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TPI with code 44

85 Jimmy

85 Jimmy

Sheepdog
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I got a lean code (44) the other day and now my engine keeps backfiring.

I tested fuel pressure which is 42 psi at idle. With just turning the key it'll get to around 55 psi then bleed off to 40 as soon as the pump stops running. Also, with the engine running, when I give it throttle the fuel pressure goes to the mid 50's psi and drops back to 42 at idle.

Where should I look first, the hose in the tank? Fuel pressure regulator?
 
Done the basics already? Good visual inspection underhood, looking for vacuum leaks, exhaust leak, etc? High pressure wouldn't be lean.

You a member over at gearhead-efi.com? This will be your guide: http://api.viglink.com/api/click?format=go&jsonp=vglnk_142290503789911&key=29cc910212b73cceb3979c64a21a012b&libId=275468d1-aa59-4bd3-8d4b-86f7b6ca5aaf&loc=http%3A%2F%2Fcoloradok5.com%2Fforums%2Fshowthread.php%3Ft%3D240425&v=1&out=http%3A%2F%2Fwww.gearhead-efi.com%2Fgearhead-efi%2Fdoc%2FTPIcodes.pdf&ref=http%3A%2F%2Fcoloradok5.com%2Fforums%2Fforumdisplay.php%3Ff%3D81&title=TBI%20Trouble%20codes%20-%20CK5%20Forums&txt=http%3A%2F%2Fwww.gearhead-efi.com%2Fgearhead-efi%2Fdoc%2FTPIcodes.pdf

MAF, you should be able to find the code 44 MAP-specific charts if you need to, but I don't see what other than the MAP sensor itself would be different, the systems operated the same way.
 
Everything looks good under the hood. I need to get a can of brake cleaner or starter fluid to check for a vacuum leak. I do have an exhaust leak at the collectors, and the O2 sensor is after the collector. It's also a 3 wire sensor for my long tube headers.
For some reason I thought TPI needed 55 psi to run right, but Google has proved me wrong.
I'm not a member on gearhead-efi. Also I'm running a MAP sensor.
Can I check voltage at the O2 sensor without using a scan tool?
 
Have to be careful checking voltage at the O2 sensor. Cannot recall the concern (backfeeding the sensor?) but it's not a good idea. It's better to get an ALDL cable and use something like tunerpro RT, especially in your case where you have the 8192 baud rate, which updates far faster than the 160 baud earlier ECM's.

Fix your collector leak before doing anything. Lean O2 means the O2 is "seeing" a lean condition (which indicates it is working), a leaky exhaust forward of the O2 can cause this, you know this problem exists, so fix it and see if the problem disappears.

You don't have to pay for gearhead-efi, register and read the link I sent. It will explain how and why the codes are set...which is the only way you can logically approach it. Of course there is a flow chart so you DON'T have to think, but nonetheless, understanding why things happen will help if something goes wrong and you are unable to reference the manual.
 
dyeager535 said:
Have to be careful checking voltage at the O2 sensor. Cannot recall the concern (backfeeding the sensor?) but it's not a good idea. It's better to get an ALDL cable and use something like tunerpro RT, especially in your case where you have the 8192 baud rate, which updates far faster than the 160 baud earlier ECM's.

Fix your collector leak before doing anything. Lean O2 means the O2 is "seeing" a lean condition (which indicates it is working), a leaky exhaust forward of the O2 can cause this, you know this problem exists, so fix it and see if the problem disappears.

You don't have to pay for gearhead-efi, register and read the link I sent. It will explain how and why the codes are set...which is the only way you can logically approach it. Of course there is a flow chart so you DON'T have to think, but nonetheless, understanding why things happen will help if something goes wrong and you are unable to reference the manual.
Click to expand...

+1 to fixing the collector leak. Chances are high that oxygen is getting into your exhaust and causing a false lean reading.
 
I'll bump this back up.

