I have a 94 AE102 with a smoking engine, 195,000 miles, and I was contemplating whether to rebuild the 7a or get a JDM 5a. I see 5a's cheap and I'm not worried about speed or acceleration, that's not why I got this car. But I was wondering about what to do with the ecu, because these JDM engines don't come with one. My Corolla has a 5-speed, maybe a re-flash or 4a-fe ecu. Thanks -Josh
You'll need the ECU and you'll need to splice wires for the 5AFE. Stick with the 7AFE, you can rebuild it if you want, but most junkyards will be happy to sell you a lower mileage one for about $300.
Seized rings, eh? You can probably free those up with some WD-40 and a thin, but sturdy wire through the spark plug hole to move the rings around.
The gap between the piston and the cylinder wall is a few hundredths of an inch. You couldn't manage to get any wire in there let alone make it move a ring. But your wd40 idea wasn't bad, I personally would use seafoam or another engine cleaning agent as wd40 still has a high content of water considering its a lubricant.
I would remove all 4 spark plugs, put the seafoam in each cylinder (just a small amount to cover the top of the piston, and let it sit for like 20-30 minutes. Then turn it over still without the spark plugs in it(ideally with someone holding a towel over the spark plug holes to get rid of the excess seafoam).
Put the plugs back in and run it as per seafoams directions. Then id do an engine flush and change the oil.
There are small holes behind the oil ring in the piston, and they are known to carbon/plug up and then as the oil builds up it heats up and thickens and ends up causing the ring to get stuck and allows oil further up and eventually get to the point of oil consumption. I have pulled a 4afe with 150000 miles apart, removed the rings, cleaned the grooves and oil drain passages, and the oil burning stopped.
If your up for a project taco, id rebuild your motor. its rewarding and its a simple motor to work on. Wouldn't cost you more then 300 bucks to do it. The oe engine set is 220 from toyotaworld if you wanted to go that way but your autozone should have the felpro set for like 120. Id check your compression on all the cylinders before making any decision though.
But if your car is a 7afe with the 4 speed auto, I wouldn't try to run the 5a off the 7a computer.
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Last edited by 1jzdreamer; 09-15-2009 at 08:18 PM.
I agree, stick with a 7a, whether you build yours or find a good running one that doesnt smoke. But with that being said here is a few things i have personally done over the years. My 92 rolla 4a-fe spun a rod bearing and i replaced it with a JDM 5a, and it worked great. I got my 94 rolla 4a-fe 5 speed with the number one rod sticking out of the block for dirt cheap and installed a 97 7a-fe long block (kept the 4a computer, harness, intake in the car and just put the 7a in its place) there were small differences such as the intake manifold support and exhaust manifold support which bolt to the bottom of the block were different, not a problem, just had to drill a couple holes in the brackets. the only really funny thing is i have a crank sensor that plugs into nothing and i eliminated the knock sensor... no big deal though, it doesnt ping in the slightest bit. my 4a dist fit perfect and everything, and this car runs great, has more power than ones i have drove with 4a's in them (im a mechanic by trade, and i have drove alot of different combinations) My 4a control system has no idea that its feeding a slightly larger engine, and the added stroke of the 7a sure gives is better low end grunt. it was well worth the upgrade.
So what im sayin is if you do decide to put in a JDM 5a, there may be a few small differences, but your 7a system wont really care about .3L less displacement. But I would try to keep with your stock setup if at all possible, its definatly an ideal setup
It would run a touch leaner or richer dependant on which ecu combo you go with. It would be fine while cruising as it would use the o2 to target a/f, but at wot it reverts to the accel map and then you will be off a little. Since the injectors are different for each motor im sure the tune wouldn't be far off but not perfect as one would want ideally. Thats all I was getting at.
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20v, 6 spd lsd
Boost, may you RIP.
True about the Fuel trims, My 7a being ran off the 4a setup seems like it has to learn if my battery is disconnected. But after a few miles it seems like it trims itself right out. These systems seem to adapt fairly well to mild changes.
some jdm engines have much different emissions stuff than usdm ones though, like different egr setups or a knock sensor that wasnt on any 5afe in north america. also parts can be harder to get since it was not an american engine, you can't get any specific parts from the dealer.
I had checked the compression in 01/09, and I think they were all roughly 195 psi, except cylinder 1, which was zero. My instructor at the college did a vacuum test and said it may be a blown head gasket. Is there anything else you can think of that would cause zero compression? It's 2:00 AM...
How do you do an engine flush? I'm going to try to do the Seafoam thing. Also, the guy I bought it from last year said his mechanic told him there was a hole in the piston. I found this to be highly improbable. -Josh
Guys i own a 93' Rolla AE100. It has a 5A-FE engine. It has done only 58,000Km and recently i've changed the fuel injectors. But now the car seems to redline at 5500rpm !!! Even if the nail the gas pedal to the floor still the needle gets no higher than 5500rpm. BTW...the car sat in the garage for almost a year. I have changed the oil and added the necessary fluids. Wot do i do now ?????
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