DamianSoul

iTrader: (4)

Every time I start my car the RPM jumps to 3300 with an AFR of around 13. It does not surge, but holds this RPM for a few seconds. It will do this whether cold or warm. (Occasionally, when re-starting a warm engine, it won't jump to 3300 until the accelerator is barely tapped). After a few seconds or so the engine drops to about 1200 where it surges to 1500 in quick short bursts. AFR is 14 to 18 (mostly hanging around 18). If I try to rev the engine to 3300 it continues to surge. The higher I go in RPM the longer the pauses between surges. The car is undriveable and will begin to surge while driving. It usually gets going, but after a few seconds or so the AFR leans out and the car begins to buck.

I've gone through extensive measures to ensure that there are no vacuum leaks. The manifold flanges have been lapped and polished and all the intake gaskets are new. The vacuum hoses were done six months ago. I double and triple checked them for leaks, cracks, or any sign of wear. They were all in great shape.

I'm out of ideas as to what the problem may be. It's acting like a vacuum leak, but I can't find a vacuum leak. This setup was working correctly as of September of last year. I installed a different engine in the car in November, and these symptoms appeared.

What my setup is:
* Rtek7 Stage 2
* Modded throttle body
* Open exhaust
* Cold air intake

What I've tried so far:
* Disconnecting the BAC solenoid changed nothing (checked with ohm meter and it's within spec)
* Disconnecting the AWS solenoid changed nothing (checked with ohm meter and it's within spec)
* Disconnecting the AFM changed nothing (checked with ohm meter and it's within spec)
* Disconnecting the TPS bumped the RPM to 3800 with no surging at all. I tried swapping a different TPS, and it changed nothing. (Both TPSs were checked with an ohm meter and both were in spec, TPS logs showed consistent readings).
* Creating a vacuum leak by removing a capped small nipple changed nothing (however removing a large hose kills the engine pretty quick)
* Turning the steering wheel bumps the RPM up to 2000, but surging continues.
* Manually bringing RPM to 4000 slows surging down, but it still continues.
* Swapping the ECU did nothing.

I'm completely out of ideas. The only time the car doesn't surge is when it automatically goes to 3300 RPM after startup or when I disconnect the TPS. Any ideas?

mazdaracer78

adjusting the tps properly...

if this doesn't work, try a spare...

it definitely sounds like a tps out of adjustment...

texFCturboII

iTrader: (17)

Agreed, I had the same problem after swapping in a tps that "checked out" with an ohm meter. I swapped back in the old one and the problem dissappeared. Get it calibrated, and see what's up. The fact that it doesn't surge with the tps unplugged is a dead give away.

DamianSoul

iTrader: (4)

I've tried two different TPSs with similar results. I'll try adjusting them both tonight. Unfortunately, the original TPS died (narrow band is jammed), so I can't swap that back in.