350 TBI Surging/ Stalling

Had a not so good morning with the wagon. I started it for the 1st time in 5 days today idled normally but once I got on the road I couldn't get past 20-30 mph and the car kept surging and sputtering. By the time I limped it home the check engine was on. Also I did read this thread: http://gmlongroof.4umer.com/t2276-tbi-acting-up but dunno if the same issues apply here. I pulled the code and if I did it right got "44" which is, according to: http://www.gnttype.org/maint/malf.html for a rich condition. These are the listed possible causes:

1) O2 sensor defective or lead shorted
2) Lean injectors (dirty or blocked)
3) Water in fuel
4) Exhaust leaks upstream of O2 sensor
5) Fuel pressure or volume too low
6) MAF sensor reading lower airflow than is actually present
7) Vacuum leaks
8 ) Incorrect or poorly calibrated PROM

Help? Anyone? Please?

First thing I would do is check for the obvious... Pop the hood, check that everything is plugged in and none of your vacuum lines are pulled off or broken. Then get under the car and make sure an 02 sensor wire didn't get yanked off on a piece of ice/snow last time you drove it. May sound silly, but costs nothing to do...

Doug

Pooge wrote:

First thing I would do is check for the obvious... Pop the hood, check that everything is plugged in and none of your vacuum lines are pulled off or broken. Then get under the car and make sure an 02 sensor wire didn't get yanked off on a piece of ice/snow last time you drove it. May sound silly, but costs nothing to do...

Doug

Checked all the vac lines, etc. Nothing looked out of place or broken. Haven't checked the O2 yet, I'll check that tomorrow. The '93 only has one correct? Couple people on Longroof suggested a fuel pump. Just what I need...

You really need to put a scan tool on it to read data, and a fuel pressure gauge. Heck, could even be $hiitty gas.

Yea, could be bad gas. Before the fuel pump died on one of my TBI cars in the past it ran similar to what you are describing. I don't want to scare you because it could be several things but I figured I would mention it. I think you can see the O2 sensor by simply popping the hood and looking down at the exhaust manifolds. It screws into the Y-pipe.

I almost hate to say this... check the coolant temperature sensor/wiring.

I had a similar problem with mine.

Yep, that will cause some terrible running conditions. I only have experience with this on an L99 engine, though.

Def. check the CTS!

And it could be bad gas or water in your fuel or something. My Blazer was sitting for a long time with the blown rear end, I started it from time to time and whatnot, but a whole bunch of times the battery died from the alarm or something draining it, so I would neglect starting and running it. When it came time to fix the truck I started it up and it ran terrible, almost stalled and didn't want to move under it's own power. I had to leave it running for about an hour with new gas dumped in, I mixed some of that marine TCW-3 oil in my fuel to help clear it up too. Eventually it kind of fixed itself and by the time the other rear end was swapped in the truck was fine, for the miles that are on the engine anyway...

I had the same problem on my 92 wagon. I rebuilt the tbi, did the TPS and IAC valve didnt change anything. I pulled the EGR valve off and cut a piece of steel and blocked it off and havent had a problem since! I would assume a NEW egr may help you if thats the problem.

V8Killer wrote:

You really need to put a scan tool on it to read data, and a fuel pressure gauge. Heck, could even be $hiitty gas.

Sadly, I don't have $200 for an ALDL/OBD2 reader

GasTT wrote:

Yea, could be bad gas. Before the fuel pump died on one of my TBI cars in the past it ran similar to what you are describing. I don't want to scare you because it could be several things but I figured I would mention it. I think you can see the O2 sensor by simply popping the hood and looking down at the exhaust manifolds. It screws into the Y-pipe.

Couldnt see the O2, but I do see that the undercoating I used sucked

boojum wrote:

I almost hate to say this... check the coolant temperature sensor/wiring.

I had a similar problem with mine.

Do you mean the block sensor or the manifold one? I'm on manifold sensor #3 and I still have no working temp gauge, it never caused a running issue before. Also has a new pigtail.

Matt Trakker wrote:

Def. check the CTS!

