Runs Rough After Engine Replace '90
 

So I had a 90 Camry as my first car, fast forward 10 years and there's another one for sale.
It has a "new engine" from Japan (waiting to see papers confirming that, it's very clean) and 196k on the body, it's mint though and I'd love to snag it.
After the engine replace it just isn't running just right, doesn't have a as much power as it should. Dude replaced the fuel filter and pump.
I really need some wheels not a headache. Was thinking either the Cat Conv might be plugged, timing?? Not sure, any help is appreciated!
Thanks!

Difficult to state without more detail.

A few questions for the car owner.

Why is the owner selling the car? Have they reached their limit in time, patience and money trying to get car to run OK?

Why did they replace the old engine?

Did the old engine ever run OK, as in have power.

Try to determine if the current engine performance issues are due to the engine swap. Not a hold over from the days of the old engine such as a plugged CAT.

Does the owner still have the complete old engine to include in the sale?

The problem could be as simple as timing. A failure to connect an electrical harness plug. Using a wrong sensor. Disconnected vacuum hose. Minor ign problems such as plug wires, rotor, cap, etc.

A caveat is Japan and US engines may be the same basic model, but they can have differences.

The Japan engine may have less emissions controls, different intake manifold, throttle body, sensors, cams and compression ratio, etc.

These differences can reflect in differences in the wiring harness. This where the US harness plug no longer fits where it should or has no place to plug into. The Japan engine not having the part the US engine did.

The Japan car may have a different ECM then US. The US ECM is now looking for signals the Japan parts may not be providing.

The results being the Japan engine may not be a direct bolt-in swap.

Find out if the owner compared the Japan engine with the old one in detail. Then swapped old engine parts to bring the Japan to the US condition, as much as possible.

This could have required swapping the intake manifold, throttle with the TPS/IAC valve, sensors-MAP, ECT for ECM, distributor, etc.

Sometimes the US engine has an EGR and the Japan does not. This could require swapping heads or at least doing something with the EGR wiring. The US ECM is expecting to see an EGR which is now not there.

Not much one can do about differences in cams and compression.

Suggest you assure yourself that in the swap the Japan engine was if required modified. This using the old engine parts to bring it up to the point it could operate with the US ECM.

Timing can be easily checked with a timing light.

A vacuum gauge installed on the intake manifold can check for excess back pressure do to a failed CAT. The internet has post on how to do this.

Swapping US engines with Japan is common. However as stated this can require also swapping engine parts. If buying the car, best to get the old complete engine with all the old parts.

Another caveat is Japan engine conditions can range from excellent to poor. There is no guarantee the engine was running OK when removed from the car in Japan.

Assure yourself the issue isn't the Japan engine and its installation before moving on.

Find out the above questions then post back.

Thanks for responding!
The original owner had a head gasket leak in 2005 and it wouldn't pass emissions, I believe her son did the swap? I'm not 100% sure on that one, "Ordered a new engine from Japan" I'm going back today to see if he has paperwork for both the engine and the swap, there's a lot of pine needles on it so I can tell it's been sitting somewhere else for a while. Tapping the Cat it doesn't make any rattling noise but could still be toast. Hoping to check some more things out this afternoon if we get time.

A blown head gasket can mean antifreeze (steam) through the CAT which is bad.

Check receipts for the date of engine purchase. Plus the license plate or registration for the last last time it was registered.

If 2005 was the blown head gasket and now 2017. Find out what happened in between these two dates?

If the area mandates ethanol fuel and sitting for a long time, check for bad gas.

Check oil for color, water, etc.

Also ign system. Plugs, wires, moisture in distributor cap.

Varmints inside the engine compartment doing damage or leaving trash. Sometimes they chew on wires.

Varmints can also get everywhere and urinate. Check interior carefully and give it the smell test.

If still interested, buy cheap! Incorporate into the price a replacement CAT. If sitting over 6 years a timing belt due to age.

If the engine installation was OK and engine at one time ran OK. Suspect fuel, ign, varmints issues, etc. from sitting a long time.