Darth Boost
New member
This has been bugging me since I got the car over a year ago... When I'm driving along under 3000 RPM, and give it more gas as if to pass someone or rapidly speed up (not floored, but about 35- 75% throttle), it will buck and jerk and the Autometer AFG will bounce back and forth between stupid lean and the very most rich side of stoichiometric. Sometimes, it goes so lean, the AFG goes black.
It will keep doing this 'till I either floor it, or it hits 3000 RPM. OR... if I'm just trying to maintain speed up a long hill, it'll go rich and smooth out after about three to five seconds. Also, when I floor it in 1st gear, the turbo spools like mad, but the car bogs 'till 3K RPM, and then it's like I'm rear ended by a truck and the car just leaps forward without any bucking or any of the other symptoms I mentioned.
The car has 201K on it, and at 166K, I installed an 18K mile JDM engine. It did this exact same thing with the original engine and with the JDM engine. I've changed the plugs, wires, distributor cap, rotor, and coil. I've also checked the entire intake system for leaks, and have checked the MAF for both spring tension, smooth operation, and for proper resistance values. It would do this at the stock boost levels, and with the boost controller set at 15 PSI. Also, there are no codes present.
Aside from ditching the entire engine management system, what other things can I test? This winter, II'll be fabbing up a 3" turbo back exhaust and charge piping for my 30X10X3 Spearco FMIC, and use an SDS EIC for fuel management, and would REALLY like to get this bug cleared out before I proceed.
I somewhat sort of almost kind of am leaning towards the TVIS being the culprit, as the problem works itself out at about the same RPM that the TVIS opens...
It will keep doing this 'till I either floor it, or it hits 3000 RPM. OR... if I'm just trying to maintain speed up a long hill, it'll go rich and smooth out after about three to five seconds. Also, when I floor it in 1st gear, the turbo spools like mad, but the car bogs 'till 3K RPM, and then it's like I'm rear ended by a truck and the car just leaps forward without any bucking or any of the other symptoms I mentioned.
The car has 201K on it, and at 166K, I installed an 18K mile JDM engine. It did this exact same thing with the original engine and with the JDM engine. I've changed the plugs, wires, distributor cap, rotor, and coil. I've also checked the entire intake system for leaks, and have checked the MAF for both spring tension, smooth operation, and for proper resistance values. It would do this at the stock boost levels, and with the boost controller set at 15 PSI. Also, there are no codes present.
Aside from ditching the entire engine management system, what other things can I test? This winter, II'll be fabbing up a 3" turbo back exhaust and charge piping for my 30X10X3 Spearco FMIC, and use an SDS EIC for fuel management, and would REALLY like to get this bug cleared out before I proceed.
I somewhat sort of almost kind of am leaning towards the TVIS being the culprit, as the problem works itself out at about the same RPM that the TVIS opens...