I'm new to this forum so I hope I posted in the correct area. If not I apologize ahead of time. I have been having issues with my 96 Blazer for quite sometime. My husband and I have had so many parts replaced on it and we still have not fixed the issue. We replaced the distributor cap and the entire distributor, the plugs, the wires, the engine have even been replaced. However it is still missing when it's raining and cold. We noticed a few weeks ago that it started missing while driving at highway speed (around 55mph) Now this morning it is missing (It's raining and cold) constantly. The only thing we didn't replace was the ignition coil. It also needs a MAF sensor and 02 sensors. Can anyone give any feedback as to what could be giving us this issue? It idles pretty bad also. We are literally at a loss as to what this cold be. We have had it at the mechanic multiple times and he insists it doesn't need the ignition coil but that is the only thing we haven't replaced. Any help would be much appreciated. This is a complete mystery to us and a costly one at that.

 

I would do a fuel pressure and leak down test. Fuel pressure should be 60-66 psi with the key on engine off. Pressure must remain above 55 psi for 10 minutes after the pump shuts off.
Whenever a distributor is removed or replaced the cam retard should be checked. I can cause crossfires within the distributor cap.

Any check engine codes?

 

We haven't had it tested in a while but it was throwing the 02 sensor code, a CAM position sensor code, the MAF sensor code, and multiple cylinder misfire code. That was a while ago. We replaced the CAM position sensor since then though. When we had the distributor replaced we had that done at a mechanic so I have no idea if he did a fuel pressure test. Since then he has passed away. I will have my husband do this test and see where this gets us. I spoke with my Father in law last evening and he is wondering if it isn't the thermostat. The blazer never gets any warmer than 140 degrees and we know it should run around 195. We recently flushed the heater core because we had absolutely no heat in it. That seemed to help however we only have minimal heat now. We are going to replace the thermostat this weekend. I know we need to replace that MAF sensor as well. We are just wondering if those two things combined are not causing the "chugging" when it's wet and rainy outside? Thanks for replying!! This Blazer has given us nothing but problems but I love it too much to get rid of hah!

 

Yes replace the thermostat. Its a good idea to replace it every coolant flush.

What were the exact codes? If you had a P1345 code it means the distributor is in wrong (misaligned).

Have you tried cleaning the MAF?
how-to-clean-the-maf-sensor-1

 

I'm not certain what the exact codes were as its been so long ago. We will test it again this week to see what codes its throwimg and I will list them as soon as I get them. It should be today or tomorrow. We did try cleaning the MAF and it didn't do anything. I believe it needs replaced. My husband just told me yesterday evening that it only "chugged" once on his way home from work so it wasn't as bad as the day before however it also wasn't as art outside either. I'm going to send my father in law the link to this forum to have a look at what we've been talking about as he can make way more sense of everything than I can. I've just been relaying messages back and forth. Your help has been greatly appreciated! No one else can seem to figure this mystery out. Fingers crossed this will lead us in the right direction. I'll get back with those codes.

 

That was to say wet not art. I apologize.

 

That multiple misfire code is most likely due to a bad SCFI injection unit gone bad. May need to test fuel pressure leak down. this is a common problem and known issue.