ycmike

Did not yet run the compression test.

The engine has very little time on it. Summary: Initial break in of 15 minutes. Then drive time of another 20 minutes. Has an additional 20 to 30 minutes of time from attempting to diagnos this problem. Total mileage since rebuild is 9 miles during the inital break in drive.

I did run the AFM resistance checks including the sweep test. I used a DVM. The sweep test is a little hard to see on a (or my) DVM. I ran it multiple times experimenting with movement speeds until I had some confidence that the the resistance was not going out of range. I was not too concerned about the actual values but I did notice the resistance going up, then back down one or more times as I moved the flapper. I was under the impression that rsistance would not be linear so I did not pay too much attention to actual values. If I moved the flapper too fast my meter seemed to overshoot or display values out of expected range. If I slowly moved the flapper, the readings were much smoother and stayed in range. I attributed the suspect results during the fast movements to the DVM and not the AFM.

I think I have a small, cheap analog meter. I could test the AFM again using this and perhaps get a better visual indication of the condition.

For fuel pressure, I did the simple test of unplugging the fuel damper while idling and noted a slight rpm change. Other than this slight rpm change, leaving this damper unplugged, makes no noticable change to the way the engine runs. I do not have the tools to check the fuel pressure.

leaky4runner

you sure you don't have air in your cooling? took me about a day of driving and parking on mounds to get all the air out
had about the same symptoms in my 85 4runner 22re(miss when warmed up(no load), around 2000rpm +). I also had surging(under load).

cleaned my tb coolant passages(blocked with solid gunk, needed a pick to get it out), and IACV... still surged and missed once in a while a day after. then realized I hadn't got all the air out(coolant low in rad., gurgling from heater core)..

all the air is out, smooth now. night and day difference.

or you can have some really complicated crap going on.

just a suggestion.

ycmike

Interesting. I never would have thought the coolant flow through the TB would cause a noticable miss in warm climates. I would think the coolant flow through the TB would be for cold environment operation - to keep the intake from potential ice formation. Stuff like that.

Looks like you are in California. What part of California? What was the weather like when you were having this problem?

I'm in California as well and the weather lately has been warm to hot. Daytime highs from 80 to 95. Even overnight, temps are not below 55F.

thook

I think the idea is that with air in the coolant, the pockets or bubbles adversely affect consistant coolant temp sensor readings.

DVM's aren't the best for reading AFM measuring plate, but yeah....going slowly will work. I've done it. Analogs, as it seems you realize, aren't as jumpy.

At this point, I suspect as you did early on. You may have an injector issue. One or more not giving good flow.

leaky4runner

the coolant flow thru tb "dictates" what the iacv does?????(I think) no flow, blocked flow, air- will confuse the IACV(I think). not sure how IDLE air control valve would affect miss at higher RPMs tho(not idling).

I do not have an answer to why coolant runs thru tb. other manufacturers have same design(coolant thru tb), some don't.(from what I've read)

my suggestion is based on the fact that you did head work(therefore drained coolant) and upon filling it back up, may have air bubbles.

if I were your position, I would clean tb(whole thing-vacuum, coolant, every single hole with carb cleaner) and Iacv(coolant lines only, with hot water only, q tips? forgot what I used... don't get crazy on iacv-there are sensitive "parts" in there) dmm your IACV while its out.

even if it's not the problem/solution, you won't have to worry about cleaning those 2 parts out for another 24years.

live in anaheim..... I got my 4runner about 1.5months ago, and its had it since I bought it(WORSE after I flushed cooling system, probably dislodged gunk and caused particles to clog up that small hole in lower tb coolant pipe).... temps then were 70ish high???? don't remember, a little cooler than it is now(80s).

when researching my problem online, it seemed a lot of people suggested IACV and alot of people were having the same issues(all the 22re were around 25 years old, and alot of people having the same issue around the same times--hmm, 25 years of gunk building up and hits us around the same time)

as thook said, you may have an injector issue or some other "complicated crap"

