myLexRX

1999 GS400 with 90K miles:

I was driving to work this morning and suddenly the car (engine) started shaking pretty badly and “check engine” light came on blinking.
I was late to work and needed to continue driving but as I would step on the gas pedal, it really felt as if it lost 80% of the power. It would accelerate slowly and continued shaking.

I never had any issues with this car and did a 90K service 2K miles ago (including plugs).

Please help.

Thanks a lot.

carbongs

iTrader: (13)

my guess is that it is either a blown coil pack, af sensor, or maf sensor. a lot of times if any of these items is not right the motor will jump into limp mode. that's what you are feeling with the 80% loss of power. it is so that you don't tear up your car. try to get it to an autozone, or somewhere they can scan the obd for you. it should tell you exactly what is wrong. good luck.

sockfocks

iTrader: (1)

Throttle position sensor is suspect too.

myLexRX

thanks guys. I'll take to Autozone tonight.
The strange thing is that the car is jumping terribly and I am watching the RPM and it stays in 400 to 600 range. I would expect it to fly up and down.

salimshah

You did not lisk any light come on.

Also, would you do something different once the you get the code dump or still go to the dealer. If you are going to end up at the dealer, why drive around and create a need for a possible tow/flat_bed.


Salim

myLexRX

Salim:
I did mention that a “check engine” light came on blinking. It would disappear for a 1-2 mins and would come back blinking.
I'll try to get the code out and get the part to my mechanic.

I was just wondering if anybody has had this issue or know why this is happening.

Thanks

JeffTsai

iTrader: (1)

Sounds like some part of your throttle assembly. Either a sensor or actuator. The car will go into limp mode if the ECU doesn't get the correct readings. When that happens, basically you're going to be stepping on the gas and nothing will happen until you reach the last 20% of the pedal. It will feel like the pedal is limp or dead.

myLexRX

I took it to Autozone and the code was P0304 - misfire cylinder #4. I had replaced spark plugs 2 months ago and I wonder if the problem relates to that.

I have an idea where cylinder #4 is located but I would appreciate if someone else tells me its location.

Thanks

gserep1

Cylinder #4 is the second cylinder from the front on the passenger side.
The cylinder arrangement is like this:

Driver side front near radiator Passenger side front near radiator
1 2

3 4

5 6

7 8


The 6 cylinder engine has all 6 cylinders in a row from front to back.

1

2

3

4

5

6

NOTE
If you have changed the spark plugs just recently, then usually that is not the problem. However, you should ask yourself:

1. What kind of plugs were put in? Hopefully you used stock plugs, not anything like Bosch Platinums, which in my opinion don't work as well. (I may get some flack for saying that).

2. I assume that you have the 1UZ-FE V8 engine.

3. Remove the coil directly over cylinder # 4 and remove the spark plug and inspect it. If it is fouled with gasoline, chances are the coil quit firing, or it shorted out to ground in some way. Clean it or replace it, being careful to note the plug gap, and taking care not to crack the porcelin when installing it

4. Inspect the wiring on top of the coil for cylinder #4. Make sure the electrical connector was fully attached and connected. There should be no loose wires that prevent the coil from firing properly.


5. Look real close at the coil, both at the top, and along the rubber that goes down the tunnel to the top of the spark plug. IF the rubber is ripped, worn out, or there are holes along the side, the spark is firing along the tunnel and shorting out before the spark reaches the spark plug. Although this in not common, it is possible and I have seen it on other vehicles with coil that go down into the tunnel (what I call it) on top of the spark plug...(pentroof design heads). If the rubber is cracked or has a hole in the side of the coil, it will have to be replaced. Each coil sells for between 80 and 100 dollars.

NOTE: A "FLASHING" check engine light indicates a severe misfire, and should be investigated and repaired immediately. It is an immediate cause for concern.

A normal "steady on" check engine light indicates the car is in "limp-home" mode, and the car wil drive somewhat normally until the car is fixed. Though not advised, some people drive with this light on for quite awhile.

Hope that helped!

GSEREP1

ElitistK

iTrader: (4)

wow great job gserep1.

myLexRX

Thanks a lot gserep1. I'll take a look at it today.

PetesLS400

I'm willing to bet its a FUEL INJECTOR.

tl.nguyen

iTrader: (5)

An easy way to find out if the coil is bad is to take the coil out of cyl 4 and put it in another cyl like cyl 5. Drive and check the codes to see if it miss fires in cyl 5. If it does then that coil is bad. Just replace it and thats it. Saves you a pretty penny. One or two coils usally go bad around the 100k mark. Hopes this helps.

e-man

Hey GSEREP. How does a spark plug get "fouled" with gasoline? Can you explain what that means? Thanks.

e

myLexRX

The problem is fixed.

It was a bad COIL. My mechanic had a used one and once he replaced mine everything started working properly. The funny thing I had to show him where cylinder #4 is.

Thanks to all for you help.