Check Codes 41 and 42 on a 307 "Y" Engine

[YellowLark]

Took my '83 Riv out for a Saturday run which went bad after about 8 miles, and limped home with two new error codes to deal with.

The car suddenly flashed the Check Engine light, bogged down and stopped. Started right up, but with a top speed of about 20 mph. Except, there were several times where it sped up as normal, but then quickly went back to "limp home" mode.

Codes 41 and 42 refer to ignition problems where the spark timing can't function, and a basic ignition mode must be used. Code 41 has changed over the years. But, for a carbureted engine like the 307, code 41 says there is no reference pulse from the distributor to the ECM at a certain vacuum.

Code 42 follows this by saying that the spark timing can't function because its circuit is grounded or open. Also, that a bad HEI could cause this.

There is a long checklist of what the causes might be. But, have any of you dealt with these errors before? Being pointed in a likely area would be very helpful.

[JohnD1956]

This sounds like contaminated gas symptoms. Is it possible the tank was left lowere than half tank for a period of time with wide temperature swings? If so you may have condensation inside the tank and pulled some water into the carb. This likely confused the oxygen sensor.

Had this issue last week with my work truck. Ran good to the first stop then the check engine light came on and the vehicle would not respond to the accelerator pedal at all. Granted this is an 07 truck with major programing differences, however, after two restarts the gas pedal worked again, and I was able to drive to my next two stops ( approx 20 miles and 30 minutes). After the third stop the check engine light went off and the truck has run correctly for the last three days.

You may want to try some gas additives, dry gas for the water and some marvel mystery oil in the gas for some topside lubrication. These are no garantee fix but an inexpensive attempt which can't really hurt.

[YellowLark]

John,

I just filled the tank from empty last week, and even added 20 oz of Techron to it.

But, I had just washed the car, and wonder if water may have gotten into the distributor.

The problem path for this appears to be with distributor components or associated wiring.

I'm learning that a primitive computer system like the 1983, is a very limited advantage. It can do some good things, like controlling the carburetor's air/fuel mix, but it sure lacks the detailed diagnostics of today's cars.

Maybe tomorrow I'll find the solution....

[51dyno]

I would start with a new fuel filter,you said emty to full tank ??????? Was this after the storm,many stations opperated with low tanks???????????????

[YellowLark]

51Dyno,

The check codes are for the distributor not sending pulses to the computer, which, in turn, totally controls the spark. Without that input, the engine then runs in a "limp home" default mode.

While fuel issues are always suspect, I'm pretty certain that this particular problem is ignition-related. Now, if I just figure out what it is.

[rick60]

I agree with Yellow Lark. I have an old diagnostic manual that would be of use to you. Email your address to me at rln31455@yahoo.com and I'll send it to you. The charts are simple to follow. It won't take long to diagnose the problem with the correct diagnostic charts. it could be a pick up coil, ign module or wiring problem. The only way to find out is to follow the charts. It is easier than you think!

[NTX5467]

BE AWARE . . . you need to use a code chart for a 1983 model GM vehicle ONLY! Some of the codes changed on a yearly basis, from model year to model year. One advance with OBDII was common codes rather than what we had previously.

Be sure to check the detonation limited (knock sensor) wiring. When that system activates, it retards the ignition timing until the engine will die, or the detonation signal stops. The check for this is to take a wrench or similar item and strike the exhaust manifold while the engine is running. Repeated taps will result in a stopped engine . . . just as if it had a knocking main or rod bearing. If the wire to the sensor might have grounded out, then there will be only basic timing and "no power" (which the Olds 307 does not have an abundance of anyway, by observation). On the Chevy small block V-8s, it screwed into the rh block drain plug hole . . . not sure where it might be on the Olds V-8, though.

In checking and using trouble codes for diagnosis, you still need to know the basics of how everything works together. One malfunction can result in multiple codes being stored in memory, especially on the newer systems. Fuel system performance issues can act very similar to ignition performance issues . . . just as in the "analog" days. Therefore, reading and understanding what can cause a particular trouble code is important . . . sometimes, reading between the lines.

Back when several auto supply chains offered free code checks, they'd print out a list of the parts needed for each individual code . . . with the intent that you'd purchase the parts from them. Many times, customers would call to inquire about what the codes were (to the parts department, rather than the service department). I'd advise them that they really needed to bring the car to us and let us put the GM Tech __ diagnostic tool on the vehicle to see what was really going on. It would cost them 1/2 hour of labor for this. Otherwise, they could chunk parts (and $$$) at the car and not get anything really fixed OR not know which part fixed it. At the time, we had some good techs that were good stewards of the customer's money, in this respect. Of course, if it didn't work, it would result in a mad (former) customer. AND it could be something else that was throwing the code, which might otherwise have not been discovered by the DIYer.

Now, you might counter that as I was paid on parts dept profits, that it was in my best interest to promote bringing the car to the dealership. Unfortunately, over the years in the business, I've heard all kinds of stories of people who took their cars to private shops and they either couldn't get the light to go out or find the problem. I also knew that we had the latest GM diagnostic equipment and techs that knew how to use it . . . PLUS look at all of the codes FIRST to design the best strategy of what was really causing them. I also knew that our techs were well aware of the importance of Customer Satisfaction, at that point in time. There was also open communication between them and the service writers, at all times, which is needed in that sort of situation. There were some private shops I knew of that did great jobs, too, but I also knew of many that didn't have the diagnostic tools. Plus, if I knew that the particular vehicle had come into the shop, I'd check to see what the ultimate fix happened to be. If I was going to recommend our shop, I wanted to make sure that things happened as they should have.

