camo31_10.50

get some hose from a parts store..(i got mine from an older Napa..) and start replacing every hose under the hood.


vacuum leaks can cause all kinds of problems.

i need to make some beefier block off plates for my EGR as well lol

i'm also deleting my cat all together....no more cat.

warmonger88

it'll just get all cloggified from the carbon that isn't reburned

camo31_10.50

what are you replying to?

theMonch

DudeMan did you ever resolve your problem?... since this is your thread.

dr1553

We did kinda hijack DudeMan's thread, but, I'm sure this info is usefull to him too because he probably has the same problems.

Mine is for sure the TPS, I drove the 4runner again today with it disconnected and besides the 1500-2000 rpm idle it runs MUCH better. I just did the test from 4crawler, it failed.

VTA-E2 at closed throttle passes at 700

VTA-E2 at WOT was infinite

I did the sweep test on VTA-E2 like described and as soon as I touch the throttle it goes infinite.

After seeing it was bad I didnt bother with using shims for the IDL-E2 test, I just decided to sweep on those also. As I opened the throttle the resistance decreased and then jumped up but it never hit infinite. The needle was very jumpy as I moved the throttle also.

I ordered a new one, it should be in today. I'll post the results with the new one installed.

thook

Excellent troubleshooting, David. <<<high five!!>>>

dr1553

I got the new TPS on and it made no difference. It still runs like crap. I tested the old one according to the 4crawler page and decided that it was bad. Thats why I bought and installed the new one. So now I dont know.

I'm thinking either it is the AFM, the wiring from the TPS to the ECU or its the fuel pressure regulator. After I got back from my test run I tired disconnecting the vacuum hose to the fuel pressure reg. just for grins. There was no change in idle speed. I have tried that 3 times now. 2 of the three times it made no difference and 1 of those times it did make the idle speed increase.

The last time it ran good was when the fuel Press. Reg. was responding to the vacuum hose being unplugged. That was also when I had the TPS unplugged. This afternoon it was running bad so I plugged the TPS back in (old TPS) but it didnt make a difference. Now that the new one is installed there is still no difference.

How much will the stealership charge to figure this out!?!

theMonch

It's not so much how much they will charge to figure it out, it's how much they will charge to not figure it out.

I think you're on the right diagnosing track so far, but you have to think about the following.

If it is the fuel pressure regulator not pressuring up when the vacuum drops, then why would it have a rough idle? While idleing it needs very low pressure it relation to under a load. The diaphragm in the regulator would have to have damage to cause a vacuum leak to effect the idle. And if this were so, then it couldn't have "fixed itself" to run good for you that one time.

Where does the unplug the TPS test method come from? is that a FSM described on vehicle test? This seems questionable to me for two reasons. One, you replaced your TPS and same problem, so apparently there is nothing wrong with it, and two, I would imagine unplugging it would simply force the ECM into a "limp home mode" where it raisies the idle and runs very conservatively in the event of a TPS failure. I know that this is the way my Grand National's TPS functions. So if it were good or bad, severing it completely from the system would cause the same effect.

dr1553 There has been so much info flying around in this thread, I forgot your specifics.

1. I know you replaced your catalytic, but have you replaced your O2 sensor? (It doesn't have to throw a code to be bad)

2. Does it idle rough upon cold start-up or does it have to warm up to start having a problem?

dr1553

1. New Cat and new o2 sensor. Both things made it run a little bit better but neither fixed whatever is wrong.

2. Thats tough to say. I think it runs the best in the morning before it has been warm for the day. But I wont say it has never han rough first thing it the morning. I CAN for sure say that it runs the worst when its warm.

Sometimes when I first start it and it runs at a very low RPM the engine light comes on, then something clicks, the idle jumps and the light goes out.

Code 41 is stored, I just checked it.

So where is the other end of the TPS wires that I need to check? A short in those wires would explain why the problem comes and goes.

TNRabbit has also recomended checking the distributor in this thread and also in an old thread of mine. I have not looked under the distributor cap in a long time, but last time I did there was a small amount of motor oil pooled up in there. I really need to take another look. What does a 'worn distributor' mean? I know the rotor wears but what on the distributor itself wears?

theMonch

Dring my long diagnosis stage my distributor actually started to make a squeal. I thought "hooray, finally an expanation". I had it replaced with a reman OEM toyota and the squeal went away, buit not the intermittent problem.

The bushing in the shaft of the distributor wears (and you get oil blowing through) like you have described. You might need the distributor, but unfortunately, I'm not sure if it will fix your problem altogether.

thook

AFAIK, this "method" of pinpointing a TPS is not from any manual. Seems to me, after reading everything I have read, it was derived by someone having some knowledge of how the TPS works and how an electrical component can affect ECU/EFI operation.

This is one of the first threads I started and participated in:
https://www.yotatech.com/forums/f116...98/index4.html

It's kinda long, but it contains some information and examples of what's happening by disconnecting it.

