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Car hesitates to move from the stop sign.


Slade901

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Car hesitates to move from the stop sign. Whenever I step on the gas while sitting from the stop sign, the vehicle hesitates for a second (as if the engine would die) and then recovers and runs fine.

 

This problem has been going for a long time. I've cleaned my IAC and even replaced the IAC and replaced the TPS. I've also done the Idle Re-learn and still the problem showed up.

 

I have to accept the fact that I could not fix the problem. My solution to the problem (at the stop sign) was to release my step on the brakes and let the vehicle move slowly without stepping the gas pedal for a few second and then push the gas pedal (that way the engine would hesitate and just move along just fine). Sometimes, if the vehicle is on a steep hill while sitting on a stop sign, I have to use my left foot holding the brake pedal and the right foot to put a little of gas while sitting at the stop sign and then release the brake pedal while putting more gas.

 

Yesterday, I was on my way to do my errand, I started the vehicle and it backfired once. Started again and the vehicle started but the Service Engine light came ON and the idle was bad. I though the problem would just go away once the engine warmed up. I tried to drive the vehicle slowly on the street but the engine is running badly and so I returned back home.

 

I’ve check for the stored error code and found 33 trouble code which shows MAP sensor and somewhere along the ignition system. I’ve checked the MAP sensor wire and it was fine and the vacuum hose to the MAP sensor is fine. It took me a while to find out that the vacuum hoses that connects on top of the throttle body was pushed out (probably when I have the backfire).

 

This vacuum hose comprised of a three vacuum hose, which is connected together as one and then attaches/connects to the top of the throttle body.

 

I reconnected this vacuum hose back to the top of the throttle body and started the engine and the Service Engine light turned OFF and the IDLE was fine and the vehicle runs fine (the hesitation problem at the stop sign is still there though).

 

I come to realize that this vacuum hoses is not very tight and can be easily pulled out. I was trying to find a way to secure these vacuum hoses to stay in place at the top of the throttle body and connected tight.

 

What I have come up was to use a thick aluminum wire and formed into the shape of ] and I just made two of them. I made the length of the wire just enough for it to properly pull in the vacuum hose and connected tight to the top of the throttle body. I then put a water hose clamp around the vacuum hose connector and the part of the throttle body to secure both the aluminum wire and the vacuum hose connector.

 

Started the vehicle and I soon realized that the engine does not hesitate anymore when I move from the stop sign. I even tried to put more gas while sitting at the stop sign when the green light lit up and the engine did not hesitate at all and it just moved the vehicle faster. No more hesitation.

 

The solution I have provided here might also solve some problem of our friend’s vehicle/engine hesitation problem when moving from stop sign. Try it to see if it works.

 

http://www.geocities.com/southbeach/sands/2476/automobile/Vacuum-Hose_and_Throttle-body_1.gif

 

http://www.geocities.com/southbeach/sands/2476/automobile/Vacuum-Hose_and_Throttle-body_2.gif

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Thanks for sharing, I'll try that out one day as my car has a slight hesitation when stopped, but it hasn't stalled yet. I just do what you did, about half a second let it idle then gas and it works. Engine still runs good so I might as well try that.

Thanks!

 

- Jeff L.

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very nice info for the future. That hesitation problem occurs with many of our vehicles when we hit a certain mileage. Sometimes its water in the gas lines and others relate to these damn sensors or vac lines. Its nice to see someone who took the time to evaluate the situation and correct it! I cant say that for myself as I'm to frustrated most of the time.

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I've found that its usauly a fuel delivery related problem that causes this. One idea would be to run some high strength fuel system through it, like the lucas brand stuff or ask GM what they sell for this.

 

You may have something in your tnk causing a slight blockage in it like rust or dirt. All Gm cars seem to be plauged by this. I never did figure out what caused it on my lumina. I went as far on it as to loosen all the fuel lines and blow air thru them to clean them out.

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The slight hesitation when moving from stop was there when I got my car. When my gas tank has a little crack in it, I've replaced the gas tank and put a new fuel pump. The fuel lines was cleaned out but the slight hesitation is still there.

 

I'm convinced that the main problem was that vacuum line connector on top of the throttle body was the main culprit as they are loose and they are connected around its outside diameter surface instead of inside diameter surface. The rest of the vacuum hose connector are tight because they connected around its inside diamter surface and making it a tight connection.

 

At idle, the vacuum is so high and any loose vacuum hose connector is going to affect the engine's performance. Once the vehicle is moving just above the idle speed RPM, then the vacuum gradually lowers down.

 

I'll keep an open mind though and re-check what you have suggested. If the problem occurs, I'll keep you up to date.

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Hey all, my i got a 93 cut sup. has same problems from a standing point it hesiates, and idles rough when I first turn over. while driving it hesitates at just about every light, etc. anyways, its a 93 with the 3100, I don't know much about the car so any help is appreciated, I had looked for the lines but did not find any on the throttle body, so maybe somewhere else? Thanks

 

Tony.

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Well, do as Slade said and check your throttle body to see if it's loose. If it isn't, make sure your fuel lines and all parts therein aren't filled with crap. It never hurts to pour engine cleaner and fuel line cleaner into your car every time you fill up. My GP never hesitated, but after sitting for 6 months, it DID like to stall everytime I put it into a different gear.

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like someone else said, it sounds like a fuel delivery problem - it could be as simple as a bad fuel filter, to a bad pump/strainer/screen to a bad pressure regulator, or even an injector on the way out.

 

it could also be a bad coil/ignition control module not offering enough spark - that too is heat related

 

--Dave.

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So what would be the best to start with? The picture that Slade posted isn't what mine looks like, so is there another part of the engine where it is? I believe my motor is Gen III 3100... but I just don't really know where to start looking... help is appreciated.. thanks

 

tony.

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So what would be the best to start with? The picture that Slade posted isn't what mine looks like, so is there another part of the engine where it is? I believe my motor is Gen III 3100... but I just don't really know where to start looking... help is appreciated.. thanks

 

tony.

 

you said that you have the 3100 in a '93, is that classified as a generation 3?

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So what would be the best to start with? The picture that Slade posted isn't what mine looks like, so is there another part of the engine where it is? I believe my motor is Gen III 3100... but I just don't really know where to start looking... help is appreciated.. thanks

 

tony.

 

you said that you have the 3100 in a '93, is that classified as a generation 3?

I guess, its a 3100(gen3 right? of the 3.1 motors?) anyways, in a 1993 Cutlass Supreme SL.
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