93 Saturn SC - Hesitating initial acceleration - Need Help
Webgas
05-04-2002, 11:28 PM
I have a 93 Saturn SC 1.9. It hesitates (stales, no power for 1 sec then kicks in) during initial acceleration. I have changed the fuel pressure regulator. It drives fine after it gets up to speed. Sometimes stalls in the intersection when I start up again. Have any suggestions as to what the problem might be?
Thanks for your help.
Randy D
webgas@worldnet.att.net
http://www.webgas.biz
Thanks for your help.
Randy D
webgas@worldnet.att.net
http://www.webgas.biz
THEDAVIDMAN
06-26-2003, 04:30 PM
Hey man,
What kind of intake mods have you added to your ride? I am guessing an aftermarket intake and throttlebody. What you are describing drove me absolutely nuts for about 1 year.
What I learned mostly through advise and experimentation is that because the Saturn ECU is set on lean after warmup, the volume of fuel is greatly decreased to keep the emissions ratings good. However if you have installed an aftermarket intake and throttle body, the Air/fuel ballance is changed radically within the lower RPMS. It is not until you mash the pedal down and get past 3800-4000 rpms that anything besides noise happens. However, is it not true that while your ride is warming up, it seems to miraculously have more power? Then after warm-up it goes back to "SNAIL MODE" until you mash your foot down. The fuel curve changes to lean when the engine reaches an internal temp of 180 degrees. Here are A few things to consider.
1.-How to richen up the air fuel mix without pissing-off the ECU.
2.-How to manage intake air for efficiency and velocity throughout the rev band.
3.-How to disperse heat so you do not loose power.
1. I devised a way to allow more fuel within low rpm ranges without upsetting the ECU. Gas mileage? Actually better within the range of normal street driving. You would not believe how simple it is.
I relocated the intake sensor within the grillwork allowing outside air to create the temp reading. I also took a home made resistor bank that becomes part of the intake temp sensor loop. This enables you to make the ECU think that it is a little colder outside than it really is, hense providing more fuel. Start with small increments. 4-6 ohms.
2. The air in a typical aftermarket intake does not reach a state of torque producing velocity until about 4000 rpm. Why? Lack of proper direction and uneven low RPM flow.
The solution for that is to direct the air in a way that allows it to compress quickly and achieve a state of torque producing velocity at lower rpms. This can be done through an idea similar to the one of those thangs that make the air spin as it goes through the intake.(can't say the name cause that would be an advertisement) Just remember the word "tornado. I have divised a three stage air turbulence mechanism made from standard pie pan metal. Stage 1 is mild and located at the filter end. Stage 2 located just after the large bend near the filter, increases the angles of the blades by about 20 degrees with more blade surface than stage 1. Stage three increases blade angle by 10 degrees and is located just before the throttle body. The effect at low rpms? The effects of velocity are derived from the air against blade surface which provides resistance. At higher rpm's the blades cause the air to spin like a tornado compressing the air for more volume and much more velocity. It is also important to allow the computor to sense the amount of air going through the intake as quickly and accurately as possible. A mass air sensor can help. I also found quicker response by deburing the rubber and plastic parts in the vicinity of the air sensor tubes in the throttle body, even slightly beveling the tube openings. Clean sensors all around is very important. There is also a small chamber at the base of the throttle body which is primarily used during low RPMs. Greasy gunk tends to build up in this chamber over time which could play havac on the git-go when you first hit the gas.
I also installed a 2 1/4 in chambered muffler cat back that passes a considerable amount of exhaust as compared to the 1 7/8 id stock setup. The results I have an unassuming sleeper that kills at lower rpms without a loss a red line. My power band is 2750rpm-6000rpm. The look on their faces when I blow past a Honda SI Civic and my car doesn't sound like its crapping it's pants. (quite is good too)
3. Removing heat from the engine bay is probably the easiest of all.
First thing I did was remove the weather stripping from under the hood just infront of the windshield. It vibrated quite a bit so I cut about an 8inch piece and located it in the center of the underhood bodywork allowing hot air to escape on either side at low speeds and a cawling air-in-the-motor bay effect during high speeds. Make a difference? About 10 degrees at the throttle body. I also used the Fog lamp inlets on the front fashia to route outside air into the engine compartment. Using three inch conduits, one points directly at the intake, the other at the exhaust maifold. (this conduit will eventually be tied into the intake vie parts I have not yet found to produce an Air-Ram intake) Result? On a 75 degree day I can actually get the computer to go back into warmup mode by running the air condition while stopped for about 10 minutes-(Fan comes on ) Yeah it's true!
