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Hey everyone, I posted a while back regarding my hesitation in my 96 na. Basically, the car has 124k miles, was garage kept most of its life and is well-maintained. When I drive the car, once it’s warmed up to operating temp, at idle everything seems fine. It idles smoothly, there’s a slight shake but it’s so light it could be engine mounts. When driving, at light throttle it seems to run great. However, the more I open up the throttle, the less power it seems to want to have. I.e., if I’m in 2 nd gear in a neighborhood and I lightly touch the throttle, the car jumps great and seems to have plenty of power driving up steep hills and such. But if I give it more throttle, it has less power and if I floor it and I’m not in a higher rpm range, it bogs down and doesn’t have any power at all. When entering the interstate, if I give it lighter throttle until around 3k rpms, then floor it, I lose power. But, same scenario, if I keep it at half throttle, it gets up ok and doesn’t kick my power out. At any rate, the power loss is intermittent during a single drive, and it seems to get worse as the engine/ambient temps rise. So far, I’ve replaced:
-cas –made no difference
-fuel pump (replaced with good oem one) –made no difference
-maf –made no difference
-fuel pump controller –made slight difference initially, then began again with the issue shortly after
-right side oxygen sensor –made a big difference initially, but still have a hesitation issue -new fuel filter –made no difference
-checked injectors –all ohm fine
-checked timing at 10* btdc (10* for obdii Z32s) -checked tps –set and functions properly I checked for codes, the knock sensor code has been coming up fairly consistently, but I wasn't sure if it was causing a problem or was a result of one, so I had another lying around and I did the relocation trick to see if it changed how it drove. The code hasn't returned, but its obvious it wasn't causing the issue as it still doesn't run right. I ran datascan to check my parameters, but I’m not exactly sure what I’m looking at for some of them. I’m at the point where I’m running out of things to check. One thing I noticed, the two front oxygen sensors sweep fine when held at 2k rpms. The left side is a bit slower than the new right, but it sweeps more than 5 times in 10 seconds so I think it’s ok. I can’t find any solid statements regarding how the rear o2 sensors should behave. Currently, when the throttle is held at 2k rpm (as if checking the fronts), they sweep one way and stay there, instead of pulsing back and forth like the fronts do. I’ve read some places that the rear o2s only check for catalytic converter proper function, others say they are used for fuel mapping, but only in certain conditions. Anyone know how to test the rear oxygen sensors for proper function? I’ve also wiggled every wire connector I could find in the bay, disconnected many to check for corrosion but it’s a 96 harness and has all newer-style connectors, so it’s all in decent shape. Can’t find any vacuum leaks either. It feels like it’s running lean when I lose power, but I can’t figure out why. Any other suggestions would be fantastic at this point.
Cheers,
JBrobst "A life spent making mistakes is not only more honorable, but more
useful than a life spent doing nothing." George Bernard Shaw |
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