DaveV85iroc305TPI

I just replaced, my o2 sensor with a brand new Bosch. for intermittent code 44(lean exhaust). Usually occurs during idle or driving down a long hill. I have an Auto X-ray and monitored the O2 voltage and sure enough its dropping down to 70, 30, 20 then 0 then stays there at idle and the check engine light comes on and goes open loop. But it only does this intermmittantly, not all the time, but most of the time. When I give it some gas and the voltage pops back up and the and cross counts start increasing again and light goes back out and goes closed loop. Does this indicate a particular problem? As far as I know everthing is stock except flowmaster exhaust, bosch platinum spark plugs. When the exhaust goes lean how does the computer compensate? does it increase injector pulses, or idle air steps or what?. I can monitor these as well as a few other things with Auto X-ray. Thanks for your help.

1985 iroc 305 TPI LB9

Xenodrgn

You know what... something just occured to me, but first... lemme say that I have the same problem... I replaced the O2 sensor and it went away for a while, but at the same time the O2 sensor was replace so was an injector, so I attributed it to that.

However, after aobut 3.25-3 months I just got a code 44 this morning. i must say there is a possibility the O2 sensor is bad because an anti-freeze leaked on it for abot a week and a half, but all things aside...

We're both using Bosch Platinum plugs... I wanna take 'em out and see what happens... I hear that these engines don't like plats very well. If I switch it'll be to Delco's.

As far as the problem goes, make sure oyu have dry gas, make sure the wire isn't grounding out for the O2. No exaust leaks... and you may wanna check fuel pressure and injector pulses. They are all possibilities.

Good luck.

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1985 Camaro SC - 2.8L, auto.

http://www.xenodrgn.f2s.com/Frontright.jpg

DaveV85iroc305TPI

Well, it was happening before I changed from Autolite to Bosch Platinum. The old plugs were dry and gray, I think that is normal. It feels like the car is running better when I did that - more power. anyway I do have a GM repair manual and some things that can cause code 44 are o2 sensor contacting the exhaust manifold( my old one did, there was a burnt insulation shorting to ground at one point)
MAF sensor- My MAF is reading 6grms per second at idle. It seems normal
Lean injectors- I dont have a tester for them. I would think this would be at higher speeds.
Fuel Contamination- water in the gas- I already filled up several times.
EGR- EGR cycles occur at higher speeds and not at idle when I am having the problem
Fuel Pressure- Too low, I would think this would cause lean exhaust at higher speeds.
Exhaust Leaks- Outside air being pulled to the sensor. Is there an easy way to check for leaks?
AIR system air being pumped to the exhaust port during in closed loop - this may be possible I guess. Would it cause it to go all the way to 0 volts though?

I've only had the car for a month and its sets code 44 intermitent ever since I had it so there is no history for me to fall back on. For all I know the car is running worse than its supposed to be and I wouldnt even know it.

Anyway, anyone have any other ideas?

DaveV85iroc305TPI

Today I heard a loud high pitched sound coming from the area of the plenum, or runners. could this be an intake leak? I found out if I gradually increase the throttle the o2 sensor stays low, but if I blip the throttle the voltage jumps up. Whats the easiest way to check for vacuum leak on the intake?

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My 85 Iroc

JoelOl75

You could use carb cleaner or an unlit propane torch. Go around all the seams and when you hit the leak, the idle will change.

Or...(a little more involved) back off all your rockers and block the PCV lines and pressurize the intake through the tb somehow (Duct tape maybe). Maybe even blow cigarette smoke in there...

DaveV85iroc305TPI

I just wanted to post the resolution here in case it helps some one else. the problem was a blown throttle body gasket. Replaced that and took care of the code 44 problem. Thanks for all the help.

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My 85 Iroc

88TAJeff

Hi Dave, What do you mean by a "blown" throttle body gasket? torn/ ripped? I also have a code 44 after doing a cam swap. The gasket kit I got came with what appears to be 2 throttle body gaskets. Why is this?
Are there different throttle bodies or something? or am I supposed to use both somehow?
Thanks, Jeff

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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams 08-408-8, everything else stock

DaveV85iroc305TPI

Blown gasket means air was forced internally out wards, there was a big visible rip in the gasket. Possibly caused by backfire. You only need one gasket. There are two different types of plenums. one as the triangle shaped hole on the bottom called an idle air passage, the later model plenums do not have this. If you use the wrong gasket you will accidently block the the idle air passage. the idle air passage is used on 85 to 88 TPI's. If you dont have it you should use the binocular style (2 holes) gasket.
Hope this helps

88TAJeff

Thanks, Dave. Looks like I used the right one.

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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams 08-408-8, everything else stock