Lean boost situation solved
04-12-2005, 08:18 PM
#1
Externally Wastegated
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Join Date: Oct 2001
Location: San Diego
Posts: 1,220
Lean boost situation solved
Hey everyone, I figured I'd post that I solved the lean boost issue I was having for the last 4 months or so. Maybe this can help anyone else who has had problems under boost. Started out when my afm took a dump. Then my plug wires got fried somehow (ever ground yourself with 25K volts?) 
Anyway, I installed a new afm and noticed that the a/f gauge would go lean once the revs hit closed loop mode. (~3500) If I made the boost gauge go anywhere near the 0 mark the gauge would go straight lean and no led's would be lit up, maybe one bar of the lean side if I got lucky.
I decided to mess with the ignition coil area since the wires there are notorious on my Z for being picky how they are situated. Well, I had the motor running and was looking around the area near the ignition module and noticed sparks forming every so often. I took a closer look and somehow the little blue cylinder (capacitor I think?) had worked itself loose from the coil bracket and was sparking every time it hit the chassis. After fixing that, I noticed the Z actually liked to idle on all 6 cylinders now. Before it would drop spark in a cylinder every so often giving the exhaust note a tone that sounded like a Volvo.
I took the Z for a quick spin and noticed that the lean boost situation was still present. I tracked down one small vacuum leak at the vacuum pump (the tiny hose had cracked at the base) and that promptly let my vacuum gauge read the full 520 mm/Hg at idle instead of 450 in Park. (my Z is an a/t) I adjusted the TPS (I adjust mine a bit differently from what the FSM states since I'm wary about opening it up) and double checked all my pin connections to the ecu harness plugs making sure they were secure and voila, no more lean boost situation!
The Z was running pig rich to the point where when cold it would idle like it had a massive cam in it. (I have 370cc injectors) I adjusted the afm to run a bit leaner and now it idles fine. During boost (~0.6 kg/cm2) the a/f gauge reads 3 bars into the rich zone which is normal. During high boost (0.75 kg/cm2) it reads 2 bars into the rich zone. It's amazing how much power is being put out now, I really missed being thrown back in the seat. Sorry about the long winded post, but if someone else has problems on their zxt, I hope this post can shorten the amount of downtime they spend. I know it was sheer torture for me driving to school and cruising with friends just limping along when they could all go WOT and have fun.
Anyway, I installed a new afm and noticed that the a/f gauge would go lean once the revs hit closed loop mode. (~3500) If I made the boost gauge go anywhere near the 0 mark the gauge would go straight lean and no led's would be lit up, maybe one bar of the lean side if I got lucky.I decided to mess with the ignition coil area since the wires there are notorious on my Z for being picky how they are situated. Well, I had the motor running and was looking around the area near the ignition module and noticed sparks forming every so often. I took a closer look and somehow the little blue cylinder (capacitor I think?) had worked itself loose from the coil bracket and was sparking every time it hit the chassis. After fixing that, I noticed the Z actually liked to idle on all 6 cylinders now. Before it would drop spark in a cylinder every so often giving the exhaust note a tone that sounded like a Volvo.
I took the Z for a quick spin and noticed that the lean boost situation was still present. I tracked down one small vacuum leak at the vacuum pump (the tiny hose had cracked at the base) and that promptly let my vacuum gauge read the full 520 mm/Hg at idle instead of 450 in Park. (my Z is an a/t) I adjusted the TPS (I adjust mine a bit differently from what the FSM states since I'm wary about opening it up) and double checked all my pin connections to the ecu harness plugs making sure they were secure and voila, no more lean boost situation!
The Z was running pig rich to the point where when cold it would idle like it had a massive cam in it. (I have 370cc injectors) I adjusted the afm to run a bit leaner and now it idles fine. During boost (~0.6 kg/cm2) the a/f gauge reads 3 bars into the rich zone which is normal. During high boost (0.75 kg/cm2) it reads 2 bars into the rich zone. It's amazing how much power is being put out now, I really missed being thrown back in the seat. Sorry about the long winded post, but if someone else has problems on their zxt, I hope this post can shorten the amount of downtime they spend. I know it was sheer torture for me driving to school and cruising with friends just limping along when they could all go WOT and have fun.
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