Famous 3500rpm lag, replacing grounds didn't work
My 1st post to this forum and new owner of a super clean 1986 RX7 N/A. So I bought this car 2 weeks ago and noticed it falls on its face right at 3500 rpm. If you keep on the gas it gets past that spot and rips in the high rpms and has plenty of power. I had found that post about redoing the grounds. I went straight for the computer ground underneath the intake manifold and resurfaced the metal parts and used dielectric grease on them. I also did the one at the back of the intake manifold that goes to the firewall because it was right there. I ported the throttle body while I was in there too.
Conclusion: The car still falls on its face at 3500rpm. I only redid the 2 grounds but isn't it the computer ground that causes this issue? What else could it be? Thanks. |
Originally Posted by DenCoRX7
(Post 12334887)
My 1st post to this forum and new owner of a super clean 1986 RX7 N/A. So I bought this car 2 weeks ago and noticed it falls on its face right at 3500 rpm. If you keep on the gas it gets past that spot and rips in the high rpms and has plenty of power. I had found that post about redoing the grounds. I went straight for the computer ground underneath the intake manifold and resurfaced the metal parts and used dielectric grease on them. I also did the one at the back of the intake manifold that goes to the firewall because it was right there. I ported the throttle body while I was in there too.
Conclusion: The car still falls on its face at 3500rpm. I only redid the 2 grounds but isn't it the computer ground that causes this issue? What else could it be? Thanks. Damn i cant for the life of me remember the name but im sure S4's had a sort of actuator that activates after a certain RPM. Dont hold me to it though as i have not wrenched on a s4 in ages |
Originally Posted by PnoyRx7
(Post 12334917)
Damn i cant for the life of me remember the name but im sure S4's had a sort of actuator that activates after a certain RPM. Dont hold me to it though as i have not wrenched on a s4 in ages
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^ What they said. Clean the auxiliary ports.
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Nah its not the aux ports.
Probably something to do with the secondary injectors or fuel system related. Was the car sitting? Have the injectors been serviced? Have you changed your fuel filter? Original fuel pump? Fuel pump voltage at idle and WOT. EDIT: I just read that you didnt fix all of the grounds. You need to do all of them. theres like 10. This is one of Aaron Cakes write-ups. He knows what hes talking about. Do it. https://www.aaroncake.net/RX-7/grounding.htm |
Originally Posted by FührerTüner
(Post 12335040)
Nah its not the aux ports.
Probably something to do with the secondary injectors or fuel system related. Was the car sitting? Have the injectors been serviced? Have you changed your fuel filter? Original fuel pump? Fuel pump voltage at idle and WOT. EDIT: I just read that you didnt fix all of the grounds. You need to do all of them. theres like 10. This is one of Aaron Cakes write-ups. He knows what hes talking about. Do it. https://www.aaroncake.net/RX-7/grounding.htm |
What about your fuel filter? You could also check the wiring on your secondary injectors and check resistance
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I had this issue. cleaned all my grounds. check my 5th and 6th. replaced plugs, wires, and secondary injectors and nothing worked. I ended up replacing the trailing coil pack with a used one i got off ebay and that worked.
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You can always throw some parts at it which may or may not help. It never hurts to check your TPS resistance to make sure it's synced up. If you can get an analog dial-type ohm meter you can also look for dead spots doing a full sweep of the throttle. Most of these 30 year old sensors are starting to lose their integrity.
I'd go ahead and clean ALL grounds, only costs you a bit of time and energy. If none of the above works, I'd say look into the secondary injectors. |
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