Vetster88

This all started a couple months ago, I went on a 116 mile round trip journey. At mile 38 the fuel mileage dropped to 15 cruising 70 mph... then it started bucking hard in overdrive, downshifted n went. figured it was dumping fuel for whatever reason, after a few miles the check engine light came on. I hit the next exit and pulled the code that would forever change my life for the next few months.... CODE 44 "lean Exhaust". "HUH?? not possible... I cant be getting HORRIBLE mileage on a lean system! Makes sense its dumping fuel but it shouldnt be lean in that case" Anywho, I called up the local parts house and ordered up an O2 sensor, had the girlfriend run pick it up at closing and meet me half way. New O2 sensor in and it ran GREAT.. for a mile then Check engine light and bucking like crazy.

After I got home I put new plugs in it thinking that when it was dumping fuel that it fouled the plugs, two were fouled.

(father passed away)

A few weeks later I was home and having to deal with this again, I picked the car up from the shop and they said they couldnt figure out why it was. The alternator went out the next day, replaced it, but still the fuel mileage was crap. I picked up another MAF and it made the car run WORSE!! If you revd up to 1500 and to 2300 it sounded like I was on a rev limiter with a nasty sbc. WTH, so I change it back to the old mass air flow... I had another ECM so I tried it, IT THRU CODE 44!! Hmmm... Checked the O2 sensor.. IT was loose... Tightened it back up.... VIOLA 32mpg... for 6 miles then it was back to 12mpg.

OK ok O K... Im missing the simple picture, its not electrical its mechanical?

I ohmd the injectors just to be safe
1-15.4 2-15.6
3-15.4 4-15.7
5-15.4 6-15.7
7-15.4 8-15.7

not where I hoped theyd be but all are the same... SO its not an injector coil problem either.

Maybe its just the fuel filter? I changed that less then 12 thousand miles ago, not a fuel pump problem its new after the fact, and I double checked its pressure 45 psi strong. (Holds psi after shut down)

IT doesnt always want to start unless WOT, has a hard time maintaining idle... IAC? Dont think so because it still bucks while cruising. It gets up and runs about 90% as fast as it did before the problem. It doesnt slide the rear out on its 1-2 shift like it used too. I have NO problem driving it (excluding the bucking) but 12 mpgs no matter what cruising speed is spooky.

I Have done:
ECM swap
MAF swap
spark plugs
New O2 sensor
Ohm'd injectors
Fuel pump

FYI: IM NOT throwing money at this!! It looks like it but it's all covered.

Im at my wits end... Code 44 is beating me senseless....

What are your ideas, thoughts, hopes and prayers accepted

Thanks in advance
~Dane

AGENT 86

Do you or someone you know, have the ability to scan with Datamaster or similar. Maybe that would shed some light.

SunCr

With the fouled plugs, sounds like it's dumping fuel it doesn't need which can be caused by air getting pass the O2 that didn't come through the MAF. Try clamping off the Air Hoses to the Check Valves at the Headers and see what happens OR remove the Check Valves to make sure they're in good shape OR remove each Header Hose with it running and there should be no air flow once in Closed Loop.

Check compression; particularly at #7 - coolant in small amounts leans out the mix - the affected cylinder is lean; everything else will be rich.

tehcarguy

go for a ride with the fuel pressure gauge taped to the windshield. I had the same problems with mine, it had good pressure at idle and rev, but when I put a load on the engine it dropped to 12 psi.

mcm95403

I just went through this on my 84. Then 2 days ago, my o2 sensor litterally fell apart. Replaced it and everything is fine now.

I didn't notice a year stated for your Vette - that might help us help you.

bczee

I had a code 44 on my 84 Z28 Camaro for a while, tried many thing to resolve. But I finally swap out the O2 and so far, it has not returned.. monitoring it, have not driven the car much.. so I am hoping..

Check your O2 and its wires again..

WW7

Just because parts are new doesn't mean they can't be defective..WW

tehcarguy

Exactly I experienced this with a fuel pump...which led my car to behave exactly as yours is

Vetster88

Dropping it at the shop tomorrow to see what they say.

Vetster88

Plugs were new just a few hundred miles ago, doesnt mean anything now. It rained the last two days so no chance to get the clamping checked out.

learn something new everyday with the coolant bit.

Vetster88

new pump with a solid psi reading

Vetster88

1988

Vetster88

O2 is new, it some how loosened up, I retightened it and it ran great w/32mpg for 3 miles then fell flat on its face with 12mpg at 70mph

Vetster88

Im with you 100%, i wonder sometimes wonder if that new O2 isnt a dud to begin with i'll learn more tomorrow hopefully

Vetster88

The local shop said "there is no signal coming from your O2 sensor."

So I replaced it again... Same thing.

I looked harder and saw a plastic clip melted to the exhaust manifold (drivers side), I tried to follow the O2 conduit but my hands are not that small

I'm going to chase the O2 wire and see if its fried, chaffed, or what.

Any "Typical" problems to look out for?

mcm95403

I hate tracing down wiring stuff like that! But at least know you know for sure where to look. Good luck with it!

Vetster88

IT appears to have been a blown fuse... Makes no sense but I love it!