I fixed the exhaust leaks that I had and I still have a code 44. After clearing the codes and running the truck the code 44 came back and now I also have a code 22. I checked voltage at the TPS and I can't remember right off hand what it was, but either the voltage was wrong or the voltage reading was wrong when giving it throttle.

I checked for vacuum leaks around the intake. Maybe I'm doing it wrong, but this is how we did it when I worked as a tech at a dealership. With the engine running, I spray the base of the intake with brake cleaner and listen for a change in engine speed. Then spray the runners and listen, then plenum, etc. I don't have a vacuum gauge or something like a mighty vac to check for the actual vacuum reading.

It's a speed density TPI, so I'm running a MAP sensor.

One thing to note, with the code 44 I should be lean, but if I give it some quick throttle it'll blow black smoke like its running rich. I'm also still getting a loud backfire when I let off the throttle and if I don't get the loud one, I get the little rumbles and soft pops in the exhaust while I coast. Also, when coming to a stop my RPM's will drop to around 400, then go back up to 550-600 RPM.
 
I think your procedure for vacuum leak testing is pretty valid. I have yet to physically be able to test, but I suspect an unlit propane torch would be a cleaner/cheaper way to test for an idle bump. Make sure none of the hoses at the rear of the plenum are disconnected, those are kind of hard to get at.

You have good gas in the thing? As in not 6 months old?

I'd like to have the 90-92 troubleshooting charts handy just in case MAP has a bit different procedure, but this covers your code 22 test here: http://www.thirdgen.org/forums/tpi/296488-code-22-a.html Note that any time the troubleshooting steps tell you a component is bad, make SURE the wires and connectors are in good shape before replacing the component.

Again MAF for code 44 here, but if you disconnect the MAP and run it, what happens? http://www.misterfixit.com/code44.htm

Your pressure seems good, but I don't remember mine ever spiking...seems to stay constant.
 
dyeager535 said:
You have good gas in the thing? As in not 6 months old?
Click to expand...

At this point the gas is almost 3 months old, but it's only got 1/4 tank now. The last time I filled it I put sta-bil or whatever the fuel stabilizer is because I didn't know how long it was going to sit. Also the last time I took it for a longish drive (about 60 miles), I dumped a can of seafoam in the tank to maybe clean out dirty injectors if that was the case.

It's been a while since I've had the plenum off, but are there fittings on the rear of the plenum? I know there's 2 on the right side, that's where my MAP sensor is and where my vacuum for the A/C comes from. I guess my fuel pressure regulator gets its vacuum from the rear one.

I'm running hydro boost, so I don't have to worry about a leak at the booster.

I haven't disconnected the MAP sensor. I guess I'll unplug that and see what happens when I get home. And just to be clear, your asking about unplugging the electrical connector and not taking it off and plugging the vacuum port, correct?
 
I'm starting to lean towards telling people don't use any junk in your fuel systems. I'm fairly convinced the stuff is snakeoil. I've got ~7+ years on these injectors, truck sits for months at a time, there is no issue. I'd be concerned if the concentration of that stuff is enough, it may cause it's own issues. Speculation, but unknown variables don't help.

Well, rear around the MAP sensor...MAP fitting, EGR IIRC, anything else? On mine those fittings are hard to see.

Yeah, just unplugging the MAP. Going to throw codes (or it should) but reset the ECM (just pull the fuse) then start it and see what happens.

Stick with troubleshooting per the GM methods. MAP vs. MAF only difference I see.
 
Seafoam worked great clearing out the carbs on my new to me bike. Saved me a few hundred on rebuilding 4 carbs. However, it took several tanks and nearly 1000 miles to get there.
 
Maybe I should modify my thoughts...no benefit for injected systems?

Another approach to that, how much was the result of seafoam, and how much was the result of just using new gas? Would be interesting to see what new gas does to the crud that develops in the float bowl from sitting.
 
Alright, I disconnected the MAP sensor and cranked it up. It idled poorly and whenever I blipped the throttle to see if I'd get the usual black smoke, it just died. Cranked it back up and tried to give it any throttle and as soon as you give it gas it dies. That's with the MAP sensor disconnected.
 
