Hey ferm help

Skools Out

Skools Out

God
my 99 tahoe has a misfire / skip on the highway usually after getting into the throttle when i let off and it goes back to OD if i ease in the throttle it tends to skip sometimes, if i let off and get back on the throttle it's gone. i put new plugs AC Delco and it has about 25k on the current plug wires and i had AC Delco cap and button replaced 25k ago so i tried by replacing the cap and button with aftermarket Sat. only due to no one had AC in stock. it ran smoother but now a check engine light with multi misfire code. i'm going to take the Advance cap and button back and get a new AC cap ordered or would you go with the aftermarket with the brass inserts? any other ideas on this skip. the tahoe has 150k on it. i have a bad feeling it's the stock original spider that is in it. what ya think?

here's a link to the type cap i was questions on

http://cgi.ebay.com/ebaymotors/GM-V...r_Truck_Parts_Accessories&hash=item4cf68a5956




Ferm would i be best off to just go ahead and change to spider to one of these and be done with it? is this a tough switch out?

http://cgi.ebay.com/ebaymotors/Delp...r_Truck_Parts_Accessories&hash=item27babaecca
 
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Most misfires are due to the crappy distributor cap design. I use the better one from CARQUEST which is a brass insert model and a blue plastic material(the blue cap with brass inserts is the marine cap). The upgraded MPI kit is a huge improvement over the stock spider injection. Most problems with the spider are rough idle or won't restart right away when hot. Make sure the fuel pressure is good on it(about 45-48 at idle and 55-58 when you stomp on it) as fuel pumps are notorious in the older GM's. Also bad O2 sensors and failed cats are a common cause of misfire codes on the 5.7L with dual cats, and a bad knock sensor can also throw a mis fire code.
 
Hey Skools, I use the mercruiser cap and rotor, been getting the mallory or sierra, they have the good brass terminals. If you get far enough along, I have a bosch intake/injector set up off of a mpi motor, its supposedly a good swap, I've talked to ferm about it, I ended up with a spare one. Don't know if you're able to get it pass emissions check(no egr). Takes some tuning and wiring, Let Ferm tell you about it.
 
what about the cap i posted from ebay guys whatya think worth a try or not. and really the only thing that hasn't been changed is the spider it has had intake gaskets replaced which not long after maybe 15k miles later this misfire issue started. honestly it has no power like it use to plus fuel milage has gone down somewhat from it use to get. it mostly started when this crappy fuel came out. i can run sta-bil green marine and it will run good but then it comes back. my dads 96 Z71 seems to have twice the pep my 99 Tahoe has. plus it has an Accel Super Coil which has been on since the factory crapped out 40k miles ago and it has one hot spark
 
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it sounds like the spider injectors to me more than the rotor and cap. What you are describing it sounds like the way my blazer used to run before I have to have the injectors changed in it.
 
Can't tell from the ebay pics, but you want the blue colored cap which is the marine version. I've had problems with the black ones on more than a few.
 
hey how about this if i do the spider change? take out the air deflector?


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do you have a part number and brand for the blue marine cap and button? spare have any in stock?
 
Theres an EBAY seller that sells the marine throttle blade and you can modify the throttle body yourself. Or you can drill out the 2 rivets that hold the air deflector on and then solder the holes closed. I opt for teh marine blade kit as I don't trust solder to hold up.
 
ok ordered the upgrade injection system MPI Spider replacement. and it suddenly would hardly crank so i thought what the hell i went ahead and put another new fuel filter went with the 10 micron wix brand last one had roughly 15k miles it was fram brand. well black mud looking stuff came out, i installed it the tahoe crank right up and ran great ugh. but still has rough idle at times not bad, guess now i know i don't have to bust butt to get the new MPI installed. they say that the MPI swap helps the idle issue and really helps fuel mileage plus more power and response. just an update.

here's a pic of the newer style replacement

$(KGrHqN,!lEE4NlfEqPqBOIffP0-8w~~_12.JPG
 
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