dropped_dime98

After picking up my 91 yota with the 3.0 it started to idle low and gets a lil jerky while driving. Had my mechanic check it out and it was throwing the lean code. He gave me a list of all things needed to do the tune up.
Cap and rotor
fuel filter
plugs and wires
pcv
and a new o2 sensor since it could be one of the reason behind the lean code and it looked like it has not been changed ever.
Also grabbed a can of sea foam.
Everything look good for my tune up? Also if I change the cap and rotor do I need to time anything or do anything diff to the distributor?

Thanks.

jason191918

No you do not need to time or do anything diff w/ the dist. Take the cap off, take the rotor off, reassemble.

You are going to have a hell of a time w/ the PCV. Almost easier to pull the upper intake....better hope you have small hands.

dropped_dime98

Lol worst comes to worst ill hold off on the pcv. How long would what Im doing take? 3-4 hours tops?

Jay351

Yep, I can tell you right now.

PVC - almost impossible to remove without pulling the upper intake. It can be done....but its HARD!

fuel filter - If your truck has a body lift, well it won't be so bad. If not, well limber up! Spray the fittings with pb blaster (or alike ) a few times before removing the old filter (on the passenger side frame rail).

Also, when doing the plugs, have you done plugs on an aluminum before?

Side note - Use ONLY NGK/NTK or Denso for ignition products. They are worth the price.

BTW, you can test the o2 sensor with an ohm meter to see if it is bad or not.

dropped_dime98

1. Might hold off on the pcv but ill take a look at it
2. Nah stock height just with bigger tires. But im deff gunna use some pb blaster
3. No i havent done plugs on an aluminum before
4. I got NGK i knew better then not to get em.
5. My mechanic didnt have one on him, but we looked over everything pulled the plugs and all then he saw the o2 sensor and it does look like it hasnt been changed in forever. And that is one problem that cause the truck to throw a lean code.

Jay351

Well, I thought the same thing on my truck. The o2 sensor had been through 100,000+km and a blown motor. After I bought a new sensor, I tested the old one just for S&G.. well it tested perfect!

When doing your plugs, use some anti-seaze. I use ARP bolt lube. The plugs should thread in by hand easily. If you feel resistance STOP. It should only require torque when its all the way in..
Be extra carefull of this on the number 5 and 6 cyl plugs.

Gap them to 0.031"

dropped_dime98

ohh yea. We added some of that while we pulled the plugs. But thanks for the reminder and I got a gauge also to gap them. As as the o2 ill swap em and when I can find something to test the old one with I will, I just want to be able to drive it smoothly.

abecedarian

i'd be willing to guess that if the ecu is throwing the lean code there is nothing wrong with the O2- usually when they go bad the engine goes rich...
so...
do the seafoam treatment through the tank
maybe spray a can of TB/MAF cleaner up the throttle body (do it in stages, like 1/4 of the can at a time, putting everything together and running the engine for a few minutes between spurts) - I'm not a big fan of letting the engine suck seafoam through a vacuum line, but what do I know? (lol)
reset the ecu by disconnecting the battery for a few minutes and then drive away and see if the lean code comes back.
if it does, start checking for vacuum leaks...
... and fix any exhaust leaks you may have too.

a bad PCV valve will usually cause either an overly rich condition or oil to blow out the crank seals.

edit: maybe I should've asked though, by lean code... do you mean the ECU is compensating for a lean mixture, or the ECU has had to lean the mixture out compensating for a rich mixture?
what was the code #?

jason191918

Assume something to go wrong....like you break every bolt that holds the fuel filter on.

PCV took me 1-2 hours of dropping it and smashing knuckles in a cool (cold as hell) fall night.

Make sure you have plenty of extensions/universals for the plugs. Wires, cap, rotor is 10 minutes. Use a torque wrench.

Also, your o2 sensor may give you problems....break off studs, studs unsrew and then strip out...you know how it goes...

dropped_dime98

Its a code 25. We check all other things that would cause it to go lean. o2 might be working but not reading if that makes sense. Im going to check for vacuum leaks and all but also doing a tune up.

abecedarian

no harm in doing a tune-up, ever. sometimes they work miracles actually.
and likely causes of a code 25 for a 91:
engine ground loose
open in E1 circuit
open in injector circuit
fuel pressure (injector blockage)
heated O2 sensor heater circuit malfunction
ignition issue
coolant sensor reporting higher than actual engine temp
air flow meter
ecu

dropped_dime98

Yea we printed out a sheet with that one it. Didnt see or find any loose grounds. I figure when i do the tune up swap the o2 and it still is acting up ill take my truck to my mechanic and leave it with him till he finds it. Either way i still wanted to knock the tune up out without paying someone to do it. Hopefully the tune up will solve but I will plan on looking for loose grounds and all again never hurts to double or triple check.

abecedarian

I wouldn't just focus on loose grounds, but also corroded ones too. break the bolt loose and check and retighten.
just a thought...

dropped_dime98

will do.

dropped_dime98

Ok. Couldnt get the o2 off but a close inspection looked as if it was changed before just the bolts were rusted to the point they have to be torched off. Fuel filter i didnt have enough time to tinker with but i changed the plugs and wires which seemed to have solved the problem. I had the battery disconnected while doing it so i know that resets the code, but i drove around for an hour with no problems then check for codes and got nothing. I was going to change the cap and rotor but those looked like they were in very good condition. Ill change the fuel filter monday night to be on the safe side. Hopefully no more probs!!!

dropped_dime98

ok so far i changed the wires as stated above and the idle prob went away for a little bit. Also changed the fuel filter. It idles now at around 600 and sometimes will idle around 400 after driving for while. It also jerks a little bit after driving for about 15min, its not hard jerking but you can feel it usually in 4th gear when giving it a lil gas. Any ideas? Also not throwing a code anymore since i last checked.

dropped_dime98

Oh and today the idle was going ever second from 300-500 or 600 when i was sitting at a light until i gave it gas then it stopped. Did that 2x today. Im thinking either Maf or TPS