And it could be bad gas or water in your fuel or something. My Blazer was sitting for a long time with the blown rear end, I started it from time to time and whatnot, but a whole bunch of times the battery died from the alarm or something draining it, so I would neglect starting and running it. When it came time to fix the truck I started it up and it ran terrible, almost stalled and didn't want to move under it's own power. I had to leave it running for about an hour with new gas dumped in, I mixed some of that marine TCW-3 oil in my fuel to help clear it up too. Eventually it kind of fixed itself and by the time the other rear end was swapped in the truck was fine, for the miles that are on the engine anyway...

See, my father said the same thing about water/ice in the line. According to some on Longroof it's not that. But I frankly have a hard time believing its the fuel pump when I drove it a week prior, it drove fine and five days of below freezing temps later it doesn't run.

Ironfistdog wrote:

I had the same problem on my 92 wagon. I rebuilt the tbi, did the TPS and IAC valve didnt change anything. I pulled the EGR valve off and cut a piece of steel and blocked it off and havent had a problem since! I would assume a NEW egr may help you if thats the problem.

EGR is about 2 years old with about 10k on it. Are those known to go bad that new?

If you got condensation where it shouldnt be from just bringing it up to temp & shutting it down, it could cause BS to happen.
Take it out for a blast & put some miles on it. I'm betting it clears up.

sdstick wrote:

Take it out for a blast & put some miles on it. I'm betting it clears up.

I can't get it above 10mph

OK, its not that then
If your not hearing or seeing vacuum problems then
you GOTTA check your fuel pressure.
Did you look for arcing last night?

sdstick wrote:

OK, its not that then
If your not hearing or seeing vacuum problems then
you GOTTA check your fuel pressure.
Did you look for arcing last night?

Yes, didn't see anything out of the ordinary. Fuel looked ok, had the airbox off and the throttle body looked like it was getting the right amount of fuel.

Did you check your cap & rotor?
Is it getting worse?
The 1st time you stumbled at 30MPH, now its 10MPH (or was that just estimates & it stayed the same?)

sdstick wrote:

Did you check your cap & rotor?
Is it getting worse?
The 1st time you stumbled at 30MPH, now its 10MPH (or was that just estimates & it stayed the same?)

Both look ok, are about 2 years/10k old. Yes, it has gotten worse. The first time I took it out I could get to 30-40 (punching the gas peal causes the CEL to light/blink) but now I can't get past 10.

Does it rev in park?
Is it different when its warm or same?
Does a TBI car have a CTS?
I dont see it in the waterpump picture. Where is it?

TBI cars have the CTS in the intake near the water neck.

Is your EGR a parts store one? Those are notorious for causing problems, try unplugging the EGR and plugging the vac hose and seeing if it runs any better, no EGR is better than the parts store ones!
You could also have a clogged cat converter.

Just went and poked around some more. Fuel pump comes on when the car is started. Also, not a fuel issue as the TBI sprays the proper "cone" of fuel. On another note, it runs and idles a bit better today now that its warmed up.

sdstick wrote:

Does it rev in park?
Is it different when its warm or same?
Does a TBI car have a CTS?
I dont see it in the waterpump picture. Where is it?

It revs but sputters in park. My CTS is on the intake manifold.

Matt Trakker wrote:

TBI cars have the CTS in the intake near the water neck.

Is your EGR a parts store one? Those are notorious for causing problems, try unplugging the EGR and plugging the vac hose and seeing if it runs any better, no EGR is better than the parts store ones!
You could also have a clogged cat converter.

EGR actually looks to be original. It wasnt replaced according to my repair sheets. I also broke a vac line trying to see the EGR Why the hell is that crap made out of such brittle plastic?

Also, heres a fancy video I made of the noise it makes at idle, its a bit quiet but you can hear it:

The fact that it happened while parked doesnt support the clogged cat
Coolant sensor maybe, but usually that is a hard start & then wierd after warming up
Maybe there are variations of that & I'm all wet. If Justin doesnt know where it is, probably never changed
Cheap part but throwing parts makes real troubleshooters MAD (not talking about myself here )
He looked at the TB so I'm ruling out big honkin mouse (or squirrel) in the intake
Waiting for feedback, I'm thinking spark (due to the 10mph max)

That is exactly what my truck (TBI 350) was doing when it had the old gas in it. It was surging and when the RPMS went down, acted like it wanted to stall out, but couldn't and kept running. It was bad in park and worse in gear. Did you run the car down low in the tank at all recently?

