I just recently rewired my engine harness, everything seems fine, it idles smooth as can be, and runs great. There is one problem though.
Under slow acceleration the car seems to "pulse"....

When looking at the Power Commander it looks as if the Injector Duty drops about 2% then regains, then drops again, and so on...

Any idea what this could be from?

 

clogged injectors or fuel filter?? just a guess

 

is your power FC set to read off the o2 sensor or the maps? If you set it to read from the o2 sensor and the sensor is old or dirty, you will get the pulsations you speak of.

 

^ Homie may be right. Read this: https://www.rx7club.com/showthread.p...hreadid=312851

You can just turn the O2 feedback "off"...No more surging.

 

yes you need a new o2 sensor

 

Where's the cheapest place to buy a replacement o2 sensor with the right wire harness?

 

Bosch Universal - clip the old O2 sensor wire, then crimp the new one in using the old connector. $20

I don't even think you need the original sensor. My O2 sensor connector got damaged, so I removed it and replaced it with a basic crimp-on blade connector. Works fine so far. As long as the wire is the same size/length, it's all good.

 

ok guys... how bout this... it is a new O2 sensor...

Im trying to get some datalog of it doing it....

 

try switching off the o2 sensor on the PFC and see if it goes away

 

Ok then have the injectors cleaned and flow checked. I know you already did that too. OK then its electrical meaning the injectors are not seeing a nice even current. How old is the engine harness? Those injector wires take a beating. I'm guessing this is happening under light throttle only or maybe you already mentioned that. Just about every fd I've owned has a slight pulse esp with the ac or any of the accessories (sp?) on. One of my cars had a terrible pulse with the headlights on but is currently normal. The o2 sensor was replaced and the injectors were cleaned.

 

Is the downpipe well grounded?

 

Even when you have a good O2 sensor, you might get surging when it goes closed-loop. Changing the fuel map in the "surging" areas may change the propensity to surge.

Turn O2 feedback off if you can't get the surging to go away otherwise and don't mind the downsides. Your mileage might be worse with the O2 feedback off, and you could have other problems (fouled plugs?) if your map is lousy. However, I've run my car with the feedback off for a long time and never had any trouble.

-Max

 

hmmm, i think the o2 might have done it. I turned it off and didn't notice it.... i will try it out in the morning..

And fritz, I take it you haven't seen my "Engine Rewiring" thread, give it a look had some fun with that one...

 

I'm having this trouble too, it only occurs below 3000rpm and only at light throttle. I've played around with the acceleration map but it doesn't seem to help no matter which way i go with it. Also it doesn't surge when cold, only once the water temps get up to normal.

I had Dave at KDR tune it just recently. It runs great at WOT and anywhere above 3000rpm, but it's a pain around town. Any ideas?

Also based on the mods in my sig what should my Accel settings be? I knwo the Accel map is just for fine tunign and I doubt it's what is causing this problem, but based on the rpm and throttle range it's affecting maybe it is?


Another thing, I was running too much premix when I took it to KDR, so I pulled the plugs and cleaned them. Didn't fix it. Could I have clogged my injectors or fuel filter? Also the surging is caused by a rich condition correct?

Thanks for the help,
Cody