frozenwave

'91 pickup, manual, 3vz-e, rebuilt, ran great.....but then...


For the longest time I was having issues throwing code 52 (knock sensor) and 71 (egr gas temp sensor). As the winter came and temps dropped, the truck would start up in the morning and die immediately. I would un plug the fuel pump relay, turn it over to flush the fuel outta the cylinders for a couple secs, plug it back in, and it'd start but id have to hold open the throttle a bit to keep it running. Once it got to WOT, it'd be fine, except idle slow and sloppy, as well as surge during accel, but sometimes accel clean and strong. I figured either i was getting to much air (did a thorough vac leak check, found one tiny leak, and fixed it), too much fuel, due to the struggling effort it made to keep running, but did not die abruptly (and fuel odor from exhaust). ORRR, the knk sensor was jerking my timing around (but same symptoms with diag. link jumpered). btw, code 52'd only pop on me if i tried to drive it before the ecm went into closed loop.... and come to think of it, when this crap started happening, and would start with a low idle instad of faster idle, and closed loop would drop idle to like 300 rpm.

i left it sit for a couple days to drive the landcruiser (ahhhh, relief)

I had to push start it down a hill to get the motor turnin' enough to be able to even get it to crawl up into the garage BARELY...

I removed EGR system, same results. Left it off.... I DID, however, chase down the knk sensor wire and found a frayed spot inside of it, where the inner and outer portions of wire had came in contact with one another. fixed that.

After many more failed attempts to get it started.....oh man, one day i turned the key and the stupid thing fired right up, idled, and sounded her good ol' self, except it wouldnt respond to any throttle movement at ALL, and then died after too much messin with it!

So, heres the strange stuff. On my old distributor, the pickup coil resistances were about double what the FSM says. fsm says about 225 range, olds were about 450. New ones are in spec, landing around 215.

When i hook my spark tester up to a good ground spot and connect STRAIGHT off the IGN coil, I get spark at about the same rate as if I had it connected to one of the wires going to a plug. It should be a fast pop-pop-pop-pop, as the coil lead has to fire in rapid succession. Then, sometimes I'll get no spark at all, and other times, it sparks when it feels like it. IGN coil and igniter tests fine according to fsm.

These symptoms occur with my old/new coils and igniters! However, tonight I used my old coil and ingiter and it acted like it was gonna fire up and run, only to tease me and do the same crap.

as of now, current work:
New and properly adjusted TPS
New coil, used igniter, new plugs, wires, and entire disributor (not just cap, and properly installed)

In my throttle valve, theres gas pooled up in it. I'll try unplugging the cold start injector and see if it comes back next time i turn it over. Could the CSI be my whole issue?

Sorry for the super long post guys, but I'm just about to accidentally push my truck off a cliff... But i loved the damn thing when it ran! and i want it back! HELP!

-Skilled but stumped, Frozenwave

lonecountryboy

Did you check the spark plugs? You might have an issue with some of them being fouled out due to all the gas.

frozenwave

yea, it was an issue. even put new ones in, but i leave the relay unplugged so i dont gas my cylinders out while im troubleshooting the spark problem. when i do the igniter tap test, the spark seems weak. can anyone make a video of what their spark looks/sounds like while doing the igniter tap test? i'd like to compare.

Noltz

Describe exactly what you're testing and I'll attempt to do the same on mine. It's -8C outside right now, so it'd better be quick

Edit; You were online...

frozenwave

oh man. 17 f is cold. thanks very much for even being willing to do such a thing, heh. here in arizona i complain when it gets as cold as 38, so i'm humbled! lol.

well, first a small update: i took out the cold start injector, and plugged the hole, with the same exact results. except this time it jumped fire a few times, but never ended up actually idling. anyhow...

https://www.yotatech.com/forums/f2/n...89-95-a-10543/

that thread has the igniter tap test im speaking of. i want to get an idea of how strong the spark is of someone else's 3vze that RUNS, heh. also, if you or somebody could record/report this: hook your coil lead up to a spark tester, or some other ground source, and turn the engine over. and tell/show me if it sparks rapidly, like i think it should. i would really appreciate it. mine sparks consistently, but only as fast as if i had a secondary wire (from a spark plug) hooked up. seems it should fire much faster out of the coil as it has to pulse for each cylinder by itself. for now, im off to check the fuel pressure and chase down the wires from ecm, to igniter. thanks fellards.

oh btw, in the tap test, when i do the first portion, if i hold the test light on the batt terminal, instead of tap, the light BARELY lights up. is this due to the coil drawing most of the voltage, or should there be good strong continuity between? when i hook the test light straight from terminal to terminal, it lights up nice and bright, of course.

lonecountryboy

Just a thought did you try unplugging the VAFM and firing it up. There was another thread on hear that had a problem with the ignition and it was the VAFM that was the problem.

frozenwave

after testing several circuits and stuff, i came across a funky, perhaps new symptom that i didnt notice, or wasnt there yesterday. as i have the primary coil lead hooked up to a spark tester, i can clearly see spark directly out of the coil, suddenly strong and crisp. but here's what's weird. i can feel it all the way through, from my hand on the key! the lead wire is totally far away from any other outside conductors. from ground to coil lead wire end, i have about 18k ohms. anyone else have that?

frozenwave

ty for the reply. yea i tried that with the fuel pump relay jumped. no dice.

frozenwave

Ok 3VZE owners, check it out. I know a lot of ppl have had these exact symptoms with no relief. I hate when i see a topic that isn't updated LONG after you know someone must have fixed the problem, and I think this is a somewhat valuable update so here ya are:

Symptoms: Rough or slow idle, surging during acceleration, setting codes 71 and 52, fires up but dies quickly, or sometimes not at all running rich, jumpy timing weak, intermittent, or sometime no spark at all.

