Bucking, kicking, and screaming... Well sputtering...

[jerd_hambone]

So my car has a really odd problem. At completely random points in time, you will be driving and all of a sudden it starts bucking and kicking like you are tapping the gas really fast. It does it in every gear. If you try to floor it, it just falls on it's face and it is pretty much like you let off the gas completely.

I don't know what to do about this, and I can't figure it out.

Oh, in case you were wondering it's a 89 GTU.

[Phoenix7]

and you've checked the TPS? All within specs?

[dudemaaan]

how modified is the car? My car does it sometimes too, i have minimized it by tuning, but it still exists. I read an article explaining that the design of the rotary allows exhaust gases to mix with the fresh mixture in certain situations and it causes a misfire and results in the bucking. The technical name is 3:3 ignition mis-fire. here's a link to the pdf.
http://foxed.ca/rx7manual/manuals/REbyKenichiYamamoto-1981.pdf

[jerd_hambone]

I forgot to add that the only way to stop it is to let the car set for 24+ hours and when you restart the car the next day to rev the holy mother out of it and it clears up.


I've not checked the TPS, I may have to do that.

[JL1RX7]

Check all of your grounds. I know if they are bad or corroded that can lead the car to do some weird stuff.

[nvno1]

I forgot to add that the only way to stop it is to let the car set for 24+ hours and when you restart the car the next day to rev the holy mother out of it and it clears up.


I've not checked the TPS, I may have to do that.

Yeh the TPS will trip like that. Also have to changed the brand of gas you normally use.? I used some cheap gas one time and that was the last time that motor ran. not trying to scare you.

[jerd_hambone]

I always use good gas, premium.

I've been thinking that it's the TPS, but figured I'd try to see what everyone else thought.

And it's not the typical bad ground bucking.

[JL1RX7]

With NA you can use cheap stuff. 87 octane works just fine. Also did you check you battery cables and spark plug wires?

[jerd_hambone]

Battery is getting juice, volts don't drop when it does it. The spark plug wires are about to get changed.

I used higher octane and the felt more peppy a tad and got better mileage. So I dunno.

[NoDOHC]

My '91 likes premium more than regular.
My old '86 never cared at all, with the 8.2:1 rotors it really doesn't car now.

On the original topic: I had my '86 buck and shake once, but it was because I had the leading and trailing plugs connected backwards. Obviously, that doesn't come and go.

I am guessing that you have a bad connection or a fueling issue (loose sock or something).

This is an interresting problem, keep us posted.

[jerd_hambone]

I will definitely keep it updated.

Today, the car wouldn't even stay running, it would just sputter and stall.

So I don't know haha

[TehMonkay]

When you say it clears up the next day when you rev the piss out of it, it sounds like there may be way too much fuel. Have the injectors been cleaned?

[NoDOHC]

Tehmonkey, Leaking injectors is the best theory I have heard yet. Dirt in the fuel system may do this too.

[Whizbang]

reminds me of how my FB is acting only it will start and run just dandy. Just hates "driving"

[jerd_hambone]

It may be flooding, it does run rather rich, but it only does it sometimes, and it has no problems hot or cold starting.

Just has alot of problems driving at completely random points in time

[Whizbang]

stupid question, but have you looked for any loose wiring?

[jerd_hambone]

Not extensively, I've checked a few grounds and plugs, but not really searched.

I don't believe it's for the fuel pump, we changed the pump a while back and made sure everything was hooked up good.



Also have a question about an 87 NA and figured I'd post it in here so I don't clutter up the forum.

I got an offer to trade my Isuzu pickup to an 87 GXL and the guy said the intake actuator and vacuum check bulb need replaced.

As far as I can remember I've never heard of either needing replaced, could be wrong though.

Guy said it idles smooth, but won't rev, just sort of sputters. Car has 114k on the clock and has been doctor owned.

I'm going to check it out, but was wondering if you guys thought it might be worth it, because it's a pretty good drive.

[JL1RX7]

for the 87 that might be just a bad ground! I have never heard of those on a rx7. They really are simple machines when it comes to whats on them.

[jerd_hambone]

I never heard of it either, but I'm not taking it.

The car is pretty busted up, inside and out.

[Rx-7fetish]

Had same symptoms then one day car died and would not start. Turns out sock fell off of the fuel pump and the pump and filter clogged up. Replaced both and ran like a champ

[jerd_hambone]

I'll check into it tomorrow for sure, as soon as I get an exhaust put on my truck.

The guy I got my truck off of decided to cut the cat and muffler off the truck, and never out a muffler back on.

[nvno1]

I don't believe it's for the fuel pump, we changed the pump a while back and made sure everything was hooked up good..

Was the fuel pump OEM or from like autozone? Is it flooding/flooded now that it wont start? I buy napa parts as i bought a fuel pump from autozone and it failed like 3wks later and had similiar symptoms to what your having now.

[jerd_hambone]

Fuel pump is still going strong, its not flooding badly, but there is a slight smell of gas.

May be because of the O2 sensor.

[NoDOHC]

The O2 sensor is only used at steady-state cruise. Not when starting.

[jerd_hambone]

Hmm then it is running rich, not too bad, but a bit

[Phoenix7]

Still waiting to hear about the TPS...did you ever get around to testing it/ looking for loose or broken harness, exposed wires.

[jerd_hambone]

The car has been running fine, and I'm in the process of doing body work and painting, so I've not even checked it out

[Phoenix7]

wonder what it was.

[NoDOHC]

I just thought of something, could it be that he had a OMP Fault and it was going into limp mode?

[jerd_hambone]

I don't think it's going into limp mode. It keeps very good oil pressure, and all the OMP lines are fine.

I really think it's either the TPS or the fuel pump. I don't think it's the injectors because it doesn't flood out. It has zero problems hot or cold starting.

It only starts this problem every now and then. You will be driving, it starts to buck and sputter, then after you let it sit a few hours, you get in, try to rev and it sputters, then keep trying to rev and BLAM, problems gone.

Doesn't come back for a week or two.

Completely stumped here.

[Phoenix7]

bad or loose harness? I hate things like this.

[jerd_hambone]

Me too, there are a million things it could be, and I just can't even think where to start....

[NoDOHC]

Does the check engine light work? Does it come on when it is bucking and sputtering?
Oil pressure has little to do with the OMP and flooring it would cause it to move to a different point on the feedback potentiometer.

Flooring the car would not be likely to clear a fuel pump problem, letting the car sit would seem to make more difference there.

[jerd_hambone]

You have to let it sit for anywhere from a few hours to 24 hours. You get back in the car, turn it on, it will idle fine but any time you try to give it gas it will sputter.

You take it to redline, and let it idle, then take it back to redline, it usually clears up.


Check engine light stays on because my O2 sensor is unplugged.

[NoDOHC]

What was wrong?

[jerd_hambone]

No clue, I cleaned up the battery terminals and made sure they were connecting good, hasn't done it since.