Alright, Everybody here should know the history behind the blazer's famous misfire problems. Luck has it, I've got a major one myself. I want to double check everything to see if there is any other repair methods before I resort to replacing the Fuel Spider. Note: The Blazer misses at idle and a little at 2k RPM. It will hesitate when launching, but LOVES abuse and Highway driving, and by abuse, I mean flooring it from launching...constantly.

So far, I've replaced:
Spark Plugs (Bosch Double Plat)
Rotor/Dist. Cap
Wires
Intake Gaskets

Other things,
Added Multiple Fuel cleaners (all at different fill ups)
Used SeaFoam (That was a fun day!)


Is there any other routes to take (For example, a fuel cleaner to try...Something more effective than Lucus. That helped slightly, but not much).

Thanks!

 

First thing... you dont read as much here as you let on.. or you wouldnt have put Bosch plats in a car that already is missfiring. They are notorious for no-load missfires.

Just new parts without saying 'acdelco' doesnt eliminate anything you replaced.
AZ ignition parts have been known to not work right out of box.

You dont give us any codes to work with.

Is the idle speed normal? 600-700

Get engine to warm.. shut off disconnect the MAF connector and drive it.. better or worse?

 

My apologies for assuming the Misfire was common. I was going by what one of my friends, who is a reputable mechanic, once told me. He believes the issue is with the Spider. I also did not know about the Bosch plug problem. What plug do you recommend?

I have stopped using Autozone recently, But I do have an AZ Distributer/Roter and their plugs. Everything seems to work well, except for a weird clicking when I first installed it.

The last code I had was just a simple Multiple Code Misfire (Which I didn't get any numbers on... Thanks Autozone.) I might see if O'rilleys has a code scanner I can use to get specific codes.

Idle is at normal 600 - 700 RPM measured by an aftermarket Tach. Everything is wired correctly, so it isn't an idle issue.

Now here is an interesting piece of information while trying to disconnect the MAF. It was already warm (Just drove it from school) and pulled the connector. Started up alright, and almost stalled when backing out of the driveway. Other than that, the truck ran beautifully. No hesitation or violent shaking. I'm going out on a limb here and guessing its an MAF sensor problem?

 

Good to hear you got a direction. You can try cleaning it. You can see if it's got a noise problem by pulling the IAC connector and tapping MAF. If engine speed goes erratic, needs replaced.

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Missfires ARE common. Point is you can take a perfectly running engine, at least in an 85-97 Ford EFI install the plugs Bosch recommends and end up with no load missfires.
From what I hear on Blazer forum, that also applies to Chevvies.. of course there's always someone saying 'They work fine for me." But I have 15 years of car forum debates where consensus says otherwise. Plus two first hand cases where I bought and installed one set, bought car with anohter set freshly installed.
AC Delco/NGK plugs

 

I actually took my time & read all that because the 1st thing I thought was a dirty or wiring issue MAF. Possibly a clogged fuel filter, but that didn't makle sence with it being allowed to being hammered on & it ran fine.
Maybe an EGR? How does the EGR effect the engine at WOT? I'm not sure because I haven't had to look into the issues an EGR may have with performance.
IAC intake & intake temp sensor could fubar things outside of WOT too. Though I don't see many issues with the intake temp sensor.

 

I would not start guessing

spider change can be a very expensive process

do you have you service engine light on? if so get the codes pulled

after market ignition products can cause misfireing conditions also
these trucks prefer ac delco

 

Hey guys!!!!!!!
Yes, it's very the MAF is either noisy or dirty. so it is a major cause.

The thing is, if the truck idles at the proper rpm and runs better with it disconnected it's faulty. If it runs worse, it's not the problem another sensor is.

You can extrapolate from that....
if the truck idles high and runs better with the MAF disconnected there is probably a vacuum leak.

 

What's the point fog? It ran at what the PCM took as WOT & we know that "disscomboobulates" other PCM readings. It changes how the PCM reads things & adjusts parameters. Idle sucked & had issues but under power it was ok. I didn;t say I was agreeing with you? MAF may have an issue, get codes pulled & we'll go from there.
Cheers & happy VD lol personally I'm misserable, my girl is in Texas on work & I'm here on BF with a beer... sad I say!

 

oppsy i missed that post

i sorta left the pc then came back and never refreshed the page

 

All due respect, Rotti.. that test is Probst EFI 101. It's as definitive as any checklist GM puts out.
The reason it ran good under power was the PCM goes rich on acceleration, giving more weight to MAP readings. If you watched the trims you'd probably see the trims show too lean a mixture for full power mode though.
OP SHOULD get codes though.. There may still be problems
That explains it! My condolences.