Engine still lagging/bucking, help! Options

[GriffGirl]

I'm still having weird engine issues. It was bucking really bad until warm up, especially in higher RPMs. I did a tune-up which helped but didn't solve it, engine would still buck while cold at higher RPMs (3000+), and at about 3500+ when warmed up. Fiddled around some more this weekend, resulting in amazing improvement; now instead of bucking, it just kind of feels like it's dragging like a dog scraping its butt on the carpet. Yes, at higher RMPs, and regardless of what gear I'm in. I've done the following thusfar to resolve this issue:

•replaced thermostat
•replaced engine temp sensor
•replaced plugs, cap & rotor, air filter (improvement #1)
•replaced fuel filter
•seafoam gas treatment, seafoam vacuum line (discovered leak in gasket around header pipes)
•removed intake housing, cleaned the hell out of throttle body/plate
•realized that did nothing, REMOVED throttle body, discovered diamond mine in carbon deposits, cleaned thoroughly including all those tiny little vacuum tentacles
•whatever that thing is called (is it just the intake?) that the throttle body is attached to, well I sprayed the HELL out of it and soaked a rag too and did my best to clean it out. It looked like a stalactite cavern. Result was a marked increase in throttle response, made my car feel young again.

But still dragging ass on 3000+ RPMs regardless of gear. What is that thing the throttle body attaches to? Should I attempt to remove the cover from it so I can get rid of the rest of all that carbon build up? Is that my problem? Does anyone have any other ideas? PLEASE?

Thanks...

[Bitter]

thats the intake manifold, and if it was that bad then YES it'd be worth it to pull it off and clean it well. you'll need 2 gaskets. one for the manifold to the head and one for the manifold cover to the manifold. i doubt that will cure your problem but it sure would help.

[Havok1997GT]

do you have a check engine light on? is it still only doing it till its harm or does it do it all the time now? did you notice any difference after the Seafoam?

[supra12big]

check timing, any codes, try letting the car run first for 10mins, then take it for a drive, tps maybe?

[6G96GT]

I've had that problem before but a spark plug wire fixed it, then a maf sensor fixed it and then it was a bad intake and air filter. Could be your fuel filter or even fuel pump getting ready to go (not giving enough gas when engine is needing it)

...Check to see if the wires that attatch to then oxy sensor are exposed at all and might be touching each other...in that case they could be shorting and signaling "falsly" to your ecu a bad a/f reading causing an incorrect fuel send. Sometimes it happens on turbo cars with the temp. senging unit too.

[GriffGirl]

There's no CEL. I failed to mention I reset the ECU a while back also, just to see if maybe I could "trick" it into doing things my way. No codes have been thrown throughout all this though.

It does it all the time, less-so when it's warmed up, but consistently at 3k+ RPMs. I talked to a Toyota mechanic last night (the guy who hooked me up with my shiny new strut bar! OW!) and he also suggested the plug wires. I think when I get paid again I will buy new wires and see if that helps any.

Any other suggestions as to what else I should check are MOST appreciated! I want this to be the smooth-running powerhouse that she's capable of becoming!

This post has been edited by GriffGirl: Jan 23, 2008 - 11:08 AM

[Hanyo]

hmm have you changed your fuel filter? one under the air filter box and one in the gas tank?

from how much junk was inside the intake manifold, it could be one of the vacuum lines being clogged up. I recomend pulling off each vaccuum line and spray some carb cleaner (with the straw connection) through each port.

It can also be your catilatic converter is clogged up that can cause the exhaust manifold to leak. But generally almost all exhaust manifolds leak when its cold. When the car heats up and the metal expands it will seal up.

good luck with that and let us know if anything changes.

[GriffGirl]

I had no idea there was a fuel filter in the gas tank. Where the hell is it and how do I get to it? And why haven't I ever heard of it before!? But yes, I did change the one under the hood. (Boy that sucked. The bottom nut was really really tight.)

I'll try the thing with the vacuum lines, it certainly can't hurt. I did spray the ports that are on the throttle body though, I even discovered that if not careful, you can actually shoot that tiny straw INTO your intake manifold. Luckily I have small hands, a small flashlight, long needle nose pliers and a bit of luck.

As for the cat, I didn't even think of that. It too could cause my car to run pretty crappy, couldn't it? Is that something I can have a muffler shop do a back-pressure test for? I know a very good shop nearby who might be willing to do that. Is it worth checking into?

[Bitter]

no, the intake gunk is carbon condensation from the EGR system. it really ****ing gunks intakes up something nasty too. as the hot gases cool the carbon literally condenses and builds up like frost on a cold window.

