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Discussion Starter · #1 ·
Okay, this question is actually about the wife's Camry, it is a 6 cylinder if that helps at all. She starts fine, idles rough. If you mash the throttle, she accelerates alright, but still kind of sluggish... (for a Camry) The car is acting almost like one cylinder is firing. I am thinking an injector is clogged. Distributor cap and rotor look fine, timing is set right, new plugs. Getting on the highway is fine, till you reach cruising speed. Then it sounds like she is gonna come apart. Shake, rattle and all. Sometimes I smell fuel, sometimes not. I have had issues with it running rich. Accordian hose is new, Coolant temp sensor is new. Vaccum lines are all new. I need some help and suggestions. I plan to work a bit the next couple of nights and then really get after it on saturday. Oh yeah, no check engine light or codes that I can find.

Thanks guys.
 

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have you replaced you're spark plug wires recently?
 

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Yeah, check spark plug wire resistance (in Ohms), including the "high tensel" cable running out of the igniter to the dizzy cap. Check primary & secondary coil resistance. Check for fuel pressure at the rail; That can rule out the pump and/or filter. Remember that you may have spec. pressure, but not volume. Check for an intake manifold vacuum leak.
These; if bad, can all lead to a decent idle / poor acceleration symptom.

If you do think its an injector, with the car on start pulling spark plug wires (one at a time, then put it back and move to the next one). If the idle stays the same, then you know you have a problem with that one cylinder.

After that, we can move on from there
 

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Discussion Starter · #4 ·
I am almost certain that there is not a vaccum leak. The accordian pipe between the filter and the throttle body is only 7 months old and came directly from Toyota. I replaced all the vaccum lines at that time. The fuel pump was replaced maybe a year ago. The cap, rotor and wires are all about 4 years old, with maybe 30,000 miles on them. I was having a problem with hard starting about a year or a year and a half ago. That is when most of this stuff was done. Turned out it was the fuel pump and regulator going bad at the same time. Both were replaced with new items from Toyota. I replaced the valve cover gaskets, the intake gaskets, the throttle body gaskets, just about every gasket on the top half of the engine. I don't think a vaccum leak would cause the racket at speed that I am hearing. It sounds like a broken rod. That is the only thing I can think of to relate it to. At highway speeds(60 mph+) it gets a really bad vibration. It could be a combination of a bad injector and bad motor mounts. One cylinder not firing right could cause the vibration that then is magnified by bad struts and a bad dog bone torgue strut. I mean the steering wheel chatters and shakes some fierce once you are at highway speeds. Nothing really noticeable when accelerating or at neighborhood speeds(> 35 mph) I plan to tear into it and if I can't figure it out I may let her drive the cressi for a while.
 

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Well, a leak at the accordion pipe would be known as an "air leak".
There is no vacuum inside the accordion pipe, vacuum is created at the throttle plate. So everything before the throttle plate is an Air Leak, and after is a Vacuum Leak. Just an interesting bit of info.

Now... if you say it acts up at 60mph+, I would look into a "load" related problem. And again, I would fall back to the ignition system as the culprit. As engine load increases, so does strain on the Ignition system (equally).
This happens because more air is being stuffed into the combustion chamber. More air= more resistance that the spark must overcome to jump the plug gap.
So if you have ANY deterioration in any of your wires... the spark WILL arc to ground (manifold / block / etc) because electricity ALWAYS takes the path of least resistance.

This would be most noticeable at a hard acceleration... so try that next time you drive it.

A rule of thumb is:
Ignition system problems get worse with Load / RPM
Small Air & Vacuum Leaks (also burnt valve) problems smooth out with RPM
Fuel system problems can go either way depending on damaged component.

Is it difficult to get down in there and measure injector resistance on that car?
That can measure the physical condition of the injector's coil.
The only other way would be to pull the injector and flow test... and that's a PITA.

Also, inspect your EGR system thoroughly.

