2nd Gen S-series (1995-2005) Tech Discuss 2nd generation s-series (1995-2005) general tech topics here.

97 4.3 random misfire and backfiring

  #1  
Old 01-13-2011, 03:32 PM
New Member
Thread Starter
Join Date: Dec 2010
Posts: 3
beccari56 is on a distinguished road
Default

Hi, I recently bought a 97 blazer 4x4 with a 4.3 that had a bad rod knock. If I would have known the dificulty of removing the engine, I probably would have rethought it. Long story short, I rebuilt the engine, replaced the sensors at the back of the engine (hard to get to), new timing chain, cap, rotor, plugs, wires and oil pump. all other external parts are original, including the intake manifold and associated parts. I now have a p0300 code that I have not been able to correct. I have cleaned out the egr, replaced the temp sensor (The one in the front), one O2 sensor(All of these were codes i was getting, even though they were showing up one at a time, fix one code, drive it and another one would show up) The truck ran a bit better with every thing I did to it, but I still have the loping engine and random backfire. It runs like it is just slightly out of time, so I have tried setting the timing one tooth forward and then one tooth back on the distributor with no success. It would not even start either time. I really want to get this thing on the road. Anyone have any ideas? Is it possible I might be a tooth off on my timing chain or could it be that injector malfunctioning? Any help will be vastly appreciated. Thanks.

Yea, thats what I will check next. I installed the chain while the motor was out of the vehicle, so I had a pretty good look at it, but that doesn't really mean I set it right. Looks like I will tear the front down and verify that it is right. Thanks.
 
  #2  
Old 01-25-2011, 11:05 AM
New Member
Thread Starter
Join Date: Dec 2010
Posts: 3
beccari56 is on a distinguished road
Default

Well, I finally was able to take the front of the engine apart to check my timing chain alignment. It was spot on. That's another possibility knocked off the list. Once I put everything back together, I checked the fuel pressure. It went to 55 psi with the key on and stayed at around 54-56 psi with the motor running. Another possibility knocked off. Does anyone have a clue as to why the engine shakes at idle and backfires when running? I'm running out of possibilities. All i have left is possible distributor timing gear, which looked ok with no play when I installed it and the injector system, which may be bad. The only code I'm getting is the p0300, random misfire. Am I missing anything else? Any help is appreciated. Thanks.
 
  #3  
Old 01-26-2011, 12:53 PM
New Member
Join Date: Aug 2009
Location: Royersford Pa
Posts: 53
theeviltwinn is on a distinguished road
Default

Does the fuel pressure hold with the key off?

Mike
 
  #4  
Old 01-29-2011, 09:07 AM
New Member
Thread Starter
Join Date: Dec 2010
Posts: 3
beccari56 is on a distinguished road
Default

Yes, it does. It stays at 55 until I release the pressure.
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
shanegreen
2nd Gen S-series (1995-2005) Tech
9
04-22-2012 10:25 AM
polarbear18w
2nd Gen S-series (1995-2005) Tech
13
09-23-2011 01:27 PM
BlaziNator
2nd Gen S-series (1995-2005) Tech
54
05-25-2010 05:15 PM
Iceman_19
2nd Gen S-series (1995-2005) Tech
2
08-26-2009 03:14 PM
infamous
2nd Gen S-series (1995-2005) Tech
2
01-07-2007 04:18 AM


Thread Tools
Search this Thread
Quick Reply: 97 4.3 random misfire and backfiring


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

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.