Ae82 4A-C Ignition Or Something Like That.

[Dadman]

Hey guys,

I have been on here for a while reading but never posted.

I have an 1985 AE82 with a 4A-C and it has a problem that although very annoying is hard to describe so I will try to be an concise as I can.

 

When the engine is cool it runs well, but as it warms it gets worse.

The first sign is the tacho becomes erratic, Even at idle the tacho is reporting 1,500-2,000RPM, If I lightly press the accelerator and raise the revs the tacho will become slightly more accurate, coming down to around 1,000RPM.

While driving at below around 3,500RPM it will miss, ping and have next to no acceleration with the problem worsening as more throttle is applied, Tacho reports jumps of up to 2,000RPM above reality.

So the timing is going all crazy and at idle sitting at lights it will even stall.

I thought it would be the TFI module so I got a couple of replacements from a wreckers and it made no difference.

Any help would be appreciated.

[bAKER]

When did it start?

Are you sure it doesn't miss all the time?

Can you find out what the advance is at tdc?

Does it get really hot?

Does it use any fluids?

[Dadman]

When did it start?

Are you sure it doesn't miss all the time?

Can you find out what the advance is at tdc?

Does it get really hot?

Does it use any fluids?

 

Problem has been there for the whole time I've had the car, 6 months or so.

I am pretty sure it doesn't miss all the time, it will run down the street at 1,500rpm in second smooth as silk when cold, but when its warm its awful.

I got to get my hands on a timing light to make sure the timing is spot on, but it has been adjusted and its at the point where it runs the best.

It is like the timing is getting thrown way out of whack somehow.

No it doesn't get really hot, Thermo fans kick in at 1/2 way up the gauge and it never gets higher, Also no signs of white on the plugs.

Does not go through any fluids at all.

[TroysRollaSX]

Sounds to me like the timing is WAYY off. When I get a chance, I'll see if I can replicate the issue on the almost identical AE82 with 4A-C project here, and see if I can get it to act the same.

 

My suggestion is to get yourself a timing light asap and see what the timing is currently at.

[bAKER]

Yea sounds like the timing is out to me. Someone has been playing with your dizzy.

Easiest way to see, is if it runs rough under load, and it should sounds reasonably ok while not in gear.

[carbonboy]

I'm gonna pipe up here, have had the same issues with my 2AC & let me assure you, checking the timing is not as easy a prospect as you'd believe with these symptoms. Double check all your vaccum lines, especially the circuit that feeds the advance on the dizzy.

[robax]

Call me crazy, I don't know much about cars and their engines but I find it all interesting & love reading here to!

 

I have an 87' ae82

 

I recently had a problem similar to yours, check your fuel filter - mine was really gunked up & $5.5 later fixed the problem!

[Trev]

Take your dizzy cap off and check to see that the windings in the dizzy are still intact.

[Dadman]

Hey guys,

Thanks for all the input.

I got myself a timing light ($1 at a festival thingo yay).

Played with the timing, experimented from 0 to 10 degrees and at all positions it was terrible.

Checked a handful of vacuum hoses in the process, all either sucked or changed the engine sound if I sucked on them.

I gave got a new dizzy cap and cleaned the rotor.

Today I will get an Oil filter and a Fuel filter.

I don't pretend to know much about engines, its why I am here for help, so thanks everyone for your ideas I will be sure to post results.

[Dadman]

Important Update:

Got a replacement fuel filter.

Upon removing the old one it rattled, I thought 'that's not right'. Went ahead and cracked it open to see what I expected.

The filter element had come unstuck from the roof of the casing, Essentially changing it from a filter to a place for fuel to pass through and get dirtied up.

Great huh.

Needless to say its much better with a new filter, Did about 60k's city driving today and didn't stall once.

Its not perfect but I am sure playing with the timing and finishing a service will certainly help.

robax wins the prize of some crap off my desk, I knew it was something simple.

When the weather clears up I will finish the service but I am feeling much relief today. Thanks guys.

[rian]

What about the incorrect tacho reading?

My tacho was reading incorrectly for a while until I realised that having the ignitor module too close to the ignition coil was causing it too read about 1000rpm too high, when I remounted the ignition coil further away from the coil the tacho problem stopped. It may be worth checking on your car.

[Trev]

What about the incorrect tacho reading?

 

This, all the things you posted are still a sign of a bad electrical issue.

 

• When the engine is cool it runs well, but as it warms it gets worse.

 

• The first sign is the tacho becomes erratic, Even at idle the tacho is reporting 1,500-2,000RPM, If I lightly press the accelerator and raise the revs the tacho will become slightly more accurate, coming down to around 1,000RPM.

 

• While driving at below around 3,500RPM it will miss, ping and have next to no acceleration with the problem worsening as more throttle is applied, Tacho reports jumps of up to 2,000RPM above reality.

 

• So the timing is going all crazy and at idle sitting at lights it will even stall.

 

When the fuel filter in the mrs 82 blocked up the car would just die, no funny tacho readings and no different from hot to cold.

Edited December 9, 2011 by Trev

[Dadman]

You are right, there is still a electrical problem, It just seems there was more that one problem.

Tacho is still just as erratic, no surprise there.

After just getting stuck in a drive-thru I can say it still gets problematic (as above) at higher temps.

The stalling issue seems to be fixed its running better, but by no means perfect.

The ignition coil is on the other side of the engine to all the other bits.

 

So to summarize- Most of the original issues still exist as written but it doesn't run anywhere near as rough.

I will do the oil change and some other bits and pieces tomorrow if weather allows.

[dashills]

hi mate

 

 

 

try niping up all the inlet and exhaust nuts and bolts as my e7 use to run like crap for that reason and your cluster might have had it try getting a replacement

Edited December 18, 2011 by dashills

[robax]

Glad I could be of some assistance :)

 

I'm almost proud of myself that I got something right in relation to an engine...