MaK92-4RnR

Still having issues with the 4Runner and I've beat my head against the wall enough and still cannot figure this out.

I constantly keep getting code 71. I've checked all the vacuum hoses ( they've been double checked by myself, and 2 different mechanics) the EGR Temp sensor has been replaced, and the EGR has been replaced. So what the hell could it be?

SYMPTOMS:
the truck's symptoms are as with everyone who gets code 71... Intermittent power loss ( completely random, it could drive perfect one day, and then a complete dog the next ). But what really gets me is that if i drive for a far distance ( with the catalytic converter on ) it will glow red by the end of tonight. I've had the cat inspected by exhaust shops, and mechanics and they say its fine ( i had it removed at 117k miles, and it was kept indoors and then put back on ) Now, I know the glowing redness can either be caused by a clogged catalytic converter or excessive fuel being consumed ( the truck is only getting 140 miles to a tank, when i usually get a little over 200 )

WHATS BEEN DONE:
The top end is brand new ( little over 1,200 miles on it ) and also has a new knock, TPS, and EGR temp sensor. and all work has/was done at a professional shop. Also, the timing has been redone 4 times since having the power loss issue. its been kept up with tunes ups ( has new plugs, cap, distributor, coil, etc etc ) This 3.0 has had everything gone over, pretty much. I've considered a new catalytic converter, and o2 sensor. but I thought maybe i should see what is truely wrong.

So does anyone have any clues that could help? I have two trips coming up in august and september and do not want to miss them over the account of some pathetic malfunction.

Any ideas? I just need a straight answer as to what to check that hasn't been checked.

Thanks

MaK92-4RnR

...bump.

nobody has a clue?

shaunneuhaus95

i think its called a egr vacuum modulator

eric924run

i agree. you should try replaceing the vacuum modulator. the little black thing with like 4 hoses going to it. the computor uses the temp sensor to monitor operation. if it does not see the proper temp rise it will set this code. so if the vacuum control soleniod or the modulator are bad it could cause this. how ever the glowing cat seems to me its dumping lots of fuel. i beleive your computor may be freaking out. id check the other stuff first. if you get no resolutions then i think try a ecm. You can find them used around. 50-75 you will need one for a cali car with the egr temp.

MaK92-4RnR

I dont understand how the truck could be throwing code 71 when it was perfectly fine BEFORE the top end rebuild. so whats the deal with that? I'll look up a vacuum modulator on rockauto.

as far as the rich fuel consumption, what could be causing that?

ToyotaViejo

Just throwing it out there (I don't disagree with the vacuum modulator idea) that O2 sensors can make you run rich, and be murderous on your power.

Have you compression tested the cylinders?

eric924run

well check all the vacuum line routings, also check the ground wire from the body to the intake manifold, and also under the intake manifold on the passanger side valve cover at the rear theres a ground attached that comes out of the wire harness. make surethose are both connected well as they both would have been disconnected during head repair. as far as the o2 you can unplug it and see if you get a change.

mihtoo

Hey guys I am interested in this thread as my 94 4runner has the same code 71. I am getting 240 to 300 miles to the tank though. Please keep me posted .

MaK92-4RnR

its back in the shop for a complete tear down again. I reset the code with the cat off, and it came back on today. code 71, yet again.

MaK92-4RnR

issue resolved.

Vacuum Modulator and a faulty TPS were the culprits. '

Thanks for all the information guys.

eric924run

Thats great. also Thanks for posting the repair.

mihtoo

Thanks so much already ordered the tps

MaK92-4RnR

where did you order it from? I ordered mine from Rockauto and it was faulty... I ended up biting the bullet and get a OEM factory one.

mihtoo

I did the same right from toyota 145.00 canadian. If it works it will be worth it. I am also installing a luk gold pro clutch with a new flywheel this weekend, and putting in a new water pump, timing belt tensioner and pulley. The old girl should be good to go for another 100 000 kilometers / 60 000 miles. I love to hit the trails and I sometimes bring my children so having a trusty rig is important.

1994 4runner sr5/3.0/5spd(California Spec)31's/northern exterior bush guard/8000lbs warn winch. 161 000 miles (factory rebuilt motor with 60 000 miles)

Redeth005

Thanks a lot for this thread man.

I have the Code 71 as well. Only difference is I had my 3.0 completely rebuilt and replaced tons of parts, added new o2 sensor, changed a few vacuum line sensors, fixed my cracked/taped up intake elbow and container problem, and it still popped up with that infamous "CODE 71." I've had it with tying to find the problem. I definitely wasn't expecting more problems after all that I did.

I'll take a look at the Vacuum Modulator and TPS as you did. Hopefully my problem will be resolved after this.

MaK92-4RnR

haha glad it could be helpful. this was a stressful couple of months trying to track that problem down

a4runnerfreak

Mak, I know this is an old thread, but do you remember what you paid for the new TPS?

Redeth005

If it helps any... I went to the dealership after checking this thread out yesterday. And I bought the vacuum modulator. I didn't buy the TPS but I did get a quote and it was something like $160.

a4runnerfreak

what was the price on the modulator?

Redeth005

No. It was the price for the TPS which is why I didn't buy it. i wanted to see if my problem went away with the vacuum modulator first. So I bought the vacuum mod. For $71.


They wanted something like $160 for the TPS.