1999 Old Alero SES Indicator Light

[sleeper583]

Hi everyone,

First time poster - long time Alero owner. Lets get the basics out front:

1999 Oldsmobile Alero 3.4L V6 4-door sedan w/approximately 144,000 miles

The problem
I've been very fortunate to not have nearly as many problems as the other Alero owners have had. Of course, it seems that for the time being, fate has caught up with me and now its time to pay my dues.

I started the vehicle and drove 10ft, when the 'Service Engine Soon' (SES) light turned on the dash and started blinking. Acceleration felt very sluggish and was accompanied by what I will term a "rough vibration" from the engine compartment. I parked the vehicle, turned it off, and attempted to restart (and was quickly met with the 'Security' light Passlock issue known to many owners).

After waiting 10 minutes, I restarted the vehicle and this time the SES light remained on. I drove to AutoZone and had the code pulled. P0303 - cylinder 3 misfire.

That night I pulled the spark plug and swapped it with a new one. Then I checked the wires to determine if any breakage or cracks had occured. I found none.

The next morning the problem occured again. I noticed though that as I drove, after 8-10 minutes the SES light would stop blinking, the engine would stop "vibrating" and the vehicle drove much smoother.

Currently I am at the point where I have switched the plugs from two cylinders, and switched the coil packs to determine if the issue follows one of those two items. If it does not, my next guess might be a fuel injector although I'm not sure.

The AutoZone code reader indicated it could be fuel pressure (high/low), vacuum, or ignition (plugs, coils, wires). I'm wondering what I should be trying next, if anything. The vehicle has quite a few miles on it and although I don't want to part with it, she has been a source of problems the past year. The alternative would most likely lead to car payments, and as a fairly recent college grad I am trying to avoid that at the moment.

I'd appreciate any feedback at this point.

[BNaylor]

Welcome to AF.

Did you check (ohm out) or replace the ignition wires especially for cylinder 3? With 144K miles are the wires still the original? Do the easy first before moving on to a possible fuel injector problem.

[sleeper583]

Thanks BNaylor.

I did ohm them out and the value of plug wire #3 seemed close to that of the other plugs. I don't recall the value but I can supply that number later tonight if it helps to diagnose the problem.

The wires currently installed are not the original - I purchased the car with 37k on it. I changed them around 3k miles ago (I believe this would make them my third set - I tried to keep up on the maintenance). The wires are from AutoZone, the plugs are the Bosch Platinum +4.

[BNaylor]

Resistance will vary with the length of the wire but around 500 ohms per foot. You have to be careful with aftermarket parts like ignition wires and running non AC Delco parts on the 3400 engine. These engines run best with AC Delco ignition wires and AC Delco or NGK spark plugs. My second choice for wires is the Taylor Spiro Pro 8mm. Some owners have experienced problems with the Bosch plugs not at initial installation but later on.

We run NGK TR55IX Iridium spark plugs and the Taylor hp wires.

[sleeper583]

Thanks again for the advice BNaylor.

I did try swapping out the suspect plug with a new Bosch plug, but the problem persisted. I could always try swapping it out with a new ACDelco and see if that helps.

As for the plugs, I logged the readings taken with a DMM:
1------2.314 kOhms
2------3.99 kOhms
3------1.976 kOhms
4------3.10 kOhms
5------2.051 kOhms
6------3.01 kOhms

These are the standard wires offered by AutoZone. I'm not sure if they are suspect as I did switch wire 3 and 5 to see if the misfire would follow the wire. I also swapped the coil packs (3 with 4) to see if the problem followed the coil. I then returned to AutoZone to once again make use of their scan tool.

I was met with the familiar P0303 - cylinder misfire detected – Cylinder #3 fault error. In addition to that code, the scan tool detected a second code:

P0203 – Fuel injector circuit condition – Injector #3
According to AutoZone probably causes are indicated below.

• open/short fuel injector(s)
• open/short electrical circuit
• high fuel pressure (pressure regulator defective-fuel return line blocked)
• check TPS and circuit for failure ç What is a TPS?

I guess my question is could the #3 injector (be going/is) bad? When the car reaches temperature (around 6-10 minutes) it seems to be alright. Anyone have any ideas?

