cheyu
01-20-2014, 10:45 AM
I've just bought my 1993 na8 four months ago, and it has been problem after problem for me:
1) First, the engine had an issue while idling. Once the engine heats up it would idle very roughly and even stall sometimes.
This was fixed once I cleaned the throttle body and IAC valve, and also readjusted the TPS sensor.
2) Then I noticed that the engine's performance was very limited below 3000 and 4000 rpm. When in WOT, below 4000rpm, the engine would hesitate for a long time before kicking in. But once you get above 4000rpm, it would suddenly become very powerful. I realised this was probably due to the engine's management system changing from closed loop to open loop control.
3) In hope of fixing this problem, I replaced the entire throttle body + IAC valve + TPS sensor with a cheap second hand purchase, but was of no avail.
4) Fitted new spark plugs and a fuel filter. Also did not fix the problem.
5) Finally, I realised the oxygen sensor (my car only has one) was at fault, it did not produce a voltage even when heated. So I ordered a new one.
6) During the time of delivery I drove my car by unplugging the TPS to force my engine into open-loop control, so I can at least get the drivability I needed when going up ramps and bridges.
7) I Finally received the new O2 sensor today and had it replaced. The car ,now, drives very nicely. No hesitation below 4000rpm and pulls linearly. BUT, when the engine exceeds 5000rpm this happens:
http://www.youtube.com/watch?v=z7jqJgd0E1Q
(Basically, the engine speeds starts to jump all over the place between 5000- 7000rpm even if I keep my foot steady)
Could I have damaged the engine somehow by driving it with TPS unplugged for an extended period of time? I've only driven it three times while waiting for the arrival of my new O2 sensor, and each time not exceeding 15km in heavy traffic.
Please can someone give me any suggestion what might be causing this problem? It seems very strange how this problem only occurs once I hit 5000rpm.
1) First, the engine had an issue while idling. Once the engine heats up it would idle very roughly and even stall sometimes.
This was fixed once I cleaned the throttle body and IAC valve, and also readjusted the TPS sensor.
2) Then I noticed that the engine's performance was very limited below 3000 and 4000 rpm. When in WOT, below 4000rpm, the engine would hesitate for a long time before kicking in. But once you get above 4000rpm, it would suddenly become very powerful. I realised this was probably due to the engine's management system changing from closed loop to open loop control.
3) In hope of fixing this problem, I replaced the entire throttle body + IAC valve + TPS sensor with a cheap second hand purchase, but was of no avail.
4) Fitted new spark plugs and a fuel filter. Also did not fix the problem.
5) Finally, I realised the oxygen sensor (my car only has one) was at fault, it did not produce a voltage even when heated. So I ordered a new one.
6) During the time of delivery I drove my car by unplugging the TPS to force my engine into open-loop control, so I can at least get the drivability I needed when going up ramps and bridges.
7) I Finally received the new O2 sensor today and had it replaced. The car ,now, drives very nicely. No hesitation below 4000rpm and pulls linearly. BUT, when the engine exceeds 5000rpm this happens:
http://www.youtube.com/watch?v=z7jqJgd0E1Q
(Basically, the engine speeds starts to jump all over the place between 5000- 7000rpm even if I keep my foot steady)
Could I have damaged the engine somehow by driving it with TPS unplugged for an extended period of time? I've only driven it three times while waiting for the arrival of my new O2 sensor, and each time not exceeding 15km in heavy traffic.
Please can someone give me any suggestion what might be causing this problem? It seems very strange how this problem only occurs once I hit 5000rpm.