Now post yours (try to do identical) so we can compare.

 

I'm out of town for a couple of days. I'll get on it when I get back.

Thanks,

George

 

I couldn't get spark advance or throttle position angle to work in Car Gauge Pro on my Blazer, so I did these things + same stuff on Dash Command. Also threw in vehicle speed. It was the only one that reliably did everything that I was wanting to do at the moment. But Dash Command is also the most expensive ($10 + $10 for Enhanced PIDs for EACH vehicle). I find each one of these softwares a valuable asset.

 

Wondered about Torque Pro. It would do timing and throttle position but would not do IAC counts or CMP retard. Here's Torque Pro at Idle in Drive and at Speed.

 

I'll look at dash command in addition to Car Gauge Pro.

George

 

It almost won't idle any longer. Just got a code today - P305, cylinder 5 misfire. Screenshots are hot idle ac on in gear first, 50mph second:

 

Even though all tune up parts are less than a year old, I just ordered a new Delco cap and rotor. If that doesn't do it it's on to plug wires and /or plugs and/or coil. I will also check the fuel pressure while the truck is running and stumbling.

Does anyone know why cylinder 5 comes up so much on the forums for misfire?

George

 

Hi George,

To me only a couple of things stick out in your data. EGR does not appear to be working for some reason - maybe try in 4th gear at steady 55 mph for a little while and see if it works then? Could it be stuck open some, causing your idle problems and possibly the misfire?

MAP (engine vacuum) at speed is about the same as at idle. Mine is significantly higher than yours at speed, but they are pretty much the same at idle. Unless you're having a misfire at speed that makes you open the throttle more, that might be something to investigate further.

Last thing you might consider is it appears to be a pretty hot day when you tested. Mine was a nice cool day.

You might have better luck with monitoring current misfire counters (rather than the history misfire counters). They reset much more often and start counting from zero again.

I would still check out the fuel pressure. Too bad no one has oscillocopes anymore. Could tell if you miss is electrical in just a few seconds.

Good luck - hope this helps some.

So problem is still the same? - rough idle, but runs OK at speed? Or has something changed?

 

I am pretty sure that I don't have an egr valve

I will eventually check vacuum but with such a massive misfire problem that's not a priority

I started with real time misfires and it's about the same I just wNted to catch the cylinders that were infrequent

I will do running fuel pressure as well as exhaust pressures

I have an O scope and I am working on a probe

Things are worse. Barely idles, more hesitation on acceleration and now misses a little at speed

I see that there is an mfi upgrade for the spyder. Is that the way to go on that subject?

George

 

Wow, Hi guys, I am new to this forum and looking for help. I have Owned many Blazers over the years and I am fighting with my 01 blazer, same as GeorgeLG. I have changed cap/rotor/wires and plugs. AND, just today did all intakes gaskets. Please dont let this thread die. I do not have access to anything but an OBD2 reader from Harbor freight. I am at my whits ends. Other than sending it to a chevy garage, I am out of options. I did find rotted vacuum lines and replaced them. I just poured seafoam in the fuel tank, thinking of dumping a can in the crank. I keep getting miss fire on #6. Thanks. Paul.