r33 idle problems

Discuss the RB20, RB25 and RB26 series engines.
NISSANbred
Posts: 5
Joined: Mon Oct 08, 2007 7:34 am
Car: 1990 240sx se

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so, I bought an s14 with r33 s2 rb25 a little less than a week ago. its had problems idling. it idles good while its cold but not good hot. also its running really rich. and its sluggish/ bogging down until about 5k rpm. Today while tinkering with it i noticed that a map sensor plug is missing.

The map sensor has got 2 receptacles on it, brown on the bottom and whats supposed to be a grey one on the top. the grey one is missing. I havent checked anything as far as bad coils etc. but this plug seems to be key. Just wondering if anyone has any info on it, what exactly does it go to and could it be the cause of my problems. any help is appreciated. thanks yall


platez808
Posts: 87
Joined: Thu May 29, 2008 11:30 pm
Car: 1989 Nissan 240SX

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if youre talking about the thing on the throttle body.. that is the throttle position sensor (tps). it has two plugs as you have stated. from my understanding, not sure if its correct but from what i've read, the brown one is for a motor with manual transmission and the top one is for use only w/ automatic transmission. someone correct me if i'm wrong, but it should run fine with just the bottom one plugged in.

did you check the voltage at the signal wires of the tps and maf? check for vacuum leaks? check the timing?

User avatar
danman04x
Posts: 25
Joined: Sat Oct 25, 2008 1:03 pm
Car: 1992 240sx hatch/RB20 swap..05 Scion tc..01 CBR600 F4I

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Im having the same problems with my rb20..I put an intake manifold on it and now im only pulling about 15in of vacuum and it idles bad when warm..Ive searched for vacuum leaks but cant find any.

Cjmartz2k
Posts: 1845
Joined: Sat May 19, 2007 1:39 pm
Car: Hunting for a '89 GTR now
Location: Okinawa, Japan

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OP, just so you know, you don't have a MAP sensor (for the factory ecu anyways).

NISSANbred
Posts: 5
Joined: Mon Oct 08, 2007 7:34 am
Car: 1990 240sx se

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yea thanks yall. after further research i found that its the tps that i was talking about, and the grey plug is used for autos. i also found that first thing to check is knock sensor, believe its located between cylinder 2 and 3 under the intake mani... correct me if im wrong. im 95% sure this is the problem. ill also check for vacuum leaks and check for a bad coilpack.

platez808
Posts: 87
Joined: Thu May 29, 2008 11:30 pm
Car: 1989 Nissan 240SX

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NISSANbred wrote: i also found that first thing to check is knock sensor, believe its located between cylinder 2 and 3 under the intake mani... correct me if im wrong. im 95% sure this is the problem. ill also check for vacuum leaks and check for a bad coilpack.
there are actually 2 knock sensors.. one for 1-3 and the other for 4-6


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