Sick AJP

[Gray_101]

Hi, today i decided to remove the air boxs on my 4.2 and set up the engine with the lap top.

Id just got the throttle pots set and was about to start the engine, when my lap top screen went black and the lap top shut down, also i noticed the usb adaptor cable was very warm.

I rebooted the laptop but no way could i connect to the ecu, so i asume my usb adaptor has had it.

Any ways i decided to start the car only to find the even bank is not running right, looks like the cam timming is off cause i can see bursts of flames behind the butterflys on every inlet, and the exhaust manifold got alarmly hot in about 15 seconds, while the odd bank exhaust manifold was still quite cool and touchable.

Because my laptop is now not working, i decided to remove the inlet manifolds and the cam covers and to check the cam timing before doing any thing else, and this as far as ive got.

Ive got a TDC tool made out of a old spark plug, and i know that if the front clyinder is at TDC the valves on the rear cylinder should be on equial overlap, on the combustion stroke.

But to find TDC i need to rotate the engine clockwise untill the piston hits the TDC tool and mark it, and then rotate the engine anti clockwise, untill it hits again to get the second mark and TDC should be between the two marks.

But is it safe to rotate the crank anit clock wise while the cams are connected ? or will i do even more damage ?

[spongy]

Bud are there no timing marks for reference,also its chain driven so no chance of belt jump etc.Also is the car running rich on the plugs or were they white or near

[Gray_101]

Ive not taken any of the plugs out yet, will do that tomorrow.

it looks like the cam timming is out or bent valves,,, but id ive thought if more than one valve is bent on the same bank the engine wouldnt run atall.

I really need to find TDC on the even bank

I thought i would use the air con pully on the crank and rig up a datum point to help find TDC.

I just dont like the thought of turning the engine anti clock wise, is it safe to do so ?

[spongy]

Will probably be shot down in flames but i cant see a problem turning crank back on its self,If there was an issue you would feel it when turning on pully.From my experience the crank should not be turned when belts are off.The last motor i had apart was a 2.5 flat four and from what i can remember there was a warning about moving pullys,but the pullys tend to spring back,you just gotta remember the correct way to reset em

[spongy]

Bud in my mind i would picture a typical cam profile this sits on a shim,so no matter what way this turns its going to run the same profile.Take your plugs out rotate motor as you have said and when you think you are nr to tdc carefully put a long srewdriver in plug hole,now carry on a tad the way you were going and it drops,now bring it back again untill it hits tdc this you can kinda feel when its there.

[itiejim]

Rotating the crank against its normal direction of rotation is not normally recommended as the bearing surfaces have worn to suit the correct rotation. However, given the circs I think that you are highly unlikely to cause any problems here. Also, just remember to only turn it in the correct direction when you're setting the timing otherwise the slack in the chain will mean that you set it completely wrong!

I would get it close to TDC and then use some kids bubble liquid over the spark plug holes, keep blowing until the bubble can't get any bigger. It's an amazingly accurate way of finding TDC. You could measure it for the second back, but personally I'd just repeat the bubble trick.

When I rebuilt my engine I made a pointer which is bolted to the timing chain cover and made a couple of notches in the A/C pulley to show the two TDCs - saves using all the kids bubbles up

[spongy]

Well you learn somthing everyday on here been into cars for 29 years and have never used chewing gum still think you can feel when its there but chewy sounds more fun

[itiejim]

Not chewing gum - the soapy liquid kids use to blow bubbles.

I guess chewing gum could work though....

[spongy]

I must learn to read things properly.Normally just look at the piccys

[Gray_101]

Thanks for the info guys ,

im gonna try and sort it tomorrow evening, but to be honest i fear the worst.

I think the valves are slighty bent on the even bank,,, but im surprised it still runs, tho not very well

[spongy]

Bud dont worry yet,normally valves get bent when timing belt jumps or snaps.Not sure how much you can adjust timing via computer etc.sounds like it could be air fuel ratio issue to me .wish i was closer would have a look as two heads are better than one.Good luck keep us posted.

[jammy_basturd]

How was it running before today? Odd that the valves would just bend or cam timing would go off for no reason, or has the engine been out/rebuilt?

[itiejim]

I've just re-read this. You'll only get valves hitting pistons if something has mechanically moved - highly unlikely on a chain driven set up.

If it was all OK before you plugged the laptop in I'm sure it will be now. If you're in any doubt just run a compression test.

[spongy]

May sound like a stupid thing to say but when was the last time she was checked with the old feeler gauges bud?

[spongy]

Sorry to keep on bud but is there a tdc sensor,would say so as it can be recorded on the old lappy.I would look here first if you think you have timing issues.Sometimes these need setting up or re new.

[Gray_101]

I thought the engine was ok untill today,

i just carnt explain it, to me seeing flames behind the inlet butterflys says the inlet valves are open when the spark plugs fire. ( all four pots are doing it in turn )

Ive check the spark plug leads, there ok and fitted correctly

Can the ecu fail and throw the spark timeing out of wack ? i dought it, but the lap top frying just before this happened could point to that. ( long shot i know ).

All i can think to do is check the cam timing, and get a new USB adaptor lead and get the lap top up and running and go from there

Edited by Gray_101 on Sunday 20th March 22:49

[itiejim]

I think an ECU / ignition timing issue is considerably more likely than a static timing one.

A couple of years ago I had an issue with mine where it suddenly stopped injecting on one bank. I reset the ECU and it hasn't reoccurred since.

TVR's don't you just love 'em

[spongy]

Flames =air- fuel issues sir;)
Mine mends its self,then somthing else happens i mend that and then the first problem comes back(noticed more hair in the bath today)

[skidoo]

ign timming all starts from crank signal may be a good place to start it may have a bit of ste stuck to it after all it is a magnet;)

[baguaman]

itiejim .. How did you reset the ecu and is there any harm in doing so?