EDIT: oops, just re read initial post- you already cleaned TB. I guess IACV or the coolant lines can be clogged. or IACV could be "broken". with all the stuff you already checked, I would not know where to go from there.(I'd come here and ask).....I would still check IACV (clogs, proper operation (open/ close in oven and freezer) and DMM).. but that might be a waste of time, you've done alot already. diagnosing is a b@#ch.
good luck

morena67

Mine is 22r and I used to have very loud misfires... they went away after the EGR valve was cancelled.

thook

Coolant through the TB is in part there to help prevent icing, yes. But, later models with a thermal wax idle air valve that are integrated with the TB operate solely on coolant. A poorly operating AAV wouldn't be the cause for a misfire and stumbling like this, though. Poor idling and stalling would raise flags, but this is something else considering the wider the throttle plate opening the worse it gets. In fact, he's already blocked off the AAV and nothing changed.

EDIT: Scratch this sentence........injectors have been rebuilt.

Otherwise, I'm stumped at the moment and believe something's being overlooked as mentioned. I've got my thinking cap on.

thook

We interrupt this posting to bring further clarification to the process by further checking our data. Please wait.........

thook

Other than verifying the system is actually going into closed loop mode (you said it was, but not sure how you've determined that) and checking the coolant temp sensor and checking at the ECU, and after carefully rereading you're thread, I'd have a smoke test run on the motor to see if there's any vacuum leaks around the manifold.

That's really all I can think of.

ycmike

I am assuming it is gpoing into closed loop. Not sure how to veriy it actually is.

I'll see if I can get to the Temp sensor to test. There seems to be two computer temp sensors or switches (not sure which) in the intake and a third one in the thermostat housing.

Update:
I located a old analog meter and decided to check the TPS again with this meter I saw some dropouts and spiking during the sweep test. these were consistenty in the same spots of throttle valve opening. I bought a new TPS to change it out.

I still had the phillips head screws on the TPS so I just removed the upper hal of the plenum. The splices in the harness were bugging me as well, so this was a good time to disect the harness and look at them.

The splices looked pretty good. hardly any corrosion and no broken wires/strands. I soldered them and wrapped the harness back up.

With the plenum off and on the bench I was able to have a good look at the water tubes in the TB and they are open and flowing coolant just fine.

I installed the new TPS and adjusted. The new TPS has a much better looking linear resistance when doing the sweep test. I detected no dropouts or spiking using the analog meter.Once adjusted, the values are all good.

I got everything back together and crosses my fingers and fired it up. All good when cold as usual. Miss is still there ater it gets warmed up to about 160F and above.

I might be wishful thinking but it seems like its just a little better now and the miss is not so frequent. It is still very obvious above 2500 rpm and holding a steady throttle at about 2700 rpm will produce multiple misfires per second. (seat of pants measurement but I'd say at least 1 misfire per second and sometimes more). Idle is still good. Might have an occasional misfire at idle like every 10 seconds but hard to tell. At idle, engine is rock stready in the mounts and vaciuum at idle is still 21.5 inches.

Sprayed some Throttle Body/injector cleaner around intake looking for a vacuum leak but could not detect one.

Have not yet gone back and looked at the AFM resistance sweep test with the analog meter. I plan to do that.

Have not done the compression test yet. I know, I know, I'm dragging my feet on that one.

ycmike

Ran the compression test. fully open throttle, dry cylinders:
1 - 215
2 - 210
3 - 210
4 - 210

Consistent, but seems high.

Again, this is a fresh rebuild so the high compression is not from carbon buildup. The block was surfaced to get it level. Machine shop said they took off 10 thousands. Head is a new Rock Products casting. Head Gasket is OEM Toyota.

Anyone know if a rock products head has smaller combustion chambers than stock?

