Car Drives Like SH!T!!! MAF Sensor?
07-06-2005, 09:23 PM
#1
Car Drives Like ****!!! MAF Sensor? I got my car tuned about a month ago for 60# injectors and for boost. The car made horrible power, 418rwhp and 408rwtq, open cutouts, which was only 3rwhp more than through the Flowmaster and cats!!! 
. I am missing about 100hp. When driving home from the shop, I noticed my car had NO power off idle. I really have to rev the motor to get it moving. When normally accelerating, the car hesitates like its missing. When letting off the throttle, the car starts to buck when in gear. The car seems okay when WOT, except for the obvious lack of power. The exhaust pops on deceleration and between shifts really badly when cold all the way until fully warm, then it pops only every now and then.
Since then, the car is getting worse and worse. This thing is a ******* nightmare to drive. Last week a few times driving off from a stop sign in first gear, I go to give it gas and the motor just stumbles really bad below idle speed. This is just normal driving. Basically the engine feels like its going to die. I have to give it almost full throttle to keep it alive. Once it started stumbling I gave it a ton of gas and it took about 6-7 seconds for the motor to finally pick up RPM. Then once I was normally accelerating in 3rd and at about 2000rpm the motor lost ALL power, then caught itself after a second or two. I am embarrased to drive it because it's like I'm trying to drive a car I have never driven before. Not to mention I am getting about 12mpg with 75% highway driving.
My tuner seemed to think my O2 sensors were bad, which I replaced. The car did not improve at all. Now he seems to think my MAF sensor could be messed up. What do you guys think about this? I would like some opinions before I shell out the money for a new one. I am confident that the tune is fine, and that its the car that isn't running right. Any help is appreciated. Thanks!
. I am missing about 100hp. When driving home from the shop, I noticed my car had NO power off idle. I really have to rev the motor to get it moving. When normally accelerating, the car hesitates like its missing. When letting off the throttle, the car starts to buck when in gear. The car seems okay when WOT, except for the obvious lack of power. The exhaust pops on deceleration and between shifts really badly when cold all the way until fully warm, then it pops only every now and then.Since then, the car is getting worse and worse. This thing is a ******* nightmare to drive. Last week a few times driving off from a stop sign in first gear, I go to give it gas and the motor just stumbles really bad below idle speed. This is just normal driving. Basically the engine feels like its going to die. I have to give it almost full throttle to keep it alive. Once it started stumbling I gave it a ton of gas and it took about 6-7 seconds for the motor to finally pick up RPM. Then once I was normally accelerating in 3rd and at about 2000rpm the motor lost ALL power, then caught itself after a second or two. I am embarrased to drive it because it's like I'm trying to drive a car I have never driven before. Not to mention I am getting about 12mpg with 75% highway driving.
My tuner seemed to think my O2 sensors were bad, which I replaced. The car did not improve at all. Now he seems to think my MAF sensor could be messed up. What do you guys think about this? I would like some opinions before I shell out the money for a new one. I am confident that the tune is fine, and that its the car that isn't running right. Any help is appreciated. Thanks!
07-06-2005, 09:39 PM
#2
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I think your tuner doesn't know what's going on. Get rid of your maf and tune it speed density. You will have much better luck.
Sounds like you are running incredibly rich w/o enough timing. Can you post a graph of your last dyno? Also what plugs are you running and what gap?
Sounds like you are running incredibly rich w/o enough timing. Can you post a graph of your last dyno? Also what plugs are you running and what gap?
07-06-2005, 10:21 PM
#3
make sure that the hardware is solid. do you know that the injectors are clean and flow consistently through all of them? if you suspect your MAF, then just disconnect it and go Speed Density. Assuming your VE is right, your car should drive better.
do this little MAF experiment, post your results, and we'll take it from there.
do this little MAF experiment, post your results, and we'll take it from there.
07-06-2005, 10:37 PM
#4
Unfortunatly I dont have the capability of tuning in speed density, and my tuner is a long drive away.
Plugs are TR6 gapped at .035. All injectors are flow matched.
Here is the dyno graph, looks like I only gained 2rwhp with open cutouts, but 16rwtq.... Strange.
Plugs are TR6 gapped at .035. All injectors are flow matched.
Here is the dyno graph, looks like I only gained 2rwhp with open cutouts, but 16rwtq.... Strange.
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07-07-2005, 08:12 AM
#8
Tough to diagnose this as either a tuning issue or a malfunction without a scanner. Either find a shop with EFILive or whatever, or make the investment yourself (which I recommend).
The last car I looked at that had suspected "tuning" issues turned out to be a damaged O2 sensor wire. The car's owner had swapped O2 sensors, no effect. We scanned it and saw bank 2 sensor 1 completely dead, he traced the wiring and found the damage. Soon as that was fixed, it woke up and behaved.
