Choking

jblot

Member


I ran very low on fuel a couple weeks ago, and since then my GN runs rough. I changed out my fuel pump and fuel filter, but it still doesn't drive any better.

It will run good for the first 10 minutes when I leave in the morning, but after that when I accelerate it hesitates alot. It sounds like I am running out of fuel.

All hoses are tight, and I tried knocking on my LS1 mass airflow sensor to see if that would cause the same choking, but it idled fine.

What's wrong w/my Buick?
Could it still be my mass airflow sensor?
 
What's your fuel pressure (FP) doing at this time of infarction? Pls don't tell us you don't have a remote FP gauge you can bring out from under hood/ tape on windshield & monitor properly??
 

jblot

Member
Yeah, it takes me about 15 min. to get to work in the morning, and right at 10 minutes after I leave it starts hesitating. Its weird.
 

jblot

Member
I just installed my fuel pressure gauge, and will see what that does when it sputters.

I also noticed that my pipe from the air filter to the turbo was coming off at the turbo bell housing.

What would cause that?
 

turbojd

Well-Known Member
Tighten the mass air pipe up tight, check your intercooler hoses and up pipe hoses also while your at it, then take it for a ride and see if thats your problem.
 
I just installed my fuel pressure gauge, and will see what that does when it sputters.

I also noticed that my pipe from the air filter to the turbo was coming off at the turbo bell housing.

What would cause that?

Loose connection, torn 3" hose (if not solid pipe). If, by chance, either this--or either of the IC pipes come loose, it could POSSIBLY cause the driveability problem--but not logically connected with the after warmed-up appearance of probs...

When a fuel pump is going bad, it will sometimes slowdown after running for some-time (thus concurrent with pump warming-up/ car run-time)?? (My Walbroke FP just went to the seized-up mode & let me down after "long-running". After pump would cool off, it/car would restart & run for several more minutes--heat-up/seize-up again, etc.-etc.-etc.)

As has been mentioned, ignition problems show up with engine-heat (underhood) and is another likely/possible cause...
 

83ttypecooled

Active Member
Hi,
Unless you want someone else to fix your car, it is time for you to invest in a scanner. The numbers will tell the story. Misfiring is probably blowing off your breather pipe. A fuel pressure reading is also essential,which I gather you have by now. Since you have replaced the pump,it is unlikely that this is the problem. MAF trouble is likely, as you have probably had some intake backfiring. I guess the MAT sensor could also have been affected. One thing to remember about MAF failures is that on the scanner,if it's F ing up, a default value will be displayed, so you can't trust scanner data.I just had a stock MAF failure on my ttype,and the default read low at idle. Typical numbers are 4 to 5 grams/second.Mine was reading 2.5. Since you have a non stock sensor and translator,you should be able to look at a digital picture of the thing, and look for glitches under load.
IF this is not the issue, then the feedback system must be at fault. This should be obvious with scanner input. Good luck with your issue!
 

jblot

Member
Here are the fuel pressure readings

at idle 35psi
normal acceleration 39-42psi
aggressive acceleration 43-49psi

There are no changes in fuel pressure during sputtering.

I have tightened the hose to turbo and it is starting to come off again.
 
Here are the fuel pressure readings

at idle 35psi
normal acceleration 39-42psi
aggressive acceleration 43-49psi

There are no changes in fuel pressure during sputtering.

I have tightened the hose to turbo and it is starting to come off again.

You should have 42'ish#FPres @ idle (vac line off) & then it should rise 1# for each 1# boost (line reconnected for operation). I'm guessing you checked it vac line on? In other words, at 10#boost, you should have 52#total FPres.

Presume you have an adjustable FP regulator??
 

turbojd

Well-Known Member
What chip is in the car now, and is this car basically stock, list mods to car, also you might have oil coating your intercooler and up pipe hoses. clean them out and replace your hose clamps with new ones. If the hoses are in bad shape replace them.
 

jblot

Member
I do have an adj fp regulator.
All hoses are good, clamps good.
No oil around intercooler or turbo.
Stock chip, I'm guessing...never really looked.
Not too many performance mods, 700r4 tranny which I hate.
This is my daily driver and I don't really get on it too much. It has been good for the past 7 years I've owned it. Not too many $$ problems. Just the usual alternator, started, radiator, etc.
 
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