L98 Acting Up
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
L98 Acting Up
About a week ago, the vette wouldn't idle correctly, and last year around november i bought an IAC valve for it because the one that was on there was old as hell. (and i had a lot of money at the time) So when i got the car out, i remembered and i put the new IAC on (after it broke off in the TB and i had to get it drilled out). After reconnecting the IAC and trying to start the car it threw a code 22 for TPS sensor. It wouldn't run for more than 1 second.
I went under the hood and looked at the TPS sensor, and noticed that the connector was missing its clip to attach it to the sensor. I thought it was loose, so i had my dad hold it together while i went and started the car, but it was still giving the code. I pulled the negative battery cable to reset the ecm to see if it would go away, and it didn't.
Went to autodump and ordered a TPS sensor and harness because the harness was missing the clip that connected it to the TPS sensor.
Went home, and installed the TPS sensor and the car still wouldn't start. I tried adjusting it to achieve .54 volts @ idle, but when the sensor is turned as far as it will go on the throttle body with the adjusting screws, it only reads .34 volts! Now it doesn't even run at all. It "catches" but dies instantly.
Help me please..I miss drivin the beast.
I went under the hood and looked at the TPS sensor, and noticed that the connector was missing its clip to attach it to the sensor. I thought it was loose, so i had my dad hold it together while i went and started the car, but it was still giving the code. I pulled the negative battery cable to reset the ecm to see if it would go away, and it didn't.
Went to autodump and ordered a TPS sensor and harness because the harness was missing the clip that connected it to the TPS sensor.
Went home, and installed the TPS sensor and the car still wouldn't start. I tried adjusting it to achieve .54 volts @ idle, but when the sensor is turned as far as it will go on the throttle body with the adjusting screws, it only reads .34 volts! Now it doesn't even run at all. It "catches" but dies instantly.
Help me please..I miss drivin the beast.
Melting Slicks
Joined: Jan 2001
Posts: 2,940
Likes: 5
From: Chesapeake VA
If I recall correctly, the TPS should give values from 0.54 volts to 5 volts. Can you see if the sensor sends signals in that range as you open the throttle? If it dosen't, you may have a defective replacement TPS.
Melting Slicks
Joined: Jan 2001
Posts: 2,940
Likes: 5
From: Chesapeake VA
I don't think it should stop at 3.5 volts, but it may depend on how stong the battery in the car is. I don't know if it makes a difference if the engine is running (thus suppling 14 volts to the battery/system) or if the engine is off and the battery is weak (say 11.1 volts or less). The only test I can think of off hand to check that is to hook up a battery charger on slow charge and retry the TPS test after checking the voltage at the battery. My charger usually shows about 14.5 volts in slow charge mode.
Again, I am not an expert, so the TPS voltage may not care about the battery/alternator/system strength.
Again, I am not an expert, so the TPS voltage may not care about the battery/alternator/system strength.
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
i think when i jump in the car, and i have the gauges set to volt, it was reading 11.2-11.4 so it might be low. I have tried starting it a lot on the battery without it having time to fully recharge because it only runs for 1-2 seconds. I will try that when i get home from school 
Hopefully i can get this stuff sorted out, in the past 6 months i have spent over 500 dollars on sensors/stuff that the people who owned it before me f***ed up.
MAF + harness, IAC, TPS + harness, new spark plugs, wires, cap and rotor, accel supercoil, 02 sensor, K&N, etc..
Hopefully i can get this stuff sorted out, in the past 6 months i have spent over 500 dollars on sensors/stuff that the people who owned it before me f***ed up.
MAF + harness, IAC, TPS + harness, new spark plugs, wires, cap and rotor, accel supercoil, 02 sensor, K&N, etc..
Race Director
Joined: Jun 2004
Posts: 13,961
Likes: 707
From: WI
Most of that stuff you didn't need and/or could have gotten good used parts for hardly any cost. I've got at least three spares o2's here, you could have had one.
Your 11.2 v reading is extremely low, I'm guessing the car doesn't have enough juice to run.
Your 11.2 v reading is extremely low, I'm guessing the car doesn't have enough juice to run.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
update: battery was low, so i charged it and adjusted the TPS to .54 volts. Now, when i start the car it idles, but if i touch the gas pedal it automatically dies.
The timing is right on at 6 degrees BTDC, the tps is at .54 volts, fuel pressure is 39 psi..what else could it be?
HELP ME!
The timing is right on at 6 degrees BTDC, the tps is at .54 volts, fuel pressure is 39 psi..what else could it be?
HELP ME!
Racer
Joined: Jan 2007
Posts: 274
Likes: 0
From: Muskogee OK
It sounds like you may have a massive air leak. Is the replacement IAC seated properly, especially if it had to be drilled out?
You may be pulling in too much air if it is leaking around the gasket.
