My aunt's 2000 manual trans Blazer has a bad misfire that I have not been able to cure.


HISTORY

Purchased vehicle last July. Barely made it home from dealer; after some searching I discovered the pre-cat broke up and clogged the exhaust. Not having much money I bypassed cats with a piece of flexpipe. Vehicle has had bad misfire most prominent during warmup. Does not miss at all for first minute or three of operation, then suddenly begins to stutter, buck, backfire. Problem gets better after fully warmed up and either goes away or barely noticeable on hot restart.

Recently reinstalled main cat only to have it melt after 4 miles operation. Ouch!

Have replaced cap rotor plugs coil coil module. Cleaned EGR; pintle moved freely.
Replaced fuel filter. Checked fuel pressure.. good.. about 60. Holds pressure almost 1/2 hour when off and even then does not drop all that far.



CURRENT

Last ignition component is distributor of course. I bought a reman and installed it. I get P1345, crank and cam correlation. Now the car will only run with the distributor in 2 positions, and in both cases I get same error. Reinstalled old distributor and was able to get error to go away. I have had the distributors out so many times the past two days I can pull it and install it in less than four minutes!

Here's whats weird:

Advancing the distributor shaft 1 tooth clockwise cures the miss. I mean really cures it. I put the old one in advanced 1 tooth and drove it all over the place the past day with only very slightly reduced performance but getting 18mpg, even without the O2 sensors hooked up. (I accidentally melted the connectors and have not yet fixed them.) I would be fine with it running that well except of course inspection is coming up next month. Holds 20" vacuum at idle.

QUESTIONS

Is there anything I can do to clear that code without having a $5,000 scanner? (or maybe should I just stick with the old dizzy?)

Any idea what is causing my misfire? If it were carbon I would think that retarding rather than advancing would cure things.


Thanks for any help at all! I want to get this car back to her running right.


Jeremiah

 

Duh! Dizzy goes ccw, so I have it retarded one. Maybe my brain is too.

I'll run a compression check later and post results; maybe I'll get lucky with carbon buildup.

Still looking for any wisdom or encouragement tho.

Thanks!

Jeremiah

 

You can get scanners on ebay for like 40 shipped. Any parts place like autozone or advanced auto can clear a code for you.

 

Resetting the code and repairing the condition are two different things.

As you have replaced the distributor, you should perform a CASE relearn procedure to set the precise variance between engine true position and position(s) reported by the CKP and CMP sensors. This can only be performed with a scan tool that has bi-directional controls. Sometimes this is not necessary when swapping out components. But first, you must verify that the timing is set correctly.

As far as the installation of the distributor goes, you should follow the steps in THIS POST. If you have followed these to a 'T', it should be timed correct and the PCM should take over things from there.

As I do not show P1344 as a valid GM code, I will assume that it is in fact the P1345 code which deals with CKP/CMP correlation errors. P1345 is covered in the DIY Article - P1345 Explained

Hope this helps!