I have this problem. Would appreciate any help. Please post or email me at coupe32@swbell.net.

Ok, here we go…..
1989 L-98 6 speed.
139,000 miles
Not blowing any oil. Runs like a champ when it runs.
Replaced:
Mass Air Flow Sensor
TPS, Throttle position sensor
Plugs
Fuel filter
Oxygen sensor (only 1 for this car not heated)
Checked the fuel pressure and its fine or was the day we checked it.

Throwing the following codes:

Lean condition 44
Mass air flow sensor 22 (I believe is the code number) we replaced it first then it started throwing the lean condition code so we replaced the tps next.

The service engine light comes on out of the blue. Stays on for about a minute and then shuts off. This usually happens when we are driving the car and the car is in motion.

Often when we pull up at a light the car will start surging for no reason. Engine light is not on when it starts to surge. It sits at 800 rpm’s when idle. When it starts to surge it will go from 800-500-900 and I’ll put the car in neutral and keep my foot on the gas at 1200 rpm’s just to keep it running. Now if I stop the car shut it off and re-start it no surging.

It does not happen all the time. I’m thinking that when it gets down to ½-1/4 tank of gas. Fuel pump ? I don’t know the age of the fuel pump. Could be the original. When we changed out the fuel filter it was pretty gunky.

Gas cap ? It’s my understanding that with older gas caps when not clicked twice it will throw an engine code. Usually in the winter or when we go from hot to cool condition’s I’ll screw on the gas cap and have it click a few times before I even start the car.

Have used Red Line fuel injector cleaner stuff about every other month for the heck of it.

Vacuum leak ? If so where ?
Ground wire issue ? If so where ?

There was at one point in time a hose blocking the throttle arm hampering it from moving freely. Moved the hose and tightened it down. That was really throwing the computer into a tizzy. If the throttle arm was not moving it was sending info to the computer to give it more gas causing it to throw a “to rich” code and the car was surging like a son of a gun in the driveway. After we moved the hose and tied it down no more issues with the “to rich” code.

This is a phantom problem. It comes and goes when it wants to. Gas mileage sucks as of late. I’ve gone form 28 mpg to 22.5.

So that’s my story and let’s see if anyone on the forum has any suggestion’s as to what’s going on with the car.

Thanks for all your help.

 

FIRST! Buy the book! www.helminc.com

A fair amount of what you posted shows things that were diagnosed wrong or just doesn't make sense.

What did you do to cure the code 44? Did you take the time to trouble shoot the code 22, or did you just replace the MAF because it sent the code? What was the rational for replacing the TPS. It has no control over the mixture.


What code(s) are triggering the service engine light, at these times?


The level of the fuel should have no influence over whether the fuel pump is good or not. Low fuel levels CAN cause problems when driving, but not for tests in the driveway. Fill the tank and sort out all the other problems, before you get to fuel level problems. A fuel pressure gauge will answer your pump questions.


I think it was several years before the gas cap was detected by the ECM.


Yeah! Right! Life should be so easy to have vacuum leaks and faulty grounds diagnosed by "remote control" and even pinned down as to their location.


This doesn't make sense. If the throttle arm doesn't move, neither does the car. At idle, the throttle arm DOESN'T move.

RACE ON!!!

 

Code 22 isn't MAF related. The MAF codes are; 33, 34 & 36. Code 22 is Throttle position sensor voltage sensor low. And if you are having idle problems a code 22 is a good indication of where to start looking.

 

Mine did that, & my vacuum leak was in the vinyl line that runs to the round canister next to the driver`s side headlight.

 

Mine was doing a simliar thing. It turned out my fuel solenoid for my N20 kit was leaking and constantly spraying fuel into the intake. You didn't say anything about N20, but that's what my experience was.

 

Ttt

 

TTT please

 

Sounds like lean exhaust, but it's really running rich. If you have a scanner, block off the air pump hoses to the headers and see if the BLM's go down. If so, it's pumping air to the headers when it should be directing it to the CAT. Suspect the Air Pump Solenoid, ECM or broken Check Valve.

 

ttt thanks

 

ttt thanks

 

I agree with CFI-EFI, but you should check the fuel pump "sock", if you havent already. On these older cars the sock sometimes breaks, causing a clog at the filter inlet. Rust and sediment are the demons in this case, and the pump has to be replaced, sometimes the lines, also. I hope you kept the receipts on all that other stuff, but you will prob need it eventually anyway.
The low fuel deal is usually associated with cornering (as in auto-x), but if you sloshed some crap into your fuel pickup, its possible that its stuck in there.