car coughs and stutters under load after rebuild help please

Bane

my zafira 2.2 has recently been overhauled after burning out a valve again (did same 18 months ago) ,
this time had a husband of a friend of the wives repair it who is a mechanic , upon stripping engine the timing chain guides were damaged so got a new complete kit for him to fit as well as a replacement head and new valves .so basically engine has had a complete top end overhaul ,
the issue we have now is the car starts and idles fine and revs up fine with no ecu lights or codes but soon as you drive it and put your foot down it coughs and splutters terrible , i have got the car back as he has had the car for 10 weeks now due to various excuses and me not prepared to wait any longer for my car to be fixed , i have checked and cant see any air leaks , car seems to run slightly better with fuel cap removed and fuel return clamped but my question is if the timing chain was out by one tooth would this cause these symptoms ?

IDI_AMIN

Possibly timing is out, Depends how competent the mechanic is .
Maybe check the egr valve is functioning properly, this could cause the problem
and check again for air leaks would be my suggestions before assuming the timing is out

patricks

Mine did the same a while back and i was convinced it was the coolant temp sensor ended up only being the plugs. Also worth cleaning the throttle body and if no improvement then the coil pack

Bane

the car has no EGR valve fitted , had new plugs , i do know that he never used a locking kit when fitting the chain so guess would it be possible for a cog to move fractionally when fitting

patricks

having done the chains on my car i can confirm its easy for the chain to jump. But personally i would investigate other easier options first like throttle body and coil pack before going thru the hassle of doing chains again. Alternatively if you have the cam locking tool that will tell u if the timing is out without having to pull the timing case off. Only need to take off the cam cover put the engine to tdc and install the locking tool and ur done...........

Bane

i borrowed the locking tool of another friend who uses to have an Astra coupe years ago , but he never used it , presumably as he had to remove the engine as the sump needed removing as there were pieces of the plastic guides missing so presumed they had dropped into sump , but i still cant understand why he didn't use it ,spoke to my friend this morning and hopefully we re gonna try and lock the cams and see if it is out

vocky

I never use the chain locking tool, it's not required on a cam chain change. I simply cable tie the chain to the cam sprockets and then align the crank sprocket, very easy to do, but also very easy for the chain to jump a tooth - so you have to double check it when the tensioner has been fitted.

Bane

update , removed cam cover , checked timing and gold markers on chain line up so timing is correct , checked injectors and fuelling fine , spark at all 4 plugs , but noticed 2 of the new plugs were very clean unlike the other 2 which showed normal wear deposits the cylinders affected were 2 and 4 , done compression test and all cylinders show good readings ,,so annoyed now as to what the issue is ?
any other thoughts , i have ordered a coil pack and thinking maybe crank sensor faulty or damaged when engine was removed ??

patricks

Bane said:
update , removed cam cover , checked timing and gold markers on chain line up so timing is correct , checked injectors and fuelling fine , spark at all 4 plugs , but noticed 2 of the new plugs were very clean unlike the other 2 which showed normal wear deposits the cylinders affected were 2 and 4 , done compression test and all cylinders show good readings ,,so annoyed now as to what the issue is ?
any other thoughts , i have ordered a coil pack and thinking maybe crank sensor faulty or damaged when engine was removed ??

That ur timing is not out and u dont have a cracked head and have good compression is all GOOD news nothing to be annoyed at. Coil pack, throttle body, sensors, or even collapsed substrate in the cats are the only possibilities that remain now

Bane

patricks said:
That ur timing is not out and u dont have a cracked head and have good compression is all GOOD news nothing to be annoyed at. Coil pack, throttle body, sensors, or even collapsed substrate in the cats are the only possibilities that remain now

if timing is correct at cams would it have these symptoms if the crank was out slightly ?
i just find it strange that 2 plugs were clean and 2 had normal wear and tear marks for engine being run for a short period as they were new plugs in and cylinders 2 and 4 would that have something to do with the firing order ?

patricks

When checking the timing, if the crank was rotated to tdc (there is a mark on the engine pulley that meets up with a mark on the oil cover) and the cams are in the right spot using the locking tool then crank cant be out