well i just noticed this tonight, after i drove my 25 mile drive home and parked in my driveway, I noticed that my rpm would float between 1000 and 700 very slowly.

so i got out and stood behind my car and listed to the exaust (its stock) and id hear the rpms slowly go down to about 700ish rpm , sputtering missfire, then jump back up to 1000ish, sit for a second or 2 then slowly fall sputtering missfire, then repeat.


when i got the car i changed the cap, plugs, wires, rotor button, cleaned out the intake manifold, and throttle body.

ill check the plugs in the morning.

it also surges up and down the rpm range if i hold the gas steady, does the same thing falls very slowly then goes back up.

btw this is a 7afe with 189,000 miles on it

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vac leak in the brake booster, shine a light into the plug wells, see if any of the spark plugs are wet. (oil leak)

plugs are dry

did the tube seals

pulled all 4 plugs, they gave me the impression the engine is running lean.

cleaned em and reset the ecu, surge gone

drove around for a bit, still lean

timing is 2 degrees advanced


i think something may be amiss

only parts left to check or replace are..

fuel pressure regulator
injectors
o2 sensors
egr, i had this mess up on one of my celicas, made it run lean

may go to the junkyard later on and grab all said parts and see if there is any differnce, untill then anyone got any ideas

about the brake booster vac leak, ive had that happens it makes a odd but distinct sound so thats not it

check your distributor position too.

reset your ecu air/fuel mix, there is a good write up on the how to section, hope this helps

why is your timing advanced.... 7a-fe shouldn't be adjusted

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why did you post a reply, your reply was neither helpful or useful

to everyone else, thank you

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A/F is going to be off if your firing is advanced beyond Zero degrees, without the proper A/F ratio to begin with of course your going to be running lean, also causing lean missfires when there is too little fuel in the mix that relate to what is known as floating rpm. if the ecu is similar to the 5s, the ecu controls timing (aside from cam gears, or the cams being set wrong to begin with)

look at your fuel system as well. Filter is most probable

if your EGR was a miss your car would smell HORRIBLE, almost intoxicating.

Fuel economy bad?

This post has been edited by Mstoochn: Nov 7, 2009 - 6:05 PM

ive changed the fuel filter

the last 2 things ill check is the mechanical timing (cam gear in relation to the crank at tdc) and the fuel pump sock filter\


my fuel economy isnt bad imo im getting 32mpg mixed driving

ill try the a/f reset as well as put the timing back to stock