sounds like running on 3

[nismoboy]

hi, my car sounds like a wrx, did a comp test and all fine, changed leads plugs etc
check for boost leaks all seems fine. Any ideas?

 

[tro||]

my mates car did a very similar thing and it turned out to be cam timing, the chain had slipped..

he did have a big **** off bang and a flame first though..lol

 

[geetee]

Takes a very worn tensioner for a chain to jump a tooth.

Check the contacts inside the dizzy for pitting or charring (black)... any sign of change the cap and rotor arm. May be tracking or arcing.

If ur sure it is firing on 3 it could be an injector stuck shut. So pull the contact off each injector in turn and go for a spin........ one of them won't make a difference. Get it cleaned and flowed. Actually if this is the problem it is likely they are all gummed up, so get them all cleaned and flowed.

Cheers
Graham

 

[nismoboy]

Takes a very worn tensioner for a chain to jump a tooth.

Check the contacts inside the dizzy for pitting or charring (black)... any sign of change the cap and rotor arm. May be tracking or arcing.

If ur sure it is firing on 3 it could be an injector stuck shut. So pull the contact off each injector in turn and go for a spin........ one of them won't make a difference. Get it cleaned and flowed. Actually if this is the problem it is likely they are all gummed up, so get them all cleaned and flowed.

Cheers
Graham

ive checked the dizziy cap and its like new only replaced it a month ago same with the rotor arm,

but yeah could be the injectors i guess, there only 2 months old though but worth trying cheers geetee.

 

[andygtir]

i had a rocker arm fall off and do the same thing. take the cover off and have a look.

 

[nismoboy]

i had a rocker arm fall off and do the same thing. take the cover off and have a look.

ive got rocker stoppers, so that should`nt happen plus no signs of any cam/lifter noise

thanks for replying though cheers nis.

 

[andygtir]

what about the injector resistor pack bolted by the n/s/f strut tower? put a voltmeter on each of the injector harnesses to see if the voltage/resistance is ok. its in the manual. you can do the same with the leads to make sure you're getting a spark.

also check no-ones been fiddling with your ecu, if you've got a pfc make sure aeverythings as it should be.

 

[nismoboy]

just checked pulling the pulgs on the injectors and it does drop out on each cylinder so i guess that rules that one out. Its sounds like it going on to 3 cylinders when underload.

yeah cheers andy i`ll check the resister pack and injector voltage next.

 

[Fast Guy]

It could be running very rich, that can make a car sound like a subaru sometimes. (ie like it's dropped a cylinder)

 

[pulsarboby]

sounds to me like you've done a valve! is it popping out of exhaust on idle? listen for misfire on exhaust note

 

[nismoboy]

It could be running very rich, that can make a car sound like a subaru sometimes. (ie like it's dropped a cylinder)

its a touch rich but nothing too bad to cause this.

 

[nismoboy]

sounds to me like you've done a valve! is it popping out of exhaust on idle? listen for misfire on exhaust note

i can hear a slight miss when loading the car then it just goes flat and sounds like it on 3 cylinders, Ive just done a compression test and all is fine. Ive noticed theres a little bit of grime on top of cylinder 3 but nothing major.

 

[nismoboy]

ive just tried using another injector ressistor pack and a different ignition amplifier and still no different!! bloody car.

im thinking its one of the injectors maybe blocked or fooked ??

 

[pulsarboby]

could be an injector but still sounds like a valve problem to me, especially if it does it under heavy load, maybe a sticking or leaky valve or valve spring bounce under load.
if it is popping from exhaust its definately got a misfire on a cylinder

 

[nismoboy]

could be an injector but still sounds like a valve problem to me, especially if it does it under heavy load, maybe a sticking or leaky valve or valve spring bounce under load.
if it is popping from exhaust its definately got a misfire on a cylinder

hi, if it was a valve would it not show on the compression test? cheers nis.

 

[pulsarboby]

no as it may be misfiring under load, especially if you have valve bounce.
and a compression check should be carried out on crank only with throttle wide open, so this alone will not show a problem if its a valve or spring.

 

[nismoboy]

no as it may be misfiring under load, especially if you have valve bounce.
and a compression check should be carried out on crank only with throttle wide open, so this alone will not show a problem if its a valve or spring.[/QUOTE

so how do i test to see if the valve is leaking? or not seating propery?

 

[pulsarboby]

you could carry out a cylinder wet test to see whether you get a different reading with compression test, but even this may not show up anything as its mainly designed as a ring check!
im not sure other than doing a visual check on valves and springs for compression rate!

only other way i can think of to do it is by using compressed air in each cylinder when piston is at tdc on firing stroke with all valves closed to see if valves are leaking through!

anyone else got any ideas how this can be checked with the head in situ?

 

[Fast Guy]

A Leak down test is the proper way to test if your valves are stuffed. It pressurises the cylinder, then checks the rate of leakage from the cylinder. If there's excessive leakage, you can tell what's leaking by where the leak is coming from.
Valves, head gasket, rings etc.

 

[nismoboy]

A Leak down test is the proper way to test if your valves are stuffed. It pressurises the cylinder, then checks the rate of leakage from the cylinder. If there's excessive leakage, you can tell what's leaking by where the leak is coming from.
Valves, head gasket, rings etc.

cheers fast guy, how do u do a leak down test?