The tune wasn't worth a turd either, but it wasn't causing the poor streetability and low power. It developed nice street manners when the O2 sensor was back online and the PCM wasn't gimping around in O/L Fault mode.
The last car I looked at that had suspected "tuning" issues turned out to be a damaged O2 sensor wire. The car's owner had swapped O2 sensors, no effect. We scanned it and saw bank 2 sensor 1 completely dead, he traced the wiring and found the damage. Soon as that was fixed, it woke up and behaved.
The tune wasn't worth a turd either, but it wasn't causing the poor streetability and low power. It developed nice street manners when the O2 sensor was back online and the PCM wasn't gimping around in O/L Fault mode.
07-07-2005, 10:53 AM
#9
TECH Addict
do you have a scanner like autotap or anything like that to datalog the car?
how is the person diagnosing the issue backing up the claims? it will be pretty obvious what is going on if you datalog the right things.
I have 60# injectors in my car and it drives just fine, still get the same gas mileage I always did, drivability is the same, etc.....
how is the person diagnosing the issue backing up the claims? it will be pretty obvious what is going on if you datalog the right things.
I have 60# injectors in my car and it drives just fine, still get the same gas mileage I always did, drivability is the same, etc.....
07-07-2005, 12:12 PM
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Originally Posted by Ferocity02
I got my car tuned about a month ago for 60# injectors and for boost. The car made horrible power, 418rwhp and 408rwtq, open cutouts, which was only 3rwhp more than through the Flowmaster and cats!!! . I am missing about 100hp. When driving home from the shop, I noticed my car had NO power off idle. I really have to rev the motor to get it moving. When normally accelerating, the car hesitates like its missing. When letting off the throttle, the car starts to buck when in gear. The car seems okay when WOT, except for the obvious lack of power. The exhaust pops on deceleration and between shifts really badly when cold all the way until fully warm, then it pops only every now and then.
Since then, the car is getting worse and worse. This thing is a ******* nightmare to drive. Last week a few times driving off from a stop sign in first gear, I go to give it gas and the motor just stumbles really bad below idle speed. This is just normal driving. Basically the engine feels like its going to die. I have to give it almost full throttle to keep it alive. Once it started stumbling I gave it a ton of gas and it took about 6-7 seconds for the motor to finally pick up RPM. Then once I was normally accelerating in 3rd and at about 2000rpm the motor lost ALL power, then caught itself after a second or two. I am embarrased to drive it because it's like I'm trying to drive a car I have never driven before. Not to mention I am getting about 12mpg with 75% highway driving.
My tuner seemed to think my O2 sensors were bad, which I replaced. The car did not improve at all. Now he seems to think my MAF sensor could be messed up. What do you guys think about this? I would like some opinions before I shell out the money for a new one. I am confident that the tune is fine, and that its the car that isn't running right. Any help is appreciated. Thanks!
. I am missing about 100hp. When driving home from the shop, I noticed my car had NO power off idle. I really have to rev the motor to get it moving. When normally accelerating, the car hesitates like its missing. When letting off the throttle, the car starts to buck when in gear. The car seems okay when WOT, except for the obvious lack of power. The exhaust pops on deceleration and between shifts really badly when cold all the way until fully warm, then it pops only every now and then.Since then, the car is getting worse and worse. This thing is a ******* nightmare to drive. Last week a few times driving off from a stop sign in first gear, I go to give it gas and the motor just stumbles really bad below idle speed. This is just normal driving. Basically the engine feels like its going to die. I have to give it almost full throttle to keep it alive. Once it started stumbling I gave it a ton of gas and it took about 6-7 seconds for the motor to finally pick up RPM. Then once I was normally accelerating in 3rd and at about 2000rpm the motor lost ALL power, then caught itself after a second or two. I am embarrased to drive it because it's like I'm trying to drive a car I have never driven before. Not to mention I am getting about 12mpg with 75% highway driving.
My tuner seemed to think my O2 sensors were bad, which I replaced. The car did not improve at all. Now he seems to think my MAF sensor could be messed up. What do you guys think about this? I would like some opinions before I shell out the money for a new one. I am confident that the tune is fine, and that its the car that isn't running right. Any help is appreciated. Thanks!
First off, if you want to give me a call at the shop and I can help you with the items you are missing, feel free to call us. I can also explain to you how you can get your drivability back and get your gas milage back as well.
I can tell you just buy reading the tuner spent no time on your part throttle work at all. You are missing so much out of your car you will freak when you get it back. So give me a call in the shop when you get a chance. Maybe I can walk you through this.
Rick