The reason I asked if it was an intake manifold gasket is because a few weeks ago my car had this BRUTAL bucking problem at highway speeds. I thought everything you did at first. All my vacuum lines were brand new too, so I threw vacuum leak out of the possibilities. I took off the intake manifold and the gasket had a huge tear in it. It was sucking in mass amounts of unmetered air, and the ECU couldn't compensate with fuel trim or timing to obtain stoichiometry.
 

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If you pull the spark wire one by one and found no change, disconnect the fuel injector one by one. My friend's V6 camry had a simialr problem, turned out to be a clogged injector.
 

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The spark plugs should give you an idea of what's going on in each cylinder right? I showed my plugs from my truck to the Master Tech I work with (how two of them looked didn't match the pics at the back of each Haynes manual). #5 and #6 the insulators were orange almost all the way around on them, but they were new plugs. He said this was a sign of dry firing. The plug simply heating compressed air.
 

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The spark plugs should give you an idea of what's going on in each cylinder right? I showed my plugs from my truck to the Master Tech I work with (how two of them looked didn't match the pics at the back of each Haynes manual). #5 and #6 the insulators were orange almost all the way around on them, but they were new plugs. He said this was a sign of dry firing. The plug simply heating compressed air.
Dready, you are correct. You can read spark plugs for efficiency much like reading tire tread for alignment. Golden insulator is an indication of overheating.
Basically... when fuel is atomized, it takes heat with it (and out the exhaust)
Much like how steam removes heat from the water, you may not be getting proper atomization in cylinder #5 and #6, (or enough fuel).

I'm not sure about other manufacturers, but the newer Fords will run pig rich when the engine is starting to over heat in hopes to cool down.
Once it reaches a predetermined temp, the engine will start dropping cylinders to get ambient temp air "pumping" through the exhaust to carry away heat. And if none of that works, the engine will shut down on its own.

On the flip side, you have a cold start injector.
As the atomized fuel enters the cold combustion chamber, it condenses (forms droplets) and sticks to the cylinder walls. And as we all know, its vaporized fuel that is combustible, not fuel in its liquid form. So the CSI will add more fuel to compensate for condensed fuel.
 

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Discussion Starter · #9 ·
Spark plug wires. That is what it was. Changed them out, now everything is fine. I did check the resistance of the front bank of injectors. They were all running about 15-16 ohms. Manual says that they should be about 13.4 to 14.5 or something. They will probably need cleaning or replacing shortly.
 

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Spark plug wires. That is what it was. Changed them out, now everything is fine. I did check the resistance of the front bank of injectors. They were all running about 15-16 ohms. Manual says that they should be about 13.4 to 14.5 or something. They will probably need cleaning or replacing shortly.

Glad to hear it's running again.
Now I need to get some new wires... haha
 

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Well, a leak at the accordion pipe would be known as an "air leak".
There is no vacuum inside the accordion pipe, vacuum is created at the throttle plate. So everything before the throttle plate is an Air Leak, and after is a Vacuum Leak. Just an interesting bit of info..
If it sucks it's vacuum. If there is a leak after the AirFlowMeter but before the throttle plate, it's going to suck in more air than was metered and run lean.
 

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If it sucks it's vacuum. If there is a leak after the AirFlowMeter but before the throttle plate, it's going to suck in more air than was metered and run lean.
Yes it is being sucked in, but it is classified as an "air leak" because the throttle plate is what's supposed to create vacuum in the intake.
In a properly sealed accordion pipe, there is no vacuum.
In a proper operating intake manifold, there is vacuum (unless its a diesel).
If you were to drill a pin whole in the accordion pipe, the velocity of the air entering the engine (and passing the pin whole) would create a vacuum because the air outside of the pipe is under a lower pressure, and wants to equalize (by entering the pin whole).
That being said, yes it is technically entering under a vacuum, but it is correctly identified as and "air leak".
A "vacuum leak" (in automotive terms) is correctly identified as being after the throttle plate.
 
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