Help with hesitation issues (LS1)
Thread Starter
Teching In
Joined: Jul 2007
Posts: 12
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Help with hesitation issues (LS1) Hello all,
This is my first post, so I apologize in advance if it is located in the wrong location or posted in the wrong manner.
I have owned a '00 Z/28 Camaro (M6, slp lid, k&n filter, slp loudmouth) since Feb. 2000. It currently has ~94k on the clock.
Last summer I began to experience engine issues (accompanied by an SES light) that started with a strange problem. When pumping gas at a local station into an empty tank on a hot day it would not fill. I took the car to a local shop and they took apart the fuel tank to diagnose the issue. The shop could not find anything wrong with the fuel system that would cause what appeared to be vapor lock. I haven't had a problem filling the tank since getting it serviced.
After the fuel tank service and to this day I have hesitation starting at 2200 rpm through about 2500 rpm. This will only occur when I have the throttle less than 75% open. If I go WOT I never notice a hesitation issue, although it "seems" that I have less power available. I took the car to a chevy dealer, and they recommended replacement of the upstream 02 sensors and map sensor. Apparently they checked voltages and they are not working properly. I had a mechanic check the fuel pressure, and it is normal at 60psi.
I replaced the spark plugs, wires, and upstream O2 sensors. Although the hesitation does not occur nearly as often, It will occur about 20% of the time. Should I replace the map sensor? What is the problem?
This is my first post, so I apologize in advance if it is located in the wrong location or posted in the wrong manner.
I have owned a '00 Z/28 Camaro (M6, slp lid, k&n filter, slp loudmouth) since Feb. 2000. It currently has ~94k on the clock.
Last summer I began to experience engine issues (accompanied by an SES light) that started with a strange problem. When pumping gas at a local station into an empty tank on a hot day it would not fill. I took the car to a local shop and they took apart the fuel tank to diagnose the issue. The shop could not find anything wrong with the fuel system that would cause what appeared to be vapor lock. I haven't had a problem filling the tank since getting it serviced.
After the fuel tank service and to this day I have hesitation starting at 2200 rpm through about 2500 rpm. This will only occur when I have the throttle less than 75% open. If I go WOT I never notice a hesitation issue, although it "seems" that I have less power available. I took the car to a chevy dealer, and they recommended replacement of the upstream 02 sensors and map sensor. Apparently they checked voltages and they are not working properly. I had a mechanic check the fuel pressure, and it is normal at 60psi.
I replaced the spark plugs, wires, and upstream O2 sensors. Although the hesitation does not occur nearly as often, It will occur about 20% of the time. Should I replace the map sensor? What is the problem?
On The Tree
Joined: Jul 2005
Posts: 191
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From: Old Bridge "Raceway Park" N.J.
Unfortunately, you don't really know what was touched when the fuel tank was serviced, which is why the majority of us favor doing our own work. If the dealership also recommended a new MAP due to a faulty voltage reading, then install one as soon as you can, and let us know if it corrected the hesitation. This needs to be done before pointing to other possibilities, it's apart of the process of elimination.... 
On The Tree
Joined: Jul 2005
Posts: 191
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From: Old Bridge "Raceway Park" N.J.
There is a "snap fit" Manifold Absolute Pressure (MAP) sensor housing mounted at the rear of the intake manifold, sealed by an O-ring. The MAP sensor itself is installed, and retained to this housing. The sensor's themselves are fairly cheap. If you decide to do this on your own, there's really no FAQ needed. Just be sure to disconnect the ground cable on the battery terminal before you do any servicing such as this.... 
EXACT same problem in my 99SS. Never have had problems fueling the car but I have the same exact hesitation at the exact same RPM range I was told a dirty MAF could cause this problem-I cleaned mine and it seemed to help some but the problem is back. Ill also try what has been suggested here.
Originally Posted by Street Lethal
There is a "snap fit" Manifold Absolute Pressure (MAP) sensor housing mounted at the rear of the intake manifold, sealed by an O-ring. The MAP sensor itself is installed, and retained to this housing. The sensor's themselves are fairly cheap. If you decide to do this on your own, there's really no FAQ needed. Just be sure to disconnect the ground cable on the battery terminal before you do any servicing such as this....
Are there any pics of the location? My chiltons doesnt show anything. How cheap are they? 20$? 30$?
Originally Posted by Whisper
EXACT same problem in my 99SS. Never have had problems fueling the car but I have the same exact hesitation at the exact same RPM range I was told a dirty MAF could cause this problem-I cleaned mine and it seemed to help some but the problem is back. Ill also try what has been suggested here.
