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New Owner of a '94, car dies when putting into drive. Vacuum leak?
Hi guys! Just got a deal on this black '94 LS 400. Hoo, it is in rough shape! The interior is absolutely trashed (but I did find a $20 bill while cleaning it out, so there's that). Here she is, in all her fallen-from-grace glory:
Anyways, onto my question: The car will sometimes die when putting it into Drive, it doesn't do it as much (if at all) once it's completely warmed up, but the only way I can get it going when cold is to take my foot off the brake while shifting, and letting the car jump forward as it goes into gear.
I do have the parts on the way to replace the transmission filter (and the appropriate Toyota Type IV ATF fluid), and there is a known vacuum leak which I've already ordered the part to (hopefully) fix (the rubber boot connecting the engine intake to the air filter box). Is there anything else I can do/should do/try? Or is a filter change and vacuum leak fix likely candidates for the cause?
The main vacuum leak I have is a 1-ish inch tear in the boot to the upper-right of the AFM, so I'll replace that boot first and see if the issue improves at all, then look into an AFM. I assume, like most air meters on most cars, it's expensive and difficult to find; can I spray it with some electronics cleaner to see if it's just dirty? It was running with a HORRIBLY dirty filter when I got it, just replaced the filter yesterday.
Ah, okay! Thank you for the heads up! I'll keep my fingers crossed the vacuum leak is the primary cause and update you all once I get the intake piece in. Thanks again!
Okay, new(?) development on this for me. I dropped the transmission pan and changed the filter, filled it back up with the appropriate fluid. It still dies when trying to go into drive when you first start up the car, however it does actually seem to shift fairly well.
However, I'm starting to suspect that the torque converter is bad. Anytime I pull up to a stop sign the car shudders and the RPM's get lower and lower till the tach is showing about 3-400 RPM and nearly die. I'm quite sure the vacuum leak isn't helping matters. It feels like the torque converter is having problems "unlocking" though, and starts to drag the engine down? Would that make any sense at all? Additionally, is there any kind of electronic control on the torque converter I can use to test?
I'm considering dropping the transmission and just replacing it with a known good used unit, which should include the torque converter. But I'd definitely like to make sure it's not an electrical issue of some kind, I know the ECU in these cars can have bad capacitors. I would love it if all I had to do was replace a few caps!
Quick EDIT: There's a '95 LS 400 transmission near me, would that work in my '94? I'm not positive what the generational changes are on these cars.
As always, any guidance is very much appreciated!
1995 LS 400 models have different transmissions. While they are very similar to 1990-1994 models, a few revisions were made that will prevent it from being an easy install. I would not recommend replacing the transmission until you are absolutely sure it is causing an issue.
With regards to your vacuum leak, take a look at the vacuum hoses, such as the one I've highlighted in red, for any cracks or openings. This could cause a vacuum leak:
So, I replaced the intake boot that's circled in yellow. The T fitting circled in blue is covered in electrical tape from the previous owner, so I imagine it's split, but if it is a leak it's not too bad - I'll still try and replace it soon.
The other hoses all appear to be in good shape.
After replacing the intake boot, the engine runs a good bit better! The transmission flush also definitely helped out with the transmission shifting in general.
But it still dies when I go to put it into drive, and it's shuddering as I come to a stop (like I'm being gently tapped from behind 3-5 times as I come to a stop, always below about 10 mph).
What else should I check or do? The engine is smooth and has no problem revving, I really do think it's transmission related. Is the torque converter bad? Cause it really feels like the torque converter isn't doing a good job decoupling power, and it's fighting with the engine to keep moving.
Any other suggestions are, as always, greatly appreciated!
Just had someone suggest to me that it could be motor mounts. I wouldn't be surprised to learn they are still the original ones. But would that really cause the car to die like that?
EDIT: Well for better or worse I just took the car to a well-rated mechanic near my house (their head tech is even a Toyota specialist, so even better), they'll diagnose the issue today or tomorrow and get back to me. I tried dropping the car into drive with the hood open and couldn't see the engine move at all, so I don't think it's motor mounts. I'm fairly certain it's either the torque converter or the transmission itself, from the "killing the car while shifting into drive" to the grinding and surging I get at a stoplight, it's gotta be something in the drivetrain. And if not, hey, I've got a '94 LS 400 for sale in Denver for $1k!
Shop just called, car needs a new transmission and torque converter. They're gonna get me a quote on a replacement transmission but frankly I don't want to put that kind of money into the car. Thank you everyone for your help, and if anyone wants a beat up but reasonably good mechanical LS 400 for $1000, let me know!
as a last pull, and depending on money, I would try and do a quick drain and fill of the transmission fluid using only Toyota ATF. also check your ECU for the very common leaking capacitors. replace those and if the car still does not revive then move on.
I would recommend expelling, and altogether cleaning within the throttle body. It might settle it, it may not - but rather it won't cost you a dime to do.
Alastair
Hi guys! Just got a deal on this black '94 LS 400. Hoo, it is in rough shape! The interior is absolutely trashed (but I did find a $20 bill while cleaning it out, so there's that). Here she is, in all her fallen-from-grace glory:
Anyways, onto my question: The car will sometimes die when putting it into Drive, it doesn't do it as much (if at all) once it's completely warmed up, but the only way I can get it going when cold is to take my foot off the brake while shifting, and letting the car jump forward as it goes into gear.
I do have the parts on the way to replace the transmission filter (and the appropriate Toyota Type IV ATF fluid), and there is a known vacuum leak which I've already ordered the part to (hopefully) fix (the rubber boot connecting the engine intake to the air filter box). Is there anything else I can do/should do/try? Or is a filter change and vacuum leak fix likely candidates for the cause?
Thank you all!
I hope you don't have the beginnings of an ECM (computer) problem. Once you have it going does it run as expected or does it stumble under any and all loads such as accelerating at times?
08-12-17, 01:28 PM
New Owner of a '94, car dies when putting into drive. Vacuum leak?