If it runs worse without it, good indicator it's at least working right.

I can't find any of the MAP specific code 44 charts. I did see someone mention that if the TPS voltage is incorrect, that could cause this code.

If I were you, I'd be watching ebay for the camaro service manual for whatever year your setup is...obviously 1990, 1991, or 1992. I wouldn't pay over ~$25 for the service and electrical manual set, personally.
 
This thing is starting to piss me off pretty bad.

I checked everything in the link that you posted earlier and everything checked out ok. So just for fun, I checked the TPS again and I had .54v at the middle, blue, wire. Then when I gradually opened the throttle there would be no change in voltage until about have way, where it would jump up to around 2.5v and then immediately go back to .54v and stayed that way until WOT.
So I thought, "SUCCESS it's the TPS". I swapped it out, set it to .54v at idle and at WOT it goes smoothly to around 4.5v. So I cranked it up and it ran great. After it warmed up it started backfiring again at idle and when I'd give it throttle and let off. So I check for codes and there are none.

While looking around I noticed that my header flanges are warped at the head, so I could have an exhaust leak there. I do have another set of headers, but they aren't as long as the current ones, so I'm scared to swap them just to find out my exhaust isn't long enough to reach the newish ones.

On the other hand, I do have a 454 sitting in my shed that I've been wanting to rebuild for awhile now... :whistle:
But that would be way more money, that I don't have to spend right now.
 
85 Jimmy said:
This thing is starting to piss me off pretty bad.

I checked everything in the link that you posted earlier and everything checked out ok. So just for fun, I checked the TPS again and I had .54v at the middle, blue, wire. Then when I gradually opened the throttle there would be no change in voltage until about have way, where it would jump up to around 2.5v and then immediately go back to .54v and stayed that way until WOT.
So I thought, "SUCCESS it's the TPS". I swapped it out, set it to .54v at idle and at WOT it goes smoothly to around 4.5v. So I cranked it up and it ran great. After it warmed up it started backfiring again at idle and when I'd give it throttle and let off. So I check for codes and there are none.

While looking around I noticed that my header flanges are warped at the head, so I could have an exhaust leak there. I do have another set of headers, but they aren't as long as the current ones, so I'm scared to swap them just to find out my exhaust isn't long enough to reach the newish ones.

On the other hand, I do have a 454 sitting in my shed that I've been wanting to rebuild for awhile now... :whistle:
But that would be way more money, that I don't have to spend right now.
Click to expand...

You could also have a vacuum leak under the intake. You need to check vacuum with a gauge.
 
The plenum or the intake base? The only thing under the plenum is a sensor for ambient air temp, but I've sprayed down every sensor, vacuum line, and the base of the intake with brake clean to see if there was a change is engine speed and there were no changes.
 
Another new development is that my fuel pump doesn't turn off after I turn the truck off. I have to grab the relay, then it turns off...
 
Sounds like you have some electrical gremlins you need to sort out, but a vacuum leak could be under the intake where the gaskets are possibly going to the lifter valley etc. But I would definitely check with a gauge and make sure you have no fluttering going on and a steady vacuum is held
 
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If the problem is only warmed up, you can be pretty certain it's something only having to do with closed loop operation. The O2 is seeing (or causing) an issue, when it goes closed loop the O2 is used to start modifying fueling for whatever problem it is reporting to the ECM.

Is your O2 behind your suspected exhaust leak?

How does your relay wiring look? Mine is pretty trashed where the wires connect to the relay plug, they were bare for too far when I got it, so I did something to make sure they didn't short to each other. No idea why GM used a different relay for the fuel pump than what they did for everything else, it seems to be an inferior design.
 
I initially had a leak at the collector gasket, and the O2 sensor is in the reducer, right after the collector. I believe I fixed that, but am not sure if I have an exhaust leak at the heads, which would be before the O2 sensor also.

Could all this be due to a faulty heated O2 sensor?

The harness was brand new from street and performance about 6 years ago, and the wires at the relay still look new.
 
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