^VooDoo^

I was going to post this as a general help question because it shouldnt matter the yr or mdl and I need help.

Ive been running around for months with about 8mpg and to no avail I cant find the problem.

Symptoms are really rich and timing retard durring accelleration and lean pinging at a cruise, I can feel the timing advance just as the accelleration turnes into the cruise then goes flat again from what I think is the knock sensor doing its job.

Thinking this was the problem and I fixed it,,,,,,"NOT"
I am on #4 O2 sensor in 1 month so far, I though my old was bad and got a new Bosch (most people say they suck, Did same thing), #3 was the Denso and again still same problem, Bought dealer, Still same so that means the first one was still good but I had to use the connector on one of the others.
I did a Volt test at the test port near the fusebox like the service man says, I can only assume its working right but the readings are all over the place, The book says use a high impedence volt meter but I just use the digital one I have. V .4-.6 rapidly changing from .45-.55, Mines like .1-.8.
(If somone could do the O2 sensor test from the port near the engine fuse box to ground with there digital voltmeter and let me know if yours shows steady or all over the place once the engine is wamed up)

Its not the TPS, checked it and ran w/o it and knowing full well what its like to not having a good working TPS.
Timing is now 8 over TDC insted of the 12 I normaly ran just to keep the cruise pinging from sounding like a machinegun.
cold idle works correctly and so does the engine temp sensor with the coldstart injector.
It idles fine, No new loping or miss firing so that means no injector or burnt valve problems, Did Compression test and thought the meter was old it was consistant and good.

I have checked and checked for airleaks and none, I can still accellerate over 5k rpm under load and cruise at 90mph so its not fuel pressure regulator, Fuel pump or filter not to mention those wouldnt have barring on the retarded timing durring acc.
plugs, wires, new cap and rotor, No change, Also no backfire, flash back or missfire so thats not the problem.

I know the Cat is old but with the above mentioned acc and speeds thats not the cause.

AFM, I ohm'd it, The airtemp sensor is working right and I can tell you it pings more when its cold then hot (odd) but I dont have a old needle type meter to tell if the AFM is ok, The digital reading all over the place so Im not sure.
Could the AFM be the problem? would it affect timing?

CEL codes, Auto or fetched Not a freaking one, Im stumped so badly on this.
The sevice manual shows CEL codes for all kinds of possibilities that could be happening now, Yes the CEL is good, Hell it told me when my sparlplugs were bad.

^VooDoo^

This is a update to the problem.

Well things got continualy worst since I posted that, I was down to 65mph at best and I think my EGT was really hot.
What Ive done and why and why Ive had continus trouble.
I replaced my FPR and TPS in june, Whoohoo got my balls back.
Well in august all hell started, Checked many things many ways, One of them was of course was putting old FPR back on to see if that was the problem, Ran the same, So off to toyota to get FPR.
It was bad outright the box no pressure build up at all, You could blow through it, Take it back and got another and put it in, Still had problem.
Fuel pump change time, Thought it helped but no dice.
NOTE!!!!!! for those that intend to do a fuelpump change on a 90-95 4Runner, CUT THE FLOOR under the back passenger seat to access the pump, Its a nightmare to drop the tank and put it back in, A small peace of sheet metal banged and painted put over the whole with sealent is so much easyer and also if you have to do it again.
A weak ago I told a friend about what was happening, He's not a verygood machanic but had a thought, FPR?, I told him I just did that and how many times, He made a bet to buy what ever part of equal value I needed next if it wasnt the problem, I took that bet and off to autozone we went.
Well, I ate that bet thanks to freaking cheap ass no warrenty parts from Toyota, I got it up past 85mph on the freeway and no pinging or speedcap while cruising.
I still have some pinging in the hard acceleration, Im going to get another pump, Not from the dealer this time.

dcg9381

Can your mechanic buddy set you up to monitor fuel pressure while running?

^VooDoo^

THats one of the points, He's not a machanic and guessed.

^VooDoo^

Well Wooohoooooo!!!!!!!!!!!! , I fixed it!!!!!!!!!!!
Heres another update and a trivia.

Now after 5 months of hell its back, I dont know what may have been comprimised for running in this condition for so long but hope it makes the 300k mark not far ahead.
Parts used to find the problem not incuding the good ones that were on the 4runner and were still good in most cases.
3 FuelPressureRegulators one of which was bad from dealer.
3 Fuelpumps one was bad from dealer,One from Autozone in it now and one Walbro from online that Im still waiting for.
1 TPS, And this was rechecked many times as was the last one.
1 Fuel filter, Old one is back on since it was good.
3 O2 sensors, One OEM, one Bosch and one Denso, THe OEM works best but I had to use the plug from my Origanal to make it work.
2 sets cap and rotors.
Checked the CAT and muffler for flow, All is good.
Lastly I went through all the wires looking for shorts and breaks again along with checking all the relays, All good and everything worked except engine running badly.
AFM ohm'd out good every time.
Engine was timed right, It idle'd good and a compression test was good.
Engine machanicly was good.
Remember I have gotten no CEL codes showing or pulled, All clear.
No problem lights on the dash what so ever.
If I sabbatoge things I can force a CEL and the code is correct.
The only thing that was left was the ECU.
Has anyone ever had a ECU go bad and still run almost normal?
I tell you now, Its wasnt the ECU.

I drive my Runner to work early morning with headlights and heater running.
The engine could be ran a little harder in the morning, I think because the coldstart injecter was richening it up, But It would bad and pinging after the temp came up, But it was cold outside.
In the late afternoon the it would cruise at a slightly higher speed without pinging from warmer air.

