helidriver

Ok, the 1987 22RE SR5 4Runner with A/C and CC, has been at the dealer ship in Henderson, NV all day. The tech is stumped......

Problem: Had a slight "bump- Bump" out the tailpipe at idle, hesitation on acceleration and slight backfire on compression slowdown, intermittent #12 Code=
MISFIRE, right?

Only real mods are: Doug Thorley header with 2.5 or 3in pipe/weld in CAT/magnaflo muffler and the K&N filter charger, both 9 years old. Has passed Oregon and Nevada smog every year since till last weeks. HC=820> 220max at idle was the only fail.

I troubleshot:
- replaced all vacuum lines
-vacuum tested EGR
-Compression tested 143-152
-Plugs, wires, cap, rotor new
-PVC and grommet new
-CSI checked
-CSI temp sender tested
-ECM temp sender tested
-EGR modulator new
-Coil tested
-Ignitor tested
-top end vacuum tested
-new oil/filter
-new fuel filter
-new Bosch O2 sensor
-Valves adjusted
-Timing set 5*

SO, what are our ideas????? His only guesses so far are too much air is coming through the AFM KN filter charger, but it's passed smog in two states over the 8 years that has been installed.

THOUGHTS!!???!! Please start spit balling......... what do you think????

Mr.Utah

Hey, I am in Vegas as well. Start and check the basics. Plugs, wires, timing, vacuum leaks, etc......Also, could be bad fuel, put a couple gallons of race fuel or octane boost to rule out bad fuel issues. .....

Mr.Utah

Re-read your post..Looks like you have done lots of basic stuff. I doubt the K/N filter has anything to do with it...

scope103

Code 12 is "No G or NE signal is input to the ECM for 2 secs. or more after STA turns ON." If intermittent, you could have an intermittent G or NE from the distributor. That would cause misfires, (and backfires) which is a very direct cause of high HC.

You can check the distributor directly http://web.archive.org/web/201212070...12onvehicl.pdf , but these are simple Go-NoGo tests. You could put a timing light on it and watch the light for missing pulses. (At idle, 850 rpm, you're getting about 3/second, so it might be hard to see missing ones).

You can pull ignition wires to see if you have a weak cylinder (meaning, only one is misfiring. This has nothing to do with Code 12, which is back at the distributor-ECM circuit.)

helidriver

Yeah, thanks Utah, did most of the basics. And I sure as hell hope the tech would have as well. Problem has been around for about 6mo or so, lots of gas tanks, dont think its the gas, 711, chevron, ect. nothing changes....

Scope- are you looking at your 2nd gen Runner codes? Code for 12 on my 87 is suppose to be O2 sensor/02 sensor circuit/ ECU..... I have an inline light for the spark test and all cylinders looked the same, nice and bright. All the wires tested good, plugs properly gapped, cap and rotor looked good, AIR GAP was good.

Terrys87

iTrader: (1)

The 85-87 fuel injector connector is a poor design and can get brittle and break. Check to make sure the wire around the clip does not have the shoulder broken off and letting it work its way on and off the injector. With engine running, pull and push on each connector and see if you can create the misfire.

I do not like the Bosch O2 sensor. I would install a Denso. 87 only have on in the manifold and is cheap from ebay or other sites.

wallytoo

iTrader: (1)

for 1987, neither of you is correct. from my 1987 FSM, code 12 is "knock sensor signal".

code 5 is oxygen sensor signal.

code 6 is RPM signal (NE).




wally

helidriver

Wallytoo= your right, before I started doing anything I was getting all 3 of those... after getting everything replaced/adjusted.... I was down to just the #12= knock sensor, that's what I meant. I'm in too deep, can't keep anything straight at this point

fdp101452

I know on my 90 6cyl. when it throws a knock sensor code, the ecm bumps the timing flat. Could that be whats happening here? You said the code was come and go so could the ecm be messing with the timing as it gets a code off and on? I had a bad plug wire cause me a lot of the same kind of trouble years ago and the wire was in a new set. Good luck with it.

blake.nemitz

ditch that bosch 02 sensor for a denso unit. bosch o2 sensors are known to not work well with toyotas.

helidriver

So, he called today and said that he has it down to cylinder #1 is the misfire. But doesn't know why said it compression tested well, spark, plug, wires, cap, and rotor all good.

So he wants to swap #1#2 injectors to see if it moves to #2...... Problem with that is my $99.99 diagnosis fee doesn't cover him the 4 hours to take the less than 10 plenium bolts off to get to the injectors, but $400.00 will...... TO TEST.

I'm thinking of paying my 100.00 bucks, getting the truck and doing it myself but I don't know how he knows that it's #1?? Any ideas how you can track a cylinder that's missing without knowing why or what's wrong first? THX>

wallytoo

iTrader: (1)

don't need to do that. just swap the injector connectors, ie, put the connector for #1 on injector #2, and the connector for #2 on injector #1. the injectors are batch fired, and the swap should take about ten minutes. if the problem migrates to #2, the wiring or ecu is at fault. if the misfire stays at #1, the wiring and ecu are not the problem. then you can look at injector #1, and remove it from the fuel rail.

wally

helidriver

That sounds awesome, however, how do you know, check, and pin point a misfire in a cylinder??? I just know its misfiring because of the bump-BUMP-bump out the tailpipe and the hesitation from idle to 2000RPM. What do you do to pinpoint a specific cylinder?????

wallytoo

iTrader: (1)

you can use a screwdriver as a stethoscope. touch the blade to the injector, put your ear to the handle, and you can hear the rapid clicking (firing) of the injector. do it first on one of the "good" injectors, to get a sense of how it sounds, then check the suspected injector. it's easier than it seems.

helidriver

With my problem likely to be a LEAKY injector, not a non-functional one, will that still work? Won't I hear it working just like the others?

wallytoo

iTrader: (1)

leaking is different. may or may not cause a misfire.

helidriver

well I HAVE a misfire and/from a too rich situation. leaky injector seams like a possibility as to where extra fuel is making into the cylinders some how.

Charchee

For a nonfunctioning injector I like the plug wire pull off test but it works better on a 6 cylinder. It's easier to hear/feel with the extra two cylinders. For a leaking injector, I would want to look at the plug on the suspected cylinder vs the rest of them. You should be able to notice a difference. I do know that a malfunctioning injector will sometimes throw an O2 sensor code and if it's intermediate, cause a knock sensor code to show up. I think you are on the right track with an injector issue. Could be caused by faulty wiring or the injector itself.

Have you done a compression test? I've been trying to work out a correlation pattern between bad injectors and compression readings for the past few years. Nothing published but I have seen a correlation between the two in my personal experience and am looking for more data. If you run out of things to do, check your compression and let me know what you find.

helidriver

Ok, took the intake off tonight and found in the rear intake passeges in the lower half of the plenum, cyl 3 and 4 had a thin film of gas. It's parked on a hill in the driveway if the CSI was leaking the fuel would leak down and settle in those back two passages, yes??? Is there anywhere else that gassy goo would come from?? Unless the 3 AND 4 regular injectors were leaking.....?

The tech at the dealership said he had the misfire narrowed down to Cyl 1 somehow. Would make sense if the CSI was leaking and depending on the trucks angle the extra fuel would run into different cylinders depending on orientation?

Anyone have thoughts on my therory??

Sending injectors and CSI to Witchhunter for a eval and cleaning anyway just to have it done. Hopefully that will be the last of it unless I'm missing something else???

helidriver

Yes, compession across cyl was about 143-152 I think. I think 1 was the low. But it's average and less than 10% across them all, shouldn't be an issue. and thats "dry" and I didn't have the pedal floored.