Engine timing question.

[ZetecVan 2.0]

I had to replace my water pump at the weekend, which involves taking off the cam belt. To do it, you lock your cams in position at TDC, and piston 1 should be at TDC too (obviously!). Only it wasn't. It was probably 40 degrees BTDC. So, I got the piston to TDC and put the belt back on.

 

The van was running ok before, but now it's popping and spitting through the throttlebodies, and according to my megasquirt log that's down to a weak mixture. A remap is in order.

 

The engine is still sparking at the same position but now the valves will be opening and closing at the right time.

 

I don't really know what I'm asking here... I want someone to put my mind at ease about the spitting. It occurrs when you plant the throttle.

[alladdin]

after making changes the 1st place to start is by checking back what you have done.

if it was running ok before then it was probably timed correctly before.

if the piston wasnt at tdc when you started work then you locked your cams in the wrong position (tdc refers to crank)

set the crank timing (tdc pos)to cam timing(cam pos's) as per haynes manual as a starting point,

double check if you think you just did.

dont start making more changes unless you know that it was wrong before you started work.

[w p e]

sounds like retarded cam timing. not all engines time in at TDC

[ZetecVan 2.0]

Cheers. The cams were locked in the right position (there's only one position they can lock). It was before I took the cambelt off I thought I'd double check the position of the piston, and noticed it was not at tdc. The person I bought the engine off had replaced the cams at some point so mustn't had done it properly. I replaced the cam belt last year before I fitted the engine, but didn't check the piston was at tcd. I just locked the cams and crank in position, marking everything as I went.

 

The timing map does seem correct, as I've never changed that when I've been tuning. I went on a rolling road day last year and it was down on power. It only produced 106bhp when it should have been 130+. Granted it's not been properly mapped, but I thought it should have produced more.

 

edit: It's a Zetec, btw, and when the cams are locked in postion (there's only one position) piston 1 should be tdc.

[louie bagel]

just a quick one when you locked the cams using a flat bar on the back of the cams did you slacken off the cam pulleys, tighten the belt then tighten the pulleys?

[ZetecVan 2.0]

just a quick one when you locked the cams using a flat bar on the back of the cams did you slacken off the cam pulleys, tighten the belt then tighten the pulleys?

 

Do you mean did I slacken the cam pulley before locking the cams? No, I didn't.

 

When I refitted the belt, the cams were locked, and I started on the left (inlet) cam and worked my way round clockwise, keeping it tight, before tightening the pulley.

[louie bagel]

just a quick one when you locked the cams using a flat bar on the back of the cams did you slacken off the cam pulleys, tighten the belt then tighten the pulleys?

 

Do you mean did I slacken the cam pulley before locking the cams? No, I didn't.

 

When I refitted the belt, the cams were locked, and I started on the left (inlet) cam and worked my way round clockwise, keeping it tight, before tightening the pulley.

 

thats probably the problem then, strip it down again set the crank to the timming mark you used the time before last, get a flat bar (timing tool) lock the cams with it then remove the belt.

slacken off the cam pulleys

fit the belt starting with the crank and go anti-clockwise so that all the slack is on the left as you look at it (tensioner side),

when you've got ot tight between the crank and first pulley (going anti-clockwise) then between the cams then pull all the slack out using the tensioner,

make sure everything is tight remove the timming bar turn crank 2 full turns and check the tension (easiest way is you should be able to twist the belt 90degrees between the crank and first pully).

 

hope thats helped if not pm me with your number and i'll give you a call