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Undriveable every other two seconds; then fine for two seconds...and repeat

901 Views 40 Replies 6 Participants Last post by  l33ch
2002 Echo, manual tranny, 270k miles on original drivetrain, 60k on clutch, probably original fuel pump.

So here's the short story. Driving at 65mph along gentle hills (no steep grades) the car suddenly loses, say, 65% power for two seconds (I timed it) and then BAM hits the gas HARD and proceeds to drive normally for two seconds. All this without any change at the gas pedal.

The car drove like this for 10 miles till I got into town, then proceeded to idle normally at a stop light. Light turns green, I take off, the whole thing repeats again: two seconds of normal power, two seconds of markedly decreased power, then a hard punch of acceleration followed by two seconds of normal power, two seconds of markedly decreased power...you get the idea...and yet it'll idle juuust fine.

It's almost like when you put your thumb over the end of the garden hose and then let off again.

So thinking it could be the pump, I bought a new one from O'Reilly's (because I was out of town and couldn't risk being stranded with my dogs away from home), installed it and it made the problem WORSE...now there's no more 2-seconds-on-2-seconds-off...it's normal under slight acceleration, Violent Bucking with any more than about 40% pedal input...definitely not enough acceleration to get me home on the highway.

Bit the bullet and paid for a tow home. Any thoughts, ideas, wild guesses, or otherwise encouraged. Thanks in advance folks. :)
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Discussion Starter · #3 ·
Fuel filter? Do you have the tools to test fuel pressure, that's where I'd start.
I considered the fuel filter...until I discovered that there's no traditional inline filter. There's only a built-in filter component to the fuel pump assembly which is considered a "lifetime" filter (yeah right), and it's unavailable from the big box stores locally. Can order it for $24 +shipping from RockAuto, but to be honest I really don't think that's the problem. In all my years I've never seen a filter "give and take" the way this vehicle is acting...I've only seen them clog up and either somewhat restrict fuel flow, or worst case scenario, block fuel flow. Doesn't mean it isn't the problem, in fact I'm probably going to end up ordering it and replacing it, because 20 years is long enough for one filter's "life" in my opinion.

That being said, I believe you're right on the money with starting at a fuel pressure test. Unfortunately, because I don't own the suggested Toyota branded test equipment mentioned in the service manual, it'll require someone to ensure proper wiring connections between the battery & pump, one to turn the key, and one to observe the readings on the gauge. So...maybe two people. I'll have help tomorrow, hopefully then we can figure something out fuel pressure wise.
 

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Yes replace the filter assembly/redo with the new pump u have. Check injectors.but also check coils. I've had a similar loss of power issue cuts in and out and it was a coil going out. Eventually a code came up too to confirm. It also happened to me in turns or a sluggishnes to a boom re-engage even tho i kept the pedal constant throughout (and took turn faster than usual, but you get the idea.).

So, fuel filter sock, and lower filter assembly (since u replaced the pump anyway, might as well do the rest). Then look at the coils and injectors. I would have gone with a denso unit. I don't know if you can truelly trust its reliaility and fuel flow, if u can, I would return it and get a denso unit. The sock and bottom half filter assembly brand doesn't matter.Be careful with the plastic tabs holding the upper and lower half together.

Just my $0.02.

*Maybe check via ODBII Throttle Position Sensor % Ranges if it looks ok while U press the gas while key on but car not running. i.e. no dead spots through the range.
 

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Discussion Starter · #5 ·
Yes replace the filter assembly/redo with the new pump u have. Check injectors.but also check coils. I've had a similar loss of power issue cuts in and out and it was a coil going out. Eventually a code came up too to confirm. It also happened to me in turns or a sluggishnes to a boom re-engage even tho i kept the pedal constant throughout (and took turn faster than usual, but you get the idea.).

So, fuel filter sock, and lower filter assembly (since u replaced the pump anyway, might as well do the rest). Then look at the coils and injectors. I would have gone with a denso unit. I don't know if you can truelly trust its reliaility and fuel flow, if u can, I would return it and get a denso unit. The sock and bottom half filter assembly brand doesn't matter.Be careful with the plastic tabs holding the upper and lower half together.

Just my $0.02.

*Maybe check via ODBII Throttle Position Sensor % Ranges if it looks ok while U press the gas while key on but car not running. i.e. no dead spots through the range.

Thanks for the $0.02...definitely worth a nickle. :)

Agreed about the coils...I've also had coils coming and going, but never at such regular, timeable, predictable pulses. I was hoping if it were a coil it'd throw a code during the ~10 miles of highway plus ~5 miles of city driving I had to do to get to the point where I could pull the codes...but no codes thus far. Doesn't rule out a coil of course, just seems odd behaviour for a coil in my (admittedly limited) experience.

