Crossflow Problem

[ICEWOLF 53]

Hey Guys

 

Been having a problem with the XE. Its a 83 XE Spac EFI manual. Sometimes it would drive fine othertimes it would idle fine but as soon as you gave it some throttle it would start dying and running really rough

 

I changed the air and fuel filters and fitted a new set of plugs and gave it an oil change. No difference

 

then i pulled the dizzy and had a look at the gear which was a bit worn. I have had the car for 9 years and had to replace that gear about 4 years ago when it wore down and broke a few teeth off.

 

Put in a crow gear a couple of weeks ago and set the timing by ear. Car was running great and the problem was all gone

 

Put in some low octane fuel on tuesday and drove to work (25km each way) and back 2.5 times (125kms) so i dont think the fuel would be the issue

 

Today the issue came back. Only slightly within the first 5km but then worse and worse till i barely got up the hill close to home.

 

When it was only slightly doing happening i could rev in neutral but not under load but by the time I was home it wouldnt even rev in neutral happilly

 

As long as its under 2000rpm and minimal throttle it runs ok enough (how i made it home)

 

Any ideas? Timing maybe or a sensor?

 

daily driver so really need to get on top of this asap

 

thanks in advance

 

[Gaz 1,085]

air flow meter ok? 

[XFGHIA747 76]

Hey man i would say its the airflow meter as Gaz has said will barly run if unpluged or playing up and most times back fire through the manifold, 9 times out of then it will run worse under load as you say, going up hill for example because the afm wants to be fully open if its cooked the computer cant function witch = your lawn mower has more power!!

if you are unsure of the air flow meter its the alloy unit on top of the factory airbox its a shutter type set up, should be able to get one from wreckers for 10-15 bucks..

 

Hope This  Helps!!

 

Jake 

[Crazy2287 1,886]

Check your plugs, Any sign of detonation, lean or rich. Will tell a lot about possible issue.

 

Have you got a timing light?

 

Does it sputter or just lack power?

 

Get buack to us on the plugs, If you dont know what ur looking at get a good macro picture of one and put it up. If they dont all look the same put up any piccys of ones that look different.

[ICEWOLF 53]

plugs looked fine when i changed them (changed them after the first time i had the issue.

 

lacks power and sputters

 

dont have a spare AFM so will have to find one. I checked the AFM when i gave it the service and the movement felt good but i know that doesnt mean much. Canberra wreckers are super expensive so unfortunately it will be a lot more then $10 but i will see if I can lay my hands on one. Wish I didnt get rid of all my spares when i moved house but thems the breaks

[XFGHIA747 76]

Yeah sound like a plan pitty your not closer i have about 3 afm here if witch were all working fine, could post one over but if thats not your problem then yeah nuf said,

[gerg 10,871]

The AFM has moving parts that wear over time. Firstly, check that the vane is moving freely. Also check that it returns to rest smoothly and easily.

 

The part that wears most is the variable resistor under the blue lid on top of the meter. The lid is glued on with sealant, so after you pry it off, you'll see a copper contact arm (which is attached to the vane) that sweeps through an arc on the carbon resistor plate.

 

As the vane (and arm) moves with the increased load and airflow, the resistance changes and the computer sees this as a voltage change. It then knows how much air is going in, then calculates fuel accordingly.

 

If the contact arm wears a groove in the carbon, the computer might get the wrong resistance at a particular point in the arc, thus giving the engine the wrong amount of fuel, or none at all. You can do a little dodgy and bend the arm so it contacts on a fresh part of the carbon. It might only need a couple of mm inwards and that's all. Just don't bend it so it's advanced or retarded in relation to the vane, otherwise it will throw everything out.

 

You can tune it to an extent by changing the spring tension and the arm angle, as well as turning the idle mixture screw in the bypass port. I'd really only play with the last one unless I knew what I was doing.

[XFGHIA747 76]

Yes i too agree with you gerg on all that well said mate ^^^ like i said a lawn mower goes harder when they fark up due to that contact being cooked,, i havent yet had a afm go to do this to move the arm but i have seen it happen similar over and over again, 

[Crazy2287 1,886]

should be able to "test" the AFm with a multimeter on ohm and test across the pins till you find a resistance that changes when you move the vain. Then move the vein through full sweep slowly and you should get a consistent and stable change in resistance that is repeatable on second and 3rd sweep attempts.

 

The AFm has 5 pins correct? If so im betting 3 of them are for the potentometer (the bit your testing) and the other 2 are for intake air temperature?

 

Alternate test is get it running, Give it a rev, Unplug the AFm and give it another rev. See if the symptoms change.

 

Get your plugs out and have a look, Don't be lazy or i will smack you. Their condition will be helpfull to the cause, The condition of the plugs can change so make sure the car is in "fault" for a moment then shut the car off immediately and remove the plugs. What they looked like last time is irrelevant, as i said their condition will change rapidly as the engine changes.