6G Celicas Forums

Hey guys,

For the last few months my car has been jerking ALOT when going on or off the throttle. Its a 97 ZR(GT) 5sfe manual. Its not the normal manual tranny shake when you let off, its very violent and all my passengers comment which kills me a little bit every time. So far i've replaced the:
* spark plugs
* dizzy
* cleaned the TB and IACV valve
* new air filter
* cleaned all moving mechanisms with the throttle cable and pedal assembly to ensure no sticking

However the jerking lives on

The only other things i could think of are the spark plug wires and the TPS sensor.
I borrowed an ohmetre and did some testing of the TPS. In the fully closed position the reading is 0.4 and the allowable range is (0.2 - 5.7). When fully open the reading is 2.6 and the range is (2 - 10.2). Theres another test that is two diff pins that reads 3.4 and the range is(2.5 - 5.9). Do the first two seem a little low? Yes they are in the allowable range but almost every other electrical connection i have tried has been smack bang in the middle of the range.
I also did a continuity test of the TPS sensor. When the distance between the throttle stop screw(most commonly knows as the idle adjust screw) and the plate is 0.5mm there should be continuity and when 0.7mm or greater there should be no continuity. Now when i have it at 0.5mm (using a feeler gauge) the ohmetre reads OL and the same thing when at 0.7mm. Does this null continuity result mean the TPS sensor is bad? And could that possibly be whats causing the jerking? If not what do you think could be causing it?

Quick one at the end, what should the idle be on a 5sfe manual? The BGB says that all 5sfe no matter what year or tranny ahould be at 700, however the BGB i have is for a 98 OBDII car and mine is a OBDI. I have also read that the manual idle should be up around 800-850. Mine is currently at 700 but there is alot of vibration and i have only recently replaced the front and rear with non-polyurethane engine mounts. Should i raise it up to 800 using the screw or leave it at the 700?

Thanks alot guys!

Reece

have you checked the front and rear engine mounts?

First off, tell your car to stop jerking before it goes blind .....

Check engine mounts, fuel injectors, fuel pressure regulator, MAP sensor ....

Yep changed the front and rear mounts for oem replacements. Will have a look at the other three suggestions!

The FPR and injectors are good, dont have a vacuum pump to test the response of the MAP sensor but all pins are reading the correct values. I forgot to put in the list above that i've replaced fuel filter and clutch as well trying to solve it.

Anyone have any other ideas? I'm getting desperate and don't want to take it so a mechanic and hand over my life savings

It's got to be drive train related.... how old are your CV shafts?

What I'm wondering is if the joints are going bad and separating a bit, so as you accelerate, they jostle. Jack it up and rotate the tire, see if the tire moves a bit before the shaft does (rotate both directions quickly too and feel for any clunking)

Also, on that rattle at idle, did you change the motor mount on the belt side of the engine? That one is what lessens engine bounce/vibration.

This post has been edited by RabidTRD: Sep 7, 2012 - 8:46 PM

Ive only owned the car for 1.5 years and never changed them so i can only assume that they are the same age as the car so about 15 years.
I didn't change that mount only the front and rear.

I'll give both of those a look at and report back.
Thanks!

Checked the mount, the rubber almost looks brand new so doubt its that. When checking the CV shafts i did it in neutral then in gear.
When in neutral the side i was spinning turned instantly all the way back to the tranny this was the same for both sides.
When in first the same thing occured with the CV's. However i thought that the other wheel should begin to spin immediately too. Through crude measurements i found that i had to move 1 wheel about 6-9 degrees before the other wheel would begin to spin. Is this normal?

I checked for codes about a week ago and came up with nothing and today i checked and unfortunately came up with code 31(OBDI) which from this website:
http://www.troublecodes.net/Toyota/
states that its my MAP sensor. As mentioned earlier i checked my MAP sensor a few days ago and all pins read correct voltages and the same again today. I can't test the vacuum response as i dont have a vacuum pump. I'm fearing that it could be on the ECU side of things which would REALLY suck.

Reset the code and went for a small drive and it didnt come back. Should it come back immediately or will it come back in time?

