1998 Blazer no spark at coil

[RatherdriveaTjet]

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!!

[MT-2500]

Originally Posted by RatherdriveaTjet

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.

[RatherdriveaTjet]

Sorry it took so long to get on this. Suffering from mild depression and haven't wanted to do much of anything lately.

I finally got the battery recharged, and hooked up my diagnostic tester.

The codes got reset. I received 2 trouble codes. Both P1351 ign control high voltage. One was E mil, the other E pend, whatever that means. The rpms are showing up in a live data test. They were on the low side... 173 the first time, 168 the second. But that was basically starter speed.


I did replace the coil and ignition control module. I also replaced the crank sensor. Would it be a fairly safe assumption that the control module I put in is a defect, or would there be something else to check first?

[MT-2500]

Originally Posted by RatherdriveaTjet

Sorry it took so long to get on this. Suffering from mild depression and haven't wanted to do much of anything lately.

I finally got the battery recharged, and hooked up my diagnostic tester.

The codes got reset. I received 2 trouble codes. Both P1351 ign control high voltage. One was E mil, the other E pend, whatever that means. The rpms are showing up in a live data test. They were on the low side... 173 the first time, 168 the second. But that was basically starter speed.


I did replace the coil and ignition control module. I also replaced the crank sensor. Would it be a fairly safe assumption that the control module I put in is a defect, or would there be something else to check first?

Have you got the battery voltage up to 13.6 volts?
Does battery crank engine good?

The code is for ign control high voltage.
When you start throwing parts at you you never know whether you have throw-ed bad parts on top of bad stuff or you have another problem.
If you are going to throw parts at it also try a computer and check all wiring and power feeds and voltage and grounds and plug-ins.

If you want to do some proper testing to find the problem.
Get a repair flow chart for code P1351 and go threw it.



A factory repair manual or a All data or Mitchell on demand online online DIY (subscription) WILL TAKE YOU THREW THE REPAIR FLOW CHART FOR THAT CODE.

http://www.alldata.com/products/diy/index.html

Good luck and let us know how that goes.