Found out that the post on the other site that labeled the one part as a regulator was in error - the part he fellow pointed to is, in fact, a #23270 DAMPER ASSY, FUEL PRESSURE PULSATION".

Any suggestions on where I go from here?

I'm puzzling over why just one bank is having problems and not both ... at least according to the scanner.

 

The Fuel Pressure Regulator is attached to the fuel pump and that whole assembly is located in the gas tank, beneath the rear seat. AFAIK there is only the one unit, not one for each bank. You can test to see if you have sufficient fuel pressure at the fuel filter. Factory specs are 44-50 PSI.

There is an factory SST setup to do it, but you might be able to do it by splicing an inline pressure gauge. The dealer should have all of that and should have checked the fuel pressure when you took it in.

The pulsation dampner is indeed that plastic thingie on the driver side of the fuel rail assembly and probably isn't related to your problem.

Chances are the problem is electrical, not fuel pressure related.

 

I know they did check the fuel pressure ajklian. That was something that was considered on the 2nd or 3rd trip and they tested it then.

 

OK, if they checked the fuel pressure and it's OK, then we can probably eliminate fuel as the problem area.

Since you got mis-fires on one bank, and that's Bank 2, the one with the coil packs, it seems unlikely that the coil packs are the problem. unless all three are bad, which would be pretty rare. Since it's the front bank, that probably rules out bad wires.

What you might try, is to get some di-electric grease and disconnect the plug wires from the coil packs. Then remove the coil packs, and the spark plugs. Clean the top metal part of the spark plugs, and the metal spring inside the snout of the long rubber portion of the coil pack. Apply some di-electric grease to spark plugs and the contacts on the coil pack where the wires connect, and put everything back together. Clear the codes, and see if they come back.

Good luck.

 

They tested the coil packs - I recall that. It was one of my first questions for them. I can try the dielectric grease and see if that helps. My wife has her car tonight so I may not get a chance to work on it until tomorrow.

 

Coil packs can test OK with a multimeter and still be bad.
When you remove them to do as Ajkalian suggested inspect the the coil packs with the boot removed from them. The brass nub of the coil pack sometimes arcs over to the side of the coil pack body leaving telltale grey marks on the insides of the coil packs from the brass nub discharging to itself.

I noticed this same thing on my own car when I changed my plugs recently. I didn't think much of it at the time because they also tested OK. Later on I suspected they were causing an intermittent rough idle so I did a test to confirm my suspicion.

I removed the coil packs with the boots, after separating the boots from the coil packs I sanded the tapered part and the very tip of the brass nubs on the coil packs to get a good contact to the spring in the boot. I used compressed air to clean the area aroung the brass nub following the sanding. I then proceeded to pack the space between the brass nub and the sides of the coil pack body with dielectric grease in an effort to stop the arcing by insulating the brass nub and direct the coil's energy to the spark plug via the spring in the boot. After doing this to all six coil packs and installing them I cleared the computer and by the second day of driving the idle was noticeably improved. This is a temporary remedy but it did confirmed my suspicion of the coil pack misfiring to itself. Guess who need 6 coil packs ????

This condition will cause a misfire but wont show up when you test them with a multimeter because the coils are intact, operating properly, and within specs but they are discharging unto themselves instead of to the spark plugs and will cause a misfire and rough idle.

I have pics of this condition on my own coil packs but cannot upload them. when I am able to upload them I'll do a writeup on this.

Good luck!

 

Thank you Le Pew. I'll look into this either tonight or in the morning.

 

Not my pic but this is what I found on my own car and they tested fine.

Check out the link for some similar conditions ... http://www.google.com/search?q=arci...12.0.11265.4.2.0.2.2.0.297.297.2-1.1.0....0...1ac.1.24.img..1.3.297.dMNiAzsf6H4

 

Hello gents,

No trace of arcing in the coil packs under the rubber boot or anywhere else plus nothing looks weird. I put silicone grease on all electrical fittings on each pack including the one in the boot and the top of each plug. The plugs looked normal - not wet or fouled. I reassembled everything and it still is missing. No error codes yet but I can feel the engine missing - still sometimes worse than others.

What next?


Also, I'm tracing down reports of fuel leaking back up some vacuum line from the fuel pressure regulator. Apparently if fuel is coming up the vacuum line, it can cause similar problems.

Here's the URL if you want to read what the original thread said: http://www.toyotanation.com/forum/1...92-1996-1997-2001/430702-1mz-fe-bank-2-misfires-p300-p302-p304-p306-solved.html

Does anyone have a vacuum diagram or can you tell me the vacuum line that I need to check that runs from the engine to the fuel regulator?

 

fuel injector control wires ... maybe?

The fuel injectors have wires that turn them on and off ... controlled by the ECU. If any of these wires have shorted out of become frayed ... maybe due to laying on top of a hot engine part, there might be an intermittent problem.

If you can reproduce the inconsistent firing at idle speed, when you have the hood open, you might get a spray can of starting ether, and manually spray this into the air intake. If the idle smooths out and sounds normal, then you have done something that is probably related to the malfunction.

I guess the main obstacle here would be whether you could reproduce the problem condition, when you are idling the engine, with the hood open.

The only other idea, relating to the fuel injectors, is to see if the connectors and plugs of the ECU are clean and making efficient electrical contact. This would mean disconnecting the ECU plugs, spraying all the connections with electrical contact cleaner, and reassembling.

So have you considered anything like this?

 

Well folks, I'm giving up and taking the car over to a friend who is a mechanic. I'll take this list of recommendations over to him as well.

Thank you for your help!!

 

Hey guys, just to update this thread in case anyone reads it in the future, my problem turned out to be the throttle position sensor (TPS). The mechanic checked and ruled out what he could think of and was very upfront that he wasn't sure. I called a cousin of my wife he who is very good with Toyotas and he recommended I try the TPS. So I did some reading about what it does and the symptoms when it has problems ranging from loss of power to surging when the computer realizes the throttle is open further than last reported. Sounded just like our Camry. I bought one from Autozone today and installed it and problem solved. The part was around $44.

 

Thanks for the update.

Surprised that the Toyota dealers were not of more help.

 

Im having very similar problems with my car but I’ve already replaced the TPS MAF 02 wideband. I’m getting manufacturer codes p1135 and p1155 along with both cat codes

 

Helps if you note what engine you are working on. V6 I assume based on the codes.

 

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