1999 - P0301 Code.

[Michael P.]

Any sugestion on what I can check. I have had a major tuneup, replaced the fuel filter, and air filter.

[wiswind]

Missfire on Cylinder #1.....
This is the back (firewall side) passenger side of your engine.
My point of reference is my '96 3.8L.....which is a different upper and lower intake manifold....but many problems in common.

I have had 2 things cause this concern (which the cause turned out to be a cheap fix....for doing it yourself).

1. Could be caused by clogged EGR ports.....
I got a Missfire on #4 cylinder, which is on the front of the engine.....passenger side. Is the only code that I got for the clogged EGR ports. I had new plugs....and filters....so I knew I was OK there. At 135K miles.....I figured that I was due for my first EGR port cleaning. All the ports seem to clog starting at the driver side....leaving the ports at the passenger side open......so the EGR flow is all going to the remaining open port....at Cylinder 1 or 4.....causing the missfire.

The way to tell if this is what is causing your problem.....is to remove the vacuum line that is on the top, front of the EGR valve (located under the throttle body, driver side of engine) and plug it.
This disables the EGR vavle from opening.....drive the car and see if the miss has gone away.....THIS WILL LIGHT THE Check Engine light....as you have no EGR flow when the computer expects it.....
If the miss is gone.....You will need to clean your EGR ports.....which is done by removing your upper intake manifold......and you will see the little roughly 1/4" hole in the lower intake manifold.....for each passageway for each cylinder....


2. If the miss still happens......another problem that I had.....that was very slight.....and gradually got worse until the CEL came on......P0301.....ended up being crud built up on the end of the fuel injector. There is a little plastic cup over the metal end of the injector.....this is where I had crud built up on each injector. I had run fuel injector cleaner.....had a clean fuel filter....the screen that is built into the top of each fuel injector was clean. I am told that any fuel injector with many miles on it with have a buildup at the end.....which is caused by the atomized gasoline meeting the air with PCV and EGR impurities. I removed each fuel injector.....being careful to clean around each injector to avoid getting crud down into the lower intake manifold....and sprayed carb. cleaner inside the cup over the end of each injector.....and that flushed lots of crud out.....it came right out. I did replace the #1 injector....but believe that it was good.....
I had replaced so many things trying to find the problem before it got bad enough to give me a code. I had moved the spark plug (new at 135K) to another cylinder....to eliminate that as a cause of trouble.....Also had new plug wires and coil pack.....which turned out not to be my problem.

I live in the Milwaukee Wisconsin area.....
The Southeast Wisconsin and Chicago area use a unique reformulated gasoline.....
I saw on the news last week....that we were switching over to the "winter formula"....and shops were getting a big increase in cars coming in with clogged fuel injectors......
This was not specific to any particular brand of car.
From time to time.....in various areas......problems can come up with gasoline....fuel injected cars are sensitive to problems with gasoline.

I am not sure if your '99 is covered by the TSB that involves a few things.....like a new valve cover that has an improved baffel to reduce oil getting into the PCV system....and new upper intake bolts...etc. Worth looking into if your are going to be removing the upper intake manifold anyway.

[Rowdysrides]

Wiswind, I would be interested in finding out more about that TSB you mentioned. I have a 96 3.8. Thanks

[wiswind]

The TSB does NOT apply to our '96 3.8L.
The TSB applys to the 3.8L....I think.....1999 and newer.
The Upper intake manifold style was changed in '99.....and that is the one that has the problems for the TSB (bolts, Bolt isolators, gaskets).
Also a redesigned valve cover to reduce the PCB oil being drawn up into the intake. 1999 was a major change year.

[Michael P.]

This may sound stupid, but what is a TSB and is this something that the Dealer should correct?

Thanks

[DRW1000]

A TSB stands for "Technical Service Bulletin". The dealer is made aware of malfunction trends and the approved method of repair comes through on a TSB. More often than not it is a design flaw correction but the dealer charges the end customer to perform the repair.

The benefit is that you do not have to pay for the "hit-and-miss" approach of the mechanic as the problem is common and well known but one can make an argument as to the moral aspects of charging us to make the repair.

Depending on the dealer and age/mileage one may get the dealer to absorb some of the costs and it can be very helpful to do your homework and know the TSB ahead of time so that you can discuss it with the dealer.

A TSB differs from a recall in that a recall is a generally a safety issue and most often the manufacturer is forced to correct the problem and in these instances they must absorb all costs. Liability issues are the driving force behind recalls.