nick325i

I just bought a 1988 4runner for my wheeling rig. It starts, and drives, but has a consistant miss on the 2nd and 4th cylinders. I have already replaced all the injectors, spark plugs, wires, cap and rotor, and fuel filter. I think it is getting fire to all the cylinders, because if you run it on starting fluid it smooths out, but I really dont know for sure. If anyone knows anything please help me out. Thanks for your help.

Swansen

even though i doubt it, it might have bad compression on those cylinders.

nick325i

Yeah, I was affraid of that too, but I checked and they all seem good.

TNRabbit

what does "seem" good mean? Did you use a compression tester?

nick325i

Yes, I used a compression tester. I dont remember the exact numbers, but they were all adaquate.

thook

Check your valve adjustments and condition. Are you getting oil on those plugs?

nick325i

the plugs arent oily, but they do look like they are getting fuel. I checked the cam to see if I had some worn lobes, but they look alright. Do you think my valve adjustment could be off enough on those 2 cylinders for them to consistantly not work? I will definitly look into it when I get home.

Does anyone know if there is a common electrical circuit or if those 2 cylinders fire at the same time or anything that could be wrong that would kill both of them? I'm open to any and ever suggestions.

b82ta3

Yeah its possible to have them out of adjustment enough that they wont fire. I had my exhaust valve on my #4 cyl out of adjustment enough that it wouldnt run on it. Took me a while to figure out what exactly was going on. Id check those esp if they were recently adjusted

nick325i

I will definitely check that out when I get some spare time. They havent been recently adjusted, but there's no telling when they were adjusted last. Does anyone know what the correct valve clearance should be?

thook

Okay, you posted the same time I asked the question....

So, do a search on valve adjustment. That will answers any questions there. Either that, or confuse you greatly...lol.

denro

you can check your injectors with a noid light, to make sure the injectors are all getting fire.

TNRabbit

That's what I was going to suggest; are the injectors on those cylinders ok? Also, you might have a distributor going bad...

cweich

I had a similar problem, the motor would run fine on carb cleaner, but would miss on just gas. I had an injector sticking. I started the motor and tapped on each injector and it came right out of it, never had the problem again. This was right after I changed injectors.

nick325i

It had the same problem before I replaced the injectors and now I have all new injectors. They may not be getting power or signal, etc. Can you replace just the part of the distributer that sends the signal to the EFI or is that how that even works. I'll check those valve specs too.

nick325i

I will look into all of that. thanks for all the advice and keep it coming. I just want to get this thing out for some playing.

Swansen

just thought of this, but when you changed the injectors, you might have accidentally not plugged them in all the way, i did that once, took a while to figure out what was going on.

nick325i

I'm going to check all my connection very well when I get the time, but I dont know if thats the case because it ran exactly the same before I replaced the injectors. I think I might have a bad connector or wire somewhere. I just wish the injectors were easier to access.

nick325i

Does anyone know if the 2nd and 4th cyl. share any particular electrical circuit or if they fire at the sametime, etc. I am trying to find out if there is any one problem that could kill both of them.

denro

on my 86 runner, I followed the wires from the injector plugs up into the wire harness...then i noticed a few of the injector wires had came unhooked in there...it was in the harness behind the battery. i tested the injector plugs with a noid light..not all were working. so then i tested at the computer behind the kick panel on passenger side floorboard. they seemed to be working there, so i figured it had to be in the harness somewhere between the injector plugs and the firewall. i started at the point where the injector wires run into the harness and cut the harness to have a look...sure enough, the injector wires had came unhooked in there...i hooked them back together and i've had no probs since then. just be sure you have power to the injectors(noid light) and the computer,before going into the harness...good luck with yours

nick325i

Well, I found a wiring diagram last night and I figured out that the 1 & 3 and 2 & 4 share a common circuit. After checking all my grounds, wire conditions, etc I check the resister that powers the injectors. I had to re-wire it when I bought my 4runner because it had been sitting and a lot of the wiring had been chewed through. I had wired it up incorrectly. I switched some wires and it runs great or great for 254,000 miles at least. Now I get to see how it drives and start planning some lift and tires.