Bad running after new head gasket - cause?
 

My Sport Edition ate her head gasket (and clutch) the last weekend in May - and I've just got her back from the very helpful garage at the end of the road.

Other faults found included a very cracked exhaust manifold (changed) a turboplus little hose not properly attached, and the vacuum hose to the brake servo leaking. Oh, and a weeping rear pipe seal on the waterpump thought to have been the cause of the H/G.

No she's running like a sack of sh1t and teh question is where to start. Using NO water, using NO oil. MPG within normal bounds. It may be my imagination but I thought the temperature gauge was at first sitting a fraction high, but after half an hour on the motorway it had gone to slightly below the middle in stead of a whisker above, but it rises to straight up or a whisker above pottering in traffic. The lambda light has come on three times (pulled no 1 fuse to re-set) and so far it has stayed off after the last time. Tickover dreadful - dithering with hiccups between about 300 rpm and 800 rpm lambda light flickering on at the lowest speed (but that's probably due to zero output from the alternator at those speeds) and occasional stalling. Chasm upon initial acceleration - but then feels lively in first to the red line. But by the time one gets to 3rd and 4th is is apparent that there is a huge flatspot containing hiccups between about 3,200 rpm and 4,200 rpm, diminishing as the turboplus takes hold. Running out to the redline in 3rd (in stead of the flatspot from 5,500 to 6,000 that she's had ever since I owned her). Of course I didn't try that in 4th, ossifer it would have been illegally fast, but it MIGHT (nudge nudge) have seemed similar.

On one of my favourite test hills I am about 15 mph down at the point where I have to break or go straight over a roundabout.

Where do I start hunting?

Possiblity 1 - build an Not-quite-OBD2 reader?
Possibility 2 - AMM and throttle body and oil breather?
Possibility 3 - it feels like electrical, to my trousers, so plugs HT leads dizzy cap and rotor arm?
Possibility 4 - keep driving, the brains might be re-learning the engine?
Possibility 5 - fuel pumps and Jimathon injector cleaning? ) It is Jimathon isn't it?)

Open to suggestions here folks!

sensors
 

Have the sensors in the cylinder head been properly connnected that lie under the inlet manifold?

Sounds to me like Timing to me , mite be out by a tooth .

is the throttle switch in the correct position on the throttle body, are all the cables set as they should be.

HT breakdown and/or weak spark will be quite severe leading to severe hesitation/stalling on the application of power or severely strangled power output.

If the emissions light is comming on, the fuelling is not correct according to the O2 sensor.

I wouldn't rule out timing belt, but I'd be looking for a post metering air leak first.

I had a similar problem when I had a head gasket done at a local general garage, which had otherwise done a really good job. It was just some of the vacuum tubing not properly reconnected. In my case I'm pretty certain it was the ones on the charcoal canister that weren't connected properly.

No Joy Yet
 

Sensors under the manifold correctly attached.
Cam timing correct.
Injectors and seals OK.
That silly electrical lead at the back of the engine (cam position sensor?) OK.
3 metres of the little turbo hoses (including turboplus hoses) replaced and OK
Various vacuum hoses off the inlet manifold OK
Throttle position sensor OK
Lambda sensor was horrible but has been changed and was not a cure.
Crankcase breather hose is a twin-layer hose (a layer of plastic and one of rubber) and one layer is iffy but surely one layer remaining will suffice and anyway it wouldn't cause the manifested fault. Would it?
Plugs checked and OK.
HT leads checked and OK.

I'm going to buy a spray can of AMM cleaner (if it foxes the AMM well a pattern AMM is not that dear).

Garage knows a bloke wot has a load of 90s adaptors for OBD (and with any luck he will know if he can't read the Volvo not-quite-OBD) and will ask him to try to read the socket.

Failing which - and failing any other ideas - I'm going to build the Volvo code reader.

Incidentally, the fault is not significantly different from when I drove the car into the garage, so whatever it is is something that would NOT normally be changed when doing head gasket (and clutch).

I don't suppose overheating could kill the EZK could it? (and anyway the engine did not get hot enough to seize so I wouldn't REALLY call that serious overheating). It is the EZK I need to be thinking about isn't it?

The crank breather could well be responsible for an air leak into the inlet. The inlet sucks at it in tickover to keep the oil in.

EZK is pretty reliable, its just a computer really with a light duty output. It either works or it doesn't, haven't heard of any failures. The output goes to the single channel ignition amplifier, that drives the coil. It can degrade or go intermittent. There is also the radio suppression module which has been known to cause problems.

You didn't mention specifically idle valve, which has 2 tubes which can split letting air in. The valve can also get gummed up.

If you are cleaning the AMM (not sure that is advised it is meant to clean itself) then clean the throttle body (often cause of idle problems) and the idle bypass valve.

The ignition amps are easy to get, so its worth getting a spare (even 2nd hand should be fine) and eliminating that.

If in doubt, drive the car to me..... I have fixed a couple of these sorts of things with my multitude of spares

Code reader
 

The local OBD2 wizard has retired defeated by the cunning of the Volvo system. All he could read was about the airbag.

I have ordered the parts to make a Volvo Code reader. Some of the bits elsewhere listed here are not consistent from thread to thread, so when they get here and I make them fit together I will put up a corrected list.

In particular the Pang OBD2 connector previously suggested is out of stock. There is a different one with a right angle entry that I have ordered.

Maplins no longer do a 1.8k resistor - funny that I'm sure it's a preferred value - so I've ordered a 1.5k one. I am not sure if it is necessary - one set of parts includes it, the other not, and text suggests it can be omitted. Watch this space. We'll try first with the 1.5k in circuit to be on the safe side and only remove it if there is no joy with it in.

One list suggests a 2-way toggle switch - fine and dandy if you only want to read two sets of codes - so I ahve got a rotary switch. The only single pole rotary switch that Maplins do is now 12 way so I expect some VERY fiddly wiring.