View Single Post
  #2  
Old 06-17-2010, 11:16 AM
MT-2500's Avatar
MT-2500 MT-2500 is offline
AF - Advisor
 
Join Date: Sep 2005
Posts: 16,690
Thanks: 5
Thanked 121 Times in 120 Posts
Re: 1998 Blazer no spark at coil

Quote:
Originally Posted by RatherdriveaTjet View Post
Hi guys. First post here. I have a 98 blazer with about 160K on the odometer. Since I bought it 2 years ago, it's had it's good days and bad days.

What I've been experiencing is on some days it will run great, and others it runs lousy. At idle it's fine, but if I mash the gas too hard at the very least it bogs down and wants to stall, goes into what sounds like pre-ignition knock (which can last 15 seconds or so) and recovers, or does the knock thing and stalls. 99.9% of the time it starts right up again (or at least within 5 minutes )and I can go on my merry way.

It died on the road right after I bought it (2 years ago) and was basically doing the same thing. Turned out to be a bad coil. Last week it died on me again and had to be towed home. Since I got it home, I've replaced the coil, ignition module, cap and rotor, and put a new coil wire on. Being unemployed makes the money really tight, so I couldn't swing genuine GM (I know, big mistake) but I have to stay within my means. I also bought a diagnostic tester. The only code I got was for the MAP high sensor.

I'm not getting any spark from the coil at all. Trying to get it started has wore down the battery some, and I understand the fuel pump needs full voltage to pump at the proper output, but could a low battery (down in the 9-10 V range by the gauge on the dash) prevent the coil from working?

I have also noticed when I crank it over now the tach doesn't move. I never really paid attention to it before so I don't know if it's supposed to while cranking, but I figure it might be worth mentioning. I used to be mechanically inclined and was able to rebuild my 69 Firebird from the bare subframe up, but this newer stuff drives me nuts!

Any suggestions welcome!!
You need to recharge the battery or jump it.
If your diagnostic tool is a scanner check for rpm signal while cranking engine.
Check all fuses both sides for 12 volts and power feeds.
If no rpm signal to VCM.
I would lean towards crank sensor.
Also clear codes and see if any return.
If so post back code no.
__________________
Remember proper testing gives us the answer to many problems.
MT
Reply With Quote