T4 Running Issues

[plato888]

Hi peeps, I recently bought a 98(S) V40 T4 which has developed some engine/performance issues, I hope that kind soul on here may be able to help !

Firstly there were starting issues and engine performance issues, and diagnostics reported it to be a faulty cam position sensor, so I replaced this with a brand new Bosch part and now the engine starting is fine.

The running issues are somewhat intermittant, however the performance is so poor that it cannot be ignored.

Problems are as follows:

Engine is VERY jerky on acceleration and surges then stops, surges then stops again, once the engine is past 70 deg ish, however up to that point is fine, if a bit underpowered.

I can just about hear the turbo whizzing away but there is certainly no real boost pressure on acceleration. (Boost was fine when I bought the car so i know what it should feel/sound like).

In an attempt to remedy the issues i have done the following:

New Air Filter
New Oil Filter
Full oil change - 10W 40 part synth
New 'Volvo' spark plugs
New Fuel Filter
Cleaned Throttle Housing
New Cam Position Sensor

When I bought the car in June (less than 500 miles ago) the seller reported to have replaced a faulty Lambda Sensor.

The engine undoubtably runs more smoothly (sounds smoother) but the performance problems still remain and I am now at a loss as to what to try next, as well as beginning to be very concerned at the money being spent to no avail !

I did reset the ECU after replacing the Cam Sensor by leaving battery disconnected overnight.

So, it appears that the problems arise as the engine gets up to temp, and having driven the car this afternoon there is virtually no boost pressure. I did suspect the MAF sensor, as the engine runs much better with it disconnected, but stalls as soon as engine is allowed to idle.

Specific questions I have are:

1) is there a way of adjusting or testing the turbo boost ?

2) I attempted to test the MAF sensor with a multimeter...black to battery negative terminal and red to sensor pin 3, however it shows no voltage at all even with engine on so i'm prob doing it wrong somehow, or does this just indicate that the MAF is duff ?

3) The car normally idles fine, occasionally blipping, does this mean that the MAF sensor is ok ?

Any answers or general thoughts about this would be very much appreciated, I have tried everything I can think of and need to spend few remaining ££ wisely

cheers, Simon

[T4Rick]

A boost gauge will tell you what you are making on boost.Is the engine managment light on?check all boost hoses for splits as well.What is your current mileage on the volvo

[Baffler]

As Rick says, is there a light on in the dash?

Have you checked the ends of the coil packs for hairline cracks? Remove the rubber insulator and look for fine cracks in the plastic ends. If there are cracks you can temporarily wrap some insulating tape around them to see if it improves things. Whilst you're at it also extend the springs, ever so slightly, so the are making proper contact with the top of the spark plug.

After that I'd then start looking to the MAF sensor and fuel pump.

[plato888]

cheers guys, current mileage 132k, no engine management light is not on, service light comes on at startup then goes off after a few mins.

I did check the coils today, both wires on one of the coils were exposed and the outer plastic heatshield is knackered, have used insulation tape as suggested, marginal improvement....will try the springs thing next.....should I literally just pull the brass spring a couple of mill downwards in the shaft to give more contact to the plug ?

Will get a boost gauge aswel, will any standard one be ok ...eg from an autospares shop ? and are they easyish to fit ? i'm not much beyond the basics of mechanics

Fuel pump ordered, bit sceptical about my understanding of how to fit it tho...any tips would be appreciated !

thankyou again

Simon

[andy_d]

if you run a search on here for "walbro pump" in the S40 section you can find a heap of info on how to fit them, 960KG has done some outstanding writeups on how to etc with those. (and a other things as well)
as for "tips" , if you replace the fuel hose inside the pump casing/housing, dont make it too long and get kinks / sharp bends in it.

oh and Deffinatly dont do a "me" and drop things in the tank,,,,

[960kg]

Originally Posted by plato888

Will get a boost gauge aswel, will any standard one be ok ...eg from an autospares shop ? and are they easyish to fit ? i'm not much beyond the basics of mechanics

thankyou again

Simon

....IMO the gauge that reads psi instead of bars is better as when tramping and along it is easier to read....

[plato888]

Thanks 960kg will take your advice, do you know of anywhere which sells a psi gauge ? dont really want to go to Halfrauds but will if i HAVE TO !!!

[zeus123]

Try spraying some electrical contact cleaner on the maf. See if that helps.

[gmain1967]

Originally Posted by plato888

Thanks 960kg will take your advice, do you know of anywhere which sells a psi gauge ? dont really want to go to Halfrauds but will if i HAVE TO !!!

Try this lot. I got a swoosh psi turbo boost gauge and an a pillar pod for not a lot of money....

http://www.autodials.co.uk/

Pic of gauge

[T4Rick]

I had juddering problems,and when i tried to pull off from a junction or even slow down to turn a corner the volvo used to cough and splutter.It turn out to be my coil packs the ends had split .