01 Blazer, Had a really bad misfire and was told the most likely causes were my injectors, spark plugs, distributor. So I went ahead and swapped out the injectors (new MFPI*) Distributor Cap/Rotor. Didn't replace spark plugs because I cant get to a couple of them. Tested it out and took it on an hour drive last night, things were going great, ran it on the highway last night topping out around 75, and was running smooth. Engine light stayed off. Didn't experience anything unusual up until my drive home from work tonight. Topped out at 30-40 mph, all back roads. My engine light started blinking, and stayed blinking the entire ride home. I stopped to check and make sure everything was reconnected and that I wasn't pissing out fuel from somewhere. The entire car shakes in idle, and the engine light still blinks in idle which is weird. I have work early in the morning and it is now raining so I'm not about to go out and remove the manifold again to get in there. I just don't get how it was driving so good for a while and now it's like back to square one. All of these problems I were experiencing before the "fix" as well. All input is appreciated. Also I put in half a tank last night, and after driving all that way last night and today I still have over a quarter of a tank. So I'm not leaking/burning fuel, if that helps. RPM's are normal in idle and driving.

 

Read (record) the codes, clear them, drive until SES light comes back on. Read the codes again (record) and report all things that occurred - we can advise from there.

 

Just FYI...the below link will instruct how to do a GM Drive Cycle Test to activate trouble codes (taken from a link posted by The Hook).

General Motors Driving Cycle

 

Not that it's necessarily the underlying issue...but when you remove the distributor, you need to have a Crankshaft Relearn done. Most have to take it to a shop to have it done.

 

Don't want to start a pissing match, but I don't agree that removing the distributor requires Crank Relearn to be done. Crank relearn is indicated when crank sensor has been disturbed or replaced.

As for distributor removal/reinstallation if your distibutor hold down has not been modified so you can turn the distributor, you just have to get the distributor back in on the right tooth. Crank Relearn will do nothing for you if the distributor is off a tooth, and a specific code will be set. If timing chain has stretched/timing gears worn or distributor gears are worn, the Cam Sensor Retard can be off a bit and this can be corrected by modifying the hold down and turning the distributor. In the case of worn distributor gear, it should be replaced.

Only concern about Cam Sensor Retard is if it is off far enough, the rotor does not point exacty where it ought to at any given time and a misfire can possibly result. Furthermore, the misfire detection system would not work properly. As far as the cam sensor input to the system..... you can unplug the cam sensor itself and the engine will start and not miss. You have to have a decent scanner ($$$$) to access the cam sensor retard value and/or do the crank relearn.

To the OP - please avoid jumping to any conclusions until diagnosis is complete. Throwing "most likely" parts at it has not fixed your problem, and we have not yet begun diagnosis. At this point just start by reading any stored codes, and determining which one is turning on your SES light as I have described in my first post. What you find will drive the direction of the diagnosis.

 

Crank relearn for just pulling and reinstalling the same distributor & camshaft position sensor, no. Camshaft retard should be checked whenever the distributor has been moved. It is easy to confuse the two.

 

Agreed - I completely confused the two myself when I first started working on my Blazer. So Rockp2 please don't take offense. That was not my intent.

 

No offense taken, I learned about doing the relearn and when it should be done from Captain Hook. Could've sworn it needed to be done when distro removed (along with checking cam retard). Must've remembered incorrectly.