Engine problems

[Zdrifter78]

First off im new to the Z Club and have searched to see if i could find some answers but came up empty handed. So, I have a 78 280 with an 82 turbo engine that im running NA. I bought the car not running fixxed a relay and it ran. The distributor was bad so i replaced it and put new plugs, wires, cap in. Then it ran fine. Put a new exhaust on it for the old one had rusted to pieces. Now all the sudden my car runs on 3 CYLINDERS, #3 #5 and #6, I checked the Compression and I got 100psi on each cylinder. I cannot for the life of me figure out what the problem is. Im thinking that its the timing chain but im not sure. The car will barely move on its own with no throttle response and backfires through the intake.

Please help, thanks
-Spencer

 

[Mr.G]

How do you now it's running on 3,5 and 6?

 

[Zdrifter78]

when iunplug the spark plug wires on those cylinders it cutsout and sputters, But on the 1,2,and 4 cylinders it dosent change at all. Its getting spark and its getting fuel so all i can think is its not getting it at the same time.

 

[Mr.G]

Have you recently changed your oil pump at all?

 

[Zdrifter78]

no but i did adjustit when i put the distributor in to try and help the timing i set it where the fsm said to.

 

[moggy240]

you might have put the distributor in 180 degrees out as you should not have any need to adjust the oil pump

 

[Throttleton]

And make sure you have put the plug leads back on in the right order before you mess on with the timing......

 

[Zdrifter78]

yea ive checked the plug order by comparing with my friends 280 and I will try flipping the distributor to see if that helps.
thanks for the help guys!

 

[morbias]

Why not just put the engine at TDC and see which point on the dizzy the rotor is pointing at? That will be ignition for number 1, then just follow the usual order anti-clockwise 1-5-3-6-2-4. Copying the plug order from another car won't help if your oil drive and distributor were put together incorrectly!

 

[Zdrifter78]

all right here is an update with my Z. I have checked the timing and it is correct. ive got fuel and spark to all cylinders. so im thinking that it could possibly be a valve issue. if the valveson the 1,2,and,4 cylinders are not opening, resulting in no combustion. adjusting the valve lash would also help regain compression would it not?

 

[morbias]

If they are not opening then they will all be bent, it's an interference engine. It's unusual for it to be running on only 3, 5 and 6, normally it would be 1, 2, 3 or 4, 5, 6 and that would be down to one of the carbs not delivering properly.

[EDIT] sorry, I was half asleep this morning when I wrote this! If they are stuck open they would be bent. I don't see why so many valves would be stuck closed at any one time. If the rocker arms have all popped off then you would be looking at a much bigger problem.

How did you test for spark?

How did you test for fuel?

How did you test for correct timing?

I think maybe the answers to these three questions would allow people to give you more helpful replies.

 

[jonbills]

If the spark plugs on the non firing cylinders are getting wet with petrol, there's spark and there's compression then the most obvious thing would be that the sparks aren't at the right time surely?

 

[johnymd]

Sounds about right Jon. Have you turned the engine over with the plugs out and carried out a compression test on each cylinder(I asume you have as you say there's compression) and what is the % variation across them?SORRY JUST READ ORIGINAL POST. The cylinders are wet so I guess your getting fuel. Is the spark good on all cylinders, ie. the same. It would seam to be a spark timing issue.

It may be an idea to step back and look at it another way. When was it last running? Has it been running? If so, what has changed since it was last running? You need to consider anything, no matter how minor. You have mentioned removing the distributor so this would be my first place to look. If it runs OK on the cylinders that do work then it probably leads me on to thinking the leads are on the wrong plugs. I guess you've already checked this but it may be worth double checking. You know the firing order and the dirrection of rotation(turning it over with the cap off and on the starter motor will show this). If it starts OK and runs on 3 then the timing is close enough so it must just be the order.

 

[Zdrifter78]

thanks for the help guys I deeply appreciate it I'll take a look at those wires again and see what I come up with. The last time it ran on all cylinders was before i put my exhaust on. she had sit for a while before I got my parts.

 

[MaximG]

Just as an added thing there is a raised line on the dissy cap which indicates the position of no1 lead. This also where the rotor arm should be when no 1 cylinder is at top dead centre on its compression stroke.

 

[jonbills]

thanks for the help guys I deeply appreciate it I'll take a look at those wires again and see what I come up with. The last time it ran on all cylinders was before i put my exhaust on. she had sit for a while before I got my parts.

perhaps also worth checking then that the exhaust manifold gasket isn't blocking the exhaust ports, and I hesitate to ask: you don't have a 6-2-1 manifold where cylinders 1,2,4 are on the same branch do you? (not sure if such a thing exists anyway).

anything else that cylinders 1,2,4 have in common?

 

[nissanabuser]

If you have equal compression on all cylinders it won't be bent valves. Try changing the dizzy cap as I have had the spark arc across the inside of the cap before if it is scratched or damp