MAF sensor ??
Thread Starter
Racer
Joined: Dec 2003
Posts: 258
Likes: 14
From: Santa Maria Ca.
MAF sensor ??
Hi,
I have a 1988 Camaro TPI system adapted to 350 chevy, in a hot rod.
I had my data scanner connected; I believe I have a bad injector, because it idles poorly at idle after it goes into "closed loop".
I removed a section of my air inlet tubing to paint it. There was no air tubing connecting my MAF to the throttle body. The paint was not drying fast enough to re-install it, so I started the car to move it out of the garage. I'm backing up and notice my scanner is showing MAF flow data changing as I work the throttle. It shows 10GPS @ idle and as blip the throttle it goes up to 40-50GPS.
.
How can that be? There was no air flow through the sensor. I did have the wiring connected, but no air hose tubing.
I did have SES light, but I expected that.
Does the computer provide some data for MAF, when it senses a MAF failure?
Anybody want to try this at home?
I'd like to hear what happens with yours.
Thanks,
Mike
I have a 1988 Camaro TPI system adapted to 350 chevy, in a hot rod.
I had my data scanner connected; I believe I have a bad injector, because it idles poorly at idle after it goes into "closed loop".
I removed a section of my air inlet tubing to paint it. There was no air tubing connecting my MAF to the throttle body. The paint was not drying fast enough to re-install it, so I started the car to move it out of the garage. I'm backing up and notice my scanner is showing MAF flow data changing as I work the throttle. It shows 10GPS @ idle and as blip the throttle it goes up to 40-50GPS.
.
How can that be? There was no air flow through the sensor. I did have the wiring connected, but no air hose tubing.
I did have SES light, but I expected that.
Does the computer provide some data for MAF, when it senses a MAF failure?
Anybody want to try this at home?
I'd like to hear what happens with yours.
Thanks,
Mike
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
I wouldn't get too excited about the minor MAF flow data change when the connecting tube was out...any air movement going across the MAF sensor wire will cool it slightly and produce the value change your seeing....you can simulate the same "effect" by blowing on the element inside the MAF from the front or back side.
I don't know what specific ECM/PCM or wiring harness your using in your "hot rod" but most OEM computer units will have the ability to store "trouble codes". These trouble codes may or may not help you narrow down your poor idle issue by revealing the trouble code.
Not saying that your problem is this but many of the fuel injected models in the year you mentioned were/are not ethenol compliant - so perhaps it is time for some new injectors.
Some other basic things that may cause irratic idle:
Worn out throttle body bushings
Improper TPS value @ idle
VSS not being connected to the ECM (link is your thread from 2008):http://forums.corvetteforum.com/c4-s...ss-signal.html
Loose/improper ducting between the MAF and TB
I don't know what specific ECM/PCM or wiring harness your using in your "hot rod" but most OEM computer units will have the ability to store "trouble codes". These trouble codes may or may not help you narrow down your poor idle issue by revealing the trouble code.
Not saying that your problem is this but many of the fuel injected models in the year you mentioned were/are not ethenol compliant - so perhaps it is time for some new injectors.
Some other basic things that may cause irratic idle:
Worn out throttle body bushings
Improper TPS value @ idle
VSS not being connected to the ECM (link is your thread from 2008):http://forums.corvetteforum.com/c4-s...ss-signal.html
Loose/improper ducting between the MAF and TB
Last edited by engle1147; Dec 16, 2011 at 02:10 PM. Reason: +ed link
Thread Starter
Racer
Joined: Dec 2003
Posts: 258
Likes: 14
From: Santa Maria Ca.
Thanks for your reply.
The bad injectors really troubled me a few years back. My wife was driving a 1990 and it always ran like a sewing machine.
Suddenly it started idling poorly, but the gas mileage on the DIC went way up at cruising speeds.
I started swapping out all ignition components until I ran out of things to change.
I had to call Gordon Killebrew at home; he clued me in to look at the resistance of each injector. Sure enough a couple were at about 9 ohms.
What a difference that made.
Mike
The bad injectors really troubled me a few years back. My wife was driving a 1990 and it always ran like a sewing machine.
Suddenly it started idling poorly, but the gas mileage on the DIC went way up at cruising speeds.
I started swapping out all ignition components until I ran out of things to change.
I had to call Gordon Killebrew at home; he clued me in to look at the resistance of each injector. Sure enough a couple were at about 9 ohms.
What a difference that made.
Mike
Thread Starter
Racer
Joined: Dec 2003
Posts: 258
Likes: 14
From: Santa Maria Ca.
I did add a vss generator a while back. That did improved things.
I am using the original wiring harness and computer from the donor car.
I'm not getting any stored codes; it has been code free...
Wore out the 350; Changed it out with a 400 small block.
Installed a pair of aluminum L-98 heads.
Slight more cam.
Iknow I'm asking an awfull lot out of an injection system designed for a 305, so I recently installed a LT-1 intake.
I have ordered a set of injectors from "FIC"; they are in the mail.
Hopefully this will fix it.
Thanks, for your input.
Mike
I am using the original wiring harness and computer from the donor car.
I'm not getting any stored codes; it has been code free...
Wore out the 350; Changed it out with a 400 small block.
Installed a pair of aluminum L-98 heads.
Slight more cam.
Iknow I'm asking an awfull lot out of an injection system designed for a 305, so I recently installed a LT-1 intake.
I have ordered a set of injectors from "FIC"; they are in the mail.
Hopefully this will fix it.
Thanks, for your input.
Mike
