My TBI finally started messing with me. First it Idle'd all over the place, than it worked fine while driving and when I put it in park it idled 1500rpm. The vacum was loud as it was pulling in air. I checked every single vacum line, and I think one of the fittings to the EGR control was out, and I put it back in. That seemed to take care of the rough idle. However, now when I drive the car and I would shift gears, I can hear a hiss if I give it gas. If I were to keep it in Drive and not shift everything is fine.
I checked the TBI while it was idling high and it seemed like all the cables were fine and nothing is being pulled. Its puzzling to me, I replaced CTS, and I have a brand new MSD coil, new Blue thunder cap and rotor, and the wires along with four prong bosch plugs have been on for about 10k miles. My good friend said that its the idle sensor, but I am thinking that its vacum related.


By the way, my coil wire is acting up, and I'll replace it tomorow.

Thanks for your help.

 

My TB hiss's too, only becuz its sucking in air, its vary annyoion

 

Oh, I know that, but its like staying at 1500rpm.

I will drive it, and if shift from drive, to overdrive, my TBI will start hissing loud every time I give it gas after that. Than once I put it in park, the idle will go to 1500rpm and sound like I am holding the gas pedal, but am not. And my cables all look fine, none of the cables are pulling. It looks like something else is holding the idle at 1500rpm. Could it be the idle control sensor at the TBI???
Anyone know???

 

Sounds like a bad gasket, I had the same thing happen to me. When you open the throttle to just the right postion you increase the vacume to the area around the gasket and it hisses louder. The gasket acts as a reed in a whistle, mine was so bad it hurt. It could also possibly be your IAC valve stuck open, they don't usually cause a high pitched hissing sound, but you never know. I would give it the old carb cleaner test.

 

I gave it the carb cleaner test, but just to the front, where I thought hissing was coming from. Nothing happened! It wouldn't hurt to change the gaskets and update that TBI. I just got a metal grinder, so I'll probably do the ultimate mods to it and change the gaskets.
Did you idle high when it was sucking like that????

 

Ohh yeah, this happend when I first started the motor, so I thought it just needed the throttle stop turned back. I turned the stop back so far that the throttle was sticking. Then the high pitched hissing started and I knew somthing was up...took me a while to find it.

 

I think you are right my friend. I've noticed while driving that every time I give it gas I can hear a little hiss right after I let off the gas. As if there is a little leak. The car is still fast, but it has some bog. It does sound like a bad TBI gasket, and I am thinking about replacing it, as well as the injectors. So, I think I'll get it together first, and see what happens. Now, I just need the gasket set and the torque wrench. Damn... I don't have one!

Could I do the throttle body without the torque wrench.

 

Ohh yeah, no need for a torque wrench. No need for any other changes either. I find that if I start changing stuff that's not related to the problem I end up with new self inflicted problems. Just to make sure we're on the same track, I'm talking about the gasket between the TB and the intake. Should only be a couple of bucks at the parts store, they have a thin section on the passenger side that usually blows out.

 

I know this will sound really dumb but ... check the connecting wires to the IAC ... make sure they're not off by 90 degrees or upside down

Also doublecheck the IAC


I had that problem ... and well... ONE of the things that caused it was the IAC connectors

 

IAC, Idle air control ????

I'll check it, but what should I be looking for???

Also, I just might take it out and clean it. They said that carb cleaner should do the trick.
Today when I drove it, I did notice a bog whenver I turned left or right. When go from a stop, it'll bog down a bit, and than run like a champ. From which I think it might be the fuel pump. I need a new one anyways. I'll replace the pump, figure out the hiss problem and we'll go from there.

Could vacum cause the bog??? What if I just tightened my TBI down a bit????
Hmmm.. Maybe I'll try that!

 

Vacume leaks usually don't cause drivability problems. They just cause a high idle. Our systems utilize a map sensor, so if you get an air leak it still sees the decrease in manifold pressure and compensates. The IAC is just a controled leak around the throttle blades. The bogging is probably another problem all together, I would try tapeing a pressur guage to the windshield and see if you can see the FP fluctuating.

 

Here is a funny thing. Since I dont have any money right now, I thought of messing with my TBI and seeing what happens. So I take out 1/2 socket and tighten the three holding bolts around my TBI. Guess what, the idle went back to normal. No hissing, just a little bit, (the normal hissing ) So, I drove it around, and it feels like a new car.!!!! The TBI has done these kinds of tricks to me before, so as soon as I get some money, I am replacing the pump, the sensors and the gaskets along with an injector spacer and ultimate TBI mods.
There, I hope this kinda helps somebody who has these kinds of problems. Try tightening your TBI cuz two of my bolts were a bit loose!

I will see how she behaves tommorow, and if everything is fine I'll let you all know.

 

Glad your babe's running alright

 

I didnt get a chance to drive her today, but she i just waiting now. Waiting to got kick some ***!
Thanks for all of your help!

 

My problem did not get fixed. She is now acting very starnge.