My problem was: Circuit I15 (hopefully you all have access a wiring diagram) had a nasty spot it in. It is a piece of shielded wire that goes from the ecm, to the dist., and is actually integrated with the EGR GTS (code 71) the knock sensor (code 52) the o2 sensor, the tps, the circuit opening relay and a couple of essential things. I'll stop there.

The solution: Hooked auto ranging DMM (digital multi meter) from + batter terminal, to a section of shielded wire on the end of the line, right before the pigtial the connects to the distributor (battery totally unhooked of course. Poked, prodded, pushed, pulled until I came to the big bundle of wires that is in the rh side of engine compartment. Grabbed em and pulled a bit and WOW, the dmm resistance reading went crazy. I didn't know I had found the problem, but I knew it needed fixing. I then found that the fat grey wires connect DIRECTLY to junction block CM2 I think (for your reference). Did some testing and found that there had been previous problems before (unless it came tape like hell from the factory, who knows).

Under the plastic wire shroud right in front of the fan, the I15's RED wire, which is G1 to the dist, had broken insulation, and wire internally corroded (as were the other 3). I cut out the section of wire, and saw it to be unfixble. I went to Home Depot and WOW, the happened to have shielded wire EXACTLY like what i needed. They even have it on a huge spool for 38c a foot for those who may be wondering. I cut the wire back a few inches and rewired it to the dist pigtail and plugged it in, using foil and a big piece of shrink wrap to keep continuity on the shielded portion.

Buttoned everything else up, hopped in, turned key, and WOW, this trucks runs WAYYYY better and smoother than it EVER HAS.

SO, if thread helps anyone out there, let us all know! So far one person other than myself has been overcome with relief.

Happy again 3vze owner

-Frozenwave

Team420

WOW!! Thanks for this!! I been having the exact same symptoms on a 93 that belongs to a bud of mine... it has been here for over a year now ( it also came to me in pieces, so the problem could have been anything.
After reading this post....I am gettin excited to go try this out myself.... I will post up my results, when I have some... The truck is currently buried under 4ft of snow tho, so it may be while before I have anything to report.

frozenwave

Wow, my friend with a 93 4runner with a 3vze said his truck runs fine and always has (whom is a also a good mechanic). But i felt his had a lack of power, and is rebuilt, too btw. He allowed me to 'run my test' with the voltmeter, and his section of I15, when moved, cause a resistance fluctuation too! I replaced it, and now he's freakin' out about how much more power/smoother it runs. Everyone hook up a DMM and move move the bundle around and see what ya get.

Tracey98277

holy crap this is what causes this? really? its been driving me nuts for a month now... sometimes it happens and sometimes it doesn't and i finally gave up last week.

frozenwave

what happens is, the shielded wire corrodes, along with the connector on the cm2 junction block. The black wire on cm2 is what i think did it. Anyhow, the resistance of the circuit increases from the corrosion, cause less voltage to pass thru the circuit. I15 runs to the dist. G-, G1, G2, and NE, and as a result, the distributor receives sporatic input from the igniter, knk sensor, egr gts etc etc. It makes perfect sense especially when it's hard to start cold, but easier warm. Corrosion, and resistance increase vary with temperature in almost all cases. The main result is crappy spark, and wacked timing. The surging a lot of pppl have is likely caused by the intermittent timing jumps.

CappyKD

Can you post up pics of the wires exact location? And the location you used to do the continuity test?

frozenwave

sure, i'll have em up tomorrow

CappyKD

Any update on pics?

mcerwing

x2

i would really like to try this, but i don't know where to look

srfive

me too.

chipcity

Is this my problem also??? '92 V6 5spd., new long block @252,000....now 322,000. When finished ran fine, then started to notice very, very slight miss at highway speeds, only under acceleration...idle or neutral going down road it revs. good without miss it seems. Miss under accel. gradually gets worse, now at idle some times....Have replaced NGK plugs, Autozone wires, factory cap and rotor....no difference....Sure feels electrical, it's like gremlins in my dist. or something.....while accel. jerky like pulling a wire off and putting on real fast, sometimes doesn't do it as bad but lately seems most of time. It's my only running vech. right now. MPG is still about 17....but going up hills or accel. hard is a jerky ride. Love my 4runner, starts right up in 0 degree weather, great heater, every thing is good except this miss. I need help with electrial, mechanical not so much, so keep it simple....I'm saving other posts to help me when weather and money cooperate.

mcerwing

bump

i have been trying to find these wires, but no luck yet.