Also checked total timing - 45* with initial set to 5* BTC

I tried several different initial timing settings. 0*, then 5* ATC (runs very poorly at 5* ATC), also tried 10* BTC to see what happened and it seems like the more advance I dial in, the more it misses although it is somewhat hard to tell for sure. Watching the the total timing while bringing the rpm up, the miss occurs when timing gets above 40*

I realize that timing increases with rpm and the miss also increases with rpm, these may not be related.

With the initial timing changes, the amount of advance seems to stay fairly consistent at about 40*. This seems like a lot of advance to me.

Anyone know what the total advance should be on the 22RE?

Also, with this amount of advance, and the compression being high, I'm wondering now if the miss is from preignition.

thook

I'm at a loss on the total advance. I've never really explored that technicality. If I have some time to do it today, I'll take a look at mine with a light.

Those compression readings are pretty high compared to factory, but I don't know anything about Rock heads. Nor am I familiar with how much machining would affect compression exactly. IOW, I know the more is taken off the head and/or block the more it raises compression, but I don't know details.

thook

The coolant temp sensor for EFI is the green one. The cold start injector timing switch is the brown.........both on the front of the engine. Of course, the coolant temp sensor is the one to troubleshoot.

The other thing.....about compression....I'd wondered early on if the ring gaps were spaced correctly and if the rings are in correct order on the pistons. This could explain the high compression. Seems hard to imagine a shop getting those wrong, but.....

ycmike

Thanks for the info on the sensors. I did not get around to testing them.

I've never heard that the rings being installed wrong could raise compression. Any details on how the compression increases with rings installed wrong?

ycmike

Well, I'm going to be out of town next week and I was very near the end of my tolerance for working on this engine. That, along with wanting someone else to look things over, so I dropped the truck off today at a shop. I've known the owner of the shop for 32 years. He is honest and knowledgable. I'm hoping he can find the problem. I won't be upset at all if its some stupid thing I've done. I would be releived to have it running correctly (and know what caused the misfires).

Stay tuned...

thook

I suppose I'm wrong on ring ordering, that would give a low compression. But, seems I recall if the ring gaps weren't spaced right, that could be an issue. I guess I'll have to recap on that, though. Dang. Sorry.

Hope he finds the problem. Sorry we/I couldn't be of more help. Good luck. I'll check back to see what your progress is. I'm curious myself.

thook

/me wrong again. Ring gaps out of spacing order would give low compression. Since the only thing I could think of that would cause the high compression in your situation would be the head and deck machining, as I'd already posted, I decided to ask someone who would have a better idea; a friend/mechanic who has worked on many Toyotas and builds racing engines. He said the high compression is NOT a problem at all. In fact, you will have more power. You lucky son of a gun....lol! I would like to have a little more power, myself. Anyway, as well, the machining would be the only other reason.......given everything you've already stated about the condition.

ycmike

Matthew,
Thanks for the reply. It was my understanding as well that the high compression would not necessarily be a problem unless it was so high that it caused pre-ignition/detonation. I would think that worse case one could retard timing or run higher octane fuel if that were happening.

Yesterday, I spoke to the owner of the shop where I took the truck. They spent some time on it last week and checked a number of things (I did not get specifics) but they had not found the problem yet They definitely "see" what I was trying to troubleshoot and agree that it is a problem and not the way the engine should run. They plan to check emissions at the tail pipe while it's idling and at higher RPM both cold and then warmed up. They are then planning to put the truck on dyno and run it up and look at tail pipe emissions as well. I'm hoping that will give more clues as to what might be happening.

He did state that the problem seems just like an EGR issue and, just as I did, disconnecting the EGR's signal vacuum it improved the way the engine ran. He was also going to verify the vacuum hose routing.

I will be kicking myself if the hose routing is wrong. I checked those hoses so many times and referenced a number of documents including the FSM to be sure I had them correct.

ycmike

Oh, in the meantime, since being back in town, I've been working on the FJ40 doing things which I know I can repair such as front wheel bearings, axle seals, and knuckle rebuild. I just love grease...

thook

Ahhh.....an FJ40. I'd love grease that much more if I owned one of those.