The car would kick *** while warming up or in Open loop. As soon as it warms up the car acts as if it doesnt get enough gas. however, my air fuel mixture is running rich which tells me that I am getting enough fuel, and that something is wrong since it will go to rich. I can hear this hiss that I did not hear before as I accelerate, and as soon as I let off the pedal the TBI will hiss for 2-3 more seconds and than subside.

This usually happens when I shift from third to Overdrive, and than my car will just act weird after that. With all that hissing I am going to replace the TBI gasket to the intake where I assume the problem is.

What else can hinder performance in closed (warmed up loop)

__ Vacum leak can do this???
-- o2 sensor could do this??
-- EGR??
-- Bad fuel pump, although I shouldnt be running rich if thats the case, right??
It defenetly sound like a vacum leak on the pass side of the TBI. I check it before, but I thought it could be some sensors telling TBI that.
Now I am going to replace the gasket and we'll see what happens.

What do you guys think???

Also, the blaster coil that I put in made me reuse the same brackets from my original one. The coil was a bit bigger than my stock one and it might have moved the TV cable a bit. But everything seems right and tight, and there is a little to no play on the cables.
It just sound like TBI is sucking air underneath itself.

Enough rant, I'll just replace the gasket and see what happenes from there.

 

make certain the gasket you buy covers the entire bottom of your TB. the ones sold with my adapter plate did not.

 

New gasket is in. THe hissing continues!?!?! I have the TBI on there pretty tight, and I drove it to warm it up and tightened it a bit more.
I took the air cleaner off and when I give it gas the hissing stops completly and as soon as I let off a big suction is heard that subdues after 1-2 secs. Its weird. I will give my computer some time to get used to the brand new seal, than onto troubleshooting again.

It seems to happen when I shift gears. Maybe when I go over 55 on my speedo.

Its defenetly weird.

What would cause problems like that when the car is warmed up!?

I am thinking EGR, or O2 sensor.

Maybe my pluggs but they were on there for less than 10000 miles. My car does consume some oil and the preassure was around 120-130PSI, here in Denver (mile high) justifys lower preassure. The motor is working great.

On my list to replace when I get paid is
Fuel pump, walbro 190
new wires, although the ones I have now are brand new.
New TBI intake and ultimate TBI mods (just got a metal grinder)

Anyways, keep helping me out. I will try to trouble shoot this stupid TBI crappiness. However, I will never change the TBI on my car!?!?

 

I am thinking its the pump or the pressure in the tank.

Since I opened my filler cap and barely any pressure came out. It seemed to be screwed a bit off.

I always had the problem with the cap, and I might just get a new one.

My car did this to me before. Whenver I turn I would not be getting gas. Than I screwed the cap right, and the car worked fine.
Its doing the same thing now as well.

A new pump is coming this month and I am doing it through the access door. Please dont flame

Other than that, I went around and tightened my intake, with two bolts in the middle a bit loose. I tightened everything, checked all my pluggs and put that anti sieze oil on both the cap and the pluggs. The car seems to have picked up quite a bit. I am impressed, but now I have a bog everytime I turn?!!
It might be the pump, so I'll wait and update once I finish the pump.
If you have any suggestions let me know now, before I go spending even more money.

 

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I am thinking EGR, or O2 sensor.

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I am thinking you are right and it could possibly be all that you mentioned so far. I would pull the 02 sensor or sensors (not sure how many your engine has i'm new to the 3rd gen engines). Clean them and if you have the money just replace them for insurance.

If you are running rich you may want to try cleaning or replacing the map sensor Too. A throttle body rebuild would never hurt.

The egr valve could be sticking or stuck open or such to which would cause problems like you are having.

Anyways g/l and make sure you update us with what the new fuel pump and other parts you mentioned do for you.

 

Well, I took the EGR out today and I checked for cloggs and such, but it was very clean, replaced the gasket and put it back in. I turned the engine on and let it idle, than I pushed the diaphragm on the EGR and the engine started sucking air. It kinda sounded like the problem I was having, the sucking of the TBI when the diaphragm is depressed. However, I am thinking if the EGR is stuck open wouldn't the car die??? My idle is good now, and when I go from drive to park the car goes up to 1200 and than drops to about 800-900rpm. One thing I noticed and this is happening almost 80% of the time is...
1. Bogging down whenever I turn, sometimes its fine.
2. Just tongiht I noticed that the car ran perfectly with the defrost all the way on!
3. I noticed very little preassure in the gas tank whenever I open it to fill it up. It only happens sometimes. What could that indicate, a leak???

I will check all the sensors tomorw and see if I can replace the EGR when I get paid.

Also, it might be the fuel pump, but my friend said that if they go they go, they don't just barely work. Is this right. I belive it is, but I need to know.

Also, how can you tell if the EGR is stuck open?? My diaphragm moves fine, but I can feel stuff in its way! Like little sand in there.

 

It was CAP and ROTOR.

Check these pieces of crap and see if they are sitting right. I had a bit of blue residue on my terminals. It was plastic of the rotor rubbing. So I cleaned it and put it in right. What a fuking difference.
So, whenever you buy a new cap and rotor, either ac delco, or get something good. MSD possibly.