t2d2

iTrader: (8)

In case no one mentioned it (it didn't show up in searching the thread), check your vacuum hoses first. If they're old and cruddy, that may well be the cause of your engine hesitation. I haven't done extensive road testing yet, but on the first few drives it was totally eliminated. Mine was the pause-lurch hesitation when accelerating from a stop if not feathering the throttle.

I replaced 12' worth of 5/32" vacuum line, plus snipped the split end off the smaller of the two lines that connect to the air intake. Some of it was extremely dry, while other pieces were still in decent shape. For a buck a foot, I say replace it all if any of it is sketchy!

BeaksSC

iTrader: (1)

few month bump.
So my sc has this hesitation issue and I'm thinking it may have something to with the ignition coils as well, like others have previously said. But my current issue is that when the car is in park, or just in drive with the brakes fully pressed, it is making this thumping noise every 5-10 seconds. With the hood open, you can see the engine jumping which is causing the noise. So can the ignition coil be a factor in this issue as well? My car hesitates from the start and then again when you reach the 40'sish. Thanks.

t2d2

iTrader: (8)

That sounds an awful lot like mine. I'm nearly positive it's related to the TPS, but I haven't managed to get it set properly yet. Will be trying again tomorrow when my new multimeter arrives. It sometimes feels "grumbly" from a standstill, which I attribute to the ECU controlling idle. Right around 40 mph at partial throttle, most noticeable on uphills, is where my really bad hesitation takes place. I get a similar thumping to what you described, but only in Reverse or with the A/C running while idling.

I also think the throttle stop screw needs to be adjusted, but there's not really any guide for how to do so. I mistakenly followed iffy instructions that said to adjust it... That may well be interacting with TPS settings to keep everything slightly out of calibration.

BeaksSC

iTrader: (1)

Yeah I'm pretty sure my throttle isn't aligned. We had it off when we did the starter and I don't think we aligned it or anything, just put it back on. And one of the bolts is broken soooo we're using one. Do you have any clue what the thump noise is? I can't notice it when in motion but it's very evident in park. Sounds to be coming from the driver side.

t2d2

iTrader: (8)

My assumption is, the thumping is from the engine lugging under low idle droops. If yours is like mine, it never happens during driving when the RPMs are up. I think the ECU catches the temporary droop and adjusts the idle.

My new multimeter arrived a day early, in the 20-30 minutes between posts, so off to see if I can get that darn TPS within specs...

BeaksSC

iTrader: (1)

So I was just trying to take a video of it (bad video, can't tell much) and it was misfiring pretty bad toward the end. Have to look that up now since it wasn't really doing it earlier. Lmk what you find out. Kind of sounds like something from the exhaust maybe? Pretty deep thud, maybe coming from the back lower part of the engine.

Edit to prevent another post:

So I'm going to assume it's the ignition coils and/or leaking vacuum line due to the misfire? We have the vacuum in the picture below just capped off because the small port for it (on the black plastic branch off part) is broken, so we are wondering if we could find an adapter in order to plug it into the larger port next to it? (What is that one for?) Need to test the ignition coils still, but need to find a better how-to.

Edit 2 (6:53):
Checked the ignition coils, unplugged the top one, car went to low power, checked the driverside one, car did the same thing. So that's not the problem. Checked the MAF sensor. Unlpugged it and the car didn't change... What exactly should have happened? It should have shut off?

t2d2

iTrader: (8)

If it sounds like misfiring, it may not be the same as mine.

Answers to what an unplugged MAF should do will be all over the board... Mine will idle okay that way, but giving it any gas will cause the RPMs to drop to the point of nearly stalling.

With my new multimeter in tow, I tweaked the throttle set screw a bit and then readjusted the TPS. I still couldn't quite find a spot that satisfied both the 0.16 and 0.26 mm feeler gauge criteria, but: a) it felt like I was closer to the razor's edge of calibration than in previous efforts either either TPS unit, and b) I'm somewhat skeptical that it's even possible for such a minute difference in throttle position to give consistent readings. Right on the edge between continuity and no continuity, the meter was jumping all over the place with no movement of the TPS. I think my old meter couldn't detect those small, rapid swings.

With that done, I went out for a test drive on the hill nearby that makes it buck every time, and it was silky smooth. I fully expect it to go back to "normal" in a day or two, though, so I'll just keep on testing as always...

BeaksSC

iTrader: (1)

Good to hear that fixed part of your issue. Will have to try that once I get this sorted out...

