KOUKI JDM trueno really hard to start but runs fine....

[japan86]

Hi all.

I have been trying to find this fault for months and still have no idea.

My car has been getting progressively more difficult to start. Its really bad now.

Things i have replaced.

~New optima battery
~New dizzy cap
~New rotor button
~New spark plugs

~compression (180 on all pots)
~Has spark
~I havnt done a fuel pressure test yet but when i put another regulator on it there was pressure at the rail (It runs fine once its started so has fuel)

It sometimes hesitates when trying to start it like the starter is on the way out but its nothing too bad.

Its not throwing any codes when i bridge the diagnostics plug either.

Im at a dead end.

Has anybody had this problem before?

Any help would be much appreciated.

Cheers
Tris

[Twisty92]

i'm a little confused..the car cranks over fine but has trouble firing up??
or does the car have problems with cranking over??

Just keep in mind these 86's do not have a starter relay ( unsure with the trueno's??) possibly you have bad contact for starter solenoid , cheapest thing to do first is wire in a starter relay which is easy and cheap! if this relates to the car having problems cranking over..

cheers twisty

[japan86]

Cheers for the reply mate.

Yeah it cranks fine. Just is a bitch to get it firing. Once running its perfect though.

I have to give it little blasts with the key to get it to start. Takes about 6-7 goes sometimes more.

cheers
Tris

[Vance]

only things left are leads and coil...... try leads. i had bad leads on a 4ag once and it did the same thing. i replaced leads first however as i had a set of spares

[tottacrolla]

Having the ignition timing over advanced will give a slow initial engine turn over, a bit like the battery is going flat
but once the engine starts it will run ok.
Mark where the distributor is now, undo the clamp bolts and turn the distributor a few degrees.
Try to start the engine and make a note of any difference.

[Golberg]

AE86 ECU's rarely throw codes for anything, regardless of a fault.

You need 3 things for the engine to run:
Air
Fuel
Spark

If you've got air and spark it must be fuel.

Too much fuel, or too little:
Too much: Black or wet injectors. If you want a simple way to test if its not enough you can squirt aerostart or something similar into it to see if it'll fire up on that. Otherwise, crimping the fuel return hose can push more fuel through the injectors.

What controls fuel (loosely):
ECU
MAP Sensor
Intake temp
Coolant temp

The engine is fine once warm, which one of these sensors if effected by engine temp?
Coolant temp

I'd be looking squarely at that, if you're at all familiar with multimeter component testing, you can check what is going on at the sensor. Otherwise a coolant temp sensor is usually a cheap sensor to replace.

EDIT: Just noticed you said this:


I have to give it little blasts with the key to get it to start.

That suggests that you're getting it going by firing the cold start injector (only fires when coolant temp is cold and key is in start position) This obviously suggests a lean on start condition. (Not good for trying to start a stone cold engine)
This isn't controlled by the Coolant temp sensor (green plug) its the brown sensor next to it.

[japan86]

Thanks very much for taking the time to reply you guys.

I fixed the problem. It was the starter motor. I took it out cleaned it up. I then filed and wire brushed all of the terminals.

Turned out it was the smaller wire to ignition that was the problem. It was just getting dirtier bit by bit and making it harder to start. I sprayed the plug with brake cleaner and hooked it up to a the clean terminal and its fine now.

Bit of a rare prob but one to keep in mind for the future.

Cheers
Tris