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2001 4.3 vortec blazer. Replaced lower intake manifold gasket.

Customer Question

2001 4.3 vortec blazer. Replaced lower intake manifold gasket. Ran great before replacing the gasket. The engine had a definite miss, but ran better after disconnecting #3 plug wire. I assumed I got the distributer cam gear one tooth off, so went to TDC re-stabbed the dist on the wrong timing mark, then I looked up all data com to see there's two timing marks. I got it set up correctly TDC, rotor pointing at 6 cyl mark etc... and now the engine runs erratic and will not stay running.
Submitted: 8 years ago.
Category: Chevy
Expert:  Carhelp4u replied 8 years ago.

Are you getting any check engine lights at this point? If the distributor is not installed correctly on this one you will get a trouble code for a camshaft/crankshaft position correlation issue. Here is what you need to do to properly setup this distributor with no initial marks on the distributor.

Object Number: 334551  Size: SH

Important: Rotate the number 1 cylinder to top dead center (TDC) of the compression stroke. The engine front cover has 2 alignment tabs and the crankshaft balancer has 2 alignment marks (spaced 90 degrees apart) which are used for positioning number 1 piston at top dead center (TDC). With the piston on the compression stroke and at top dead center, the crankshaft balancer alignment mark (1) must align with the engine front cover tab (2) and the crankshaft balancer alignment mark (4) must align with the engine front cover tab (3).

  • Rotate the crankshaft balancer clockwise until the alignment marks on the crankshaft balancer are aligned with the tabs on the engine front cover and the number 1 piston is at top dead center of the compression stroke.
    Object Number: 301395  Size: SH

  • Align white paint mark on the bottom stem of the distributor, and the pre-drilled indent hole in the bottom of the gear (3).

    Notice: The ignition system distributor driven gear and rotor may be installed in multiple positions. In order to avoid mistakes, mark the distributor on the following components in order to ensure the same mounting position upon reassembly:

    The distributor driven gear
    The distributor shaft
    The rotor holes
    Installing the driven gear 180 degrees out of alignment, or locating the rotor in the wrong holes, will cause a no-start condition. Premature engine wear or damage may result.


  • With the gear in this position, the rotor segment should be positioned as shown for a V6 engine (1) or V8 engine (2).
    The alignment will not be exact.
    If the driven gear is installed incorrectly, the dimple will be approximately 180 degrees opposite of the rotor segment when the gear is installed in the distributor.

    Object Number: 34397  Size: SH

  • Using a long screw driver, align the oil pump drive shaft to the drive tab of the distributor.
  • Guide the distributor into the engine. Ensure that the spark plug towers are perpendicular to the centerline of the engine.
    Object Number: 4350  Size: SH

  • Once the distributor is fully seated, the rotor segment should be aligned with the pointer cast into the distributor base.
    There may be a 6 cast into this pointer, indicating that the distributor is to be used on a 6 cylinder engine or an 8, indicating that the distributor is to be used on a 8 cylinder engine.
    If the rotor segment does not come within a few degrees of the pointer, the gear mesh between the distributor and the camshaft may be off a tooth or more.
    If this is the case, repeat the procedure again in order to achieve proper alignment.

    Object Number: 366609  Size: SH

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  • Install the distributor mounting clamp bolt.

    Tighten the distributor clamp bolt to 25 N·m (18 lb ft).

    Object Number: 301393  Size: SH

  • Install the distributor cap.
  • Install two new distributor cap screws.

    Tighten the screws to 2.4 N·m (21 lb in).

  • Install the electrical connector to the distributor.
  • Install the spark plug wires to the distributor cap.
    Object Number: 387772  Size: SH

  • Install the ignition coil wire.

    Note the correct orientation of the wire boot.

    Important: If the MIL is turned ON after installing the distributor, and a DTC P1345 is found, the distributor has been installed incorrectly.

  • Customer: replied 8 years ago.
    I did everything you pointed out except replace new cap screws.
    Expert:  Carhelp4u replied 8 years ago.

    Yes they are somewhat optional. Are you getting a check engine light? If so have you pulled any trouble codes? Have you checked this engine for vacuum leaks?

    Customer: replied 8 years ago.
    When it was running just missing, it had a temperature t/c, which I had forgot plug in. The code went away. I do not have scanner as of yet, but will attempt to get one in a couple of hours. When it was running, before reinstalling the dist,, I checked for vacuum leaks but had none.
    Expert:  Carhelp4u replied 8 years ago.
    Ok how did you verify that you were at tdc at the crank?
    Customer: replied 8 years ago.
    Removed the fan and shroud, pulled #1 plug and inserted finger. Turned the engine over by hand until compression released and the two timing marks were aligned.
    Expert:  Carhelp4u replied 8 years ago.
    Great, that is exactly what I wanted to make sure. Otherwise we could have been 180 out. You seem to have the distributor in correct from what you are telling me. I would recommend going over the electrical connectors at the distributor to verify that none of the terminals have been damaged. I would also recommend making sure that the oring around where the injector body comes through the upper intake is intact and has not slid out of place. Another item to look for would be a problem with the large rubber gasket that runs around the upper to lower intake manifold. Other than this, I would like to see a result of the diagnostic scan to see what trouble codes may exist.
    Customer: replied 8 years ago.
    I will have more to do tomorrow. I am an ex-mechanic ASE certified and I am not use to being stumped.

    Thank you. I how do I get back in touch with tomorrow. I work for myself and plan to dedicate time until the problem is fixed.
    Expert:  Carhelp4u replied 8 years ago.
    You should be able to log back in and come back to this post. Let me know how you make out and if you need further assistant. From what you are telling me you have done all of this correct.
    Customer: replied 8 years ago.
    I have it running now. I replaced the upper intake gaskets, which did not fix anything. The marks on timing on the damper are wrong.   I am now back to my #3 miss.

    Thanks for your help.

    Clint "the SnakeMan"
    Expert:  Carhelp4u replied 8 years ago.

    Wow that is strange for sure. I cannot say I have ever ran into that before. As far as the #3 miss, you have verified that there are no vacuum leaks that could affect this cylinder. I would recommend checking for spark at the #3 cylinder to verify that you have good blue-white spark at the spark plug. I would also look very closely at the porcelain part of the plug to verify that it has not been cracked for whatever reason.

    If this checks out, you are getting to the point where a compression test and an injector balance test would be in order. My honest feeling is that possibly you may have a faulty injector stuck open or not opening correctly. If the compression test shows that this cylinder is within 10% of two other cylinders then we must very much assume this is being caused by a fuel type problem. You may also want to check to verify that all the contacts that plug into the top of the fuel injector body are in tact and none are damaged or bent over. Feel free to contact me with any questions or findings! Good luck!
    Customer: replied 8 years ago.
    Thank You.
    Expert:  Carhelp4u replied 8 years ago.
    No problem! Hopefully you get this figured out. Thanks for giving us a shot!