an AVO for a proper check...does it happen at the same speed say if you stick in third gear, gradually increasing the throttle?

Do the plugs first though.

[Greg_S]

yeah plugs are gonna be first port of call. I notice with holding back a little when cruising along at a steady speed. I'll see if I can pull the codes later on and see if anything is on there that shouldn't be.

[merlin's S4]

yeah plugs are gonna be first port of call. I notice with holding back a little when cruising along at a steady speed. I'll see if I can pull the codes later on and see if anything is on there that shouldn't be.

My S4 didn't like NGK or those Denso irridium plugs at all. I had similar symptoms to you so I stick with the Bosch originals now!

[bigdan]

i use NGK's in all the marine outboard engines we work on. although generally a good choice, some particular models throw up the same symptoms after about 18 months of running.....a change of plugs always sorts it out. it seems to be a time issue rather than running hours...

i would go with the change of brand as suggested

HTH

[Greg_S]

Yeah that sounds about right, these plugs have been fitted for about 15 months now. Wonder if Bo has any bosch ones left....

[Greg_S]

Well I got some new plugs from Bo, and a bit of time to take a look at the car yesterday and thought id try a few other bits first.

I cleaned the earth points and cables up on the IM and the coil ground to the cam cover to try and improve those.

Then I took the plugs out and checked the gaps on them and re gapped them to 0.6mm, took it out for a run and what a difference. The car is running so much better than it was last week. Plus I still have the set of plugs if it starts playing up again.

I didnt manage to start doing some prepwork on the aquamist unfortunately since I need to get the undertray and bumper off to start it. I'm planning on mounting the injector on the xmember after the intercooler to give a decent length for the spray before it reaches the cylinders and to keep the amount of pipework to a minimum

[A80Avant]

Greg, nice to hear about the success on the poor running.
If you need any pictures as to where to mount and use the aquamist,im glad to help!!

[jameswkr]

Greg, how did you re gap platinum tipped plugs?? I understood this was a "no no" for fear of fracturing the electrodes ?

[A80Avant]

make sure you mount the pump lower than the tank(or at its lowest point if you are using the windscreen wiper tank,and the injector higher than the tank it self.If you are to mount the injector lower you will need a selenoid valve to prevent siphoning