Also, hook up your DVM to the TPS and manually open the TB (engine off) and see if the voltage increases.
You may be pulling in too much air if it is leaking around the gasket.
Also, hook up your DVM to the TPS and manually open the TB (engine off) and see if the voltage increases.
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
the IAC seated perfectly in the hole that it came out of. I will feel around the car tomorrow for leaks. Do you think it could be the injectors?
ill resistance check the injectors (what are they supposed to check in at?)
check for air leaks
and do the TPS & TB thing mentioned above..
if that doens't work i'm just gonna put it on the railroad tracks and claim insurance
lol jk
ill resistance check the injectors (what are they supposed to check in at?)
check for air leaks
and do the TPS & TB thing mentioned above..
if that doens't work i'm just gonna put it on the railroad tracks and claim insurance
lol jk
Burning Brakes
Joined: Oct 2004
Posts: 898
Likes: 1
From: Pearland Texas
The injectors should ohm out fairly evenly. I'd say between 11 and 16 ohms. If they are way off that may be a problem. Have you reset the IAC ? There is method for grounding the ALDL and unplugging the IAC. A search for IAC reset might answer that question, I remember there was a tech tip for it,, but I can't log on to that, for some reason.
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
is there a way to reset the IAC without the engine running? As soon as i plug the IAC in, it automatically dies..
the car runs with IAC and EST connectors unplugged, but it is VERY rough and dies. i have to keep starting it until it gets to operating temperature, where it will idle all day but if i touch the gas it dies.
the car runs with IAC and EST connectors unplugged, but it is VERY rough and dies. i have to keep starting it until it gets to operating temperature, where it will idle all day but if i touch the gas it dies.
Pro
Joined: Nov 2002
Posts: 737
Likes: 11
From: Charlotte MI
is there a way to reset the IAC without the engine running? As soon as i plug the IAC in, it automatically dies..
the car runs with IAC and EST connectors unplugged, but it is VERY rough and dies. i have to keep starting it until it gets to operating temperature, where it will idle all day but if i touch the gas it dies.
the car runs with IAC and EST connectors unplugged, but it is VERY rough and dies. i have to keep starting it until it gets to operating temperature, where it will idle all day but if i touch the gas it dies.
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
the fuel pressure is right at 39 psi.
Is there a way to reset the IAC without running the engine? It won't run long enough to reset it, it only runs for 1-2 seconds when the EST and IAC are hooked up.
Is there a way to reset the IAC without running the engine? It won't run long enough to reset it, it only runs for 1-2 seconds when the EST and IAC are hooked up.
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
update:
did a leakdown test, and its holding its fuel pressure right at 39 psi. that eliminates injectors right? I am now convinced that this is a fuel issue.
its kinda weird that the car starts right up like all is well then it just dies..
could this be a sign of a failing pump?
any help is appreciated.
did a leakdown test, and its holding its fuel pressure right at 39 psi. that eliminates injectors right? I am now convinced that this is a fuel issue.
its kinda weird that the car starts right up like all is well then it just dies..
could this be a sign of a failing pump?
any help is appreciated.
Burning Brakes
Joined: Feb 2009
Posts: 785
Likes: 3
From: Richmond Virginia
did a leakdown test, and its holding its fuel pressure right at 39 psi. that eliminates injectors right? I am now convinced that this is a fuel issue.
No it does not.... check the resistance with a VOM
No it does not.... check the resistance with a VOM
Pro
Joined: Nov 2002
Posts: 737
Likes: 11
From: Charlotte MI
The Idle Air Controller should home itself when you turn the key to the on position. Use a DVM to see if the 5 volt reference, common to the air temp,TPS, and coolant temp sensor goes to 0. Also see if you happen to have a shor that is pulling that reference voltage to O. Given that when you plug the connectors in the car quits, this may also be the problem. Oh, what year is your car?
Thread Starter
Tech Contributor
Joined: Oct 2008
Posts: 3,729
Likes: 190
From: Custer, WI
The Idle Air Controller should home itself when you turn the key to the on position. Use a DVM to see if the 5 volt reference, common to the air temp,TPS, and coolant temp sensor goes to 0. Also see if you happen to have a shor that is pulling that reference voltage to O. Given that when you plug the connectors in the car quits, this may also be the problem. Oh, what year is your car?
Burning Brakes
Joined: Oct 2004
Posts: 898
Likes: 1
From: Pearland Texas
is there a way to reset the IAC without the engine running? As soon as i plug the IAC in, it automatically dies..
the car runs with IAC and EST connectors unplugged, but it is VERY rough and dies. i have to keep starting it until it gets to operating temperature, where it will idle all day but if i touch the gas it dies.
the car runs with IAC and EST connectors unplugged, but it is VERY rough and dies. i have to keep starting it until it gets to operating temperature, where it will idle all day but if i touch the gas it dies.
