Robbie2222

I am looking for some help.

I have a 87 NT MT RX7 coupe. It has about 192000 mile on it. Since I got it it has always hesitated slightly on acceleration around 3000 rpm when it is cold. After it warms up this seems to go away. It use to idle rough and stall but a new TPS about 15000 miles ago fixed that. Other than the above hesitation it was running fine. When I started it today after sitting for 3 days, it started normally. After I left my house, and stopped at a stop sign a half mile away, it seemed to die for a second as I accelerated away from the stop. Then at a stop light a mile away, it did not want to rev up or go when the light turned green. By reving it up good with the clutch in I was able to get underway. I drive 65 miles to work and it was missing and hesitating most times whenever I tried to accelerate in any gear, but especially under heavier load. It also did not like to rev-up from an idle in stop and go traffic - I had to keep it rev'd up to about 1500 rpm to avoid this. Idle was at about 750 rpm. At times it was okay and it acted normal. I thought I heard it backfire a bit a few times.

Any thoughts or ideas of what may be wrong would be helpful.

Josepi

Whens the last time you've done basic maintence. IE plugs, wires, fuel filter. Has the fuel pump ever been replaced? Have you set the TPS per the factory service manual?

Robbie2222

Thanks for the reply.

I did basic maintenance at 180000 miles replacing plugs, wires, and fuel filter. The fuel pump has never been replaced to my knowledge. I plan to check the fuel pressure when I get a chance on the weekend. I am the 4th owner of the car.

On the way home last night, it started fine, but anytime I tried to rev the engine up it started missing and "popping" kind of like when the timing is too far advanced on an engine. It lacks power and any time I step on the accelerator it starts with the popping and missing. As long as I keep the rpms constant it seems to not miss. It cruised home at 65 mph just fine as long as I stayed in 4th gear and kept the motor speed constant.

Robbie2222

Yes the TPS was set per the book.

Josepi

Original injectors?

Robbie2222

Original injectors as far as I know.

Rob500

check the electrical connector on the MAS. Make sure it is plugged in all the way.

Rob

Robbie2222

Thanks for the suggestion. Everything seems to
be fine with the MAS connection.

Turbonut

iTrader: (1)

A cracked seal will also cause this problem under load. Idles fine, and can cruse at a steady speed without any problem, but when under load combustion actually is going past the seal to next chamber. This problem may/may not show up on a compression test.
Hopefully, it will be something minor, so check out the suggestions first.

Thaniel

How's the engine wiring?

Robbie2222

Thanks for the input. I hope it isn't a seal, but it could be. It was running fine on Thursday night. It sat over the weekend and started the missing Monday morning. What makes me think it is something other than a seal is at times it ran normally on Monday and would pull fine under load even in 5th gear. It appears to be somewhat intermittent - always fun things to find. Hopefully on the weekend I'll get a chance to do more indepth trouble shooting.

Robbie2222

The engine wiring and other under hood wiring is in excellent condition in general.

Robbie2222

Just wanted to close the loop on this problem for those of you who are interested and for others with the same problem in the future.

Spent some time troubleshooting on the weekend and finally found the problem. The oxygen sensor wire at the connector on the engine side was broken. The oxygen sensor itself was replaced at about 180000 miles and the wire was ok then. I guess it just eventually broke from vibration and fatigue. On this
car at least the engine runs like crap without the oxygen sensor.

Thanks to all who made suggestions.