JDM Engine Swap - 1995 LE SC AWD - Vibration on accelleration

[merdlb]

I recently swapped my 240k 2TZ-FZE out of my previa for a JDM equivalent. The swap went smoothly, I have a lift in my driveway and dropped it out the bottom. Now that everything is back together except the tailpipe, the engine idles fine, but when given any gas it gets really loud- louder than I'd expect even without the tailpipe in place, and there's noticeably less power than expected and a tight, fast vibration proportional, it seems, to the pistons firing. The first section of exhaust is in place, with the o2 sensors connected before and after the cat, but the second cat is not in place leaving the tailpipe disconnected. I don't think this has anythign to do with the vibration and loss of power I'm experiencing. The vibration, it should be noted, is independent of vehicle speed, it only happens when you try to give the engine any gas.

I originally suspected this was a timing issue- but the timing is not adjustable on the S/C engine. Any ideas what this would be?

[Kurtanius21]

So there's no vibration at idle? Lack of power could be because of fuel delivery, air restriction, or ignition issues, assuming your transmission is ok. Your supercharger also may not be engaging, which I have read causes sluggish acceleration. I think you should double check all your hoses, vacuum lines, and listen for any leaks while the car is running, or immediately after shutting it off. The fact that idle is ok leads me to think something isn't right with vacuum and air metering.

how do you know ignition timing cannot be changed? Can't the dustributor be rotated just like on the NA engines? I have not owned an OBD-II Previa...

[edmyers]

I recently swapped my 240k 2TZ-FZE out of my previa for a JDM equivalent. The swap went smoothly, I have a lift in my driveway and dropped it out the bottom. Now that everything is back together except the tailpipe, the engine idles fine, but when given any gas it gets really loud- louder than I'd expect even without the tailpipe in place, and there's noticeably less power than expected and a tight, fast vibration proportional, it seems, to the pistons firing. The first section of exhaust is in place, with the o2 sensors connected before and after the cat, but the second cat is not in place leaving the tailpipe disconnected. I don't think this has anythign to do with the vibration and loss of power I'm experiencing. The vibration, it should be noted, is independent of vehicle speed, it only happens when you try to give the engine any gas.

I originally suspected this was a timing issue- but the timing is not adjustable on the S/C engine. Any ideas what this would be?

I did a jdm swap a year ago and just today i addressed some vibration issues, this is what i adjusted and replaced so far.
Sad couplers , transmission mounts, right side engine mount, there's alot of bushings and mounts on this thing..., plugs, distributor, rotor button, plug wires, a bad #2 wire did cause some engine vibration, adjusted the sad assembly mounting bushings, vibration a little worse after that adjustment... ? The SC engines use a crank sensor for timing, not adjustable. Like kurtanius21 indicated a broken vacuum tube at the fuel pressure regulator for example could be a issue or a stuck open egr valve... re-trace everything. Eliminate the exhaust system as a issue for a vibration and engine performance. I would do a upper intake/fuel injector cleaning service, it can help. After I did all that I'm still experiencing some vibrations at acceleration, around 30mph then on cruising speed with slight pressure on acceleator pedal? Still looking...

[merdlb]

The van was running fine- including the s/c before the swap. The head gasket let go on the freeway which provided a dramatic steam cleaning to the internals and the exhaust.... hence the swap. Eventually I will rebuild the old one and document that.

I did verify it revs fine, with no vibration, in neutral. I am going to check the drivetrain before i move to check the vacuum lines. By the way, the trsnsmission mount and sad bushings are all new. I ended up painting my driveshafts and inadvertently lost the sharpy orientation marks I had put on them. note to self: next time use a punch.

thanks to both of you for your responses. I will post the fix.

merdlb

So there's no vibration at idle? Lack of power could be because of fuel delivery, air restriction, or ignition issues, assuming your transmission is ok. Your supercharger also may not be engaging, which I have read causes sluggish acceleration. I think you should double check all your hoses, vacuum lines, and listen for any leaks while the car is running, or immediately after shutting it off. The fact that idle is ok leads me to think something isn't right with vacuum and air metering.

how do you know ignition timing cannot be changed? Can't the dustributor be rotated just like on the NA engines? I have not owned an OBD-II Previa...

[merdlb]

What you describe in your last sentence is exactly my issue. I noticed some front axle gear oil loss through the c/v gaskets. I'm going to start there.

I did a jdm swap a year ago and just today i addressed some vibration issues, this is what i adjusted and replaced so far.
Sad couplers , transmission mounts, right side engine mount, there's alot of bushings and mounts on this thing..., plugs, distributor, rotor button, plug wires, a bad #2 wire did cause some engine vibration, adjusted the sad assembly mounting bushings, vibration a little worse after that adjustment... ? The SC engines use a crank sensor for timing, not adjustable. Like kurtanius21 indicated a broken vacuum tube at the fuel pressure regulator for example could be a issue or a stuck open egr valve... re-trace everything. Eliminate the exhaust system as a issue for a vibration and engine performance. I would do a upper intake/fuel injector cleaning service, it can help. After I did all that I'm still experiencing some vibrations at acceleration, around 30mph then on cruising speed with slight pressure on acceleator pedal? Still looking...

[cb97alltrac]

Some of the previa sc engines have knock sensor issues which results in power loss. I found this out by hooking up a scanguage ii and seeing way negative or retarded timing on acceleration. Some have placed a resister wire 1k or so, between the knock sensor wire and ground wire at the ecu to attenuate the knock sensor signal which has fixed this issue for some. You cannot adjust or rotate the distributor cap to adjust the timing on The Supercharged previa, it does use a crank sensor as described in an earlier post. I would definitely check the timing and see what it's doing with acceleration.

[edmyers]

Pulled my spark plugs a couple of days ago and it looks like i have a fuel injector not firing properly on #2 cylinder could be a source for my engine vibration, so I'm wondering if i should use the injector from my old motor or if there is a fuel efficient replacement for all the injectors? Also is there really a ecm replacement/reprogram for better fuel economy for a 95 altrak?