displacedAlaskan

I just installed headers and a true dual exhaust system in my 94 4runner. I had the old o2 sensor mount welded into the new pipe. I'm curious as to whether or not I should go ahead and buy a new o2 sensor since it is a well used stock sensor on a truck with over 172,000 miles on it. I'm not sure how to tell if it is still working correctly.

Another question I have for those experienced: my 4runner starts hard, it takes turning the engine over quite a few times before it starts up. I was told this is probably because my fuel pump is going out. What is the best way to tell? I've installed a new distributer cap&rotor, new plugs, wires, air filter, fuel filter, oil changed...so I know its none of those things.

Also: I've noticed a lot of buildup on my valves

Anybody have good results from installing a Jacobs ignition system in their vehicle? I'm going for gas mileage improvements...and with the mileage I get some power increase (which I don't mind). What do most stock 4runners get for mileage? What's the best way to up your fuel mileage?

stock87

Well, for starters, on a 94 no matter which engine you have, you have EFI, and pumping the gas isn't going to do a darn thing when trying to start it. That habit is a carryover from the carbureted days when the gas pedal actually directly affected how much gas was going into the engine (via acceleration pump).

The hard starting itself could definitely be the fuel pump. The fuel pump has a check valve in it that is supposed to maintain pressure in the system while the truck is off. If that valve is bad, pressure bleeds off, and it takes several seconds of cranking for pressure to build up again. One way to check would be to jump the Fp and R (I think R, anyone want to correct me?) terminals in the check connector under the hood. Then key it to 'ON' for a few seconds before trying to start it (this will force the fuel pump on, normally it only runs in the 'START' position when you're trying to start it). It should build pressure and start easily then. Another potential problem is the fuel pressure regulator.

As for the O2 sensor, a new one can't hurt. Make sure you go with an NGK or Denso unit however. Bosch units cause nothing but trouble on these trucks. sparkplugs.com has the best prices I've found.

toyota_mdt_tech

[QUOTE]O2 sensors are usally dead by about 150K max.

Pumping will do nothing but wear out the throttle body shaft and cable. Fuel pump? I doubt it, it would stumble when running. Look for cold start injector operation or make sure the fuel line isnt bleeding off.

I didnt know you could get "non detergent oil"? Those deposits come from the fuel.

Waste of money, nothing will be more reliable then the stock set up.

MMA_Alex

Definately go with a new 02 sensor at that mileage. That'll probably make the most difference in gas mileage. Which engine and what kind of mileage are you getting? whens the last time it had a full tuneup? Might just be worth getting a new fuel pump. Could also be the cold start injector, or something else. I wouldn't be surprised at all if the pump was dieing at that mileage.

Not sure off the top of my head which terminals you jump to make the fuel pump run, but there are some good tips for troubleshooting all these issued in the fsm's

93 p/u fsm

and yes you can get non detergent oil, its just hard to find. there still is some really early grade api stuff available. Some of the cheapo stuff that they sell at the dollar store etc can not even be the right api spec for your vehicle

motoriderbc

If the carbon build up is excessive on the intake valves it can cause long crank times. The carbon absorbs the fuel until it is saturated, only then does enough fuel get into the cylinder to start. Try an aintake/combustion chamber cleaner, see if it improves.

TNRabbit

Seafoam that puppy!

Buck01

I saw on 4crawlers site something about hard starting. It said to jump a couple of terminals on the Diag box under the hood. Look at 4crawlers site.

I will see if I can find a link and post back if I do.

ok I found the link.

http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump

Emms4runner

Intresting thread, ive just bought a Denso 02 sensor myself, cant wait to fit it!

Brenjen

I married a yankee from Ohio; she's never come at me with an attitude like that. I have nothing against northerners but if you think just because the previous owner took care of the vehicle & didn't abuse it was a bad thing....why didn't you buy one that had been abused by one of your precious northern brethren instead of one from Florida?

I mean really, how smart are you? Pumping the gas on an injected engine? Non-detergent oil?

Run a fuel system cleaner through it - send your injectors to an injector cleaner service if it doesn't clear up after a few tanks of gas with solvent like Techron or Seafoam in it - check all your vacuum lines for leaks - check the timing - get used to the bad fuel economy - don't bash Southerners if you're going to ask them for help in the same breath.


Also, what plugs did you use when you changed them? People around here that are experienced with these Toyotas say to use NGK or Denso. They say if you have Bosch in there that can cause similar problems as what you have described. Good luck here in the South, sounds like you're going to need it.

displacedAlaskan

Thanks for all the input fellows. Sorry Brenjen for the southern bashing...I just was ticked at how people down here don't get insurance and then they go smash in the back end of my buddy's rig, and don't pay didley squat...and that's not an isolated incident, it seems that down here it is quite common. And they don't know what turn signals are for down here, either. And also....you must not have read my post very thoroughly...the poor thing WAS abused bigtime.
Yes, and there is such a thing as non detergent oil.
I'm using Mobile 1 synthetic now and it's running smoother now.
I'm running NGK iridium tipped plugs with a jacobs ignition system. Thanks for the tip MotoriderBC, I'm going to try the intake cleaner. I'm planning an ISR mod really soon too so that will definitely help. I'm getting 19mpg highway right now, and about 15 city. Also, replacing the 02 sensor really made a difference.

CoedNaked

If it were me in your situation, I would go buy 3 cans of seafoam.I would run a 1 1/2 cans through your gas tank. Put 1/2 a can in your oil, and use 1 full can to do 2-3 treatments through one of the intake hoses. That should help with cleaning some of the carbon.

The other option is to take your truck into a dealership or similar and have them do a fuel injector cleaning. Or you could pull the injectors and have them professionally cleaned somewhere. Try and stick with Chevron Gas if you can from here on in.

I myself would keep the synthetic oil thing going and consider switching all of your driveline (tranny/transfercase/front & rear diffs) to a synthetic like Amsoil or Redline. This will help with mileage and over the long haul be cheaper b/c you can double the service life of these synthetic fluids if you want to without any issues (just make sure you research exactly which fluids to buy and that they will indeed work where you put them - if you have a manual transmisson, only use a GL-4 gear lube but the transfer case and front/rear diffs can take a GL5 which is what I would use).

Have a look at cleaning the throttle plate. It could be crudded up with baked on carbon which reduces air flow.

Stick with stock parts, wires, etc, and disposable stock parts (filters, spark plugs, etc.). These trucks run well with the stock parts.

Also have a look at maybe some BG44K Fuel system cleaner. Never used it myself but guys who have say it's worked wonders for them in their gas tank (supposedly).

CoedNaked

Out of curiousity - what size exhaust pipes did you use for your "true dual" exhaust system? and do you have pics of your set up?

UncleBob

Yea, us slow talkin' stoopid Floridians know better than that.

Brenjen

I read your post, you said you bought a nice rig that was driven slow. Sounds like it was taken care of.

All motor oils have some detergent in them just like all gas does, even the cheap ones.

I know what you mean about the no turn signals & no insurance; we have a state law here that you must have liability insurance to drive. I went up through Illinois, Indiana, Ohio & Pennsylvania & I probably didn't see two turn signals used the entire trip up to the point where that un-insured motorist from Ohio ran a stop sign a hit my Mustang GT.

Edit: Hint-Hint Those problems are universal brother. I apologize for taking offense; I should have ignored it.

MMA_Alex

There are idiots everywhere who drive without insurance, and refuse to use their turn signals. And yes there is such thing as detergentless oil. Its called API grade SA. Grade SA is designed for automobile engines built before 1930

Brenjen

Well I wasn't talking about specialty oil but ok I concede the point.