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Discussion Starter #1
Im sick over this guys. I had a shop put a 95 corolla 7a into my 96 st. It fires right up everytime, idles great. Then randomly it loses power and and wont accelerate but never loses power. We replaced with new plugs wires and cap and rotor. It ran great for a few miles now the problems back. Is the fact that its a 95 in a 96 the problem? Any help is appreciated. This car means so much, just wanna get it running again.
 

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This part of your sentence makes no sense: Then randomly it loses power and and wont accelerate but never loses power. The first part of the sentence contradicts the last part. Which part is accurate?

What bolt-on items from your old 96 Celica ST 7A-FE engine did you reuse on your 95 Corolla 7A-FE engine? The intake manifold and EGR systems were very different between these two engines, for example. Helps to know what you reused from your old engine and what you did not reuse.

Engine power was higher in the 1996 version compared to the 1995 version due to a different antipollution system and different intake. If you kept the 1995 engine intake and EGR, and also kept the 1996 ECU, I would think that would cause a problem due to the generation difference in the 7A-FE between 1995 and 1996.
 

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Discussion Starter #3
I meant it wont accelerate but it dont cut off. I asked the shop owner, he said they used the harness and sensors from my old motor. I mean..if it was something bad it wouldnt start at all right? My dad said it seems to be something with the small air hoses mixed up or something? Would switching over my old intake work? Would that make the egr correct? Thank you for replying btw.
 

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So with the 95 engine you are using now, you are using the intake and EGR that came with the 95 engine in your Celica now? I would think that is problematic as your ECU is looking for some sensor inputs and is outputting come control signals to a system that is different.

Can you swap your 96 engine's intake and EGR to your 95? It all depends if the head on the 95 is the same as the head on the 96. I don't know if it is or not. If they are identical, I would have all your bolt-ons from your 96 put onto the 95 long block. Sometimes when engines change rev levels, they have head modifications. The 96 has more power output. I would think that makes a difference if fuel mapping. You have have different fuel injectors between the engines. So its more complicated usually. You would have been better getting an engine of the same generation as your 96 Celica's, rather than the previous generation as the 95 Corolla has. Would the 95 Corolla engine be the same as a 95 Celica - YES. Would a 96 Corolla engine be the same as a 96 Celica engine - YES. But a 96 7A-FE engine is not the same as a 95 7A-FE. So when you cross generations of engines, you have to be very cautious of what those changes involve to know if your ECU can work properly with a previous generation engine.

I would be better at helping with the 4A-FE (predecessor of the 7A-FE) from 5th Gen Celica's, since the 5th Gen Celicas are what I have. Sometimes that experience doesn't crossover to later generation cars though. So I'm not sure about your situation.
 

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Discussion Starter #5
So im using the 96 sensors and harness. Only thing they didnt switch over is the intake manifold. Maybe thats the problem?
 

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I'm not sure you can switch intake manifolds - maybe you can. The EGR setups between the two engines are very different - your original Celica engine uses integral path in the intake while your Corolla engine uses an external tube, so I'm not sure you can swap intake manifolds. I'm sort of thinking a 96 ECU controlling a 95 engine - there may be some incompatibility there along the line, and it could be how your EGR is controlled (your EGR may be operating different than your ECU intends for it to operate. Not saying that is it though. Maybe disconnect and plug your EGR vacuum hose and see if you get the same symptoms or not. If not, you know the EGR system is the issue. If you can't swap intakes, you may need to leave your EGR valve inoperative for it to run properly. You'll have to watch/listen for pinging or knocking if your EGR is disconnected, as your ignition timing advance may be off a bit w/o use of EGR (your ECU is mapped for use of EGR, so it may advance timing too far without it working).

Good luck!
 

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Any idea which hose is egr valve?
Which hose is the EGR valve? Sorry, don't understand this question at all.

Below is an attachment of what your 96 Celica engine EGR looks like. And also attached is what the 95 Corolla engine EGR looks like. They are different because your 96 Celica engine is a generation newer than the Corolla engine.
 

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You might be able to get away with swapping the intake from the 96, but you'll get a check engine light because the EGR port in the head wont be there.
Best thing to do would be put the head from the 96 on the 95 block. I did that exact thing a few years ago and it worked fine.
 

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I've swapped 4A-FE heads due to things like this in the past, but didn't know for sure if the 7A-FE heads/blocks allowed this same interchange, so I didn't want to suggest this without knowing. The fact you did and it worked is good to know. And your suggestion has a good chance of resolving the issue stated here.
 
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