I have a mild code 44 problem. I have changed many things on the engine in an attempt to fix the problem but all to no avail.

The symptoms are as follows. Runs great when first started until it warms up enough to go into closed loop. Then if nothing else is done the check engine soon light comes on and it runs a little rougher. If you drive the car the code will usually disapear if you accelerate quickly to about 45 and won't come back until you stop at a light and idle for about 30 sec or more. again once you start off again the code will usually go away. The code only goes away when driving it will not go away when just reving up the engine in park. The exhaust does smell a little rich so i'm thinking the engine is not really running lean.

Would an incorrect base timing cause something like this (off by only a few degrees)

I have elimiated the following possible sources of a code 44

: o2 sensor (changed many times)
: MAF sensor
: IAC valve
: TPS sensor
: fuel presure (checks fine and pump was replaced a month ago
problem was there before pump replacement)

My car is a completely stock 86 camaro 305 TPI all the emmisions control devices are still in place and connected. Although many of them are quite old. The AIR pump was replaced when i first purchased the car about 6 years ago.

Any help or ideas would be appreciated

 

86/305,

You have already addressed most of the common causes of the elusive '44'. There are a few more things you can check to solve the problem:

Double-check all the engine and ECM ground connections. Meter for resistance between the left exhaust tube and a good engine ground in case the exhaust is no longer solidly bonded for some reason.

Make sure there are no exhaust leaks, including the A.I.R. injection tubing, hoses and check valves.

Check the operation of the A.I.R. injection system. Make sure the PORT solenoid is not energized when the ECM is in closed-loop. Make sure the PORT valve itself has fully closed and that the injection pump is not dumping air to the manifolds instead of the cat converter. Any minimal air leakage at low load/idle ranges can set the '44'. Probably the easiest way to eliminate this possibility is to remove the A.I.R. hoses from both check valves and tightly cap the valves to seal them. It may take a bit longer to reach closed-loop, but you only want to do this for diagnostic purposes, fix the problem, then reinstall the hoses.

Make sure your injectors are flowing fuel at the relatively short duty cycle at idle RPM. This can be nearly impossible unless you remove the fuel injectors, but a fuel pressure gauge and injector test set (even like a cheapie Actron CP7819) can fire the injectors while installed and you can get a crude idea of the flow of each injector. If one or more is low, you may need to have them cleaned and flow-matched.

You can try setting the TPS to the upper limit at idle, or 0.61VDC. That may coax the ECM into a bit more fuel delivery at idle, but is really a band-aid and should be done as a diagnostic step only. Incidentally, the meter you are using to set TPS IS calibrated, is it not? It should be, since the signal level is so small that a minimal difference can have a major impact.

Another thing you may or may not be aware of is peculiar to the 1986 TPI cars. That model was the first year with the Bosch analog MAF and new 1227165 ECM, so there was no experience other than a few factory test cars upon which to base these parameters. It seems that the engineers programmed allowable parameters and variables that were too tight for some TPI engines. While there was no recall, there is a factory TSB (# 86-6-GAS-66) regarding the problem. Several issues were addressed, including false error codes for the MAF, lean/rich mixture, TCC lockup, rough idle, hesitation, etc. The problem was not addressed until October of 1986 - after the end of the model year. Thus ALL 1986 TPI engines are suspect. I installed the upgraded EPROM in my ‘86 and noticed an immediate improvement, even though I wasn't experiencing any of the listed symptoms nor error codes.

Hopefully one of those will get you closer to the solution, or at least eliminate some more possibilities.

Get any ice yet this year? I've got a buddy that lives in Jackson (well, actually Ridgeland, but close enough.) If you see an old guy with a spare tire and curly hair named Dave, tell him "Pig said 'Hey'." And make sure you ask him "You ain't from around here, are ya, Yankee?" He'll know exactly who to chew on.

 

OOPS! I forgot....

Welcome to ThirdGen.org!

 

In addition to what vader said (all great advice!), here's a few shots in the dark.

Have you done any recent engine work using non-sensor safe silicone and maybe something is outgassing and killing sensors? Just a guess. What brand of O2 sensors are you using, and does the problem go away for a while when you switch O2 sensors?

It sounds like the sensor is having a difficult time staying hot enough to read the AFR, or their is raw air getting into the exhaust somehow upstream of the o2 sensor at low rpm/idle.