Usually it takes some time.

Ok ill keep looking at it. What about the wheel spinning? When i turn the front left the front right will not turn till the front left has travelled about 6-9 degrees. Could this cause jerking or is that normal?

That's normal.

If you got a code 31 your MAP sensor is probably bad, even though it tested good.
Jump TE2 [yes 2, not 1] and E1 in your DIAG box and go for a drive, see what pops up.

Thanks for the replys guys. Unfortunately bigger problems have resurfaced, my clutch took a dump on me a while ago racing so i had it replaced with a new exedy heavy duty sports clutch, as my transmission was grinding horribly they also rebuilt it for me. Before the clutch was replaced i could hear a grinding noise on deceleration which i thought was the gearbox. After it was replaced and the transmission rebuilt i could still hear the noise very faintly and was told that it was gear whine since a previous owner has prob used auto trans fluid which will cause that noise(never believed that but what the hell the grinding was gone and shifting was super smooth). Since then i have not been to the track in the celica so no horrific loads have been put on it. But this horrible grinding noise has reappeared on deceleration. I took it back and they said something is causing the transmission to vibrate and the gears are rattling which is causing the noise im hearing(not there initial gear whine bs story). They took the transmission back out and said that its fine and that the clutch is causing the noise. When they removed the first clutch the centre had seized and expanded which caused the noise. He then told me that the same thing has happened and the springs have stretched too. So i said it cant be the clutch just dying for no reason what could be causing it? He said something along these lines i think and this is what i need clarification on:
Our cars aparently have some sort of valve so if we pull our foot all the way off the accelerator suddenly it wont just close the throttle body butterfly valve and cut injectors immediately. He is saying that this was malfunctioning which was causing the clutch to go bad. I asked if he could fix it and he said he couldnt work out why it wasnt working properly and to fix it would be too expensive. I have the BGB and have done ALOT of reading trying to find this valve but the only thing i can think of the IACV which is working correctly. Can anyone tell me if such a valve exists and point me in the right direction on how to find it and possibly fix it.
I should add the guys doing it are a friends parents but even having people do it that i have known for a long time i still feel like i being screwed

Thanks guys

Sounds like he's blowing smoke up your ass to me. Ive never heard of a blowoff valve for a naturally aspirated engine.

I dont think it was a blow off valve he was referring to, doesnt a blow off valve just release the pressure once the butterfly valve has closed in a FI system to prevent the air going back through the turbo/SC?

it could be your motormounts. if the passenger side mount is loose or broken it will shake alot it could be any of the mounts though. If its your mounts, its very possible the last time they were messed with the bolts may have not been tightend all the way, if they werent they could have broken off and youll have to tap the broken bolts out of the motor. If they are loose and they arent broken well then all you need to do is tightten them! Another common problem that will cause your car to jerk or shake violently is your clutch. if you clutch is getting old you can get something called clutch chatter. If it is clutch chatter you could either accelerate more carefully or replace your clutch. i would suggest replacing your clutch.

I had terrible clutch chatter before I had my cluth, slave, fly, replaced. BUT I would not have chatter if I started off in 2nd gear. for some reason it didn't do it(only do that test on level ground). Also if I revved engine extra high and let it out in 1st I could avoid it. It was worse on hot Cali days.

why do you use a super heavy duty clutch?

I track the car, so i figured i would upgrade it a little to make sure it lasts through that and DD too. It feels the same as stock when taking off just a slightly heavier pedal feel

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it could be your motormounts. if the passenger side mount is loose or broken it will shake alot it could be any of the mounts though. If its your mounts, its very possible the last time they were messed with the bolts may have not been tightend all the way, if they werent they could have broken off and youll have to tap the broken bolts out of the motor. If they are loose and they arent broken well then all you need to do is tightten them! Another common problem that will cause your car to jerk or shake violently is your clutch. if you clutch is getting old you can get something called clutch chatter. If it is clutch chatter you could either accelerate more carefully or replace your clutch. i would suggest replacing your clutch.
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The clutch is only 4 months old. It does have 2 track days on it though but both have been wet so no where near as hard on it as in the dry.