Hesitant And Jerky Under Acceleration

[Obey_R 23]

It's a new alternator I fitted less than 1000 miles ago, I will test it tomorrow when I test the TPS because I'm secretly hoping it's that, that has failed! Tomorrow should rule out the TPS, if it does the only thing left to try is an AFM.

 

Will also change the fuel pump relay for what it's worth, how can I test to see if the fuel pump is up to the job?

Edited June 8, 2011 by Obey_R

[Anthony 1,003]

Just unplug the TPS to rule it out - all you'll lose it full-throttle enrichment (so it'll feel a bit flatter than before) and fuel cut on overrun (so fuel economy will be a touch down)

 

It isn't a TPS in the modern sense, but rather a glorified switch to show throttle closed or throttle wide open

[Paul_13 212 1 Cars]

Kyepan used a pressure gauge installed on the return (could be wrong) pipework, he attached it right near the pump under the rear seats I believe.

 

My money's on the alternator (longshot!)

Edited June 8, 2011 by Paul_13

[Obey_R 23]

Well I did take it out for a quick spin with the TPS unplugged and didn't seem any different. Certainly at idle it made no difference, only making a sudden 'blip' when it was plugged back in.

 

I will test the TPS with a multimeter tomorrow, to see for sure.

 

I certainly hope it's not the alternator! I know when I fitted it, it was pumping out a good 14v from the battery, so the wiring is in good enough condition, too.

[Paul_13 212 1 Cars]

Any problems with starting it?

[Obey_R 23]

Nope, no problems starting it at all.

 

I took it to a local garage today who said they would take a look, FOC. Had it running for a little while, opened the expansion tank and stuck a block tester/sniffer in it. Sure enough, head gasket failure. Between the cylinder and the waterway he tells me. Says its burning antifreeze, thinking it is petrol and trying to lean off the mixture, hense the flatspots/hesitation as if the fuel pump was failing.

 

It also explains why it got worse with heat, and why it has started playing up from cold now, instead of just when it's hot.

 

He quoted me £300 all in, possibly less. I can get the headset inc bolts for £40, and a cambelt kit inc waterpump for another £50.

 

I'm going to do a bit of research, but the options are do it myself, take it off the road for a few weeks and bike to work again!

 

Or because I'm going on holiday in two weeks, leave it with them so when I get back I'm £300 lighter, but have a working car to come back to.... but I'm tight.

[smithy 1]

£300 all in does that include pressure test and skim as required?

 

personally i would have head off myself get it pressure tested and skimmed if needed,i would also have valves out to re lap,change seals and then check/adjust shims.

 

if it is comong off may aswell be done fully dont forget to change thermostat aswell.

[Obey_R 23]

Thermostat was done only a 1000 miles ago by myself. That inclues a skim, not sure on the pressure test. I'm tempted to do it myself, but it's the first time I've done anything this big, so will need to read up and grow some balls! I can get the head skimmed locally for £30 or so, if I were to do it myself it would be over a few weeks of evenings, so could do things like cambelt and waterpump at the same time. Anything else to add to the list, re-lap the valves, valve stem seals the ones you mean?

 

Off to the GFs tonight but will do some swotting up tonight before I fix the bike ready for work!

[smithy 1]

Thermostat was done only a 1000 miles ago by myself. That inclues a skim, not sure on the pressure test. I'm tempted to do it myself, but it's the first time I've done anything this big, so will need to read up and grow some balls! I can get the head skimmed locally for £30 or so, if I were to do it myself it would be over a few weeks of evenings, so could do things like cambelt and waterpump at the same time. Anything else to add to the list, re-lap the valves, valve stem seals the ones you mean?

 

Off to the GFs tonight but will do some swotting up tonight before I fix the bike ready for work!

 

 

yes the stem seals.

 

it really is not that hard to do so long as you take your time and have a write up with torque figures etc.

 

i have a pug workshop manual for the xu5 and xu9 engines that i liberated when apprentice,if you want to tackle yourself i could post it to you so long as you promise to return it when finished?

[Obey_R 23]

That's a very kind offer! I will take you up on that if I go ahead with the work myself, should know in a few days. Is it worth replacing the valves whilst I'm there, or is that only worth doing if they're bent or damaged? What about the valve springs?

[Daviewonder 533 3 Cars]

Says its burning antifreeze, thinking it is petrol and trying to lean off the mixture, hense the flatspots/hesitation as if the fuel pump was failing.

 

Sounds a bit far fetched to me, afaik the only fuel mixture control on these engines is the AFM and the management temp sensor, neither would have a clue about the engine burning antifreeze.

[Paul_13 212 1 Cars]

Worth doing a compression test?

 

There's no lambda so can't see how it would tell as above ^

 

Is it smokey? Any mayo?

Edited June 9, 2011 by Paul_13

[Obey_R 23]

Using water, bit of mayo in the breathers as normal. Did a compression test myself and got 180 175 180 190 but that was dry with the throttle closed (forgot!).

 

Is the sniffer test on the expansion tank not a good test then?

 

EDIT, yeah a fair bit of smoke on start up until it's warm.

Edited June 10, 2011 by Obey_R

[smithy 1]

What garage are getting at i would think is burning antifreeze would cause it to run like it is lean due to mixing with the fuel and air in 1 of the pots.

 

I would examine the valves but probably won't need renewing just lapping in.

The valve springs should be ok aswell.

[Obey_R 23]

Ok cool, I will have the valves out for a good clean and am planning on lapping them in anyway. I'm pretty confident I can do it myself, I've got three local mechanics who have said they will give me a hand if I get stuck.

 

I want to do the cambelt, waterpump and tensioner at the same time so whats a good order?

 

I will start a progress thread soon so I can keep it altogether.

 

Thanks so far!

[marc t 0]

Did the head gasket cure your issues? I have exactly the same issue but I am not loosing water and there is no steam coming out of the exhaust.