Code 44 lean exhaust / Fuel injectors

[yellow3800]

1989GT 5spd sets code 44 one min after NOT >1200rpm ; code shuts off if engine returns to idle , returns after conditions above met again.

is there a diagnostic tree other than check O2 sensor ref voltage?

Realizing ign components may set this, I suspect fuel inj. because this whole mess started when I'd hit ~2500rpm and open the throttle slowly from there, the car would bog down slightly [no engine codes at the time], after 2 bottles of fuel inj. cleaner tearing the driveability of the car down to heel-toe just to pass a stop sign, it runs smooth now, but code 44 is left, and my gas milage drops from ~30mpg to 20mpg.

CPS okay
O2 ref voltage okay
ign module okay
coils okay
plug wires at 40% of lifespan [12k ohms on a 3' wire] so are fine
platinum plugs 20k miles ago and are still fine
tps checks on resistance meter to be clean and smooth as it is wound up / dwn
wire harness seems to be in great shape, and all connect wires check 100% had 2nd tps laying around that I tried - also fine, did not change a thing

IAC - can this go bad and NOT set a code? I suspect its not the healthiest in the world but heres its story, other than ref voltages are in spec , and I've not yet seen a code from this:

when throttle stop is backed off all the way, car is fine until NOT, after NOT, it won't idle itself, and it does idle high and pulses like a bad IAC, SOMETIMES, but may iron itself out, and again, no code, so I don't think its going to correct the problem - problem is code 44 setting at driving 50mph at 2krpm, not idle, so I'm ruling this out for now.

I hear the GTs eat fuel injectors. say this one has 140k miles on the car, I say thats not too aweful bad, so is it a possibility? Is there a maintenance interval on these?

So I removed the plenum for gasket inspection on way to check injectors. Injectors fire fine at full 12v input under pressure. Now, I did not check partial operation visually. ...Put new o-rings in , re-installed old injectors and moved on.

code still persists.


Andy

[Mr. Beefy]

Why the hell would you do all that when the code 44 is a lean o2 reading??? You said that you have a good reference signal TO the O2 sensor, but did you test the sensor itself? Replace the O2 sensor.

As far as hearing about 3.1mpfi's eating injectors, I have not had a problem before(90GT 3.1 with 146K on it when I got rid of it, 88GT with 156K on it when I got rid of it, and the 88GT(current) with 79K on it. I have a spare engine that had over 250K on it that I gave the injectors to a member on bstuff for his 3400 swap and he had no issues with them.

[2nejunkie]

ANDY!

Has this car been sitting? Maybe it has bad Gas in it. My GTZ (OBDII) did that to me after the swap for a few hrs. Never checked the code but it started to bog down at same rpm. I dropped some HEET and a full tank of the Good stuff. Cleared right up.
You have piks of this 89 GT. 89 needs a 3400! lol

[Cliff8928]

I've had a ton of bad injectors on my 2.8s. The symptom is that the injector coils short out and the car will stall when hot. No other adverse symptoms.

Also, I would second the sensor replacement just to make sure. The rated lifespan of the oxygen sensor is only around 30,000 miles.

[Money pit Beretta]

Not all cars are the same, but I had 213K on my 3.1 and the injectors never gave me any trouble. I may be way off on this, but it sounds like an EGR problem. When was the last time you cleaned out the port on the intake? With it out of gear does the light come on when hold the throttle open above idle?
O2's are cheap for your car and I'd do that anyway.

[yellow3800]

I did not check the O2 sensor. Its been replaced inside of 30k mi [about 7k ago] , and is not setting its code 13 [or is it 31?] anyway, I've only got the code 44 here. It did cross my mind, but I'm not a parts replacer [thought it could be the IAC but I don't have a code for that either]. Around 2k rpm , engine code or not, the car runs rougher than the rest of the engine speed range [which is why I suspect injectors].

I've run 3 bottles of fuel inj. cleaner through it... each time, it seems to help except the last time. I want to pull the injectors and soak/clean them with carb cleaner inside/out, top / bot. A friend told me about a fuel inj. rehab site:

http://www.deatschwerks.com/catalog/inj ... rvices.php

I haven't looked long enough to figure if its worth servicing the injectors on a dialy driver b/c it looks to be a performance site, but the option is there!



Car has not been sitting, its the daily driver.


Code sets when above 1200 rpm for one minute [as the book states for code 44], and is intermittent... code often clears when returning to idle rpm only to return after >1200rpm after a minute or two, such as back up to 60mph in 5th gear...

thanks for helping me think thru this guys!

...and yes, $80/ per injector at advance autoparts totals the car, lol. so putting a 3400in makes sense! lol because I could get one for the same amount of money!

andy

[3X00-Modified]

http://www.witchhunter.com is a little cheaper for injector service... I've used them and had someone else use them for a Daily driven Camaro, injectors came back looking brand new.

Very good company and rather quick turn around times.

[SuzukiGhostRider]

I would be leaning more towards a clogged/failing EGR valve in this case than an O2 sensor. O2 would give sufficient problems to be very noticeable at idle too, believe me. However, that said, replace it, it's time it sounds like. But , yes, pull your EGR , clean it well, and the port it attaches to and check your throttle body for build up as well. GL.

[yellow3800]

Got my fuel injectors back!

They weren't the best, but it did improve the situation.

Code 44 persists. Rough spot at 3.5k rpm, and my 2nd TPS did not change anything.

EGR checks okay too.

I find it hard to believe I could have two bad TPSensors. Could this be the ign module? getting weak? maybe coils? coils do spec. out okay...

Andy <--- lacks code 44 flow chart

[yellow3800]

Still eliminating EGR tested okay, I decided to see if I could bypass it...

I disconnected the vacuum line and plugged the Throt. body.

Took rpms to that 3.5k rpm dead/skip spot and it wasn't there.

The passages were clear, so I'm not sure why this was happening, and the actuation is like new...

doh whell, NO CODE.

NO CODE!
NO CODE!

Thank you for the help, I did a quick test drive reaching NOT, so we'll hope the egr doesn't set a code from a plugged vacuum line on a long drive in the future.

and what a smooooooth throttle!

Andy

[Cliff8928]

You won't have any issues with EGR codes. Mine hasn't had one since the 3400 swap and I've never got a code.

[yellow3800]

I guess not - do have a 13 now though... thinking its because all the egr does is lower exhaust temps by creating a higher intake air temp [exhaust air into intake manifold]

I think my oxy sensor is okay though, my guess is that its reading out of spec due to high exhaust temps...

I'm going to start a new topic on that one after a bit of research as to see who removed vac line to egr

andy <-- can't wait to see what gas mileage comes!
89GT , fuelinjectorconnection.com serviced injectors [smooth as silk]
bypassing egr sys