Bad running after new head gasket - cause?

[Laird Scooby]

Originally Posted by aardvarkash10

if its input from the lambda, it can only swing 1v, not between 5 and 0

http://ipdown.net/jetronic.info/tiki...nector_pin_out

That was among the information i found. Something did cross my mind - if it's actually pin 28 then the voltage measured would be a bit more along the lines and should be (according to that chart) about 7.5v which still leaves a problem as the voltage is only about half that.

However that chart doesn't seem to apply to turbo models unless i'm missing something and there's every possibility that the pin outs for the turbo cars use different pin assignations.

[rogerthechorister]

I don't know how I ever found time to work. G/F living an hour's dreive away in Croydon does not help I suppose. Right now I am very grumpy following a tooth extraction...

Anyway

Max the mecco applied a constant +12V to the pin in question. No change.

Max the mecco found a wire under the dash going to the pin in question - and it was iffy. Not severed as such but the wire inside the insulation was broken. New section spliced in - no change.

Bah.

Next test will be to blank off the EGR system completely at the inlet manifold end.

[rogerthechorister]

Max the mecco has smashed his hand up with a wild lorry halfshaft. So yesterday went went to Tim the Mecco. Does that remind you of an Elvis Presley song?

On a dark and grey
February morn
Another sad Volvo mecco is born
Tim the mecco...

[Laird Scooby]

............ an' if there's one thing he don't need,
it's another Volvo turbo bleed,
Tim the mecco........

[rogerthechorister]

Till one day in desperation
I bought cap for the dizz-ee
And the other bit that goes with it - it's the rotor arm

For Tim the Mecco

[Laird Scooby]

At the risk of breaking the lyrical interlude, has that fixed it?

[rogerthechorister]

No idea yet, it hasn't arrived, and I much doubt it because I was told yonks ago that the cap was OK but the bloke who said that was at times economical with the truth and for a mere £20 it's worth eliminating - particularly after the Exxon Valdez misfire story!

[Laird Scooby]

I totally agree, i've just got rid of most of a flat spot (more of a pimple than a spot now ) on mine, particularly when cold by cleaning up the dizzy cap and rotor arm. It still needs a new cap and arm but cold starting is much improved, the engine is much smoother and the flat spot when the mixture is weakest (like when yours comes on boost i expect) is almost gone. I daresay a new one of each will get rid of it completely.

This was after cleaning with a wire brush in a Dremel and brake/carb cleaner :



It's done well at 30 years old though! The yellow staining is the lacquer that has discoloured from the carb/brake cleaner, just trying to source a reasonable quality cap and arm for less than the price of a set of (cheap) tyres!

[rogerthechorister]

Yes I saw that on your V6 thread.

[rogerthechorister]

To cut a VERY long story (see above) short, here is teh potted version.

Well here's a little story - to tell it is a must!

I think it must be 7 years ago, the ground was wet and awks at Piggy and there was a smell of hot clutch before I got the caravan located. And I had just installed a subwoofer in the caravan. A certain person with me did not know how to turn the sound system off (not her fault) and so turned it down in stead. That left both the head unit and the sub amp powered, so that drained the battery. And when I looked, the sight glass on the generator was leaking fuel. So while I fixed that I hooked up the caravan to the Volvo to charge the battery. When I'd fixed that the Volvo had stopped. I assumed she just got bored with ticking over, but the next day I went into Edenbridge and she drove like **** - no power, big flat spots. Managed to get home although the lack of power on the M25 was annoying.

Took Volvo to the garage on the corner who said "head gasket and clutch". So about £1000 later I drove her out, round the block, and straight back in. 5 different mechanics. Ever since, I and others have been hunting for that misfire. 5 different mechanics. Air mass meter, lambda sensor temperature senders, knock sensor, injectors, distributor cap coil HT leads and plugs, fuel pressure regulator, exhaust gas recycling, turboplus system, vacuum and pressure hoses. Pretty much ran out of things to change. Much money ****ed up against the wall.

Garage on the corner (new owner) told me a story about AMMs. So I had spares and he changed it. Radically worse. Today I've tried all the rest of my AMMs - two are in the bin, one is in a box 'cos it nearly works - and one makes her run perfectly!