 

Ooh! Excellent point. I glad you were able to catch that or I might have him chasing his tail forever. I'd completely forgotten about the dead sensor/RTV issue. I guess I just presumed we're all aware of that, and you know what happens when we assume...

 

I have no RTV problems as far as i can tell. The only substance used in the installation of the sensor is the anti seize compound that the sensor manufactuer's include on the threads of the new sensors.

I have used factory GM sensors, and the Bosch replacement that autozone sells. Right now i think it has a GM installed.

An additional piece of info that may be helpful:

When the check engine light is on and you put the car into diagnostic mode the check engine light flashes open loop.

I haven't had time to check any of the things listed in the previous posts yet. Been very busy this close to christmas.

Any and all help is appreciated

Stephen

 

It woudln't be RTV just at the sensor - RTF used anywhere in the engine that wasn't sensor safe can cause the problem - for example, even as far 'up' as the intake manifold.

good luck, i think when you try some of the above ideas you'll probably find your problem!

 

I finally got a free weekend to check out the suggestions on how to correct the code 44 i keep getting.

I double checked all the ground connections with my ohm meter and both the engine, and the body read parctically zero to each other and to the negative battery terminal. So it doesn't apprear that i have a bad ground wire.

I checked the driver side exhaust manifold, and from the manifold to engine ground and from manifold to body ground also read practically zero.

Finally i checked from the sensor case to engine and body ground and also read the same practically zero.

I checked all around the engine and can find no visual or audible sign of an exhaust leak anywhere. All the AIR hoses look just fine and all the connections for the hoses are tight.

I Haven't checked the injector flow yet because i have not gotten the needed test equipment yet. (how likely is it that this may be the cause of the problem?)

What would be a good source for replacement injectors that are reasonably priced and reliable?

Do you have any more info on the Technical service bulletin you mentioned or a place i can obtain the replacement Eprom from?

I know of no RTV in the engine that could be killing the sensor but i will replace it once more to see if it helps (i haven't had any engine work done in over a year that would use RTV.

This problem is very annoying in that it will run just fine then when stopped at a light it will idle rougher and the check engine come on (only code 44 stored) and if put into diagnostic mode while the code is set the sensor flashes open loop.

Any more suggestions would be appreciated

Stephen Edmonds

 

there's still several suggestions above that are worth a try, such as disabling the A.I.R. system. You might also try disabling the EGR system if somehow it is leaking vacuum into the system.

At this point you'd benefit greatly from a real ALDL data stream monitor. Do you have someone who can lend you one? Perhaps you can use craig moates' free software and build the cable?

 

I did disable the AIR system by capping the check valves that go into the exhaust manifolds and capping the lines that fed them. No change was noticed in operation or the problem.

As for the EGR system. I have replaced the valve about 3 years ago and have checked the diaphram in it recently which is good (no vaccum leaks here) I also replaced the EGR vacumm solonoid about 2 years ago to correct an EGR error code. I have not tried disconnecting the valve completely yet. Do you think that might have an effect?

I don't have access to an ALDL Monitor. I can build the cable you mentioned but know nothing about how to use the program in diagnosis. I also don't have access to a laptop. So i may have to seek the expertise of someone with a Monitor, but i have not had good luck finding good mechanic help in the past.

 

If your car is completely stock then you have the emissions. First thing I would do is take the air pump belt off and drive it a bit. If the problem goes away then look at the air diverter solenoid. What could be happening is the valve doesn't shut off and at idle or coasting there is too much air and the O2 sensor sees a very lean condition. It then richens up the INT and the BLM and when that doesn't work it goes into open loop or limp. I would check the valve that controls the drivers side valve first. Sorry I started typing before reading all the posts so you have already input on my thoughts
Rob

 

I disconnected both the AIR lines going into the exhaust manifold and caped both the lines to the manifolds and the Air Hoses that fed them. I did not disconnect the line down to the Catalytic converter. I think this would do the same as taking the belt off the pump since it would prevent the dumping of air into the manifold before the O2 sensor. If there is something else in the emmissions system i need to check please feel free to post a response or email me directly.

 

You say the exhaust smells rich, does it smell like burning oil?

 

It doesn't smell like oil to me. And i would hope its not an oil burning problem since its a brand new GM replacement engine (not a rebuild) with only about 7500 miles on it.