PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Runs awesome one second...

Thread Tools
 
Search this Thread
 
Old Sep 17, 2009 | 11:49 AM
  #1  
'02TA's Avatar
Thread Starter
TECH Apprentice
 
Joined: May 2006
Posts: 361
Likes: 0
From: South Florida
Angry Runs awesome one second...

So this problem is completely random and effectively pisses me off to no end on a daily basis. My car is an 02 T/A, cammed, full bolt ons, full exhaust, stalled and tuned.

Ill be driving the car and it'll be running fantastic, top-notch, like a top, amazing...and then out of nowhere it'll start missing very badly and the ses light will flash and the car has no accelerational power. The thing that is very odd to me is that if I floor the car during on of these episodes it runs awesome as long as my foot is planted. Flooring it also seems to cure the problem sometimes as well. And then just as quickly and randomly as is appeared the miss is gone and the car drives perfect again. Sometimes I can make my commute to wherever I'm going without an incident but like I said it happens at least once everyday I drive the car.
Reply
Old Sep 17, 2009 | 11:51 AM
  #2  
blackhawk0251's Avatar
TECH Apprentice
iTrader: (6)
 
Joined: Oct 2007
Posts: 315
Likes: 0
From: Pensacola, FL
Default

Does it snap back into timing when it does that? M6 or A4?

Pull your kick panel under your pedals and check the clutch cruise safety switch, this same thing happend on my firehawk and I ended up taping the button down so the switch remained open.
Reply
Old Sep 17, 2009 | 11:57 AM
  #3  
'02TA's Avatar
Thread Starter
TECH Apprentice
 
Joined: May 2006
Posts: 361
Likes: 0
From: South Florida
Default

It's A4. When it starts missing the car has to be at very low timing like maybe 3 or 4 degrees but when i punch it it goes back to full timing and hauls a$$
Reply
Old Sep 17, 2009 | 12:13 PM
  #4  
blackhawk0251's Avatar
TECH Apprentice
iTrader: (6)
 
Joined: Oct 2007
Posts: 315
Likes: 0
From: Pensacola, FL
Default

Ah ok..A4..sup lol.

I would start by checking the cam position sensor and making sure its reading the correct voltages.
Reply
Old Sep 17, 2009 | 12:21 PM
  #5  
'02TA's Avatar
Thread Starter
TECH Apprentice
 
Joined: May 2006
Posts: 361
Likes: 0
From: South Florida
Default

I could see checking that but if it's missing and I floor it and it runs fine and then misses again for a little bit and the cam position sensor was bad wouldn't it not run great when @ WOT???
Reply
Old Sep 18, 2009 | 08:44 AM
  #6  
'02TA's Avatar
Thread Starter
TECH Apprentice
 
Joined: May 2006
Posts: 361
Likes: 0
From: South Florida
Default

C'mon guys I'm gonna work on it this weekend and I kinda wanna get a couple possible sources so i can check them all out...
Reply
Old Sep 18, 2009 | 10:04 AM
  #7  
oddwraith's Avatar
TECH Fanatic
iTrader: (1)
 
Joined: Aug 2008
Posts: 1,283
Likes: 0
From: Canada
Default

Sounds like your wide open throttle settings are fine then. What about your timing? Need any retard there maybe? Is it only after the car warms up; never doing it on a cold start?
Reply
Old Sep 18, 2009 | 11:26 AM
  #8  
'02TA's Avatar
Thread Starter
TECH Apprentice
 
Joined: May 2006
Posts: 361
Likes: 0
From: South Florida
Default

Its always after the car warms up a bit, maybe not always at full running temp but when it would be in open loop I would assume. Also forgot to mention that these $hitacular episodes only everlast a couple minutes at most and thats without me trying to "fix" it by flogging the gas a couple times.
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-1

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-2

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-3

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-4

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-5

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
story-6

Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

 Verdad Gallardo
story-7

Awesome K5 Blazer Restomod Comes With C7 Corvette Power

 Verdad Gallardo
story-8

10 Camaros You Should Never Buy

 
story-9

10 LS Engine Myths That Refuse to Die

 Verdad Gallardo
Old Sep 18, 2009 | 11:36 AM
  #9  
jmill96Z's Avatar
10 Second Club
iTrader: (3)
 
Joined: Feb 2006
Posts: 2,554
Likes: 1
From: Movin' On Up
Default

Do you have tuning software? Any chance you can log?
Reply
Old Sep 18, 2009 | 01:24 PM
  #10  
'02TA's Avatar
Thread Starter
TECH Apprentice
 
