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Ask Amedee Your Own Question
Amedee, Toyota Technician
Category: Toyota
Satisfied Customers: 24123
Experience:  ASE certified tech advanced level specialist. Wisconsin certified emissions state inspector
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Customer Question

Submitted: 5 years ago.
Category: Toyota
Expert:  Amedee replied 5 years ago.
Hello and Welcome to Just Answer. My name is XXXXX XXXXX I will try my best to assist you and your 100% satisfaction is my goal. I have been working on these vehicles for over 10 years so I am very familiar with this system and how it works. However, keep in mind, that I need some solid concrete facts/evidence from you in order to give you a good answer about your vehicle. Please realize that all my answers are based solely on the info that you provide me with....I don't know if you are a tech or a just working on your own vehicle so we may have to fine tune the answer. I only know as much about your problem as you have told me in your post, so my answers will be based on what you tell me so please add all the details you can.

Do you know what the engine vacuum is at idle?

Do you know what type of spark plugs are installed in the engine?

Does the engine seem to run rough or misfire at times? If so, is it more at idle or more under a load?
Customer: replied 5 years ago.

Toyota plugs are installed (all services except this one was done at the dealer --- dealer recommended a new head gasket when there were no leaks --- did a block test. Valves were replaced 50,000 miles ago (4 years).


The engine occasionally gets rough, but nothing to complain about. I do not know what the vacuum is at this time. My co-worker and I were discussing this problem, and he thinks it might be a slight vacuum leak, and I was going to replace all the vacuum hoses for the emission system to make that no longer a possibility.

Expert:  Amedee replied 5 years ago.

Anything that can cause a slight misfire can cause this code to set. A worn engine with low compression. Lazy oxygen sensor, Incorrect spark plugs, worn distributor and many other things.

Add supplemental fuel and see if the engine runs any better. If so, then you just have a fuel delivery concern. Try to identify the missing cylinder. Monitor the O2 sensor voltage at the OX terminal in the diagnostic connector to see if it is showing lean (near 0 volts) at idle and while driving. Verify that the fuel pressure is correct. If just too lean and no vacuum leaks and fuel pressure is good, can check injector ms - look for about 2.7 ms at warm idle. Have had dirty injectors on these too, so try performing an injector service. Verify that this is not an ignition misfire. Perform a compression test to check for a mechanical problem.
Customer: replied 5 years ago.

A compression check was done, and it was fine. Stupid question --- where is the diagnostic connector, and how to do I monitor that?


The reality is this car is 15+ years old, and I simply don't want to spend thousands of dollars repairing what could be something simple. If I start replacing all of these things, it could run into that amount or more. At that point, it's time for a new vehicle. As the original owner, I know how it has been maintained (very well and on-schedule).


What is "supplemental fuel", and is that added in the same method as fueling the engine??

Expert:  Amedee replied 5 years ago.

I know.... I am not telling you to replace these things. I am telling you to check these things so that you don't replace un necessary components.

Supplement fuel would be either starting fluid or propane.

The Data Link Connector is located at the right front side of the engine compartment.

I DO hope you found my Answer to be helpful regarding your vehicles condition. IF SO-please hit **ACCEPT** as you read this Answer, in order that I may receive credit for my time, thanks. BONUSES & Positive Feedback Most appreciated!

Please Note: I receive ZERO Credit until & unless you choose to ACCEPT my well thought-out Answer.


Amedee and 2 other Toyota Specialists are ready to help you
Customer: replied 5 years ago.

Ok ... so where would I add this "supplemental fuel"? In the normal fuel system, or is it something I spray on? I'm a bit confused here, as this is an injection engine.

Expert:  Amedee replied 5 years ago.
You add this right into the air intake. Just unclip the air box and spray either or let some propane go right into the air snorkel leading to the throttle body.

Just be careful., You don't want to add too much at once.
Customer: replied 5 years ago.

Honestly, when the tech told me he wanted to drive it back and forth to his home (45 miles each way), I almost had a heart-attack! He wanted to keep it for 2-3 days (let's see ... 200-300 additional miles on my car, and he gets a free ride back and forth to work). They were "quite sure" these were the problems, but I guess they figured wrong. I should have taken it to a dealer for the repair, but the reality is when you're lied-to without test results over-and-over, you try any available option. Luckily, I did get a good dealership recommendation from an auto upholsterer I have used in the past, and the new dealer has been great. I just don't want to pay for what has already been replaced twice; there's no way to go back and forth between Goodyear and Toyota.

Expert:  Amedee replied 5 years ago.
I hear you loud and clear! Just be sure that they stand being their work. If your paying for a diagnoses, then if they diagnose it wrong, you should not have to pay. If they are unsure of the problem, you bring it somewhere else that has a sharp tech that will be able to diagnose it.

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