Just some thoughts,

NTX5467

[YellowLark]

NTX,

Thanks for the advice. I have a 1983 Buick Chassis Service Manual, which is where I'm referencing the codes.

There is no knock sensor on a 1983 307 engine. The V6 turbo had them.

My diagnostic tool for this ALDL system is a paper clip, and counting the blinking of the "check engine" light. High tech for 1983

Earlier, I checked the pulse wire coming out of the distributor with a dwell meter, and its perfect. And, now I just drove about 10 miles (circling my neighborhood) with no problem.

So, the question now is whether to trust that this won't re-occur far from home? If the ignition module or the coil went bad, would that be intermittent, or permanent?

[NTX5467]

HEI coils can fail if they are not grounded. There's either a "wire" ground strap or a sheet metal ground strap which attaches to one corner of the coil "square".

HEI modules can fail due to heat, as in if the dielectric silicone grease is not put between the module and the distributor body when the new module is installed. I don't see any intermittent issues in modules, though. Or, as in the case of my '77 Camaro several years ago, I took the distributor cap off to look at things and touched the inner part of the top of the module . . . it moved slightly, so I cringed and put the cap back on immediately. "No Start". This would have been an age issue, though.

Both the coil ground and module heat issues don't happen too soon, but after time.

What might cause an intermittent would be the pickup coil mechanism.

What kind of condition is the distributor rotor and the spring-loaded carbon contact, under the ignition coil? We used to see rotors with the center contact burned away, which generally resulted in an "engine stop" situation.

What about the condition of the spark plug wires? Years ago, on an '80 Chrysler I bought, it would go into limp-in mode sporadically and unexplainably. When it did that, the idle would get a little flakier than normal, but when I would try to accelerate, it would run very rough. One day, it did that while I was on the opposite side of town from my shadetree shop and where I kept the car. I drove it back, in limp-in mode, as it would do good to crest gradual overpasses at 45mph in 2nd gear. It also used a phenominal amount of gasoline, too!! When I got it back, I didn't dare turn it off, so I raised the door and drove it inside, THEN I turned it off, glad to be there, finally. I then tried an immediate re-start and it ran perfectly as the computer had reset itself (this resulted in a "You DUMMY!! Why didn't you do that earlier???" moment). Later, I was going to check #1 spark plug. As I gently pulled on the spark plug wire boot, it came off a little too easily, leaving the clip on the end of the plug. THAT was the problem, I suspected. Every so often, the engine would probably vibrate a certain way and it would cause a misfire, which would then send a voltage spike back through the system and signal the limp-in mode to activate. I reattached the clip to the wire's conductor, gently slid the insulator back into place . . . end of problem. Prior to that, I'd checked all of the engine and wiring grounds I or a Chrysler tech friend could think of, to no avail.

Another time, we had a GMC pickup in the shop which had an intermittent "engine stop" situation. It had been "everywhere" in an effort to find something wrong, but everything checked good . . . as it didn't stop with the particular techs. One of our techs found a flaky connector in a terminal block for the distributor. He re-terminated it and reinstalled it. I then drove it about 100 miles one Saturday afternoon, with no problems. THAT might be where you end up on this deal. There is a special tool to compress the "springs" on the terminals to get them to slide out of the connector block for inspection. Usually, these connectors are stocked in their special tools section for the service department (no GM parts numbers that work, other than for the complete pigtail repair harnesses) . . . there is an online pictorial color representation on these that can possibly be accessed via ACDelcoTechConnect.com. Some of the terminal blocks have the "weather-tite" construction and can be unsnapped for repairs/inspection. These will have the multi-rib rubberized plastic seals where the two terminal blocks mate.

Thanks for the advisory and updates.

NTX5467

Edited September 5, 2011 by NTX5467 (see edit history)

[Guest pfloro]

YellowLark:

Since your car did 'limp home' with no EST advance (electronic spark timing) from the ECM, I would suspect your primary & secondary ignition systems are OK. However, a complete check as NTX5467 suggested makes a lot a sense.

However, I would also disconnect & reconnect the 4 terminal connector in the EST harness near the distributor as well as the connections to the HEI module within the distributor. Even a slight amount of oxidation can disrupt the flow of electricity in these low voltage/low current circuits. While you're under the hood, it wouldn't hurt do the same for ALL the other ECM components (TPS, MCS, VAC, O2, coolant temp sensor, etc.)... None of these contacts are gold plated and the harsh temperature & moisture conditions under the hood over the years will cause oxidation.

Go so far as to disconnect the negative battery terminal, and 'break & re-make' the two big connectors to the ECM board inside the car.

Because this problem is intermittent and setting error codes, this may very well be a poor connection issue in the EST circuit... Over the 27 years I've owned my '84 Toronado, I have had CCC issues which boiled down to oxidized connectors.

Keep us posted,

Paul

Edited September 6, 2011 by pfloro (see edit history)

[Harold]

I had an '89 Buick Century with a Code 42 issue that no one could diagnose. I found it myself one dark rainy day. When I opened the hood, there was a spark jumping from one plug wire to another. A set of wires cured it. Hope this helps.

Harold