Ajm1991

Hello all. I have a 90 Toyota 4Runner i purchased about a month ago and i really like it so far...way nicer than my first 90 4Runner years back. But ever since i drove it home its had a pretty bad miss at idle and it stumbles under acceloration...Ive done a tune up (NGK plugs,new plug wires,air filter, rotor and cap, and a oil change) which it needed BADLY... All this seemed to help some but not as much as i had hoped. Im also losing oil somewhere and its not leaking anywhere i park in the same spot everyday. The coolant is always full with no signs of oil in it. It is a 90 4Runner with the 3.0 and auto w/ 132xxx miles. Also it will have a fit about every other day where it will push black smoke out the exhaust and i have to clear it out or let it sit a while to be able to drive it normally?? Any help is appreciated I did use the search tool but i found nothing consistant with my issues..

Ajm1991

Well just to update im currently doing the timing and the marks dont match up.. at all. When you turn the distributor it will only barely touch the plate on the left side? Does this mean its way advanced? I jumpered E1 and Te1. Also the CEL is blinking i counted over over 100+ blinks so im not sure that could even be a code

Thanks, Alan

sam333

Sound like your doing the right stuff( tune up). If the blinks are 1/4-1/2 second apart with no pauses and continous, that means there are no codes.
132000 miles is low , but if your losing oil and its not leaking, then you are burning it.
If its less than a quart every 3000 I would not worry.
Do you have a manual to figure out your timing?

Ajm1991

Thanks for the reply. Yes they are about 1/2 second apart so that solves that. I have a Haynes which is what walked me thru timing but i didnt see anything that points to the way-off timing. As far as the oil goes i lose about a half quart a week...400 miles or so.. so thats not such good news. Another thing i didnt state is i had to replace the rod bearings right after i got it because it developed a low hollow knock. The crank journals were worn even tho via using a plastigauge so i havent had any issues with a knock since then. Might not be related but i am having low oil pressure too.. cold start up it climbs to a half on the gauge but once its warm it never gets passed 1/4 accelorating and barely keeps above the low line at idle

blrider2001

my timing doesnt match up on my 90 but in runs and accelrates great. at idle it has a slight shudder every ten to twenty seconds but that hasnt been a big deal..have no idea on the timing. un less when someone did the head gaskets before me they have the timing chain off a tooth and moved the distributor a tooth to compensate for it.

sam333

There is not much you can do about low oil pressure at idle except usuing heavier weight oil. When a rod starts knocking there is usually damage to the( crankshaft) rod journal, material is removed and clearances are increased. When you put in new standard bearings you have excesive oil clearance and low oil pressure. I am not saying you didnt do a good job, its just very hard to get acurate measurments with plastigage( especially with the engine in the car). If your pressure is worrying you , you can install a PSI oil pressure gauge.

Burning oil wont hurt anything ( kill your cat a little sooner) except the air and your wallet. The worst thing about burning a quart every 1000 miles is if you dont watch it inbetween oil changes you can run out of oil, and with only 132000 miles and rods knocking, Id say thats what happend to the previous owner.

MudHippy

If I understand what you're saying then yes. It's way advanced for stock timing.

But, just to be sure, what you're saying is that turning the distributor all the way counter-clockwise puts you at, or around, 15° BTDC?

Turning it all the way counter-clockwise should put it right at, or around, 10° BTDC. 10° BTDC is the stock base ignition timing with the check connectors jumped. Turning it clockwise from there will take it all the way past 15°, and off the scale to the maximum advance point somewhere around ~28-30° BTDC. IF the distributor is installed correctly.

So to correct this, and likely correct the hesitation/miss too by being able to time the ignition properly/close to stock, you'll need to remove the distributor and re-install it in the correct position. It has to be atleast a tooth off at present, to be that far out of it's adjustability range.

Here's the FSM pages describing how it should be installed. See pages IG-25 & IG-26 for illustration on how to.
http://personal.utulsa.edu/~nathan-b...13distribu.pdf

Here's the rest of the FSM for future reference. It's a little more thorough than the Haynes.
http://personal.utulsa.edu/~nathan-buchanan/93fsm/


Where to begin?

1. It has a timing belt, not a timing chain.

2. The timing belt is for timing the valves. A.k.a. valve timing. It has nothing to do with the ignition timing, technically speaking. Though in extreme cases of incorrect valve timing, the camshaft ignition timing gear may be too far off to get the ignition timing to within stock specifications. But that wouldn't likely be a big factor unless it were off by quite a bit, say 2 or 3 teeth.

3. Since the timing belt has little to nothing to do with igniton timing under normal circumstances, where the ignition timing is set after the belt is installed will not be significantly affected by it being off just a tooth. If it is off by a tooth that may explain why the engine runs abnormally/shudders though.

