Great forum.

94' 4runner, 3vz-e

Within the last few weeks the Check engine light began showing up intermittently until it finally stayed on. This was accompanied by a distinct loss of power, and gutless/choked acceleration. The idle is very rough with fluctuations (500-1100 rpm's), and no power up inclines (max 25mph). It also takes some coaxing to start.

I pulled the code #25 from the diagnostic box and have begun troubleshooting:

-Replaced spark plugs, plug wires, cap &rotor, pcv valve, fuel filter, and air filter.
-Had dealership run diagnostics and was told the injectors needed servicing, so i removed them and had them cleaned and flow tested (cold sart included).

So, the problems continue. Next on my list of things to check include testing and cleaning the throttle position sensor, testing and cleaning the Volume air flow meter, and cleaning the O2 sensors.

Am i missing anything obvious here. The search engine has been very helpful in regard to similar threads in the past, but i have yet to pinpoint this problem.

Any insight from this knowledgeable group would be more than appreciated.


-fsbii-

 

A loose vacuum hose, TPS or the timing's off, would be my guesses at this point. Let us know what you come up with.

 

btw - code #25 suggests 'Air/Fuel Ratio Lean Indicator'

hey 94x4, checked the timing with one of those timing guns and looks dead on.

However, the other day when i took off the intake air chamber to get at the fuel injectors i noticed a small crack in the air cleaning hose (hose leading from air filter to throttle body) that was creeping down the tube from the fastening end near the throttle body. Thinking this may have something to do with it i checked it out and noticed there was definitely air escaping out of this growing crack (no vacuum). So, i patched it up as best i could with duct tape to see if it made a difference. Well, i don't know if it was my imagination, but i think it ran a little better - the engine sounder better (more full sound) and my acceleration was a little smoother. But, i still didn't have full performance back and inclines were still slow going. The duct tape certainly wasn't a great seal, so i would think a new hose would help this even more???

Anyways, after this makeshift tape job i was returning home up an incline when something went out, i lost more speed (max speed uphill 10-15 mph) and the engine cuts out every second or so with a quick drop in rpm's - like the fuel has been cut off all of a sudden. And the engine backfires quite a bit.

At one point after waiting at a stoplight the rig wouldn't even go as the rpm's would get to 1100-1200 and then it would cut out and drop down to 600 again before attempting to accelerate and cutting out again. This went on for a minute or two until it stalled. Two attempts to get her started and she fired up and limped the few hundred yards home, cutting out and backfiring all the way

Pulled some new codes from the CEL (love the blinking CEL ) and got codes #24 - Intake Air Temperature Sensor Signal, and code #32 - Air Flow Meter Signal.

I'm stumped as to why the codes changed all of a sudden. Also, just because the CEL diagnostic is throwing those codes, does that mean it is definitely the trouble area, or is it the result of something else?

I apologize for the length of the post, just running out of ideas here. Please Help!

 

Go through your entire air intake system and check for leaks, fixing or replacing the necessary parts as you go and, by the way, how many RPM's do you idle at? You may want to try adjusting it as well with the idle adjusting screw located on the top rear of the throttle body.

Other than that, try typing your codes into the Search window to see what all's been posted in relation to your codes.

 

Used the search engine religiously over the past couple weeks and have yet to find an answer (not that there is going to be some magical cure all )

The idle was around 700-800rpms before the trouble started, so that shouldn't be an issue. I think the rough idle is due to a problem with something else.

where would one start in checking the whole air intake system? I've read about people spraying something on all the hoses or inside them to look for leaks, the posts i read weren't specific. I'll use the search engine for more specifics on that one.

Thanks for the tips.


-fsbii-

 

The TPS would be my next best bet.

 

Cleaned and tested the volume air flow sensor and it looks good.

Cleaned and tested the TPs and this is where it got confusing. In testing the TPS an ohm meter is supposed to show 'continuity' or 'no continuity' and different feeling gauge thicknesses. What will the device read for continuity or no continuity?

I had the multimeter set to ohm's at the range of 20k and got the same reading (.560) for both feeling gauge thicknesses - which may indicate a faulty tps. But without knowing if the circuit is continuous or not it is difficult.

Any ideas?


-fsbii-

 

"Continuity" will be displayed as something less than 1 ohm.

Try typing the word "continuity" into the Search window to see what you come up with as there should be several posts on this. You'll also get several hits on "TPS" as well.

Should you not find what you need here, I'd suggest paying a visit to Roger Brown's www.4crawler.com site as I fairly certain that he's done some in depth analysis on this very item (he's got a little green flashing "search" button at the top of his page).

Good luck.

 

Searching 'continuity' did little to explain a reading that a continuous circuit would give on an ohm meter, but there was a plethora of threads that contained the word, haha. And 4crawler's site deals mostly with the tps adjustments (very helpful and will continue to use that site) but even the ohm meter tutorial didn't clarify continuity.

Anyways, from another post of mine and some more electrically inclined friends i believe the ohm meter will read as close to 0 as possible for a continuous circuit and will read infinite if no continuity (evident when holding the diodes in the air without touching them)

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Noticed that my TPS is facing the passenger side (upside down) making the IDL and E2 terminals the top two (rather than the bottom two shown in the chilton). Has anyone come across this? I see it was briefly mentioned by one or two 95' owners in an older post

Well, testing the top two terminals on the TPS gave no continuity for both feeling gauge thicknesses(using my understanding of continuity on the ohm meter). The chilton suggests this would indicate a faulty TPS. Is this certainly the case or could it just need to be readjusted??


-fsbii-

 

www.allaboutcircuits.com should be able to answer all of the questions that you have in regards testing for continuity, circuits, voltmeter usage and general wiring issues.

Mind you, it's not that I'm trying to be evasive here, it's just that it seems to me that the general practice of this board is not to do the work for you, but rather to show you how so that you can do it for yourself and learn in the process..., you're not going to learn anything if we do it all for you and that's why there is so much emphasis on using the Search feature.

Case in point was this one person who wanted the diameter of the "stem cushions" (those little bushings that sit between the upper frame mount and the washers on the shock mounts) who became upset apparently because I would'nt get up and go out and do for them what they could do for themselves, i.e., measure the diameter of the bushings.

They made me feel as though they expected me to spoon feed them when they demonstrated in their posts that they were perfectly capable of doing so themselves.

Sorry for the rant and to get back on subject: do a Search for "TPS" to see what all you find and should you have any further questions, post back and we'll see what we can come up with for you then.

 

First off let me apologize if i sounded testy in my previous post, i have read enough of these threads to understand the process you all go through. Lord knows how many times you all have answered the same question over and over and how many times some have looked to be 'spoon fed'. That being said i thought the question i was asking was something that someone could simply pull off the top of there head if they had used an ohm meter for continuity. Your tips and encouragement to search have been helpful 94x4, thank you.

I solved the continuity problem!!! 3$ continuity tester from home depot, haha (lights up when continous circuit is found ). Still looks like the TPS is on the way out, i will find out for sure when i take the throttle body off and go from there (TB needs the cleaning anyways).

If the TPS checks out allright (or is replaced), and the cracked intake hose is replaced and i'm still having idle and power loss problems i will look at the EGR valve. Searching on alot of these threads, including 'EGR', has lead me to believe a bad EGR valve could cause symptoms similar to mine.

I still don't understand why CEL codes for Intake Air Temp Sensor Signal and Air Flow Meter Circuit Signal have come up. I'm still looking into these, guess i'll find out, plenty of work to do before hand anyways.

Will check back with results soon, thanks again all.


-fsbii-