If you push in the EGR diaphram what happens?
You cant predict higher RPM fuel pressure, but your problem is at low rpm so we'll give the FP a pass.
You can hear the fuel pump & still have no pressure after prime. That would be a no start situation.
Did you pull your cap? What does it do for a coil?
Did you trace each wire down just for kicks?

One time I drove my car into the driveway, went in, came out & it wouldnt start.
Spark Plugs.......Why then who the ef knows. I'd have bet $1M against it being that.
I'm not saying this is your situation, just pointing out little things WILL shut you down.
Keep looking, It's not getting any warmer

Matt Trakker wrote:

That is exactly what my truck (TBI 350) was doing when it had the old gas in it. It was surging and when the RPMS went down, acted like it wanted to stall out, but couldn't and kept running. It was bad in park and worse in gear. Did you run the car down low in the tank at all recently?

Nope. Tank never gets run low. Mostly because I'm afraid of what will happen to my wallet at $3.40/gal . That said, the last time I got gas it was at the discount chain. I really have a feeling that it might be their shit gas.

sdstick wrote:

If you push in the EGR diaphram what happens?
You cant predict higher RPM fuel pressure, but your problem is at low rpm so we'll give the FP a pass.
You can hear the fuel pump & still have no pressure after prime. That would be a no start situation.
Did you pull your cap? What does it do for a coil?
Did you trace each wire down just for kicks?

One time I drove my car into the driveway, went in, came out & it wouldnt start.
Spark Plugs.......Why then who the ef knows. I'd have bet $1M against it being that.
I'm not saying this is your situation, just pointing out little things WILL shut you down.
Keep looking, It's not getting any warmer

I'll check the EGR diaphragm once I patch the broken vac line. Cap and rotor are good from what I can tell. Plugs were done at the same time and have about 10k on them. I havent run the wires yet, just looked for arcing.

spray the whole intake with shaving cream, maybe you have a gasket leak, every 91-93 caprice i've owned had a leaking intake gasket. i really think the problem is with the egr or your IAC valve I'd replace it anyway cuz an IAC valve for these is like 20-30 bucks. (the video sounds just like mine did) when i blocked my egr off with steel i didnt hook up the lines to block tehm off and it never threw any codes or caused issues. (dont know what thats about!!) if your ever through the sturbridge area i'd be happy to check it out.

Intake manifold gaskets were done last spring. No leaks there, that was one of the first things I checked.

OK discount gas is a clue, but if you just top off it shouldnt shut you down like that.
Did you pull the cap? or is this the old it LOOKED good
Dump some fuel conditioner in it if your afraid of the gas

sdstick wrote:

OK discount gas is a clue, but if you just top off it shouldnt shut you down like that.
Did you pull the cap? or is this the old it LOOKED good
Dump some fuel conditioner in it if your afraid of the gas

Took the cap off, checked it out, nothing seemed out of the ordinary, however I'll admit I've never had a cap go bad on me so idk what to look for.

On another note. Anyone know what size vaccum hose the 5.7 uses? I may go and replace all of it with something that wont break just by being looked at the wrong way.

Cracked or EXTREMELY corroded w/ white ash
Rotor same
You'd know it if you saw it
The EGR vacuum is the tiny hard plastic with 90 degree rubber boot connection points

sdstick wrote:

Cracked or EXTREMELY corroded w/ white ash
Rotor same
You'd know it if you saw it

Yeah, nothing like that.

Kinda sidelined atm, have a broken vacuum line and I can't find the proper fitting to fix it. Replaced the PCV valve last night as per another suggestion. Another suggestion is that I have a split fuel hose near the pump.

Dont we have any members near you?
Someone has a fuel pressure gauge.
It's 60 degrees out.
That car better be fixed today

sdstick wrote:

Dont we have any members near you?
Someone has a fuel pressure gauge.
It's 60 degrees out.
That car better be fixed today

I'm looking for someone with a fuel pressure gauge. HF has one for $119, but thats $119 I dont have if I need parts too.