Also agree about the Denso unit. Not sure if I can return the one I bought since it's been installed, but I have a Really Good parts counter guy who'll do it if at all possible. O'Reilly's would have to special order the Denso, but that's a price I'm willing to pay. Generic parts give generic performance, and with today's highly computerized cars seeking very specific data ranges, sometimes generic works and sometimes it just plain doesn't. In fact the first pump I bought didn't fit the plug and I had to return it for the lesser grade pump they had in stock at the moment. Given I was 45 miles from home with 3 dogs in tow, I was anxious to do whatever it took to just get the thing home...so I went with the cheapie unit at the time. Had I known it wouldn't solve the problem I'd have ordered the tow about 4 hours earlier than I did and saved myself the hassle of trying to install a non-Denso pump...heh...

I'll have to research how to check the TPS ranges...I'm not very tech savvy so it may come down to playing "parts darts" and replacing the TPS rather than actually reading the ranges. Worst case scenario I have the original, still good TPS in a box for later on down the road.

Thanks again l33ch, I appreciate the reply. :)
 

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OBD2 not showing any electrical cutouts when running? sounds electrical to me..is it timed perfectly to every two seconds or fluctuate? maybe tied to the engine turning,, how about the alternator? a relay? the alternator has the relay and charging circuit built in, maybe it thinks it is charging and says no more but it cuts the voltage to the whole car. and reverses and does it again?
 

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Discussion Starter · #7 ·
Yes, every two seconds almost on the dot, no fluctuations, I timed it and it stayed the same the whole time at higher RPMs.

Hadn't considered the alternator, since the car will idle at normal rpm (800 or so) without the two second problem. If it is electrical, it definitely only does it at higher RPMs.

Thanks for the reply; definitely something to consider.
 

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Discussion Starter · #9 ·
Do you have a scan tool to look at the ecu data?
It may be a sensor issue!
Unfortunately, no, I don't. I'm sadly low-tech & wouldn't know how to use one if I had one. Any thoughts on which sensor it could be? I do have a factory service manual and a basic multimeter, maybe I'd get lucky & be able to test it that way.
 

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Discussion Starter · #12 ·
Quick update on what we've found thus far...

The factory service manual has two tests for the MAF. One is measuring resistance across two points, the second is measuring voltage as you blow through the MAF. It failed the first one, but passed the second one. We're thinking, if it failed the first test...THEN IT FAILED and we need to replace it. Bit the bullet and ordered the factory original Denso MAF from RockAuto...because, simply, IT FAILED and we need to replace it. Will chime back in once the new one is installed and let yall know how it's going. Thanks again to everyone for the pointers and advice! :)
 

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Discussion Starter · #14 ·
Quick update:

Did a fuel pressure test and it showed good fuel pressure, steady needle, no upwards/downwards hunting, just a solid steady pressure at idle and with increased RPMs.

Changed the MAF (since the old one passed one test, failed a different test) with a Denso unit from RockAuto (O'Reilly's wanted double the $$$ for the same part).

No luck.

While I was in the area I went ahead and cleaned the battery posts (even though I didn't think they were the problem) and changed the air filter (also didn't think it was the problem).

The car will idle up to high RPMs and hold them there as long as it's in neutral. Put it in gear and things go wonky. Slipping the clutch will get you up to speed...but only barely, eventually, with a lot of two-steps-forward-one-step-back idling as it seems to lose signal, find it, lose it again, find it again, back and forth. I'm lucky I live in a rural area where I can test it on long, empty streets...but at this point I'm back to scratching my head.

Any thoughts? Thanks in advance folks. :)
 

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Discussion Starter · #18 ·
Are you saying you have a high idle after you replaced the MAF? Where is it idling at? Double check the MAF, make sure it is sealing properly again the housing!
Sorry for the confusion.

The idle is fine, it's exactly where it should be, and you can rev it up as high as you want, smoothly without any of these problems, as long as the car's in neutral and sitting still.

Once you're in gear the hesitation and driveability problems creep in and make it impossible to rev up smoothly. Strange thing is...once the car is in motion, it doesn't want to rev up smoothly anymore, even if you're rolling down the road in neutral or with the clutch pedal pushed in. It's as if the car is afraid to move. Does fine sitting still...freaks out while in motion. Completely strange...first time in all my years to see something like this.

One of my first thoughts was something clutch related, but the clutch is strong. I did a few clutch tests just to make sure, like accelerating up to ~25mph, shifting into 5th, and dropping the clutch quickly to see if it grabbed immediately or if it kinda slumped its way into gear. It grabbed immediately, so I don't think there's a problem associated with the tranny.
 

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Discussion Starter · #20 ·
Do you mean the car is not rolling along very well even if you push the clutch in and trans in neutral?
Yes, that's it exactly. But come to a stop and it almost immediately clears up. For the first, say, 5 seconds after coming to a stop, it's still hard to rev up...but once it's physically stopped for more than that...magically clears up and will rev up smoothly again.
 
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