Acceleration Problem HELP!!
#1
Registered
Thread Starter
Acceleration Problem HELP!!
Hey guys, I'm new to this forum! I had a question that I'm hoping you can help me with. My Rx8 has 113,000 miles on it, with a brand new motor from Pettit Racing that has only 3,500 miles on it. Just recently (last 500 miles), the car hasn't been able to rev past 7k rpms when WOT. Then when it gets up to 7k, if I let out on the gas and try and rev it past 7k gingerly, it will go all the way to 9k. So I took it to 8k with about half-throttle, then gave it WOT at 8k, and it bogs down and the rpms go back down to 7k. It has a stage 2 fuel pump, new coils, plugs, wires, etc. I gutted the catalytic converter thinking this was the problem and it had no effect. I have no idea what could cause it to do this (maybe clogged fuel filter or something). I'm just trying to get some ideas of what to check that im not thinking of. Its not throwing any codes, idles perfect, has all of its power until I hit around 6k rpm, then slowly makes its way to 7k rpm. Gas mileage is not so good anymore either.
#3
Registered
Thread Starter
I have searched around, just trying to see if anyone has any certain ideas based on these specific symptoms.The ignition was replaced after motor swap.
#4
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 239 Likes
on
109 Posts
Something is clogging up your system. Being able to get to 9k with light load points to this. What are your AFRs throughout the rev range? Can you data log it occurring?
I'd point to your cat, but if you gutted it, that won't be the problem.
Edit:
By clogging up your system, I generally mean AFRs. Something is restricting fuel flow, air inflow, or exhaust outflow. If you drop the demand low enough that each is under the threshhold you are experiencing, you can rev fine. You should be able to get a direction to start looking with some OBD2 data.
I'd point to your cat, but if you gutted it, that won't be the problem.
Edit:
By clogging up your system, I generally mean AFRs. Something is restricting fuel flow, air inflow, or exhaust outflow. If you drop the demand low enough that each is under the threshhold you are experiencing, you can rev fine. You should be able to get a direction to start looking with some OBD2 data.
Last edited by RIWWP; 09-17-2013 at 12:51 PM.
#6
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 239 Likes
on
109 Posts
With the coin dropped on the rest of the stuff you mentioned, I assumed you would have something.
You can spend as little as $20, as much as $150 for a bluetooth OBD2 adapter, pair it with your smartphone and your choice of OBD2 app. If you have an Android, Torque is by far the best. Pony up the $5 for the paid version, it's TOTALLY worth it and only increases your total cost by a fraction. The OBD2 adapters largely get faster and/or more durable the more you pay, though there are exceptions.
You can spend as little as $20, as much as $150 for a bluetooth OBD2 adapter, pair it with your smartphone and your choice of OBD2 app. If you have an Android, Torque is by far the best. Pony up the $5 for the paid version, it's TOTALLY worth it and only increases your total cost by a fraction. The OBD2 adapters largely get faster and/or more durable the more you pay, though there are exceptions.
#7
Registered
Thread Starter
Additional: While I have it pinned WOT, the revs bounce around from 6.8k - 7.5k, it doesn't sit at one particular RPM, and the exhaust stutters and backfires while this is happening.
#8
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 239 Likes
on
109 Posts
Oh, ok, that seems different, and sounds like a severe misfire. Possibly a problem with your intake valving. If the valve that opens around that RPM is fluttering, it could be completely messing up the air/fuel mixture pretty randomly, and could produce that effect.
Just one option. Anything else that starts interrupting the spark, drenching the spark, etc... could do it too.
Just one option. Anything else that starts interrupting the spark, drenching the spark, etc... could do it too.
#10
Registered
iTrader: (2)
Join Date: Oct 2007
Location: Pacific Northwest
Posts: 16,684
Likes: 0
Received 239 Likes
on
109 Posts
Yes, I believe so. Check the technical document attached to the bottom of this post: https://www.rx8club.com/new-member-f...4/#post3663975 (Post #5 if that link doesn't bring you to it)
#11
Registered
Thread Starter
It looks to be the Auxillary Port Valve or the Variable Intake Valve. The CEL is throwing 3 different codes: P0420, P0455, and P0620.
Last edited by DefiantSE3P; 09-22-2013 at 08:21 PM.
Thread
Thread Starter
Forum
Replies
Last Post