Intermittant misfire, now dead. - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


GMC/Chevrolet Truck/SUV When starting new posts, please specify YEAR, MAKE, MODEL, ENGINE type, and whatever modifications you have made.

Reply
 
 
 
Thread Tools Search this Thread
Old 11-16-2011, 03:17 PM   #1
Senior Member
True Car Nut
Thread Starter
 
rjolly87's Avatar
 
Join Date: Jun 2003
Location: Las Cruces, NM
Posts: 6,857
Thanked 298 Times in 246 Posts
rjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant future
Default Intermittant misfire, now dead.

A friend of mine has a 1997 Jeep Wrangler that he swapped a 4.3 Vortec from a 2001 Blazer. Lately, he has had an intermittent misfire affecting all cylinders, and on his way home today, he states that it misfired, then died while driving. He states that it almost tries to start, but just never does. I go look at this thing tomorrow, what should I look for?

The details:

Custom PCM, with tweaks, VATS programmed out, Emissions Programmed out, etc
He also has a stock PCM with VATS pulled, he has had that in for the last 2 days trying to get the PCM to throw codes to diagnose the misfire.
According to him, no codes are in the computer currently
He checked fuel pressure. It builds with key on, drops off, as it has always, and then when the fuel pump fires back up, it comes back up. Truck is not starting even with fuel pressure up.
He swapped ICM, coil (stock, and msd), etc, and the truck is still not starting. He is getting some pretty hefty spark, timing unknown.
He has the system that replaces the injection poppet system with straight injectors.

Ideas? It sounds like a fueling issue if I had to guess. He plans on putting the custom burn PCM back in the truck to see if it will start.
rjolly87 is offline   Reply With Quote
Old 11-16-2011, 05:18 PM   #2
Senior Member

True Car Nut
 
2kg4u's Avatar
 
Join Date: Sep 2006
Location: Windsor, Ontario / Detroit, Michigan
Posts: 4,804
Thanked 220 Times in 181 Posts
2kg4u has much to be proud of2kg4u has much to be proud of2kg4u has much to be proud of2kg4u has much to be proud of2kg4u has much to be proud of2kg4u has much to be proud of2kg4u has much to be proud of2kg4u has much to be proud of2kg4u has much to be proud of
Default

Check the vacuum hose on the fuel pressure regulator by removing it and smelling for gas. Once it builds up the fuel pressure should not be dropping when the pump is not running.
2kg4u is offline   Reply With Quote
Old 11-16-2011, 09:01 PM   #3
Senior Member
True Car Nut
Thread Starter
 
rjolly87's Avatar
 
Join Date: Jun 2003
Location: Las Cruces, NM
Posts: 6,857
Thanked 298 Times in 246 Posts
rjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant future
Default

He found what the issue was. Turns out the bolts sheered off of the ignition rotor.
rjolly87 is offline   Reply With Quote
Old 11-17-2011, 09:12 AM   #4
DINOSAURUS BOOSTUS

Expert Gearhead
 
BillBoost37's Avatar
 
Join Date: Mar 2005
Location: Enfield, CT
Posts: 41,391
Thanks: 0
Thanked 0 Times in 0 Posts
BillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of lightBillBoost37 is a glorious beacon of light
Default

Wow..thanks for the update.
BillBoost37 is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Dead laptop, dead iPod, dead life rant wjcollier07 Lounge 24 02-20-2007 07:47 PM
95 bonneville intermittant starting problem.. diebye 1992-1999 3 11-02-2004 08:16 AM
Intermittant "Low Coolant" light. jmark 1992-1999 3 06-29-2004 12:14 AM
Sub Dead or Amp Dead? 79ford Audio (and aftermarket electronics) 24 02-22-2004 01:55 PM
Intermittant Low Coolant ??? Drifter420 1992-1999 5 09-24-2002 09:55 AM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 06:58 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.