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

 

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?