4age, Ignition Timing

[DearmanKE]

Hey guys.

Car model: Te72 T18

Engine type: Bigport 4age, Jap

Problem: ...

Just put my motor back together after blowing headgasket a while ago, its a standard bigport 4age

Ive started it and run it and checked timing and when its set at about 15 it does not want to rev up quickly.
when u open the throttle it hesitates slightly befoire revving up.
I advanced the timing further and it revs beautifully. but the timing at approx 800 rpm is about 35 degrees BTDC.

The cam timing is set right and the harmonic balancer is good(mark is not out)

I do not have a diagnostic plug that im aware of, my loom has been cut and is quite a mess. so i cant bridge any terminals.

but still it seams like the timing is wayy to much, but if i put it lower it hates revving.

can anyone shed some light on this?

[timbo]

Check with the timing gun that when you rev the motor that crank pulley isn't retarding (mark moves clockwise) and that it would advance (move anti-clockwise).

What you have described sounds similar to when a wire in my TPS loom was broken, so on throttle movement then ECU wasn't advancing the timing.

[Matt]

You need to bridge it... At your ECU , splice a switch into the T and E1 terminals and add a switch.

Flick the switch to put you into diag mode and off again to come outta it.

You'll find the ecu terminals under the lid of the ecu / printed on the circuit board or here

http://www.ae86drivingclub.com.au/forums/showthread.php/16050-AE86DC-Technical-Documents

[timbo]

Even so, at 15-16 degrees unbridged the motor should rev.

Did you remove the distributor at all? Is so then it may be out.

[DearmanKE]

TIMBO

u may be my saviour

just tryed again and exactly as u have described, when i blip the throttle the timing jumps back from 35 to approx 20 or just under.

can you give me any more info?

[timbo]

I would say it is your TPS. Unplug it and see what happens, a 4AGE should still run with it unplugged, just not as well as it should. It is time consuming but you will need to find which wire is broken or if the TPS itself is stuffed. The 4AGE manual in the tech documents section outlines all the checks you need to do with a multimeter.

edit: On idle when you remove the TPS the car should start to idle higher, if it doesn't then I would say it has to be your TPS.

[DearmanKE]

I did the multimeter checks and the Ecu is receiving the right signals from the tps. So maybeim looking in the wrong place

[slide86]

are you sure the dizzy is refitted correctly? sounds like its out by a tooth......

[DearmanKE]

Removed it while running and it ran a oil different, slight change in idle and seams to rev a oil quicker with it connected so maybe it's not tps. Maybe an Ecu fault?

[DearmanKE]

Ok dizzy may be out, correct me if I am wrong but if it's out why does it matter as u can adjust it around itself.

[H8CHIR6KU]

because it doesnt adjust to whatever postion you want. it only moves a few degrees. so if its on one tooth to the left or right, you are only going to be able to retard it or advance it 'x' amount instead of having an equal amount of adjustment. if its a tooth out retarded you wont be able to advance it enough to get the timing right.

the fact that you said that it runs better when you advance it to me sounds like you got the dizzy one tooth out.
either that or your a tooth out on your exhaust cam sprocket.

[DearmanKE]

I can adjust it as far as tdc and up to 50 or so before tdc. But tonight I will remove and refit it. Cam timing is right have already checked that. Thanks for the replies guys

[DearmanKE]

Ok dizzy is right, cam timing is right, tps is working. But still on acceleration the timing is retarded 20 or so degrees so for it to actually accelerate at idle it needs to be set approx 35 degrees.
Any more ideas ppl, ?

I may try swapping the computer for another

[DearmanKE]

any ideas

[timbo]

Double check the dizzy, the gear easily moves when you put it back in. I know as I watched it line up on the camshaft with the cover off. Seems to be a real mystery...

[Matt]

^ agree with this... Lost count the number of times i've seen this happen

[H8CHIR6KU]

yeah. seen it happen alot with apprentices. they line up number 1 on the dizzy before they put it in.
not lined up with number 1 after its put in.

easiest way to tell is that at tdc with the dizzy in it should have the rotor pretty much sitting on the nodule of the cap

[DearmanKE]

had a look and it looks pretty good to me

[Corolla86]

are the dowel pins on the cams in the correct position?? dowel pin on intake cam on top, dowel pin on exhaust cam on bottom.
just because all the timing marks line up doesn't mean its correct.

Cheers Jarrod.