MR2 jerks at low speeds??

[DONTERI]

Can someone help me out, I'm not even sure if I'm putting this in the correct arear. I Just bought a 1991 Mr2 and at low speeds the car has a hard jerk to it. Almost as if you were in first gear and you let off the gas really quick, but even harder then that. It happens in 2nd and even third gear, usually around 2k rpm.

[GQBalla]

taking your foot off the clutch too fast?

[DONTERI]

When it happens the clutch is fully released. Makes the mornig drive into work pretty brutal. To avoid it I have to push in the clutch before it gets to that certain speed.

[BokCh0y]

Had that except same issue but with a 1991 Turbo. Never resolved it.

What was happening to me was it would jerk at low revs - 2-3k but once it got higher like 3500+ then it would be alright. Also no power and acceleration either yes? After mine warmed up it went away.

Tried this too:

Replaced with OEM Genuine Toyota parts as well.

Plugs
Wires
Dist. Cap
Rotor

My guess is either it was a vauum leak of some sort, O2 sensor or timing belt as it was at 98000kms. Car also burned really lean.

You can try replacing the stuff I have listed above along with O2 sensor and maybe have the timing checked....but I heard its common and usually resolved by doing the stuff above. Just ensure you are replacing with OEM Toyota Stuff straight from the dealership.

Goodluck.

[DONTERI]

Thanks for the tips, I will try that this weekend. Mine does go away for the most part at higher speeds but it remains even when it's warmed up. I've never experienced anything like it. It's a pretty violent jerk. No coffee for me on the drive in.

[BokCh0y]

Yeah i know waht you mean, mine used to hesitate so bad it was like i got rear ended.

[teggypimp95]

Replacing;

Plugs
Wires
Dist. Cap
Rotor

Would be a good place to start. You may not be getting very good spark at lower rpms, but it seems fine at higher. Also checking your air filter and putting in some fuel injector cleaning would not hurt also.

[Annoyingrob]

Had the TPS been adjusted at all? If anyone touched it, I would suspect it. It's a VERY delicate calibration. If it's off, it'll run like you described. I would check the calibration on the TPS too.

[DONTERI]

Thanks for all the help guys, I unfortunately haven't had a chance to do anything yet. I'm not sure if the timing belt had been done or not. I think the poor car wasn't looked after at all by the previous owner. Hopefully I can bring her back to life. I have to make time this weekend to get this done as it's to the point where I hate driving it.

[stevo 27]

Originally posted by Annoyingrob
Had the TPS been adjusted at all? If anyone touched it, I would suspect it. It's a VERY delicate calibration. If it's off, it'll run like you described. I would check the calibration on the TPS too.

my tps was all funky and fucked up quite a bit

does the 5sfe have a MAF or is it map

if it's airflow i would suspect that aswell

check for vac leaks

[ninjak84]

Yes ... Toyota MR2 drivers ARE jerks at low speeds.
haha jk

My guess is your problem is (1)vac leak or (2)throttle position sensor.
The way you describe it sounds universal to the throttle position sensor. But when you consider the car and symptoms, I'd guess vacuum leak first. A friend had similar problems and it was an air leak. Easy fix depending on where it is ...

Definitely don't go replacing any of the things teggypimp95 suggested. Why the hell would you replace your air filter? It certainly isn't an electrical problem. BokCh0y already said he tried replacing all those parts, and they didn't solve his issues ... Its either an air or fuel delivery problem.

[DONTERI]

Any ideas on how I would track that down. I know the basics about working on cars, tune ups, brakes, that kind of stuff, but beyond that I could be in trouble. I'm sure I can figure it out with a little giudance but I hat et otake it to the shop and get raped. Especially if what your saying to do is pretty simple.

[Supa Dexta]

I get a violent jerk in my daily driver, if I fuel up too much, this car doesn't like you to round up to the next dollar after the pump shuts off.. Non turbo here, if thats any help...

[misterrick]

i had this problem recently, but it turns out my fuel gauge wasnt right anymore. filled it up and it was fine lmao. damn walbro pumps...

does your car have a "limp" mode when a sensor is unplugged or fukt? if the jerking is bothering you that much just unplug something. my former engine in my car jerked at low speeds for months until i unplugged the water temp sensor. temp fix but at least its easier on the temper.

[Annoyingrob]

Originally posted by misterrick
damn walbro pumps...

Offtopic:
I hear this a lot. Walbros just don't seem to like low tanks.

Makes me wonder why people keep buying them

[Berg9987]

I had a similar problem in my MR2 not too long ago. I did a coolant flush and it went away. After reading up on it a bit it looks like I had air in my coolant system that would pass the temperature sensor to the ECU. This apparently caused the ECU to have trouble dertermining whether the car is at normal operating temperature or if it still needs to run in warmup mode. Once the revs were high enough the waterpump was throwing enough coolant past the sensor that it got a good enough reading to run properly. The other symptom that the car showed with this problem was an unsteady idle. Just something to think about...

Cheers,
Berg

[mr2mike]

Originally posted by teggypimp95
Replacing;

Plugs
Wires
Dist. Cap
Rotor

Would be a good place to start. You may not be getting very good spark at lower rpms, but it seems fine at higher. Also checking your air filter and putting in some fuel injector cleaning would not hurt also.

+1

Also what's been done to the car? Is it stock? What boost? piggyback systems like an AFC, etc?

Have you ever compression tested the engine?

[DONTERI]

Nothing done to the car. He is stock N/A, so no boost unfortunately. =0(
I had the rad replaced as it was leaking and it was happening before and still doing it now so I don't think that's it. I think it may be the vac leak as someone suggested but I'm still hoping to hear how to check that. I replaced the plugs wires etc and unfortunately no change. I didn't think it would but it needed to be done anyways. I guess it could be the timing as well but again, not sure how I would go about checking that. Any info on how to check either of these things would be great.

[mr2mike]

Sounds like you need this:

http://www.mr2-tech.com/

Those symptoms on a n/a is a little different than a turbo. I would suspect a boost leak now. I thought it was a turbo so I assumed you needed ignition components.

[03ozwhip]

i had this problem. changed all of the tune up parts, mostly OEM some NGK and it totally stopped it. and has run like a dream ever since.