Injectors?

[dafeeder]

After searching many Threads, I couldn't find the answer to some of my questions.

My 1996 3.1 Lumina is running rough. Codes were pulled with P300 and P134 showing up.

In the last 3 years I have replaced Fuel Pump, Cat, all ICM's, new plugs and wires, just replaced fuel filter, cleaned injectors 3 times in the last 3 years, 1 being about 6 months ago when I put new LIM gasket in. Recently ran a bottle of B-12 Chemtrol and a bottle of Heat, but neither seemed to help.

Questions:

1. Can you check the injectors without pulling the pelnum?

2. How do you tell if the injectors are good or what voltage should they have?

3. What should the Pressure be at the rail and should the engine be running or turned off?

4. Should the pressure stay up for a long time?

5. Can I run the engine with the Pelnum off, so I can disconnect each injector for testing?

6. Where is the cheapest place to buy new injectors or should I just have them rebuilt? How long does it take to rebuild them?

Any suggestions other then testing the fuel pressure at the rail?

Maybe I am way off base and it's not fuel related but I have changed a lot of the most suggested things over the last 3 years.

[maxwedge]

Running rough too broad a description, do you have a dead misfire? If so isolate the cylinder by pulling one plug wire at a time unitl there is no change in engine rpm or idle quality. Then focus on that cylinder, the code says random, but that can be misleading.

[dafeeder]

Originally Posted by maxwedge

Running rough too broad a description, do you have a dead misfire? If so isolate the cylinder by pulling one plug wire at a time unitl there is no change in engine rpm or idle quality. Then focus on that cylinder, the code says random, but that can be misleading.

I pulled the front 3 plug wires one at a time and the engine wouldn't start when I pulled the 2 and 3 wires on the front left side.

When I pulled the 1st plug wire on the front left side, it didn't make a difference in how the engine ran and the engine would start. I am not sure what cylinder that is. Would that indicate a Valve or maybe an injector? I took the plug out and the gap was at about 62. I regaped it at 60 and went back with it, as the plug looked fine.

What is a dead misfire? My car will start and even cruise at 60 mph, but it won't hardly idle and the engine is missing going done the road. Engine light also flashes.

[jeffcoslacker]

Get a $25 vacuum gauge and make sure you didn't break a valve spring or toss a rocker before you do anything else.

If it's mechanical engine fault, it'll show as a sharp, profound drop every time it misses. The needle may even chatter.

If it's pretty steady it may be just a spark or injector issue.

[dafeeder]

Originally Posted by jeffcoslacker

Get a $25 vacuum gauge and make sure you didn't break a valve spring or toss a rocker before you do anything else.

If it's mechanical engine fault, it'll show as a sharp, profound drop every time it misses. The needle may even chatter.

If it's pretty steady it may be just a spark or injector issue.

Bought vacuum gauge and ran test. The test showed a steady reading(no fluctuation) near 14, which is near the 15-22 range that was in the vacuum gauge information. I also checked the fuel pressure at the rail and it tested 41, which is in the 41-47 suggested range.

The engine still is missing. I am leaning toward a injector since I have fixed about every other thing on this car over the last 3 years. I am thinking about sending all my injectors to Mr Injector for $16 a piece, just to rule that matter out. Anything else to look for before I tear into the injectors?

[maxwedge]

How do you know it is an injector?

[dafeeder]

Originally Posted by maxwedge

How do you know it is an injector?

I don't. Over the last 3 years I have changed a lot of the known issues the 3.1 seems to have, but I never changed any of the injectors. I am just trying to eliminate things at this point. I originally thought the front left spark plug didn't make a difference in the way the engie ran when I pulled the plug wire off, but it did today. I am sure it could be a lot of things. Do you have any suggestions?

[maxwedge]

Pin down the cylinder by the method I suggested ( which youy are doing), get a tach on the engine to determine the rpm drop when each cyl. is disabled, then you can focus on the cylinder.A high line scanner can do a power balance test also.

[dafeeder]

Dumb question but I have to ask. Since I can't get to the back plug wires very easy, can I just pull the plug wires off the ICM, one at a time?

[maxwedge]

Yes, careful here as that spark can jump a large gap.

[dafeeder]

Originally Posted by maxwedge

Yes, careful here as that spark can jump a large gap.

How do I test a coil other than swaping with 1 of the other 2 to see if it's good? All coils were put on new less then 3 years ago but it appears I have a bad coil and I didn't buy the LLW coils.

Update:

Old coil tested under the range so bought a new coil. New coil didn't stop the misfire.

[dafeeder]

I guess Injectors are fine.

After coaching basketball and going to a State Track meet this weekend, I finally broke down and took the ICM in to get it tested. I was dumb and didn't take the ICM in when I tested the Coil, but was in a hurry. Of course it only takes an extra 5 minutes to take the ICM off with the other coils. Autozone has a neat tester to test the ICM and it tested bad, so since no bone yards were open on Sunday a 6PM, I dropped a $100 bill(tax included) for an ICM(LLW or another 100,000 miles).

3.1 started up and runs great again. Only 156,000 miles and I am planning on driving it another 100,000. Just like the posters said, test, test, test. I put a fuel filter and Coil on I didn't need. Also bought a vacuum I might never use again, but it probably did tell me the engine was fine. The key find was lack of spark on a couple of plugs. Also fuel pressure tester Loan Tool from Autozone verified my fuel pump was in good shape.

Total cost to fix:$165 plus fuel to get parts. Anytime one of my cars goes to the Auto shop, it's usually $300 to $500 to get it back, so probably saved $150, plus I doubt their ICM would be Lifetime Warranty.

ICM - $100
Coil - $25
Fuel Filter- $10
Vacuum Gauge - $25
My time - Free(shouldn't be)


Thank you for all your input.

[mrslawrence]

This sounds like the problem we are having with our 98 LTZ (Lumina). I drove the car to and from work all week without a problem. My husband started it tonight and heard a "POP" sound followed by a puff of smoke from the engine. Engine immediately died.

I came out and restarted the car. It would only stay running if I had pressure on the gas pedal. Subsequently, after a few times revving the engine, it stayed on by itself but idled up and down almost sputtering. The interior lights fluctuated with the engine. We drove it around the block and while the gas was being pushed it drove alright. Did notice the brake stopped working altogether.. the pedal got stiff and wouldn't be depressed at all.

My question: What is an ICM and does anyone think this could be my problem? I'm super dooper broke (with a mini van that needs front end work) and would like to hear about cheapest fixes first...

thank you

[dafeeder]

Lose of Brake with engine missing, sounds like a vacuum. Autozone can check out the Ignition Control Module(ICM) and coils for you and they all come off real easy. I would do a search under loss of brake or vaccum.