New thing we thought of. I've been trying to estimate my gas mileage so I drove the first half of the tank in pwr more (what I've almost always driven in) and then at half tank realized I should see how normal compares. I switched to normal on Sunday night and now this is happening. It's been about 40 miles so far and now this is happening. Could there be any correlation between that and my misfires/whatever is happening?

t2d2

iTrader: (8)

Took it out for another drive and still behaving nicely. I did feel what I thought were a couple moments of the grumbly intro to bucking, but nothing came of it. I'm probably just so queued into that now, anything peculiar in the road surface makes me think it's imminent.

I've never thought to experiment with PWR vs Normal on that... My guess would be that's coincidental. PWR doesn't do anything other than hold you in each gear longer, does it? Maybe doing so matches just the right combination of RPMs and gear, which highlights the underlying issue from elsewhere. My experience all points to it being TPS related, although we may or may not have the exact same symptoms.

BeaksSC

iTrader: (1)

Fixed the intake tube port that was broken so that vacuum line is fixed now. Took another look at the ignition coil on the top and the bottom connector is a bit broken (the inside plug part). So could that be a part of my issue? Not rally sure how to fix that though, I guess buy a new connector or something?

t2d2

iTrader: (8)

My passenger side coil also had a broken clip on the lower, low-voltage connection. Fixing it didn't have any effect, but I figure it's always best to replace bad connections before problems arise.

If I remember right, that's the one that the connector crumbled when I was trying to de-pin it, so I was able to just plug the old wire/pin into my new connector and didn't have to do any splicing.

BeaksSC

iTrader: (1)

Can someone tell me how to check the idle rpm's with a multimeter since my rpm gauge doesn't work? Can't seem to find anything about it

BeaksSC

iTrader: (1)

We may have fixed my problem. I really hope so. I got my tps all set yesterday using a connector we cut off a car in the junkyard so that we could pull accurate readings, and today we spliced in a new bottom ignition coil connector to replace my broken one and put a junkyard coil in (the old one had it's prongs pushed in) and then started it up. Then it still did it... So we were looking at it while it was running and you could feel something wrong in the spark plug wires. Shut it off, looked at the wires, and the ignition coil wire was almost completely cut in half. I guess it lost a fight against the little ridge thing on the back of the cam (The NGK wire set is a little longer than OEM, especially that ignition wire, so when we tried putting the cover back on, it pushed the wires in weird ways because of their length, just leaving those off for now on). So swapped that out with a junkyard wire and started it. Didn't do it when in idle, didn't do it when the idle slowed down when it got to operating temperature, and didn't do it for 5-10 minutes after. So hopefully we're good. We're done messing with it so if it comes back, it's probably going to the dealer. Nothing more we can do at this point. But I'm praying it's fixed. That would just make my week. Just painted the wheel wells in the front to get rid of the ugly overspray white/black that I had. Next is the rotor hats and then the wheels are going back on, then off for a drive. Thanks oldmantan and t2d2 and whoever else for the help.

1uz4runner

So after having driven this 1UZ swap in my 4runner for a while. Here is where I am at.

I get about 12 mpg in town and 16 on the highway.

I have devolped an issue with the 1uz while not terminal does cause a distraction and I like things to be perfect.

I have a high start idle if the vehicle is cold or has sat for more than 20 minutes even after being ran. Idle is 2000 rpm for a minute but will settle to 750 rpm as soon as temp needle is back at normal range. For the first 6 months of life in my rig it didn't matter if it was cold or hot it always idled at 800 rpm. I did run the rig for a nice 2 hour highway drive the other day. I found that under WOT and on a hill that I had an occasional hesitation or stumble. It is not every time but does happen. It is only for a split second but definitely noticeable.

I have replaced the cap, wires, rotors, ecu temp sensor, new 02 sensors, changed my MAF with another spare I had sitting on my shelf. I also had a spare IACV that I tried and it was not within ohm's so it was a no go. I also replaced both coils during the tune up.

I think I will check the ECU for leaky caps in the next few days. I will also check the ohm readings on the TPS, MAF, IACV again.

Anybody have any other input? The two issues I have are the high cold start idle, occasional WOT miss.

Over all very happy with this swap

t2d2

iTrader: (8)

I'd be surprised if it isn't your TPS. I've never been able to find a spot along the adjustment range that is perfectly within spec, including on a replacement TPS and with two different multimeters, but I got it pretty close on my last attempt and it almost eliminated the characteristic hesitation/stumble. I still get it occasionally -- just enough to be annoying but not enough to want to reset the super finicky TPS and risk making it worse again.