dundfaukus

I just changed the plugs on my car with the NGK Laser Platinum plugs exactly 2 weeks ago to fix my hesitant acceleration and semi-bad idle. Car ran perfect until this morning where I noticed, it would idle fine then car would start shaking a bit as if plugs were bad again. Acceleration is a bit hesitant now as well, but it is not always consistant....meaning sometimes care will run fine, with no missing or anything.

Since yesterday(when car ran fine) I have not done anyting with the car except drive to school. Only problems I could point out would be the car was in need of gas, which I filled up this morning and still hesitated(I've always used regular unleaded on the car btw). I added octane booster just in case.

Another thing I noticed the oil light came on now and then, it is about time for an oil change anyways. But I dont know if oil has anything to do with car hesitating like that.

All my hoses and intake lines seem in tact just fine. I don't want to have to buy another set of plugs, because at 6 bucks a pop, it aint cheap for a college student.

Pianoman72

Did you replace your distributor cap and rotor when you changed the plugs? Go ahead and do that if you haven't because you don't have to take anything apart to do that job.

Otherwise it is probably your plug wires or moisture in the cylinders - especially if it runs fine and then starts hesitating/missing once the engine warms up a bit.

Check your oil level - if the yellow oil light is on you need to add oil right away. I think you can add up to two quarts - I know at least one.

Let us know what you find out.

dundfaukus

Yeah it does it while warmed up, although I dont know how moisture would get in there. I havent washed the engine or anything(learned my lesson with that already).

I put about 1/2qt of oil and the light went away.

turbogs300

More than likely it's the plug wires, however, replacing cap and rotor can't hurt as everything usually is replaced at the same time. You may also need to clean your throttlebody

Kstyle55

I agree with turbogschange the cap, rotor and the plug wires. and if that doesn't work check your fuel filter it doesn't hurt to check everything

dundfaukus

My cap and rotor were both old and needed replacement, so I replaced both of them. I also changed my oil today. When I fired up the car, it idled perfect, then after few minutes it began to bog again. The way it is acting it almost seems like the air intake system(which the filter is brand new), maybe something with AFM? Because it'll fix the idle for a little bit, then start bogging again!

I am going to check the fuel filter I guess, where is the location of that btw?

wannasc300

fuel filter is a pain in the ***, although not as bad as a mazda RX7 (FD). its on the drivers side, either right in front or right behind the rear tire. I cant remember now. theres a metal pan you have to remove to get to it. get ready to lose some fuel too!

turbogs300

Did you replace the plug wires as well, it sounds like you're getting close. Replacing the fuel filter is not that bad, as stated have something to catch the exess fuel that will flow out. I would recomend using teflon tape on the threaded connections as mine leaked until I did.

dundfaukus

I also changed the PCV valve, in case that was leaking vaccuum or clogged. That did not fix the problem, my wires are only about a year old and I checked in the dark for them arcing and did not see any such thing.

For some reason I still suspect something wrong with intake system, maybe a leak that I missed. Fuel never has given me a problem before, I usually clean my lines with Chemtool about ever 3k miles. Maybe the cold/low gas caused some condensation in the lines so I also added some water remover just in case. Car still idles rough, it is the kind of idle that may suit a older honda coupe, but not a lexus...I want the idle to be back where it was like..."umm is my car on?".


Also could the TPS by a culprite too? I dunno if they just go bad though.

Pianoman72

Check your heater valve - look and see if it looks like coolant has been dripping from there.

dundfaukus

Heater valve, where is that one located?

BTW thanks for the help/advice everyone...

Pianoman72

On the right of the master cylinder. Check for any discoloration. Also coolant could have leaked out of the TB when you took it off or sometime afterward. Into the cylinders. That's what happened to me.

Actually a hose running to that heater valve sprayed coolant all over the engine. But there is a coolant line under the TB so yes, even though you didn't wash the engine you still might be in trouble. Hope that's not it, though. I think if it was an intake problem the "check engine" light would come on, though.

I installed the TPS wrong and trust me you know if that is out of whack. The car just revs and revs and revs until you turn it off.

Funny thing is, those coolant lines won't leak until the coolant reaches a certain temp. So they can be hard to trace. I was about where you are and I gave up and took it to a mechanic. I thought it would be fun to work on the GE engine but then everything I do myself I have to turn around and have it done again. lol.

If you want the official Lexus instructions on how to change the spark plugs, PM me your email address - you can check and see if maybe you inadvertantly missed a step that might have made a difference.

dundfaukus

Alrighty, I will check it out.

Sure I'd like to see a copy of the actually instructions on how to change the plugs, danathar@comcast.net .

turbogs300

There are 2 things i would check as I said before, clean the throttlebody and replace the plug wires. The TPS doesn't usually just go bad. Checking for "arcing in the dark" is not a good enough check.
Measuring for resistance is much more reliable.

dundfaukus

I finally got around the check out the wires, the yall had good resistance, less than 25k ohms.

I also cleaned out my TB.

Car still seems to miss and shudder . One thing I did notice is there was little bit of oil on my 6th cylinder spark plug wire. The plug was dry though.

Other than that, I inspected each plug and they all seemed to have normal color, tannish white. Their gapping is fine as well.

I am pretty sure my ignition system is OK. Question is, what is still causing the car to act like this...?