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Originally Posted by Whisper
EXACT same problem in my 99SS. Never have had problems fueling the car but I have the same exact hesitation at the exact same RPM range I was told a dirty MAF could cause this problem-I cleaned mine and it seemed to help some but the problem is back. Ill also try what has been suggested here.
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Verdad Gallardo On The Tree
Joined: Jul 2005
Posts: 191
Likes: 0
From: Old Bridge "Raceway Park" N.J.
Originally Posted by Whisper
Are there any pics of the location? My chiltons doesnt show anything. How cheap are they? 20$? 30$?
Thread Starter
Teching In
Joined: Jul 2007
Posts: 12
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Thanks for the insight. The last time that I cleaned my K&N I noticed a few large particles on the MAF screen inlet (leaves and bug parts around 1 inch) I'm guessing that I had a leak in the slp lid, I just can't see this debris getting through the K&N. I'll clean my MAF as suggested above before buying the MAP sensor. (this part costs $58.99 at autozone) The MAP looks like a real biotch to get at.
Can anyone recommend some sort of cold air induction/intake for my set-up?
Can anyone recommend some sort of cold air induction/intake for my set-up?
Originally Posted by urmanjoshie
Thanks for the insight. The last time that I cleaned my K&N I noticed a few large particles on the MAF screen inlet (leaves and bug parts around 1 inch) I'm guessing that I had a leak in the slp lid, I just can't see this debris getting through the K&N. I'll clean my MAF as suggested above before buying the MAP sensor. (this part costs $58.99 at autozone) The MAP looks like a real biotch to get at.
Can anyone recommend some sort of cold air induction/intake for my set-up?
Can anyone recommend some sort of cold air induction/intake for my set-up?
12 Second Club
Joined: Mar 2003
Posts: 334
Likes: 0
From: jonesville, MI
People don't realize how much a few little pieces of debris on the MAF sensor can effect performance and fuel mileage too. It makes the fuel trims go lean due to unmetered air and then the PCM keeps trying to compensate by adding fuel.
I have found that alot of times it takes actually using a 90 degree pick very delicately to reach around the MAF wires from the outlet side (because screen is in the way from inlet side) and the debris will stick right to the pick when touched. I have always used brake parts cleaner too after this and then a light puff of compressed air to help dry it out. You can't always see the debris from the outlet side either...hence the pick. I know guys who have just sprayed off the sensor but it didn't get it clean.
Also, the oily film from the K&N tends to stick to the MAF wires and makes debris stick easier.
I have found that alot of times it takes actually using a 90 degree pick very delicately to reach around the MAF wires from the outlet side (because screen is in the way from inlet side) and the debris will stick right to the pick when touched. I have always used brake parts cleaner too after this and then a light puff of compressed air to help dry it out. You can't always see the debris from the outlet side either...hence the pick. I know guys who have just sprayed off the sensor but it didn't get it clean.
Also, the oily film from the K&N tends to stick to the MAF wires and makes debris stick easier.
Thread Starter
Teching In
Joined: Jul 2007
Posts: 12
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It's a good idea to check the fuel pressure, I was fine at 60psi. I cleaned out my MAF and found an oil build-up on the throttle body. Would a bad EGR valve cause oil build up in the throttle body? I'm not losing oil. I reset my SES light and it was fine for ~30min of driving, but tripped in 2nd gear after leaving a stop sign at 25% throttle. It seems that the hesitation is worse in hot weather. I guess I should just suck it up and change the damn MAP sensor. Thoughts?
Launching!
Joined: Sep 2006
Posts: 265
Likes: 1
Originally Posted by urmanjoshie
It's a good idea to check the fuel pressure, I was fine at 60psi. I cleaned out my MAF and found an oil build-up on the throttle body. Would a bad EGR valve cause oil build up in the throttle body? I'm not losing oil. I reset my SES light and it was fine for ~30min of driving, but tripped in 2nd gear after leaving a stop sign at 25% throttle. It seems that the hesitation is worse in hot weather. I guess I should just suck it up and change the damn MAP sensor. Thoughts?
let foucs on the hesitation issue
i think now few factors could be the problem first:
check and replace the fuel filter .why? because it doesnt cost alot of mony
second: the problem now it lean more towards the MAP sensor so replace it.
third: if you got your car tuned before ,i think you better give that tuner a visit and check with him whats goin on in the PCM.
tell us man if you found the problem so we can avoid it in the futuer.
