I need some help - I've got rough starting issues. This has been intermittent for the last few years but has been happening pretty steady for the last week.

Truck is a 5-speed 1985 4Runner.

Battery is good (bought a year ago, load tested last month, and on a tender all night, every night), starter is a month old, and a couple of months ago I installed a starter relay (the truck didn't come with one and I was getting intermittent starter operation).

Codes are 6 and 10:
It cranks ok, usually catches pretty early when cranking but then seems to run on only a couple of cylinders for a while. After a bit you can hear something that sounds like a relay click then it smooths out. When it's running rough I have to add a lot of throttle to keep it running. When cranking, if I don't catch the first firing with some throttle it'll die quickly then it's a lot harder to start (the video is of a second starting attempt).

Once all this shenanigans is done it runs really well.

Here's the video: YouTube

Any ideas?

Thanks!

Typical symptom of rough start, low idle.


The relay is most likely your C.O.R. When rpm is too low, you lose air-flow through air flow meter which shuts off C.O.R. IF it recovers C.O.R. clicks back on and restores fuel flow.

Does it matter that it still runs rough when I hold it to 1500-2000 rpm? Keeps running rough like that, then will immediately smooth out after 15-30 seconds.

Also, I disconnected the EGI fuse and the ignition and when it’s cold I’m getting that same uneven crank like in the video. When warm it cracks smooth with no fuel or spark, and fires right up when started.

Intermittent compression issues? Sounds weird.

I’m running an ATF treatment on it today. I was going to run a compression test cold then hot but left my tester at the hangar and won’t have time to go get it this weekend. New NGK plugs and an oil change tomorrow as well.

I’ll check out that relay, thanks!

Don't worry about the C.O.R. it's just doing its job. When you have rough idle there is not enough air flow to the AFM flapper. C.O.R. thinks engine is dead (i.e., truck rolled over) so it shuts off fuel pump to prevent fuel from spilling somewhere.

I suggest you inspect the intake plastic duct and rubber parts to make sure there is no crack / leak.