[Havok1997GT]

Normally if your Cat is clogging like that its because the Catalyst has cracked and broken off in the Cat. If you've ever had a bad Cat, it will sound like something is rattling around in your exost pipe. and you'll hear it just with the little shaking you do when you get into the car. Best way to tell is get on the ground near the Cat and shake the car if you hear rattling id put my money on a bad Cat.

Follow the Spark idea first. and one of the best ways to do this is take the car to someone who has one of those computers they use to check what kind of engine code your pulling when you have a Check Engine Light. Ask them to see if you misfiring. If you are that would be your best bet to your problem. After that its a matter of finding out what's causing the misfire, Spark Plugs, wires, cap,rotor, and so on. Most of these are cheap fixes until you get to distributor and that's when things get up in price. Word of advice, with distributors, should that be the problem, spend the extra money and get it from the Dealer. Most part stores only deal in rebuilt parts. Took me 3 distributors to figure out they all where bad because of that reason.

if your not misfiring, i really don't know how much you need to worry about the vacuum leaks or clogs. I just spent 4 months working on my cars EGR system and i had a engine light on, so if you don't have a engine light on i wouldn't go vacuum problem because if you did have one it would seem to me that you'd also have a Engine light on. normally when you have leaks in the Manifold or a clog you'll get a check engine light because one of the sensors would pick up a problem, or at least that's my experience. but a leak might get past the sensors too, so have a vacuum test done and that should eliminate that.

After that. check exiting Exost. see if you have any leaks in the Exost manifold, see if the Gasket is good, make sure you don't hear any rattling in the Cat,

little thing that you might want to check is make sure the Timing is right,

that's what i would do.

This post has been edited by Havok1997GT: Jan 24, 2008 - 8:57 PM

[Hanyo]

I had no idea there was a fuel filter in the gas tank. Where the hell is it and how do I get to it? And why haven't I ever heard of it before!? But yes, I did change the one under the hood. (Boy that sucked. The bottom nut was really really tight.)

The intank gas filter is that little white baggy in this picture:

its located under the rear seats. To replace it, you take the rear seats out and remove a couple of bolts and screws, unplug one or two wires and easy the fuel pump out of the gas tank. Its not hard to do, but remember to keep touching the metal car body to ground yourself and prevent static electricity.

If you've ever had a bad Cat, it will sound like something is rattling around in your exost pipe. and you'll hear it just with the little shaking you do when you get into the car.

generally the rattling is correct way to see if the cat is bad. But I've experience cats that are not fully clogged/broken.

But I do recomend changing your spark plug wires, it by far is the cheapest solution. If that does not help, my second guess would be the distributor. (i'm assuming your engine runs fine at idle and cruising).

Hmm... what did your old spark plugs look like? Was it black? Worn electrode? ect...

[GriffGirl]

No rattling around the cat, I've actually banged around under there before. I even had the exhaust looked at like 2 days after I got the car in July because of a thumping sound... it's suspension related. Exhaust looked great.

No CEL, plus it's a 94 so it's OBD 1 which means DIY paper clip and a printout of CEL codes

Plug wires look fine, that's why I didn't replace them when I did the cap/rotor/plugs. No burn marks, actually they looked brand new. I do know they were put on in May, before I bought the car. At the time of purchase they had approximately 5k miles on them, so to date they have approx. 15k on them. But the plugs were done at the same time, and replacing them helped although didn't solve it. Wires will be replaced w/next paycheck, on the 5th. This chick is BROKE A$$ and has just enough to get into the car show this weekend!

As for the exhaust manifold, yeah, it's leaky, although I haven't looked to see if it's leaky when the engine is warmed up fully. Will check that hopefully this weekend if it's not raining/snowing/freezing-crap-falling-from-the-sky-ing.

Regardless of what the solution winds up being, I'm still going to try to take the intake manifold apart to clean the cavern out. I can't stand knowing all that build up is there. It's already a 7A engine, it needs all the help it can get!

This post has been edited by GriffGirl: Jan 25, 2008 - 11:52 AM

[st18]

hey sounds like my car check the motor mounts see if their busted or have some one who can tell look if u cant like a toyota dealership give that a try might work looks like you are going to have a pretty long check list sorry man

[GriffGirl]

Saturday should bring new spark plug wires, that'll help narrow it down some

[GriffGirl]

tiny update:
NGK WIRES FTW!!!

seems that was the last bit it needed, I replaced the wires and now she runs smooth like polyunsaturated butter product.

[thespacepanda]

tiny update:
NGK WIRES FTW!!!

seems that was the last bit it needed, I replaced the wires and now she runs smooth like polyunsaturated butter product.

Have I told you recently that I love you?

[GriffGirl]

oh, panda, *whistful sigh*