4. If the belt really were off by just a tooth though, I'm actually not sure your engine would run at all. Let alone run well. Especially if it were only off by one tooth and not two, as in one tooth on each cam timing pulley. One tooth off on one side and not the other would throw the engine way out of balance. Maybe if it were off one tooth on the crank timing pulley, or what would be ~1/2 tooth on each cam timing pulley, it might run kinda/sorta. But not likely very well, and probably wouldn't have a significant effect on setting the ignition timing.

5. If you can't get the timing mark to register correctly on the scale, then your distributor is off by atleast a tooth. Which may also be causing the engine to display abnormal running symptoms/shuddering. So you should probably think about re-installing it as described above to rule that out as the possible cause.

6. It sounds like it's just an ignition timing issue to me. I'll bet once you address that issue the shuddering will cease.

Happy wrenching!

Ajm1991

Thank you for the replies and i apologize for the delay in replying... life gets busy. And happy turkey day to all!! Anyways to add i just did a compression test on the engine i had 1-168
3-180
5-170
2-168
4-170
6-168 Which seems pretty reasonable... I am about to try to reinstall the dis. the correct way with the FSM (thank you Mudhippy) and see if it helps. Also i filled the truck up 2 days ago have used almost half a tank and have gone 70 miles... This seems very low... I have the correct tire size too. This might be caused by the black fuel smoke i always see

vital22re

iTrader: (2)

is your cold start injector stuck open? could be flooding.

Ajm1991

.....

Ajm1991

Im trying a seafoam treatment on this tank of gas lets see if it lives up to its reputation!! Lol

Ajm1991

Wow.... I was pretty hesitant to try this but it is night and day and worked very well for my truck. All the hesitation is gone and overall has smoothed out. Ive only driven it 20 miles or since so ill update how it does with mileage on this next tank The exhausted still sounds strange up to 25oo tho... Dunno what that could be it still also shutters in overdrive (only). And itll hop itself out of overdrive on trips short and long. Maybe this is related? I read something about a coolant temp sensor causing similar symptoms..

Ajm1991

Well as an update as soon as the Seafoam ran thru the tank and i filled up again the issues are the same as before. It currently idles fine on warm up but if you press the gas AT ALL for the first ten minutes or so it will hesitate at 2k RPM's then break thru it after 1 second or so. It also smokes black when this occurs. After 10 minutes or so the idle is rough but the hesitation is gone entirely. Another thing i failed to mention is that the idle screw is completely turned in (bottomed out) and it still idles at 1100 RPMs in neutral/park.

sam333

Yes the coolent temp sensor can make the engine run really rich and in some models controls shifting on an auto trans. Also check what vital 22re said, your cold start injector and timmer( also can make it run very rich). The last thing to check is your fuel pressure and regulator. These are the big three for really rich running. Check your plugs and see if they are fouled with soot. If your are running rich it can quickly ruin your cat.
If you can get your hands on an IR temp gun you can check your cat to see if it is running hot( alot unburned and partly burned fuel can make your cat glow red hot).

Ajm1991

Thanks for the reply i will try all these things tomorrow. Is there an easy way to test the CSI? And the temp sensor? There a little on the pricy side so i would like to try and check them before throwing parts at this thing

sam333

Go to the menu ( forum jump) at the bottom of this page and then to maintenace and reapair, you will find manuals listed.

Ajm1991

Well tonight i FINALLY checked for codes the correct way (detached the battery for a few minutes to let the ECU reset) And got two codes.... 41+43... and after doing some searching 41 is TPS and 43 is starter related. So upon finding this can a bad or out of adjusted TPS cause a hesitation, stumbly idle and excessive fuel consumption at start up?? It will literally DUMP black smoke when accelorating while still cold and fall on it's self from about 2k-2300 RPMs. You can watch the fuel gauge move upon warm up Ive burned a over 1/4 tank of fuel just starting it cold and letting idle to running temperature 3 times to track down this issueThen once its warm it runs a little better tho still has a more slight hesitation. I apologize for the vague descriptions in my postings. Certain issues are just hard to describe

Ajm1991

Well an update im still dealing with a rich condition. Ive averaged 12 mpg since ive gotten it. The TPS checked out fine today so i know its set correctly. I notice my issue most while under load ( accelorating from a stop until it gets to about 2200rpm's and feels a bit smoother, tho is still there). The exhaust sounds like its firing on every other cylinder. Also ONLY under acceloration i get a really strange muffled howl from under the hood on the drivers side, which perfectly matches the exhaust popping.


Ive checked for vacuum leaks, compression test, i also installed a new fuel filter, spark plug wires, cap, rotor and air filter. I have not installed a new o2 sensor, because my problem occurs in both open/closed loop (i would assume since its so consistant. I appreciate the input ive gotten already and if any one else has ideas let me know!! Thanks, Alan

kwnate

What do your plugs look like?

sam333

Yes , you are not checking what has been suggested. Check your plugs for soot( dry/black) to see if you are running rich on all cylinders.The three biggest thing that will cause rich running are : To high a fuel pressure ( bad regulator), Bad coolent sensor(ECM enriching mixture because it thinks the engine is always cold), stuck open cold start injector.