I have a 1997 Chevy Silveradoo with a 5.7 litre engine. Recently it has
started to miss badly when in idle. I had it scoped of which the
computer stated that at first cylinders 5 and 7 were missing....less
than a minute later 5 and 7 were firing again but cylinder 4 was now
missing...then it was neither 5,7, or 4, but only 3 missing. I have
recently changed all spark plugs and wires less than 60 000km with
orignal OEM parts (AC Delco). Also, it is becoming harder to start with
the first turn of the key. I suspect the fuel pump, but was wondering
if anyone else has had similar symptoms before. Thanks for your input
into the matter.
It's good to hear that you used OE tuneup parts. I'm going to suggest
two more: AC Delco cap and rotor. Your engine has a funky distributor
cap that I can only assume was designed using the 'style over
substance' method. You will notice that the plug wires exit the cap
neatly to the left and right sides, unlike on conventional caps where
each wire is equally spaced around the diameter of the cap. Cool, huh?
The problem is that to make the cap look like that, most of the cap's
spark plug wire terminals aren't anywhere near where the rotor "fires"
their respective cylinders. If you inspect the top of the cap you will
see the molded-in routing that dictates which terminal is fed by which
clock position on the distributor.
The real damning evidence here is that cylinder 5's plug wire enters
right where the cylinder 7 terminal is inside the cap. It's the same
for the cylinder 4 wire and cylinder 3 terminal. Now you can see why
an ignition crossfire is so likely, and it is also likely that
something like this would be intermittant, setting the misfire codes in
no particular order. The 4/3 combination is *really* close on the cap,
as is the 7/2. There are many problem areas where ignition crossfire
is facilitated on this cap, so you could conceivably see more misfire
codes in the future.
Try the cap and rotor for ~$50US and see if that takes care of it.
Toyota MDT in MO
I, for one, do not understand why Comboverfish's comprehensive
response--obviously laborously created to help one specific person out of
his plight--called for or deserved such an insulting reply. His responses
have pretty much all been unselfish sharing of real-world experiences, not
mere quotes from repair manuals or highly theoretical guesses. He even
admitted having been 'off the mark' about his analysis of an unusual vehicle
when he said, "Geez, you ever get the feeling you just wasted 200+
words?"--obviously a self-deprecating remark and an apparent apology.
Please continue offering your expertise, C-Fish, as many of us benefit
from and appreciate your ideas. s
Please ignore the vomitous expellations of the anti-American
Anti-Americanism is Canada's national sport. You'd have to live up here to
understand the insanity. If you didn't see and hear it first-hand (every
day), you wouldn't (couldn't) believe its pervasiveness, fury, idiocy, and
Canada is America Lite: Tastes great, but not nearly the same thing.
And don't the Canadians know this.
And don't they resent the disconnect, with a passion!
Very kind of you to reply in this manner, Sdlomi2. I appreciate your
contribution to this group as well.
I actually meant that the OP wasted my time by posting incorrect
vehicle info, or not enough info to give a "correct" answer. If he
really had a 1997 Chevy Silverado with 5.7, and I don't care what trim
level, Suburban or truck, short bed, long bed, whatever, then he would
have the Vortec with a distributor -- no coilpacks. His description of
which pairs of cylinders were misfiring was a classic case of cap
crossfiring based on the design of that tried and untrue cap design.
Of course I had to find a picture of one online to verify which
cylinder pairs were most suspect... Neil even replied that the OP must
have a distributor if it is a 97 5.7. He lives up north and knows a
thing or two about Canadian spec vehicles, so I figure his to be a well
considered reply given the OP is somewhere in Canada (apparently). Now
if the OP had a different engine or some aftermarket ignition system
(not likely) it still should have been mentioned.
Enough soapboxing, I just heard the bell ring....
The decision... TKO!
I'll take it... :)
Toyota MDT in MO
Good call on the stuck poppets.
Shame on me, I've been using compressed air.
100% success rate though...
(just ask my brother in law who's too cheap to use a bottle of
Techron a couple of times a year.)
Do you have a homemade adaptor for the schrader valve, or ? What kind
of PSI gets the job done without being dangerous? Which scanner do you
bidirectional the solenoids with, or ?
Thanks for your time,
Toyota MDT in MO
I made an adaptor out of 3/8" steel line to fit the fuel line
connection (O-ring) either at the back side of the intake
manifold or at the fuel filter, the Mastercool flaring tool:
makes the GM O-ring fitting, the nut is available thru Edelmann
as part number 109600:
I use my OTC injector balance tool:
Gonna see if the AE can command injectors on next time a Vortec
This is all done with the engine off, if you block the throttle
plate open, you can actually hear when the poppet un-sticks by
Nope. Tempted, but the lure of a Mastertech (in the works) and a trade
up for a Solus for adequate CAN generic coverage has put AE on the back
burner. I really don't want to use a laptop at work and I don't want
to plop down additional $$ on a Palm at this point. The Solus deal
actually works out to less than AE if you figure in my Snapon MDT
credits through Toyota and the fact that I need to unload my POS
MTG2500 anyway. I've heard that AE's coverage of Toyota is one of it's
weaker points. I'll take Snappy's marginal but reliable coverage in a
shop-friendly design over spotty coverage on a Palm. I think Jay is
focusing on stuff the Snapy doesn't do at all like Prius or hybrid in
general, and coverage of many of the non-engine modules. Like I said
it's just to spotty to rely on now. So a Mastertech for Toyota only
and a Solus for all others seems to be in the future.
How would you rate Toyota coverage so far? Any glaring glitches like
freezing up during active tests or ??
I think he would figure it out right quick :)
BTW, check your email... I wrote all I done know about the question you
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