ENGINE MISFIRING

[Onyx]

Hi guys,

I need your help, or valuable advice.

My engine doesn`t run well and after last reparation it didn`t change at all. One guy, who knows a lot about AE86 is helping me, but doesn`t really know, how to find the routecause of it.

To take it from the beginning.

1) when i start the engine, it runs fine. 1000 rpm isn`t a problem.

2) when it gets warmer and I push the throttle to go slowly higher and higher, when it goes above 2500 rpm, the rpm-meter goes crazy and counter goes up to 7000 or even higher. Real revs of engine are of course still around 2500-3000. Then engine diagnosis controls is on and the engine swithes off. When I keep on revving it, I can allow it to do not let it die, but after a while, the engine turns off anyway. This is how it looks from inside.

3) From the outside it is different story. 1000 rpm is of course still fine, but when I go higher, whole engine starts to shake and do weird noises, like ticking. Timing of these ticks isn`t consistent. Sometimes it is more, sometimes it is less. Location of this noise seems to come from the bottom of TVIS injection manifold.

4) false codes: 3, 6 and 10 if I remember correctly. Even if we take out the fuse of ECU, after plugging it back in, false codes are still in.

I have changed sparks and cables. Yesterday I swapped also distributor with different one, which normally works in another car, but nothing helped.

I have also driven car with these conditions for about 300 kilometers, with consistent shaking like sh*t, engine sometimes turns off by itself.

And this was coming step by step. Car wasn`t running for 6 months and for first two days after pick up it was running perfectly. Then there was one tick in one hour, then two, then 10 and then it end up like this.

Whatever you have in your mind, please let me know.

THANKS FOR YOUR SUPPORT FELLAS!

PS: If you want to hear the noise, I can make short video and place it on youtube. Let me know.

[Ivan141]

If the revmeter looks like it's going crazy, then it's most likely an ignition problem (revmeter takes it's signal from the coil). Since you've already replaced the distributor, it might be worth a shot to swap in a good coil and see if it helps.

Your "false"codes seem to support this diagnosis since the first two are directly ignition related (igniter failed to fire 4 times in succession / no rpm signal to ecu above 1000 rpm). Most likely coil/igniter failure or trouble in the wiring thereabouts.

[Onyx]

Hi Ivan,
thanks for trying to help me out.

Well, I changed the coil with Sekiguchi already. We used his, which works fine. It was the same, nothing changed.

The wiring could be a problem, but this can take years to find it. No idea where to start.

Any other ideas? Does it sound familiar to anybody?

THX
O.

[dikolotour]

I don't know as much as Ivan knows about codes e.t.c. but i do support his opinion.

I do believe that this is an electrical problem because the rev counter has to do with the coil. You also mention that your engine shakes which is similar with taking off one of your spark cables.

I suppose an electrician could help you!

[Onyx]

Thanks Dikolotour! I will see, what we can do with my colleague. If we will be in a corner, I am afraid I will have to find one.

Onyx

Further suggestions are welcome.

[Lipinhu]

Quote:when it gets warmer and I push the throttle to go slowly higher and higher, when it goes above 2500 rpm, the rpm-meter goes crazy and counter goes up to 7000 or even higher. Real revs of engine are of course still around 2500-3000. Then engine diagnosis controls is on and the engine swithes off.

I dont think it it is a firing problem.

I had the same in my white ae86. It was because of the battery, i had to source power from another car, and when i took off the battery cables, the symtoms were exactly the same. Check some groundings. The revmeter goes that way because of the incorrect voltage. Just my 2 cents.

[Ivan141]

Yep, grounding is also a good thing to check.. leaving one ground loose can cause the weirdest problems. Finding wiring defects is a job that can be done best when the wiring loom is out of the car, but it rarely happens that this is the problem (have seen it before though).

[senna]

i'm with the last 2 posts, on my Rx7, the revmeter went crazy when i had battery problems. The belt from the dynamo was slipping so it wasn't generating enough power. Tightening that belt fixed my problem. Good luck

[Lipinhu]

so...

How it is now? I´m curious!

[byd1380]

I would agree about it being electrical, since the rev counter needle is jumping alot. Just get a DVM and check the battery voltage. Also go through each pin on the ecu and +5/12Vdc. I had a problem were the car would run for a short time them lose all power until it stalled. I was convinced it was fueling and after alot of messing about found I was loosing my +12Vdc to the ecu due to poor wiring in the loom. This was also causing a misfire. Picture below! It also caused a fast idle!

Ivan