89 custom cruiser lurching even at half throttle. No problem revving in neutral. When under even light load it starts to surge or lurch at about 40mph when attempting to accelerate. Still showing codes 15, 21, 44. Would that be the tps? Seems like it's starved for fuel. Please help.

 

Little more info please. Did this just start all of a sudden or has it been progressing a little at a time.

 

it's been getting progressively worse over the past few days. I initially only noticed it at wot. Now you can feel slightly at about 1/3 throttle i guess. If i stomp on it it all but dies now.
thank you

 

Any exhaust restriction? got a clogged cat converter?

 

exhaust seems to be flowing okay. Had some leaks i took care of about a week ago. Running rich though, so maybe. Probably filled up 3 times in the last week. Used 93 octane every time. Have noticed an old gas smell coming from it at times. Hoping it makes ot to and from work tomorrow. Will change fuel filter over the weekend. Hoping that helps. Dont really have a means to drop tank at this time. Wasn't getting any flow through muffler initially. Changed donut and patched some holes throughout tail pipe. Seems to be flowing well now. If the cat was clogged would it run well in park/ neutral/ under no load? No hesitation at all unless in gear.

 

So it is showing low coolant temperature, is it getting to temperature? If the sensor goes bad, it reads -80 or so and goes pig rich. Do an ohm test on the sensor, super high is bad. The TPS could be going. With the key on, engine off, there should be a 5 volt wire, a ground and the actual sensor wire. Should be .5 at idle to around 4.5V full throttle with a nice steady climb as the throttle opens. The lean O2 can be tested running with a voltmeter. By AC Delco parts if anything is faulty.

 

Hit the Cat with a temp reader most stations have them

Mine was also doing that and seem to run fine at idle. Is the floor over the Cat hot that's what I noticed.. Clogged Catalytic

After replacing the Cat there was a significant improvement

 

thanks. Will keep that in mind. May just lop that thing off and run a new tailpipe.

 

Two easiest ways to check for plugged exhaust.
first using a vacuum gauge watch vacuum while you rev the engine parked. The reading should drop close to zero and then climb back up as rpm stabilizes. If it goes low and stays there you have a restriction. Second less technical way is to remove the egr valve and watch how the exhaust flows out of the port in the intake. If it has a really strong flow at idle you have a restriction. When i say strong flow i mean loud and alot of soot. Normally if you start it with the valve off you will have minimal flow at idle.

 

Thank you. I will check flow with eqr valve removed prior to cutting off catalytic converter.

 

With the egr valve off you will have a pretty big vacuum leak but with the choke set it should stay running.

 

thanks. It has some trouble starting in the mornings. Still coming up with code 44. Replaced the coolant temperature sensor earlier and it stayed off this time. Think im gonna try to change out the O2 sensor again in the morning. May take a hammer after the cat to see if it improves. Still didn't pull off the egr valve. Would excessive pressure still be apparent after it warms up a little? A new cat from rock auto was pretty cheap if that ends up being the problem.

 

Well something is definitely causing the o2 sensor to read lean still. Finally got it changed. And if the sensor os over compensating then that would cause the clog at the cat. Still haven't changed the tps. Its running a little better but still acting starved around 40-50 mph at about half throttle. Was doing it at quarter or less. Really starting to think its not getting enough fuel.

 

Did you change the fuel filter?

 

There's a very detailed troubleshooting flowchart in the Chassis Service Manual that tells you how to diagnose the cause of a Code 44 (and any other MIL code) without buying and replacing a lot of unnecessary parts.

Just sayin'

 

yes sir. I should have purchased one by now and plan to soon. Can't hurt for sure.

 

no sir. Seems like a good place to start, but i wasn't sure where it's located. Thought it was in the carb. Cant really get under the car to see if it is there. Are there multiple filters?

 

It is in the front housing, paper filter and spring, where the fuel line meets up with the carb. Get a 5/8" line wrench and hold the housing nut with a 1" wrench to prevent twisting the fuel line. The brake line wrench gives more grip with two extra sides over an open wrench. It happens often, I have done it and nearly every Olds I bought, came with a pretwisted fuel line. There is only one fuel filter unless someone added an inline filter.

