Sporatically my car will buck back and forth when I am in 2nd or 3rd gear and low rpms (<3000). Feels like I am pumping the clutch pedal. It does this for about 10-20 seconds then is fine. I was thinking my fuel pump is going. It hasn't happened in a week and now it is happening again. I don't know if this is a common problem but it is real annoying.



Things I have done recently...

wires (2weeks)

plugs (month)

Alternator (month)

fuel filter(2 months)

Oh yeah the specs on the car



1990 GTU N/A

Mazda reman motor 10,000 ago

Downpipe, High Flow Cat

Exhaust



Thats pretty much it engine-wise

Oh and I also changed my O2 last month too



Trying to be as complete as I can

oddly. mine does the same thing and i get check engine light. damned if i know what is wrong https://www.nopistons.com/forums/pub...DIR#>/wink.png

No check engine light here.....I put it on the dyno at work today (damn state inspections) and noticed I am running rich at idle but appears to be lean at about 2k in 2nd gear. I don't know what is normal for this car and noone at the shop really knows rotaries.



Have you ever scanned yours vosko??

i tried to run the codes once but wasn't sure what the code was. my car has almost everything new so i dunno what's wrong. i'm just happy as long as my car runs........

Mine kind of does, but no check engine light (it has never come on, thank god! ). I found that it'll do that at low rpms only if my foot is into it, so when it happens I let off the gas a little and it stops. Really the only time it does it is when I'm pulling into my apartment complex, trying not to wake everyone up, or if there is a cop behind me and I'm trying to be quiet.

Thats about the same time mine happens, when I am pulling into the apartment complex, in a development, or driving in a parking lot. The only thing that bothers me is that this just started.

Wonder if it could be dirty injectors or something.

That is another thing I was thinking.....We have this thing at work that works really well to clean injectors and all the fuel system. I wasn't sure if it was safe for rotaries so I call the company. They said as long as I didn't have carbon apex seals I am fine. I am not sure what apex seals I have. I don't think they are carbon but didn't want to chance destroying them. The Motorvac Service Webpage

I'm pretty sure that you don't have carbon apex seals. Unless your engine is built up, but from what you listed earlier it doesn't sound like it. Your engine ported or anything?

No ports or anything. I just wasn't sure what mazda uses to rebuild. And I didn't think it was worth the risk. I called NUCAR mazda where I bought it and they had no idea and noone that they could send me to to find out

First try it with the short range TPS unplugged. If it's better then that's your problem. It could also be that the AFM is a little loose.

my car did the bucking when i was gogin really slow and the rpms where down low like 1g. When i always pulled into me garage or alleys it would do it. But never going above 5 miles per hour. I got an racing beat engine torque brace and it whent away. it feels like drving a bob-cat going really slow.

13bace.....I will try that tommorrow. The only thing it will take awhile to see if it worked cause it doesn't happen all the time. It is sporatic.



I am not sure if I want to run the cleaner through the engine. Don't know if that is good for rotaries or not.



1Revvin.....I am going to get the torque brace anyway. After I pay for the springs, sway bars and links I just bought from them...



Thanks for your help everyone.....My goal is to get it running, driving better then it did in 1990....so hopefully it'll work out

Try the easy things first. You may also want to check the timing too. One time my CAS wasn't tightened well and it was moving while I was driving. :wow:

Sounds like a good way to blow your engine. https://www.nopistons.com/forums/pub...#>/biggrin.png

Sounds like a good way to blow your engine. https://www.nopistons.com/forums/pub...#>/biggrin.png[/quote]

Luckily I didn't go fast, and it wasn't my car.