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I have a 99 Honda Accord v4 that I did an engine swap on,

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I have a 99...

I have a 99 Honda Accord v4 that I did an engine swap on, the motor before the one I installed ran like dirt and had milky oil inside. The idle revs up and down on its on so i took it to the smog shop and they said it was this and that and nothing solved the problem. They finally came to the conclusion it was the ECU but i want to make sure of that before I do install another computer but then my concern is how will i program the Key to turn the car on once i do swap out the ECU

Mechanic's Assistant: Is the car in "Park" or "Neutral?" Do you know if your car has a "wheel lock" feature?

Neutral, it starts and run. Its a 5 speed manual

Mechanic's Assistant: Are you fixing your Accord yourself? What have you tried so far?

Yes

Submitted: 1 month ago.Category: Honda
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Answered in 4 hours by:
3/21/2018
Mechanic for Honda: Matt, Engineer replied 1 month ago
Matt
Matt, Engineer
Category: Honda
Satisfied Customers: 22,896
Experience: Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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Hello and welcome to Just Answer

It is possible that the ECU is faulty but you are right to be concerned about the consequences of swapping it out as it will need 'coding' up to match the rest of the security system on the car as the modules will send a 'handshake' to the ECU that has to match before it will all wake up

this can be done but you need dealer level software to do it

although this chap seems to think it can be done by swapping immobilser chips about

https://www.youtube.com/watch?v=u0NB_zT_oMU

this isn't something I'd recommend as its very easy to cook an ECU with static or overheating with a soldering iron

90% of the time the better option is to send your existing ECU off for testing / repair

that way its still coded correctly

so I'd get in touch with one of these firm

https://modulemaster.com/rebuilds/

http://www.autoecu.com/

http://www.ecudoctors.com/

http://stores.digitalautotech.com/StoreFront.bok

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Mechanic for Honda: Matt, Engineer replied 1 month ago

My goal is to give you the best advice that I can and I hope that I've helped today. Please remember to rate my service by selecting from the 5 stars at the top of the screen before you leave. If you need more help, use the reply box to let me know.
If you're not pleased, also let me know because rating bad does not result in a refund, there are better options. Rating now will not close this post nor prevent further replies
Thanks Matt

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Customer reply replied 29 days ago
is there a way to diagnose the ECU to make sure thats what's faulty before I send it out?
Mechanic for Honda: Matt, Engineer replied 29 days ago

can you tell me what parts were already replaced by the smog shop?

as it sounds like you'd already tried checking for vacuum leaks, and replacing the MAF and MAP sensors, cleaning the throttle etc?

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Customer reply replied 29 days ago
It says they put 4 new spark plugs, wires, distributor cap, distributor rotor, ail filter, 1 fuel pressure reg, Idle speed control.
and 02 sensors
Mechanic for Honda: Matt, Engineer replied 29 days ago

Ok

If its not already been done then I'd check for an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane or brake cleaner around each joint in turn. If the engine rev's up you've found your leak.
Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.
Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

Air leaks are very temperature dependent as gaps can open up as things expand with temperature so depending on how the leak occurs ( on a hose joint with a clamp expansion will help seal and on a vacuum hose expansion will make a leak worse) so leaks can be better or 1 vacuum leak path that you won't find with the above test is if the brake servo is leaking
so try clamping off servo hose to see if this has any effect

It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine

Might also be worth cleaning out the throttle body as these get clogged up with carbon and some brake cleaner washed through helps free things off.

Might also be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick fault find if you unplug the meter and run the engine without it.
if the engine condition is the same then chances are the meter or the connection to it is faulty

It’s also worth cleaning the MAF sensor wires, as they can get coated with dirt over time which then offsets the reading
Use some contact cleaner or brake cleaner to spray onto the wires to remove the dirt – on no account touch the wires with anything as they are very fragile

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Customer reply replied 28 days ago
i retrieved the codes on the Honda Accord and it comes up with P1121 and P0325. I want to go ahead and tell you that before I swapped the motor, the car had the same issue. But when I pulled the Motor from my other Honda Accord the Engine ran perfectly like a charm.
Mechanic for Honda: Matt, Engineer replied 28 days ago

Hello

OK those codes relate to throttle position not where expected and a faulty knock sensor?

so it would be worth while swapping the throttle body over or at least the position sensor from the old engine and also check that the knock sensor is plugged in

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Customer reply replied 28 days ago
The knock sensor I new
Customer reply replied 28 days ago
The old engine had the same codes before I swapped it out
Mechanic for Honda: Matt, Engineer replied 28 days ago

Ok then check that the wire from it and into the loom isn't damaged

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Customer reply replied 28 days ago
What’s te loom ?
Mechanic for Honda: Matt, Engineer replied 28 days ago

Hello

loom = wiring harness

sorry its british english term rather than american english

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Customer reply replied 28 days ago
Its a single wire right?
Mechanic for Honda: Matt, Engineer replied 28 days ago

Hello

the knock sensor should be a shielded 2 wire harness ?

it may look like a single wire from the outside but inside the wire sheath there will be 2 wires

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Matt, Engineer
Category: Honda
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Experience: Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.

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