2003 Nissan Sentra Se-r Spec v surging

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deadlightsoul@gmail.com - 16 Aug 2007 20:56 GMT

Hi All, I am currently a student at WyoTech, and during my last
class(fuel management systems) i clean the throttle body on my car.
After I did that, i found a surging problem when coasting to a stop (6-
spd manual). I have followed the diagonostioc tree that Alldata, and
Shop Key respectively have given me, i refuse to condemmn my ECM till
i have done everything under the sun. I have used a Modis in global
and specific mode, i have looked at freeze frame data, live data
strems, i have check the voltage and resistance of the MAF, the TPS,
and the ect, all were within in manu specs. The maf cofused me though,
from the ecm i was getting a voltage reading on 1.4 (spec is 1.1-1.5v
at idle), but on a dvom it was reading 2.8-3.1v. I have checked and
re-checked the grounds for the ecm, tps, ect, and maf, i do have
aftermarket intake, but the car was running fine before the throttle
body cleaning. If anyone can give me any more ideas, please, i am
trying hard to understand this. I have been tearing my hair out.
Thank you for taking the time to read this. PS the surging happens
comin off the freeway, in town when the car is warmed up.

Chad

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Scott Dorsey - 17 Aug 2007 14:44 GMT

>Hi All, I am currently a student at WyoTech, and during my last
>class(fuel management systems) i clean the throttle body on my car.
[quoted text clipped - 13 lines]
>Thank you for taking the time to read this. PS the surging happens
>comin off the freeway, in town when the car is warmed up.

If you move the throttle by hand, does it move smoothly and cleanly or
does it stick or hang up near the lower end of travel? If it's sticking
open a little, you'll see this problem.

Probably not the MAF, but you can see all kinds of weird MAF issues
on some vehicles which show up when there is flow; the static resistance
is correct but once it's going the reading is not correct. The mechanical
ones are much more prone to trouble than the hot wire types, but are
easier to check.

My guess is that your butterfly isn't quite clean enough, or you need a
little lubricant on the thing, because it's not moving freely.
--scott

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"C'est un Nagra. C'est suisse, et tres, tres precis."

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Mike - 17 Aug 2007 18:11 GMT

> Hi All, I am currently a student at WyoTech, and during my last
> class(fuel management systems) i clean the throttle body on my car.
[quoted text clipped - 15 lines]
>
> Chad

Disconnect the battery for a few minutes, this will clear the IAC memory
in the ECM.

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