sleonard

Hi all, newbie here with a headache of a problem. I've been reading the forum regularly for over a year but finally going to post my issue. Lots of simialr issues but none I have read are exact. Here goes.. Randomly #3 cylinder dies. Has plenty of spark from dist., has spark at plug. Acts as though injector is not working. I replaced the injector and it ran great for 4-5 days then same thing #3 is dead. I replaced fuel filters 3 different times all of which has some fine contamination when I drained the filters. Each time the truck runs great for maybe a week then #3 goes dead. I felt like it was maybe a pressure isse based on others posts. I replaced the pressure regulator, worked great for about a week then same thing #3 is dead. I replace filter again and VIOLA' works great for 1-2 weeks then same thing again. I replaced the fuel pump and strainer and checked the tank while it was apart and it was really pretty clean. Ran unbelievable for 1 week then same old #3 not working. I've checked for vaccum leaks with carb cleaners , brake cleaners, starting fluids etc. etc. Nothing of any significance. Everytime I have replaced something it seems fixed for a week or even up to 3 weeks one time then the same old problem again. I have no CEL at all. No coolant loss, no oil loss to mention between oil changes. When its working it drives great, even get about 19+ miles per galllon on the daily commute with 31's, then the #3 death factor and then of course my MPG drops big time and the truck shakes rattles and barely rolls. Sorry for such a longwinded first post. I either can fix it asap or be forced to sell it and find something else. Did I mention I love this truck. 89 4runner 3.0 v6 5 speed, new paint, tires 189k miles beatiful old truck just getting the best of me now. Hate to part ways ,would rather cure it and keep it. ANY HELP AT ALL PLEASE???
Thanks, Seth

myyota

Have you tryed checking the wiring going to that injector ?, trace it back into the wiring harness were its spliced into the main harness, sometimes the wiring can corode and cause an intermitant short.

sleonard

Thanks for the reply. When I replaced the injector I did check the wiring all up and down that side to each if the injectors but really only found the plastic sheathing that incases the wire bundle to be cracked. the wires themselves all looked fine.

turboyota1

Sounds like the plug is falling off and on....just what I think from my experience
Derek

sleonard

what do you mean falling off and on. When I pull the plug wire loose from the distributoe end (while running) i get NO change on #3. it has constant spark from dist to #3 plug. while clearly #3 is not firing or being fueled or whatever the correct discription would be. No life from #3 although spark is present.

weaselman

ever done a compression test on your truck?

maybe a ring is getting stuck, causing the intermentint misfire due to weak compression?

i have had this happen to me on my 86 22re.

turboyota1

sorry for the confusion....I meant the injector plug might keep falling on and off...which would make sense as to why the spark plug wire would cause no change in the engine running any worse...try that...i had that happen on and off to me and I put a little permatex on the outside of the plug on the injector and havent had a problem since.
Derek

sleonard

thanks guys, I'll check the injector connections again. I plan to open and clean all visible connectors on saturday. I figure it cant hurt. Has anyone ever had a pressure regulator get clogged? I had mine off again last night, with a compressor I blew in each opening with NO flow through. After repeating this to each opening 2-3 times puff, I small white puff came out and then all of the sudden air could pass through. I could hear the diaphram vibration inside. After the reinstall, it missed as usual for about 1 minuter then magically cleared up again. I drove to work today and it was great. We'll see what happens in 2-3 days if the usual pattern holds true. What confuses me most is that every time I've changed anything it appears to solve the problem, but only for a couple of days then the same issue returns. So I know I haven't ultimatley solved the true issue.

88'22re

WOW. i have had the SAME..( dead huts same)...issue with my 88 p/u. only difference is that my miss never goes away.

I don't feel rings would be a good enough explanation. He is changing nothing about the ring configuration, or anything internal...simple swaping and fixing on the top side. I am personally to the point of checking each part under the hood other than the mechanical aspect of my engine. first..ignition. make sure it is allllllllll functioning properly...then the daunting task of repeating that process with the FI. make sure connections, in jectors..plugs...EVERYTHING is working the way it should be.

IF all pans out...then maybe a mechanic issue inside. I still say lean misfire for me.....but that ( after 12 months) has yet to be proven by me..my ASE cert. neighbor with 35 yrs exper. or any shop in town.

Good luck....and please keep continuing results posted!!

sleonard

well, we made it just over a month maybe month and a half with great performance. I had replaced the fuel pump last and my truck ran great, maybe better than ever. This morning it started the same old stumbling, missing, kicking and loss of power at speed or on acceleration. I cant figure out what the heck is with this thing. It seems everytime I think I finally have it fixed and my confidence in OLE' BLUE goes up again, it starts the same old mess. Any more ideas? No, I'm no losing coolant, I'm not running hot, my plugs look good, my wires are good, etc etc etc. It just is randomly losing fire on a cylinder it feels like. I haven't pulled the hood this morning to see for sure but I would bet almost anything the #3 cylinder is dying again. It's the only one that ever does. It has fire on the plug,but is dead. Oh yeah, did I mention it has a new injector on #3 about 4 months ago. 3 new fuel filters. Everytime something is repalced fuel wise, it runs great for a brief period then right back to here..

Lifelongtoy

Look for a short somewhere. I had your exact same problem. I fixed all sorts of things that would temporarily fix the dead cylinder but the problem always came back.

I had a wire grounding out the injector and in the process of fixing whatever I was fixing, I would knock the wire away from the ground spot. Driving for a week or so would vibrate it back to the ground. Pissed me off for about 6 months.

If that isn't it, then it really sounds like you have a bad wire inside of the plastic casing. Run a wire directly from the injector power source to the injector. Just take the injector plug off and match the colors of the wires. Two of my injector plugs are spliced like this.

But you do have an electrical problem somewhere

sleonard

Thanks for the ideas on wiring. I currently have no electrical issues other than my windshield washer pump is dead. Otherwise everything works as it should. The truck when not missing or breifly losing all power runs better than ever. I took the cap and rotor apart today. The rotor had some discolorationa and the cap had some corrosion in it on the contacts. I replaced both and had ZERO benefit. Once again I'm baffled. I hate to do it but pulling the intake plenum to check for faulty wiring will have to be next I guess.

sleonard

yes I agree, but I have the 3.0 v6 and ALL of the injectors are underneath the intake plenum. I cant access them to check them when the engine is able to be running. I have to take the intake off to get to them.

Lifelongtoy

It really sounds like an electrical problem. Something mechanical would be more regular. Tear open the wiring harness. The wires can rust over time even when still properly covered. Try the splice.

sleonard

ok last night I replaced the cap and rotor and I put in a new ECT or CTS-coolant temp sensor I bought when I bought the fuel pump a month ago and today the skipping/missing was even worse than yesterday. It does not do it at idle now, mostly at 2200-2800 rpm while under a load such as going uphill trying to maintain speed. At low speeds and low load it is smooth and feels powerful.