car engine ramblings- low compression symptoms

[slim_boy_fat]

yeah good call does point toward it...ive had it all off several times now , nothing from spraying carb cleaner around the joints etc

It's not unknown for vacuum etc pipes to collapse internally, showing no external evidence of what's happened. Try squeezing carefully all along the pipe(s) to see if they feel 'squashy' [technical term there ]

 

[Farside]

loathed to buy a china leak down tester incase its rubbish , cant really be buying a premium one , spose i could whip the cam out so all valves closed and find a way to pressurise the inlet see ifs theres any leaks

Depending on how your compression tester is made, you can adapt one to being a leak-down tester, for next to nothing.

 

[steveo3002]

It's not unknown for vacuum etc pipes to collapse internally, showing no external evidence of what's happened. Try squeezing carefully all along the pipe(s) to see if they feel 'squashy' [technical term there ]

there not much to it ..theres only a foot of new vac hose on the whole engine

 

[130]

If it's not getting idle air through the valve it's getting it somewhere

 

[8ob]

Am I the only one here that thinks that there could be an ignition/spark/coil problem. Sounds like its getting a scattered spark to me

Bob

 

[steveo3002]

Am I the only one here that thinks that there could be an ignition/spark/coil problem. Sounds like its getting a scattered spark to me

Bob

not a bad comment ...ive been over it and over it , what can i do to chase it further /confirm it

 

[8ob]

not a bad comment ...ive been over it and over it , what can i do to chase it further /confirm it

Assuming its got a coil, distributor cap , rotor arm and leads I would start by putting a timing light on all of the leads including the king lead and observe whats going on. I am only going along these lines as the engine has compression, fuelling issues are sorted and air leaks eliminated, that sort of points to the ignition rather than a lean burn misfire.

Bob

 

[steveo3002]

yes coil , dizzy rotor etc

ive tried a spark tester and observed an equal spark on all leads ,can try the timing light on the others

still sort of says air leak to me , but i cant find one if it is ...might see if anyone local can re surface the inlet flange

 

[steveo3002]

you say scatter ? what would cause this /why

you know rotor arm goes round and a spark goes to each lead , what can go wrong ? tried other dizzy /cap/lead combos , cam timing is correct

 

[li150ss]

tracking in distributor cap, (can look like 'pencil lines'), my first thought was air leak

 

[steveo3002]

thanks...tried many caps and arms now no change

yeah still not convinced its not an air leak ...it changes to an even note above idle if thats any clue

 

[Roberto]

How about a long shot. Contaminated fuel?

 

[Wightsparks]

Sorry but I am confused.As i understand it your problem is ONLY at idle.
The Idle Control Valve makes the car idle smoothly. -Your car is not idling smoothly. When you stop the ICV from "working" there is no change = ICV not working no ? If it was working surely it would get worse or there would be some sort of change.

Also I can't see how some of the things suggested would suddenly disappear above idle.

 

[steveo3002]

fair point...other enthusiasts with the same car suggest if blocking the hose doesnt help then no fault

will make more enquirys

keep the suggestions coming ..all appreciated thanks

 

[steveo3002]

right asked another owner

its a valve thats open when cold to raise the idle , as it heats it closes to lower the idle , thats all it does , it cant raise the idle when the headlights are on etc

simple as that ...so when hot its close and crimping the hose would have no effect

 

[130]

is this a crank sensor or points / hall effect or similar in the dizzy?

 

[steveo3002]

hall sender no crank sensor

 

[130]

Check for freeplay in dizzy shaft side to side (rarely an issue without points)
Find the advance curve in an auto data book and check it if you have an adjustable light
And check exhaust not obstructed as said earlier.

 

[130]

Have you swapped the ignition amplifier?

 

[130]

The Bosch dizzy has a diagram of a circuit you build on the net to test them