Kind Of A Strange Problem I'm Having

[jcrome04]

Hey guys I need all of our brains B-storming it up here for a bit. I'm having a little bit of a problem every now and again and I'm not too sure what it could be..

Here's the rundown

There is a dip in my RPM's and it feels like the car is slowing down.

It only happens when I take my foot off of the gas pedal. From either cruising or accelerating. Mostly accelerating.

The RPMs only dip for about 1-2 seconds.

I may be forgetting some info... It's a strange problem I've never experienced before. I just seafoamed through my brake booster again... maybe a bad plug??? I've also never changed my spark plug wires due to the price of OEM ones. Also...I just did the "turkey baster" method of refreshing my PS fluid with 2 quarts of Mobil1 full Synth ATF. I don't know if any of these are the coulprits but I'm just trying to snowball some ideas around.

Thanks everyone again for any ideas or light shed on this situation!!!

[jcrome04]

Also... I did the transmission drain and fill procedure a few weeks ago.

But it was happening even before this so... I'm still not sure of what to think of this. Just thought I'd add any info I could remember.

I'll try and think of more things that I have done or have happened.

[python]

so let me see if i understand this correctly....you let off of the gas and it slows down? hmmm thats odd!

[nc211]

A few things come to mind with this one. One, your TPS (throttle position sensor) might be a little off, the MAF (mass air flow sensor) might be a little dirty, torque converter is holding lock-up for a brief second (I don't know a lot about how that works though). If you start feeling a stumble in the car around the 40-50mph range when lightly removing your foot from the gas from a gentle constant speed, then I would say the engine computer is acting up (off-throttle-shock). It drops the fuel to the engine too quickly when you take your foot off the gas, causing the engine to act like it's starved and causing a reversing-torque in the transmission. It's quick, but quite noticable if you have it.

[smooth1]

You may just need to clean and lubricate the throttle cable and lever on the throttle body. It may be sticking.

[fencera]

I had something similar to that after seafoaming... turned out I needed to replace my plugs. Took care of the problem right away :)

Good luck!

[jcrome04]

Ok so, possibilities:

New TPS? Local autoparts store is $150

How can I clean my MAF if that's possible?

What can I do for the computer?

How and what do I use to clean and lube the cable and lever?

Maybe new plugs....

And NC what you describe sounds EXACTLY like whats happening. Like the engine is starved and chokes down for a second. But it's not only 40-50mph. It's any speed it seems like I'd say over 20mph..

Thanks guys. I'll wait patiently ;)

[jcrome04]

So I kinda lubed up the throttle stuff.. while I was in there I tightened the slack out of my throttle cables.

Still seems to happen now and then...

The 2nd gen doesn't have the same trunk hinge wiring problem as the 1st gens does it??

[nc211]

J', you don't want that throttle cable too tight though man, as it can cause harder shifts in the gearing. I learned that one the hard way myself once. The other cable that ties to that connector connects to the transmission ecu port, and if it's too tight the balance gets wacky, which tricks the transmission ecu into thinking you're flooring it, so it shifts faster than normal.

[Alexander the o.k.]

The 2nd gen doesn't have the same trunk hinge wiring problem as the 1st gens does it??

J,

I'm not familiar with the setup of the wire runs in the trunk of a 2nd gen. But I will describe the 1st gen. The harness runs inside a J channel in the hinge loop.

It is accessed by popping off a plastic bracket on the hinge. The whole mess moves with every movement of the hinge. Bad design there.

It is certainly easy enough to check. If yours looks like that description, if it is not shorting now, it may possibly do so in the future. Mine started after 13 years of service. Of course if you're in and out of the trunk every day, well, who knows?

Mine started, if I remember, when it was rainy. It hit all of a sudden, and was far more pronounced than what you describe. Some signs prior to the bucking, hesitation, and wild RPMs were, when braking the radio would drop out. Then the dash lights. Then the headlights. Then they would come back on, be fine for awhile, then randomly start again. It seemed the battery was faulty, or the altenator.

Very weird behavior, and a lot of seemingly unconnected problems. There were other symtoms as well which I've posted elsewhere.

All traced back to that stupid wire harness.

It seems that your prob is probably something other than this, or it could be the very beginning, early stages of it.

It would take about ten minutes or so to strip it down to the individual wires for a visual inspection.

Any other elec. problems?

Good luck

[jcrome04]

AH Thank NC once again ;) hahah

I didn't do the pedal cable TOO tight, not that I think anyways so I'll give it a 2nd look and put some slack back if it's too tight.

and I don't think I tightened the other one cause there wasn't much slack.. and no there are no electrical problems or harsh bucking, just a dip in the RPMs and a "starved" feeling..

[jcrome04]

Update:

Just took a second look at the cables and they aren't super tight. There's still slack in them, just not a ton of play, or wiggle room, or whatever you want to call it... if that makes sense.

NC did you just mean not to have it SUPER tight?

[SKperformance]

I say TC is still locking up . Flush the tranny again.

[jcrome04]

Will do, I have 4 qts left so I'll get on it today

[jcrome04]

Did the drain and fill with the rest of my ATF yesterday and I haven't noticed it happening anymore.

I'll report back soon. Hopefully that fixed the prob!

[nc211]

Update:

Just took a second look at the cables and they aren't super tight. There's still slack in them, just not a ton of play, or wiggle room, or whatever you want to call it... if that makes sense.

NC did you just mean not to have it SUPER tight?

Right amigo, not super tight. Sorry, i missed this one earlier. You want some slack, but not like a loose piece of string. If you notice hard engagement with the a/c running "since it kicks up the rpms", just put a turn or two of slack into that line to counter balance the effect. The dealership showed me this one shortly after I bought mine. It was really kicking into 2nd and 3rd under normal acceleration, but was smooth as glass under heavy acceleration. Two turns of that little nut and no more problems...

[jcrome04]

Hey thanks a lot (again) NC. I'm going outta town tonight so I should have plenty of time ( and road ;) ) To test things out! :D

[jcrome04]

Well, It's still happening....but it's happening smoother.... does that make sense?? lol

I THINK it's happening less.. Maybe my last Seafoam treatment messed up my plugs a little but didn't foul them enough to throw a check engine light?? I need to get new wires too....

Is it IMPERATIVE that I get OEM wires or would aftermarket ones like the NGKs at sparkplugs.com, or Vitek's work just fine????

[SKperformance]

if you flushed it and it went away and is only now showing up but slightly , i would say drop the pan on the tranny , clean out the screen filter, buy and inline filter from wix and it should slowly clean out the particles that are blocking and sticking the valve. It seems to be cleaning the valves with eh new fluid as it has fresh detergent and reappears as it builds back up.

No use taking of the valve body for service , way to o much work. The easiest is just flushing again and throwing in the filter as the mush might be clean.

Also use a nice synthetic tranny fluid like Mobil 1 which i have in mine.

[jcrome04]

I just flushed a case of the Toyota IV in it.... I'd hate to just buy MORE fluid already! What Mobil1 fluid specifically?

Do you think it would be causing harm to the tranny if that IS the case??