Tough diagnosis on a Code 44 (lean condition).

[larry bud]

Well, this one had me stumped for quite a while. Was getting a lean code (code 44) on an '86. Not too many mods, fuel regulator, breathable exhaust, cam. When I would get the code, the motor would burp and churn like it was about to throw up. The code would come and and off while driving. Sometimes I'd go 2 or 3 days without any lights, car would work great. Then the next time I'd start it, it'd go haywire.

Started with the O2 sensor, as the wire going to it looked pretty bad. Probably was time for a new sensor anyway. No luck. Then I checked for vacuum leaks, and found the IAC was not tightened all the way. Then the exhaust at the manifold was loose. What the hell, did someone come in over the winter an loosen all my stuff on the car!!!?!?!

Replaced the plus, cap, rotor (which the center conductor actually had a hole worn through it). So tonight, I thought I had it solved. Figured the vaccum leak was doing it, although that still didn't explain the intermittent nature of it. I had thought all along: electrical. It's just the nature of the beast.

So I was going to go out tonight, and a couple miles down the road, engine light, and the car died on me. First time that's happened. Coasted into a side street, messed around under the hood in the dark wiggling wires, etc. Car finally started, and I limped home.

I'm in the garage, the car sounds like it's on its death bed, and I notice the cooling fan relay clicking on and off. That's strange, it should be on 100% of the time... Turn the motor off, and it sounded like everything electrical under my hood was clicking on and off! Nearly every relay AND INJECTOR. Aha! There's only one thing that controls the injectors: the computer!

Pulled the computer, wiggled the wires around, no luck. Pulled the chip and, viola! The clicking stopped. Put the chip back in, and as I wiggled the chip back and forth, the clicking under the hood would sometime start, sometimes stop. I thought it was a broken trace on the board, but I happened to still have my stock chip from 10 years ago. Plugged it in. NO CLICKING. It was making solid contact. I've got a GD bad computer chip! I don't know if it's just not making good contact anymore (I've sprayed it out and will try it later), or if the chip itself has gone bad. Not very typical for an IC to go haywire, though. I took a look at the solder joints on it, and they look fine. Almost as if the power to the chip was intermittent, since ALL the injectors were clicking on and off....

So, I put the old chip in, the car started right up, drove it around for a while and no engine lights (knock on fiberglass). We'll see what happens after it cools down overnight. Hopefully that's all it was!

 

[Edmond]

I would've thought that with that bigger cam, it wouldn't go too well with the stock chip. How does it drive with the stock chip?

 

[larry bud]

Well, it drives without any error codes, but certainly the get up and go isn't the same, even with the lousy hypertech chip I had in there.

 

[MBDiagMan]

Integrated Circuits that are burned in before installation have failure rates much less than 1%. Burn in, however, due to the expense is typically only done for IC's going into critical applications such as aircraft, space shuttle, etc. or sometimes for semiconductor products with production problems, that way they can at least weed out a bunch of bad ones and still sell the rest.

I would say that the chip in our cars doesn't fall into the same safety category as aircraft so I would be shocked if they go through burn in. For IC's NOT burned in the failure rate varies, but I would say it could be as high as 2 or 3%. I worked in a burn in house while going to college so that's where my info comes from.

So, although I expect that failures are rare, they do happen. Also, it is common for IC's or any semiconductor to intermittently behave when they do fail.

BTW, nice troubleshooting job. The key to troubleshooting is sticking with it until you find the problem. You grab it by the throat and don't let go. That's exactly what you did.

Have a great day,

 

[larry bud]

Update: Drove the car all weekend without 1 code being thrown. It's driving great, albeit not as peppy with the stock chip.

 

[Edmond]

Update: Drove the car all weekend without 1 code being thrown. It's driving great, albeit not as peppy with the stock chip.

Larry,

Have you considered having a chip custom burned to your mods? You should contact Jeff, the C4 mods guy and talk to him. He can burn a chip for your specific mods instead of a generic burn like Hypertech, etc... Shoot him an e-mail; I bought a chip from him and was pleased with it.

 

[larry bud]

Yeah, I was reading about Jeff. Looks like a good way to go.