The idea is that the ECU will go into default by disconnecting the TPS and still be able to operate the engine fairly well. It's in the programming of the ECU. If anything else is malfunctioning, the engine will still not operate very well. But, if it does run better it's because the TPS is gone and not giving the ECU erroneous info. It's the erroneuos info that's causing the problem. But, this can only pinpoint to the TPS. Testing is still required to find out if it's the sensor or the wiring. In which case, one should test the sensor and, if it fails, condemn it. If it passes, test the wiring at the ECU and compare the readings. The connector at the TPS could be problematic, or the wiring connector at the ECU, or the wiring, or the terminals at the ECU, or the circuit in the ECU.

In this case, if the TPS failed testing, then it is correct to replace it. But, if the engine still runs like pooh, then there is still a problem on the circuit. Connectors, wiring, etc.

thook

If there was a problem with either of those components, when you disconnected the TPS, the engine would still run poorly because those two components are still connected to the entire system. I don't know how else to explain it, man.

warmonger88

Im on about the same page as dr1553.
1. Ive replaced the tps and it got a tiny bit better( i'm idling at 700- 500 instead of 250).
2.it no longer dies while in neutral while warm, but runs excellent when cold.
3. i,ve also got the 41 code stored, but the light doesn't go off
4. also within the last week i removed the egr
i'm wondering if the things i've done so far are being more counter productive to the situation. what i havn't done or know how to do is test the afm, i was going to pick one up from the monch, but my cash flow took a dive.
5. the engine surges while holding steady at 1500 rpms

dr1553

My symptoms sound a lot like warmonger88. Differences are that mine has not idled under 400-500 ever, never down to 250. Mine has never died on me. Other than that it sounds about like mine.

I have noticed that mine does run better when cold. First thing in the morning it runs very well. Once its warmed up it starts the bad hesitation during accelerating and cutting out/surging while at steady speeds. Since I put on the new TPS the idle has only gone below 850 one time. Before the new TPS it was going to the low 400-500 rough idle at least half the times I was at a stoplight.

So I think my TPS was part of the problem but I dont think it was the biggest problem.

It really feels like its missing on one or more cylinders while accelerating.

I did notice today that there is oil coming out from under the distributor cap. Its enough that its a concern. I need to pull the cap and see whats going on under there.

I also checked and the coolant temp sensors are only $15 from Oreilly. I'll probably get one and replace it just to say I did. Any pointers on removing/replacing it? I havent looked really close but it looks like its hard to get to.

TNRabbit

Issues like that AFTER warm up are usually related to a vacuum leak. Unmetered air isn't an issue when you have the cold start injector pounding in extra fuel, but it becomes a problem after it leans out. I chased an idle issue for 2 years until I found a HUGE hole in the A/C idle up vacuum hose.

dr1553

I have had the intake off twice. I have to wonder if I left something loose, or by removing and reinstalling the old hoses they no longer have a good seal. Whats that large hose on the passenger side under the intake that makes a sharp 90.....short hose with a sharp bend. I left that off the second time I put the intake back on and I wonder if its still loose and letting in air. If was tough to get it back on....its been three years so sorry I dont remember more specifics.

I really need to check ALL the hoses and lines on the engine. That damn 3.0 looks like a spaghetti bowl it has so many hoses. I cannot hear any vacuum leaks and I have sprayed starting fluid around the engine bay, but not for at least a year now.

The oil coming from under the dist cap has me really wanting to check that as a possible culprit.

Where is the A/C idle up hose?

theMonch

That big hose with the 90 is the PCV valve and vent hose. If you have a leak at the gasket to the valve cover it will act just like you took the oil cap off. (ever done that? it runs like s*#t)

The A/C idle up VSV is in the cluster of three or four VSV's that should be on the passenger fender.

Another good place to look for a vacuum leak is the idle-up from the power steering. It is down on the side of the PS pump and has a feed and return line to it.

warmonger88

i actually found the air leak causing my surging, but my idle is still ˟˟˟˟. i noticed that my dashpot has a crack in the top,would that contribute to or cause the idle problems?it does suck a little air

dr1553

During my lunch break I decided to remove the dist. cap and take a look. While getting ready to remove it I noticed the #1 injector wire was unplugged. That might have been the cause of my missfire. What happened is the connector has broken and is no longer snapping in. For now I will have to check it often and make sure its not working its way loose again. I guess I can get a new connector from Toyota but it does not look like there is much extra wire in the harness to get a new one connected. I am also going to take a flash light and check the three on the passenger side under the intake.

Its still not running great but its much better. I need to get the new TPS properly adjusted, I just used the while running idle speed trick to set it. Once that is dialed in I can go from there.

I will still check under the dist. cap also. I'm betting there is oil slung up in there and maybe my dist. is worn and loose.

I might have time to mess with a little this weekend. Check your injector connectors warmonger88, maybe yours are starting to get brittle and crack/break like mine.

808-3VZE

Did it fix the problem?