Joined: May 2006
Posts: 361
Likes: 0
From: South Florida
Default

It's tuned with HPtuners but I'm not a tuner by any means, It was tuned by a very good local shop who is a sponser on here. I don't have any logs but I do plan on trying to take it down there to see if he can log it when this problem strikes...problem is that it never happens when im down there. Go figure...
Reply
Old Sep 18, 2009 | 04:48 PM
  #11  
MRZ28's Avatar
Launching!
iTrader: (15)
 
Joined: Jul 2005
Posts: 231
Likes: 0
From: Wright Patterson AFB
Default

Possibly a bad or loose MAP sensor.
Reply
Old Sep 20, 2009 | 10:17 PM
  #12  
mrfrostberry's Avatar
Banned
iTrader: (10)
 
Joined: Jul 2006
Posts: 45
Likes: 0
From: Korea / OKC
Default

have you checked all the grounds? i know i've had a ton of weird intermittent problems from loose grounds.
Reply
Old Sep 21, 2009 | 12:06 PM
  #13  
'02TA's Avatar
Thread Starter
TECH Apprentice
 
Joined: May 2006
Posts: 361
Likes: 0
From: South Florida
Default

The MAP sensor has been throwing a code for the longest but I've always just credited that to the cam...even tuned with, from what I'm told by the tuner, parameters that should never throw a code.

And yes my tuner also told me to check the grounds and I'm going through them now doing voltage drop tests. Does anyone know exactly which grounds I should be paying more attention to? Are any that are more prone to loosening or rusting?
Reply
Old Sep 21, 2009 | 01:01 PM
  #14  
therealthatguy's Avatar
Launching!
iTrader: (23)
 
Joined: Feb 2007
Posts: 278
Likes: 0
Default

O2 sensors?
Reply
Old Sep 21, 2009 | 01:06 PM
  #15  
'02TA's Avatar
Thread Starter
TECH Apprentice
 
Joined: May 2006
Posts: 361
Likes: 0
From: South Florida
Default

My car isn't throwing any codes for O2's, if they were an issue then they would come up as a code right?
Reply
Old Sep 21, 2009 | 06:52 PM
  #16  
Bad30th's Avatar
12 Second Club
iTrader: (13)
 
Joined: Nov 2001
Posts: 1,898
Likes: 0
From: San Diego, CA
Default

Originally Posted by mrfrostberry
have you checked all the grounds? i know i've had a ton of weird intermittent problems from loose grounds.
That's what I was gonna say... Are you SURE it's the tune and not mechanical in nature ?

Rob (Bad30th)
Reply
Old Sep 22, 2009 | 06:52 AM
  #17  
rpmauto's Avatar
11 Second Club
iTrader: (14)
 
Joined: May 2007
Posts: 709
Likes: 0
From: Wisconsin
Default

the tune itself cant change, once it is loaded it is there. It sounds to me like an electical issue. Either ground, or input-output from the pcm, bad wire ect.. Those are fun to find. Start moving the harness around while it is running and see if you notice any changes.
Reply
Old Sep 23, 2009 | 10:01 AM
  #18  
'02TA's Avatar
Thread Starter
TECH Apprentice
 
Joined: May 2006
Posts: 361
Likes: 0
From: South Florida
Default

Originally Posted by rpmauto
the tune itself cant change, once it is loaded it is there. It sounds to me like an electical issue. Either ground, or input-output from the pcm, bad wire ect.. Those are fun to find. Start moving the harness around while it is running and see if you notice any changes.
That makes good sense...gettin to it right after work
Reply




All times are GMT -5. The time now is 04:46 AM.

story-0
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-1
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-2
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-3
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-4
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-5
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-6
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE
story-7
Awesome K5 Blazer Restomod Comes With C7 Corvette Power

Slideshow: A heavily reworked 1972 K5 Blazer swaps its off-road roots for a low-slung street-focused build with modern V8 power.

By Verdad Gallardo | 2026-03-09 18:08:45


VIEW MORE
story-8
10 Camaros You Should Never Buy

Slideshow: There are thousands of used Camaros on the market but we think you should avoid these 10

By | 2026-02-17 17:09:30


VIEW MORE
story-9
10 LS Engine Myths That Refuse to Die

Slideshows: Which one of these myths do you believe?

By Verdad Gallardo | 2026-01-28 18:10:11


VIEW MORE