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Matt, Mechanical Engineer
Category: Toyota
Satisfied Customers: 20360
Experience:  BEng, Repaired my own cars and others for 20 years, worked in Formula 1 for 10 years
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2000 toyota corolla ce: 1.8l..awhile..slow acceleration the engine

Resolved Question:

Hi, I have the same type of problem with a 2000 toyota corolla ce with a 1.8l engine. On start-up it takes awhile to start, upon slow acceleration the engine rev. ok. Quick acceleration it bogs. The mass air flow , fuel pump, and fuel strainer has been replaced. The timing chain and timing marks are ok. The exhaust is not plugged. Is there any other causes for this condition? (ie) idle speed control...Etc. HELP
Submitted: 5 years ago.
Category: Toyota
Expert:  Matt replied 5 years ago.

This could be 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 around each joint in turn. If the engine rev's up you've found your leak.
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.

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

Might also be worth cleaning out the idle speed control motor / valve 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

Air leaks are very temperature dependent as gaps can open or close up as things expand with heat, so they can be effected by the weather and engine temperature.

This leads them to be quite intermittent in the case of mild leaks

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Customer: replied 5 years ago.
what is the proper way of checking the engine exhust back pressure using a vacuum gauge?
Customer: replied 5 years ago.
Thank you for your suggestion, I will use your advise on the vehicle. One more question, what is the proper way of checking the engine exhust back pressure using a vacuum gauge?
Expert:  Matt replied 5 years ago.

you need to tap into the engine down pipe before the catylst

when I've done this in the past I've gone in through the tapping for the O2 sensor, can't say I've used a vac gauge to do this but a pressure reading of around11-15 psi is about the maximum you should see

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