Thanks!

[BNaylor]

With the fuel injector DTC revelation I would say or guess the fuel injector is suspect. The TPS is the throttle position sensor located at the throttle body and I would hold off on that and concentrate on the #3 fuel injector issue or replace it outright. Due to the design it is difficult to ohm out the fuel injector coil (11-12 ohms). It has to be done at the big electrical connector by the alternator which is all part of the fuel injector wiring harness. But you have to know what pins and color coded wires go to the respective fuel injector. To get to each individual injector you'll have to remove the upper intake manifold (UIM).

[sleeper583]

A service manual (not a Haynes manual) would probably provide the wiring diagrams complete with color codes, correct? If I measured the resistance of the fuel injector from the connector located by the alternator as you indicated, wouldn't I also be measuring the resistance in the wires? Or will it be quite obvious if the injector is a problem (possible short or open condition)?

Is there any other way to test the injector to determine if it is the faulty component, particularly after removal (maybe apply a voltage across it and look for a reaction?)

I'm no stranger to the IM - I performed a LIM a few months ago. If I remove the fuel rail to access the injector I'm assuming I will have to replace o-rings on all the injectors, correct? I will also need to replace the UI gaskets. Am I missing anything else or is there anything else I should check while I'm down to this point?

AutoZone has a Gp-Sorensen fuel injector:Part Number:800-1087N
Has anyone had any problems with this AM part or should I go OEM or OEM/junkyard?

Thanks again for the troubleshooting assistance.

[BNaylor]

Originally Posted by sleeper583

A service manual (not a Haynes manual) would probably provide the wiring diagrams complete with color codes, correct? If I measured the resistance of the fuel injector from the connector located by the alternator as you indicated, wouldn't I also be measuring the resistance in the wires? Or will it be quite obvious if the injector is a problem (possible short or open condition)?

The GM FSM does show the wiring, pinout, and color coding. The resistance of the wiring to each injector would be very minimal and not skew the resistance readings. As far as voltage checks basically you will have a constant 12 volts on one side of the fuel injector coil with ignition to ON. The other side is goes low when the PCM sends the fuel injector pulse. It may or may or be obvious but the fuel injector appears to be your issue.

Originally Posted by sleeper583

Is there any other way to test the injector to determine if it is the faulty component, particularly after removal (maybe apply a voltage across it and look for a reaction?)

Once the UIM is removed all you have to do is remove the injector electrical connector and test the injector by itself. You could apply 12 volts and a ground to see if the injector reacts or sprays.

Originally Posted by sleeper583

I'm no stranger to the IM - I performed a LIM a few months ago. If I remove the fuel rail to access the injector I'm assuming I will have to replace o-rings on all the injectors, correct? I will also need to replace the UI gaskets. Am I missing anything else or is there anything else I should check while I'm down to this point?

At least the bottom FI o-rings that go to the intake manifold. The top injectors can be left intact on the fuel rail so you would not have to replace the top o-ring. You will need new UIM gaskets. Also, a new throttle body gasket if you decide to remove it but you could can leave that on.

Originally Posted by sleeper583

AutoZone has a Gp-Sorensen fuel injector:Part Number:800-1087N
Has anyone had any problems with this AM part or should I go OEM or OEM/junkyard?

I have no experience with that brand and normally go with Delco.

And you're welcome. Let us know how it turns out and good luck!

[sleeper583]

I took the vehicle to the dealership for another issue, and they pulled the codes and offered the following recommendations. I figure this information can be useful to fellow Alero owners.

The service tech read two codes in the vehicle:
"P0203 #2 INJECTOR STUCK"
"P0300 RANDOM MISSFIRE"

(both of these are as typed from the invoice)

They recommend replacing all six (6) fuelinjectors at a cost of $1237.23.

On a related issue they mentioned that typically the misfire can destroy the oxygen sensor and recommend having that replaced as well. Cost: $265.95

My question is will I need to replace this and where is it typically located? They mentioned it was the "Bank1 Sensor1" if that helps. Would this set a DTC in the system?

The other issue I mentioned (and primary reason for taking the vehicle to the dealership) was an ABS issue. Link (http://www.automotiveforums.com/vbul...rrerid=566028).