2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Limp mode when shifting into any gear.

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Old May 30, 2010 | 10:23 AM
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From: Fredericksburg VA
Limp mode when shifting into any gear.

88 rx7 T2 S5 Engine an Trans swap.

So got the Water pump an T stat done yesterday. Went out for a Quick drive to day.
Runing great. I Broke her a little sideways in 2nd. Every thing seemed fine Drove her back home. Parked her.
When to Start her up an go to the Gas station. And Shes acting funny.

In neutral She is fine. Revs up hits a little boost, no misfire.. Dosent matter weather clutch is depressed or not.
Shift into any gear. RPM die down. Wont go above 2k Missfire and surging. Sound like some kinda limp mode.

Anyone ever experienced this?

Last edited by Reddraco; May 30, 2010 at 10:24 AM. Reason: Spelling
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Old May 30, 2010 | 10:53 AM
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Update, Jacked up the car an unpluged a sensor and its Fine.
Its the sensor thats More towards the end of the Trans were the U joint is connected.
Guess I gota figure out What that sensor is an replace it..

Black Top. Red bottem.

Last edited by Reddraco; May 30, 2010 at 10:54 AM. Reason: So can remember were wires go.
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Old May 30, 2010 | 11:05 AM
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That would be your 5th gear/reverse switch
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Old May 30, 2010 | 12:17 PM
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Cool thanks.
BTW what happens if you leave it unplugged an drive? Got a car show to enter in tomorrow.. lol
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Old Jun 10, 2010 | 09:31 PM
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Nothing will happen if you leave it unplugged besides not having reverse lights and the air pump not turning on in 5th gear...

Have you pulled the codes? A transmission switch would not cause the engine to mis-fire and not go past 1500 RPM.... See what the ECU is telling you (or isn't) and we will go from there...

By the way, how well does it idle in neutral? What you think may be normal may not be.... I will see if we can get this thread moved to the main 2nd gen section for more help...
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Old Jun 10, 2010 | 09:44 PM
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Havent Pulled codes yet. Dont know how to yet on a JDM LOL.
Runs great in Neutral. No misfire what so ever.
Idles Perfect. Revs smooth an powerful. Even builds a little boost..
But the second you shift into any gear, right back down to 1500 and misfire.
Take it out an shes fine again... Also only seems to happen when its Pretty Hot.
Ill have to figure out, and pull some codes...
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Old Jun 11, 2010 | 10:02 AM
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I don't see why pulling the codes would not be the same as in a A-Spec....
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Old Jun 11, 2010 | 11:04 AM
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the main diffrence is gonna be if hes running an s4 ecu or an s5. s5's are easy to obtain codes, and only s5's have an actual "limp mode" and only the OMP can set off limp mode. but you'd know if it was limp mode b/c it wouldnt take effect right away, instead about 4 seconds after the engine is running, limp mode turns on.
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Old Jun 11, 2010 | 12:13 PM
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If the sensor is on the top passenger side of the transmission, near the shifter then it is the neutral switch. If if the one on the drivers side of the transmission then it is the reverse/5th gear switch.

From your symptoms I would guess it's the neutral switch that you have a problem with. If you have a multimeter and want to check it, you should have continuity in neutral but none in any gear. Check it with it while it's unplugged (wire going to the switch).
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Old Jun 11, 2010 | 05:20 PM
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Ok, ill give that a shot. Also when I looked on All Data today. Theres a heat Hazor Sensor under the Passenger seat. That would make sense also. Beings that it has to run to op temp. Then if u KoIo, then KoSo it will run limpish.. Only In gear...

Just Found out that she has an N332 Ecu, witch is S4.
BTW Were is The OMP? I read a Post about doing a water pump then having similar issues.. Maby I Failed at somthing.. lol

Last edited by Reddraco; Jun 11, 2010 at 05:46 PM. Reason: Update
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Old Jun 11, 2010 | 05:54 PM
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Now I just thought about this. How do I have an S5 motor and all S4 Electrics...
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Old Jun 11, 2010 | 08:46 PM
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Originally Posted by Reddraco
Now I just thought about this. How do I have an S5 motor and all S4 Electrics...
They probably used the s5 block and attached all the s4 electronics... Unless whoever did it retro-fitted all the wiring...
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Old Jun 11, 2010 | 09:13 PM
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Originally Posted by jjcobm
They probably used the s5 block and attached all the s4 electronics... Unless whoever did it retro-fitted all the wiring...
Yea you are right. I just got a hold of the Guy who did the swap. Sure enough. S5 Block/trans. S4 Ecu wiring harness and sensors... He also sayed somthing about having to use PreMix because the Ecu dosent know the OMP exists and the S5 omp pump is Inop...

So were do I stand now? Could not using Pre Mix be causing a knock issue? or maby some kida over heating issue?

Also what kinda Premix do you guys RCM? How much per tank?
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Old Jun 12, 2010 | 04:29 PM
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Update: All data TSB on heat soak after siting 15-20 min. Diag Start: Pull Codes, ohm out prety much all sensors....

Brought my VM home. Will do it Sunday.
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Old Jun 14, 2010 | 10:00 PM
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Coolant Temp sensor wiring was shotty. Problem solved.
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Old Jun 15, 2010 | 05:57 PM
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Well, we got the thread moved for you : )

Glad you solved the problem!
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