Can anybody guess what was wrong?, What was the one thing that was bad and wouldnt tell me, Heres a hint, It was causing a cascading affect of all electronic devices acting on or against eachother.

I also have some nice A/F gauges along with the other fuelpump in shipping to help with this problem, Oh well, They will still be usefull.

jasonbrink

so... what was the problem?

TNRabbit

Voltage regulator/alternator?

CILO

Do tell, inquiring minds want to know

surf4runner

bad ground / cable?

^VooDoo^

TNRabbit wins a prize, If I only had one to give.

Bad altinator, It would always produce enough to keep the regulator on but no enough to run any electrical at full streingth, eg. anytime the o2 sensor show lean the ECU would open the injectors up longer in turn robbing power from say the fuelpump, Also the ECU couldnt Keep a regulated source and signal from the AFM and all this prolly came back to the o2 sensor heater not getting enough power.

Sad part, New one just went bad, Wont keep the engine running on its own w/o keeping revved up.

dcg9381

Voodoo, diagnosed by random replacement or did you test what it was doing while it was on the car? Good tech post.

^VooDoo^

Diagnosed the problem and started testing, But when nothing shows bad its hard to find the fault.

TNRabbit

Do you have a minor short somewhere causing alternators to fry?

CILO

Im confused ( not hard for me ) you mean to tell me the alternator wasnt giving out enough amperage so that caused all the other sensors to go haywire? how did you test the output of the alternator?

jht3

interesting. what was your voltage gauge telling you during all this?

my first thought was to tell you to check the water temp sensor that feeds the ECU (there's another one that feeds the temp gauge, but that won't effect running condition).

^VooDoo^

jht3, It always shows the same with the battery hooked up as it has for years.

Tonight I started pulling the electrical appart, I went through the fuse box and electro greased every plug and blade contact I could reach in the engine compartment.
I just started it again and did the battery disconnect and turned on all the acc, It stayed running, Not sure if this is because the coldstart was on also and holding the idle better, Tomarrow I will go through the connectors at the ECU, I got my gauges and cluster to mount tomarrow.
The engine temp to ECU is working, CEL'd right away from disconnect, The book says it would have CEL'd if there was no change in temp as in bad.
I know the coldstart sensor is fine, I can tell its working when it starts and I can feel when it shuts off, This along with the cold idle up valve in the throttlebody.

Does anyone know if the caps on the ends of the fuelrail thred off or are they pressed and sealed, They are extreamly tight, I need to drill and tap for a fuel pressure gauge.

^VooDoo^

Ok, Latest update before a possible good test tomarrow.
I started bypassing alot of electrical to make sure it wasnt wire going bad.
Before I was done last week I went around wiggling all the wires I could get my hands on (except sparkplug wires "jitters"), Behold when I pulled on the harness jumping across from the body to the engine it started to stutter and almost die, Yay a lead to my troubles????.
No, I just happen to find something that was about to happen but It lead me to the possible real problem.
I ended up recrymping and soldering all the fusable splices in the harness across the engine, Durring this I found that the wire to be severly oxidized and had to scrap the copper to even get the solder to take but I fixed it all, I think the stutter was a bad passengerside injectors splicing.
Also to check the connectors on the injectors, Wow talk about brittle, But they will work.
Also new Plenuum Gasket and a touch of sealer to make sure that wasnt leaking.
Still not running right if not worst now, Pinging really bad, Feels like the timing is normal now but for some reason I think its just fuel starved and has put me at no higher rpm then 2.8k "sad".
Got my gauges installed, Only one that would work at the time was the vacuum, Cant hook fuelpressure since theres no where to put the sensor.
Air/fuel meter didnt want to work the first time I hooked it up.

Today my brand new Walbro pump came in, After mounting it it was splice time, I thought about just splicing the new harness to the old wires but since the first time I changed the pump I thought the wires were kinda whimpy and after seeing how the engine harness wire oxidation was I cut the old wires off completely and spliced straight to the old rivited wire crymps (You people who have done a fuelpump before know what Im talking about.)
Got the Air/fuel meter working right and its not running lean even floored.
I will know for sure tomarrow when I hit the freeway and the coldstart injector shuts off.
Now if I finaly got fixed, Does that mean the wires to the other 2 fuelpumps was the problem or were they bad pumps from dealer and autozone.

Whats a normal vacuum for idle on the 3vz, Mine shows -15 psi, All the books say it should be about -10 psi, Just wondering, Because that means its still pulling hard for almost 300k.

Also no one answer to my fuelrail question, Are the brass caps pressed or thredded?

Fingers crossed.

just a 22re

yeah my little 4 cly does the same i just was to lazy to look into it like you did but hey good job on testing and taking down what you though it was and it was'nt the alt?? cause i have the little 55amp alt and it powers my SPL set up nice )thats big loud BOOM) and mine still is slow someone told me to check your contacts on the inside of the air flow meter they make groves and cause a little bit off single to go to the ecm thats not really sean hope that helps oh and yes i forgot who told me even though i just read his pm lol go team lazy!!!

^VooDoo^

Its done, Except for a little pinging now and then its finaly working, It was the stupid wires to the fuelpump in the tank, Not bad enough to make it stop working but bad enough to not get pressure up to full and since Toy was to cheap to put a pressure sensor in I wasted 6month and alot of $$ trying to find the problem, Not to mention all the fuel Gauge didnt budge going to work and back today, I have been going through a quarter tank aday easy otherwise.

Except for that little Ujoint vibration its great to be able to cruise at 80mph again, Not to mention just to pass people now.

surf4runner

nothing like taking 6 mos to track down the 'voodoo' bad connection