Red 86 rx-7

My car is a 1986 fc n/a my mods are pd/banjo bolt,No AC pump.The car will only want to rev if you plug off the boost sensor line.I'm talking about the sensor on the right front strut tower.The car will rev fine.If you hook the line back up to the sensor and try to rev the car it stutters and wants to die?I also was getting a o2 sensor code on my led scaner.I replaced the o2 sensor and I'm still getting the code?I tried unhooking negative battary cable and holding down the brake pedal.I'm still getting the o2 code?

HAILERS

The wire to the o2 sensor is probably shorted out somewhere. Probably where you connected the new one to the harness. Put a meter on the input wire at the ECU and see if the sensor is putting out. Or if you want, disconnect the plug at the ECU and check the socket for the o2 wire being shorted to ground.

Good/bad o2 sensors will not effect the reving of the engine under load at all.

Explain stutters and dies when reving with the vac hose connected to the sensor. Is that while driving? At around 3500 to 4000 rpm? Or sitting in the driveway?

HAILERS

Put a vacuum hose on the sensor. Suck on the other end. Does it hold a vacuum?? It should. If not...get another.

Red 86 rx-7

stutters when in driveway and driving at any engine speed.What wire do I test at the ecu?

HAILERS

On a 86, the 02 wire is pin 2D. The middle plug. Bottom row. Counting from the right to the left, it would be the second socket from the right.

While your there, go to pin 2B, and with the engine idling and the connector connected up, see what the voltage is on that pin. That is the output of the pressure sensor. It should read approx 3.5 to 4.0 volts. That's if the vac hose to the sensor is disconnected and plugged with say a small bolt/screw (to prevent vacuum leaks that might effect the idle). Pin 2B is on the middle plug, bottom row. First socket/pin from the right.

So now you know how the plug is read? Count from the right to the left in a up/down fashion. Pin A on top, Pin B below it, next pin over on top is C, the pin below that one is D and on and on from right to left.

HAILERS

And although the 02 sensor should be made to work.....it won't cause a stuttering if disabled.

There is a slight chance someone has put a turbo boost/pressure sensor on that car instead of one for a non-turbo. Small chance. If that were the case, when you do the voltage check for the boost/pressure sensor as described in the post above.....the voltage will read like 2.3 to 2.7 volts instead of the 3.5 to 4.0 volts that it should read. Small chance that might be the case, but a chance.

Describe just where the vacuum hose that is connected to the boost/pressure sensor is coming from. As in the location of the nipple at the other end of the vacuum line. Is the nipple sticking straight out at you or pointing straight up???

HAILERS

Just thinking. The boost/pressure sensor can/will effect timing. I wonder. Was your timing set with a timing light and is the timing set right on the spot, so to speak? Check out the timing with a timing light. Cheap light will do. Expensive light will do also. Either way.

HAILERS

I forgot to mention. On my non turbo, I changed the vacuum lines out. When I went for a drive the darn thing did the stutter thing your talking about. That's when I found out that the original boost/pressure sensor had a *orifice* inserted in it by the factory. I put the old vac hose back on that had the orifice, and walla, ran just fine. I cut the vac line open and took the orifice out and put it in the new line.

Its just a small plastic piece with a small hole drilled thru it. It dampens any surges to the boost/pressure sensor. See if you have one installed. It will be about an inch from the end. Which end??? It should be the end near the intake manifold. Cheap part. Maybe two bucks maximum from the dealer. This sounds like its your problem.

Red 86 rx-7

I have to tear the uim apart again to install new injectors.I plan on replacing all the vac lines.The orfice is in the line I checked.I have two boost sensors 1 from my 87 parts car and 1 from the 86 they both hold vaccume.I drove the car to work today it ran ok with the vac line to the boost sensor pluged untill the car warmed up then it started to stutter again.No power in any gear.This sucks!!! What is wrong with my car? I removed the uim and lim to clean the 5th and 6th ports and used new gaskets.I had a 3800 rpm skip.The car ran fine before I did the work.I wonder if the atf I put in the engine fubared the engine?It smoked like a mother when I got it started.Then it put out the o2 code and it ran like ****?I have to get this fixed the car is my daily driver and it's too cold to ride my motorcycle to work.I refuse to pay a shop to fix the car.Also there is no one in my area who knows how to work on a rotary anyway.