Z22YH Fails to start unless crank sensor unplugged!

Brendonm9477

Hi all,

New to the group as i didnt think z22yh would count!
ive had this signum a few months now and originally it was drinking oil.. prett much 50/50 with fuel!
so i replaced the engine and was told the engine had timing chain and full service a little over 1000 miles ago... oils clean can see new shiny tensioner on head so i assume its all good, came from a running car, my car ran fine,
other then lots of oil...
now originally i had crank shaft sensor fault and maf sensor fault.
now with cp com i get all sorts coming up!
but it will not start with crank sensor plugged in. i can unplug turns over twice then springs into life,
plug in will just keep turning over and wont fire!
any help much appreciated!
if it helps i can up load screen shots of op com/ vauxcom,
Thanks In Advance!

IDI_AMIN

A faulty crank sensor possibly

Brendonm9477

originally i was advised to swap both crank and cam sensors from original running engine which i did, then ive tried any which way using all the sensors and still no difference..

Brendonm9477

ALL IM GETTING IS CRANKSHAFT SENSOR CIRCUIT A OPEN WHEN DISCONNECTED (obviously)
but no faults when connected still just turns over and over and over.. could the timing be out? i cant see how it could be but i feel as though ive exhasuted pretty much every option or is it worth trying a new sensor..

evocarlos

normally when the chain is long/jumped on the yh the cam sensor prevents the engine from starting
do you have a pic of the code list ?

Brendonm9477

I had read about it jumping but like I was told and visually it seems to be a new chain

Brendonm9477

Also mention that when it does run. Spanner light is on and won't Rev over 3.5k

Brendonm9477

After clearing and plugging majority of sensors back in

IDI_AMIN

Brendonm9477 said:
After clearing and plugging majority of sensors back in

Big improvement.

So you either have a faulty sensor or a jumped chain or possibly both. You could try the new cam sensor a lot less hassle than changing a chain

Brendonm9477

cam or crank sensor?

IDI_AMIN

Brendonm9477 said:
cam or crank sensor?

Yeah sorry should have said crank sensor

Brendonm9477

the fact it had a new chain, done 1000 miles then the veccy it was in was written off...
engine was removed and in dry storage for 3 months then i got it... not sure if its at all possible for the timing to change..
or chain to stretch.. but when cold it does rattle.. so could be tensioner? am i right in thinking that>?

HarleyPete

Where was the damage on the written off car. If it was front end I suppose the impact could have made the chain jump who knows. I could be way off on my thinking but if the chains jumped ether the tensioner has gone or the impact could have caused it. The car may have been running prior to the accident but was it running immediately after and did you see it running. You see where I'm going with this? I'm sure someone will correct me and say it cannot happen but I'm just thinking out loud.

Brendonm9477

No I haven't seen it running with my own eyes. And other car was rear damage.. Is it safe to assume the new chain should or atleast might have the coloured links? If I take rocker cover off. And rotate it by hand until (if they do) line up?

HarleyPete

Well the issue with trying to line up the links again is a difficult one. Certainly on just the timing chain it could take 90 revolutions (I did work it out and that was my answer) but that won't line up the balance chain as well. You may have to start from scratch and re-time it unless anyone else has an easier suggestion. Might be worth trying the sensors as @[deleted] suggested.

Brendonm9477

new sensor no joy... though the tensioner does tap loudly when cold so is it possible that with the tensioner slack it has loosened.. and some advice on where to go in terms of checking timing... really at a loss with this and tempted to break it soon...

HarleyPete

This at the very least will give you a good idea about how to replace the chains. The YH engine isn't vastly different to the SE engine in respect of the chains. As has been mentioned numerous times across the forum, the guru of all things chains is @[deleted]. He will be able to give you the most help on how to check everything mate. In fact re-reading the thread he's already replied further up.

Brendonm9477

thanks alot @[deleted] fingers crossed @[deleted] steps in 😉

IDI_AMIN

evocarlos said:
normally when the chain is long/jumped on the yh the cam sensor prevents the engine from starting

This can be the only solution to your problem you have tried a new crank sensor so all that is left is to get a new chain fitted either you do it yourself or pay someone else to do it

You can never be 100% certain of the history of a second hand engine even if you are told a new chain is fitted. Could have been a cheap aftermarket brand
So for peace of mind you get a GM brand chain

Brendonm9477

brilliant..