My mechanic neighbor checked it out. Fuel pressure is a bit iffy. But he seems to think its not the pump. Swapped out the fuel filter (it was the original, or close to it judging by the crap on it ) still nothing. Back to square one...

has the spark been tested or checked for arching or a broken wire? i had same problem on my 89 and i threw parts at it coil cap rotor plugs and found out while doing plugs about a broken wire. ran prfect after .

Wires are fine. My fathers buddy has a set of GM fuel pressure gauges, we're gonna pick em up tomorrow and monday we're gonna test the pressure. Just so we can rule out a fuel issue.

did you ever solve this problem because mine is sorts doing this now but only whaen warm and egaust smells really rich after its warmed up. im thinking temp sensor on mine plus when it does it cel comes on then stalls and wont start till its cooled for like 30sec to a min and when it starts it acts like its choking out.

Ok, tested the fuel pressure, its not quite what it should be. I'm going to try a fuel pump this weekend. New vacuum lines are done too. That should help the car breathe a bit easier too. I want to be driving this thing Saturday. I miss my wagon

i just posted on mega's thread about his 94 stalling. maybe its the sock on the end of the fuel pump....maybe you'll luck out and it'll be a quick fix. i know if its the sending unit its a bitch to find a replacement, on my 92 it took me forever to find one

POST the #'s man.....Not quite what it should be?
Is it 35psi.....30......25
Was the regulator unplugged?
Details
I say this because a car will run just fine with 30 or 35 (not talking about WOT)

Ironfistdog wrote:

i just posted on mega's thread about his 94 stalling. maybe its the sock on the end of the fuel pump....maybe you'll luck out and it'll be a quick fix. i know if its the sending unit its a bitch to find a replacement, on my 92 it took me forever to find one

Advance has them in stock for the wagons and sedans.

sdstick wrote:

POST the #'s man.....Not quite what it should be?
Is it 35psi.....30......25
Was the regulator unplugged?
Details
I say this because a car will run just fine with 30 or 35 (not talking about WOT)

It was about 20psi.

Yes, 20 is low (some will run but its iffy) could you tell if the regulator was functioning properly?

really??? wtf!! i went there all summer and they said we have this one here it fits everything BUT wagon, then they asked what the code was from the plug. i said i have no friggen idea. i did some research and apparently the 91 wagon has only 1 possible code for the plug and 93-96 has only 1 possible code BUT 92 can be either one (the 91 code or the 93-96 code) something about they swapped it halfway through IDK but it pissed me right off! the sending unit rotted right where the metal line came off the top of the unit, causing a nice trail of gas wherever i went.. reminded me of Yosemite Sam with a barrel of gun powder LMAO!

sdstick wrote:

Yes, 20 is low (some will run but its iffy) could you tell if the regulator was functioning properly?

My only knowledge of how it works is from the FSM, but based on that, yes it is.

Ironfistdog wrote:

really??? wtf!! i went there all summer and they said we have this one here it fits everything BUT wagon, then they asked what the code was from the plug. i said i have no friggen idea. i did some research and apparently the 91 wagon has only 1 possible code for the plug and 93-96 has only 1 possible code BUT 92 can be either one (the 91 code or the 93-96 code) something about they swapped it halfway through IDK but it pissed me right off! the sending unit rotted right where the metal line came off the top of the unit, causing a nice trail of gas wherever i went.. reminded me of Yosemite Sam with a barrel of gun powder LMAO!

Heres the wagon unit. They told me its a special order, but would only take like 2 days to get.

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_Sender;-Includes-Fuel-Sender,-Float-and-Strainer-%28Fuel-Pump-Not-Included%29-Spectra-Premium_20370344-P_2159_R|GRPFUE2AMS_1614057198___#fragment-2

read my post on stalling the beast is going up for sale aution style 1000 to start

Well, found the problem... a hole rusted into one of the sending lines on the fuel sending unit. So, that'll get special ordered this week.

did you smell gas at all?

mega wrote:

did you smell gas at all?

When? because once the tank was dropped I smelled a lot of it

before tank dropped

mega wrote:

before tank dropped

Nope. But I can't see how it isnt the problem, its a hole that shouldnt be there.

true true hope it goes well how cheap are they in case i need one to