 

traced line from tank and then remembered id worked on a quadrajet before. Was a decent fight, but i ended up finally being able to loosen the rigid fuel line from whatever block that is down by the compressor. Fought the other end at the carb longer until finally getting it loose. Filter was gross and clogged. Put it all back with a new filter knowing i needed to seal the threads... Cranked it up and has a small leak. Tool it all back apart and put some thread sealer on all three fittings being careful to not get any within the id of the fittings. Threaded everything back by hand and then tightened everything carefully. No leaks, no starving engine. Working well at WOT too. Still idles high due to tps, but that is a weekend job i hope. She really is running much much better. No more lean condition being reported. Im glad it isn't the fuel pump yet. Thanks for the help everyone.

 

You shouldn't have to put any sealer of any kind on the fuel line nut. It is not what does the sealing. What seals is the flared end of the fuel line compressed aagainst a tapered fitting. Check both surfaces to make sure they are clean and smooth. I personally wouldn't drive the car until you fix the fuel line connection properly.

 

all the fittings looked to ha e thread sealer on them already. I cleaned them all and used a small amount of sealer that is rated for gas. It didn't look like any of it had ever been tampered with, but i am often wrong. What would the sealer hurt as long as it didn't get inside the fuel line or filter?

 

Sealer won't hurt anything if its' kept outside the flow area except goober up your threads. As previously stated, flare fittings do not require any sealer on the threads to work. It will do nothing for any leak. Sure, with enough goop you can mask the problem at best but usually it will still leak because the nut and tube have a specified clearance. Threads don't do anything so any teflon tape or sealer there doesn't do a damn thing. The nut is simply a follower to clamp the flare fitting tight to the flared seat of the fuel block/pump/carb. If you have found sealer there, someone else was there before you and didn't understand how flare fittings work. You'll find no sealer there from the factory.

Sometimes to get a good seat is to ensure the flare mating surfaces on tube and seat are clean and free from dirt/junk and smooth and undamaged. Also ensure the tube goes into the seat area as straight as you can get it. Don't try and force the flare to seat by grinking down the nut to force it. You may damage the flare and it will never seat. Snug it tight, loosen it a bit, then snug it down tight again. You may need to do it a couple few times but usually this method has rewarded me with a leak-free seal first time out.

If it's not leaking now- Great. Don't mess with it any more and no need to go back and remove any sealer or tape you applied unless it leaks again.

 

You will be fine, the sealing is done by the little clear plastic seal at the end of the housing.

 

i guess thinking about it, i understand. If its a compression fitting then the seal is at the mating surface and dependent upon seamless alignment amd the nut and threads only work to compress the fitting so doping the threads is rather pointless except maybe as a sort of lubricant for tightening. Thanks again everyone.

 

Perpetual advice for drivability problems on computer-controlled vehicles:

1. Verify fuel pressure, especially under load.
2. Connect a scan tool, LOOK AT THE DATA STREAM. What takes hours to verify with a multimeter and vacuum gauge, takes five minutes with a scan tool. You can view coolant temp, O2 voltage, O2 cross-counts, fuel trim, knock sensor activity, vacuum, TPS, IAC, and more in seconds--once the tool is connected.

Of course, all the usual "tune-up" issues need to be checked--fouled plugs, dead plug wires, faulty cap/rotor, plugged air filter, stuck EGR valve, base ignition timing, timing advance, etc.

I don't doubt that the catalyst has failed, but that doesn't generally involve "lurching". A plugged catalyst will decrease horsepower and RPM, but typically it's a smooth decrease--the vehicle won't go over "X" RPM or MPH, and it's progressively sluggish below that RPM/MPH. The proper answer is to fix the problem that caused it to plug, then replace the catalyst with a "high-flow" monolithic cat instead of the older, pellet-style. Typically under a hundred bucks, including a couple of band-clamps to connect it to the exhaust pipes.