If you have questions send me an e-mail @ [email]fretburn@juno.com[email]
Rock on bro's
Dave.
What kind of intake mods have you added to your ride? I am guessing an aftermarket intake and throttlebody. What you are describing drove me absolutely nuts for about 1 year.
What I learned mostly through advise and experimentation is that because the Saturn ECU is set on lean after warmup, the volume of fuel is greatly decreased to keep the emissions ratings good. However if you have installed an aftermarket intake and throttle body, the Air/fuel ballance is changed radically within the lower RPMS. It is not until you mash the pedal down and get past 3800-4000 rpms that anything besides noise happens. However, is it not true that while your ride is warming up, it seems to miraculously have more power? Then after warm-up it goes back to "SNAIL MODE" until you mash your foot down. The fuel curve changes to lean when the engine reaches an internal temp of 180 degrees. Here are A few things to consider.
1.-How to richen up the air fuel mix without pissing-off the ECU.
2.-How to manage intake air for efficiency and velocity throughout the rev band.
3.-How to disperse heat so you do not loose power.
1. I devised a way to allow more fuel within low rpm ranges without upsetting the ECU. Gas mileage? Actually better within the range of normal street driving. You would not believe how simple it is.
I relocated the intake sensor within the grillwork allowing outside air to create the temp reading. I also took a home made resistor bank that becomes part of the intake temp sensor loop. This enables you to make the ECU think that it is a little colder outside than it really is, hense providing more fuel. Start with small increments. 4-6 ohms.
2. The air in a typical aftermarket intake does not reach a state of torque producing velocity until about 4000 rpm. Why? Lack of proper direction and uneven low RPM flow.
The solution for that is to direct the air in a way that allows it to compress quickly and achieve a state of torque producing velocity at lower rpms. This can be done through an idea similar to the one of those thangs that make the air spin as it goes through the intake.(can't say the name cause that would be an advertisement) Just remember the word "tornado. I have divised a three stage air turbulence mechanism made from standard pie pan metal. Stage 1 is mild and located at the filter end. Stage 2 located just after the large bend near the filter, increases the angles of the blades by about 20 degrees with more blade surface than stage 1. Stage three increases blade angle by 10 degrees and is located just before the throttle body. The effect at low rpms? The effects of velocity are derived from the air against blade surface which provides resistance. At higher rpm's the blades cause the air to spin like a tornado compressing the air for more volume and much more velocity. It is also important to allow the computor to sense the amount of air going through the intake as quickly and accurately as possible. A mass air sensor can help. I also found quicker response by deburing the rubber and plastic parts in the vicinity of the air sensor tubes in the throttle body, even slightly beveling the tube openings. Clean sensors all around is very important. There is also a small chamber at the base of the throttle body which is primarily used during low RPMs. Greasy gunk tends to build up in this chamber over time which could play havac on the git-go when you first hit the gas.
I also installed a 2 1/4 in chambered muffler cat back that passes a considerable amount of exhaust as compared to the 1 7/8 id stock setup. The results I have an unassuming sleeper that kills at lower rpms without a loss a red line. My power band is 2750rpm-6000rpm. The look on their faces when I blow past a Honda SI Civic and my car doesn't sound like its crapping it's pants. (quite is good too)
3. Removing heat from the engine bay is probably the easiest of all.
First thing I did was remove the weather stripping from under the hood just infront of the windshield. It vibrated quite a bit so I cut about an 8inch piece and located it in the center of the underhood bodywork allowing hot air to escape on either side at low speeds and a cawling air-in-the-motor bay effect during high speeds. Make a difference? About 10 degrees at the throttle body. I also used the Fog lamp inlets on the front fashia to route outside air into the engine compartment. Using three inch conduits, one points directly at the intake, the other at the exhaust maifold. (this conduit will eventually be tied into the intake vie parts I have not yet found to produce an Air-Ram intake) Result? On a 75 degree day I can actually get the computer to go back into warmup mode by running the air condition while stopped for about 10 minutes-(Fan comes on ) Yeah it's true!
If you have questions send me an e-mail @ [email]fretburn@juno.com[email]
Rock on bro's
Dave.
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