88 Chevy 1500 Ext cab Long Bed. 350 CID TBI 205,000 miles
About a week ago I did a tune-up, changed wires, plugs, cap & rotor. It ran
great after that. My son was driving it to school and while on the highway
it started to slow down and finally stopped on him. On the side of the road
he tried to restart but it would crank but would not start. Had it towed to
the house and I started to troubleshoot. It seems that its not getting any
spark. I tried pulling the #1 plug out and holding it against the block and
didn't see spark. (It was in the daytime so it could have been there but I
just didn't see it). I had a coil from another vehicle (it currently isn't
running but had no ignition problems the last time it did run) and nothing
changed. Since the #1 was out, I bumped it to TDC. At TDC the rotor was
pointed to #8 on the distributor cap instead of #1. Assuming that the
distributor can be either 180° out or right on, I moved the spark plug wires
instead of the distributor. I put the #1 wire on the #8, #8 to #4, #4 to
#3, and so on, following the firing order. That didn't help so I put the
plug wires back in their original places. I had a mechanic tell me that it
sounds like the timing chain had jumped. That shouldn't be a major problem
to change after getting the accessories out of the way. Before I start on a
project like that I want to know if anyone out there has any ideas or
suggestions that I can check before I try to tackle the timing chain &
gears. If the timing chain and gears are defective, what other indications
are there. What else in the ignition system could I have missed? I know it
could be something else simple. I double checked all the wires and
everything else electrical I think, but I may have missed something. The
truck was running fine until this problem.
Frank, there is a black module inside the distrib that all the wires (not the
spark plug wires) connect to at the base.
Replace it... buy two, and keep one in the truck.
http://www.lmctruck.com/icatalog/cd/0141.html Number 6 on the left side of
run the spark plug wires the right way. The firing order is stamped on the top
of the intake manifold.
205,000 is really great for that module... they normally don't last that long
PS: LMC truck carries everything for your truck.. get one of their catalogs.
Glad I could help Frank. You ever need help with that truck, give me a holler
here.. I know those
things inside and out.
Chevy made some great classic trucks.. the fifties, 67-73 years, and without a
doubt, the 88 to 96
years will be sought after classics down the road. Hold onto it.. its one of
Thank you and all others that helped. I love the truck and eventually hope
to restore it as much as financially & mechanically possible. (88
Silverado, 350cid, Ext. Cab, Long Bed TH700 tranny)
Here's an intermittent problem I've had since I bought it. After driving
for a while (engine nice & hot), it'll drive great. Once I slow down,
(parking lot speeds) it wants to die out. I hear the RPM drop, the only
indication besides the "feel" & sound of it is oil pressure, which drops
towards zero as it dies. Oil pressure was checked with direct reading gauge
and it's pretty close to what the dashboard gauge is reading. It only
happens in drive and reverse (especially reverse). It will idle forever in
park or neutral with no problems. It doesn't seem to happen when it's cold.
It may drive normally for several days, then it'll happen a couple of times
and disappear for several more days. I see it as more of an annoyance than
a problem, so I haven't really worried about it. Once it dies, it'll start
back up without any problems. About the only maintenance done is tune-up &
oil change. The worst part is that when it happens, it's at the most
unfeasible time to troubleshoot. When I try to duplicate the problem, it
runs great. Sometimes I think it may be something on the transmission since
it only happens when it's in gear.
Any advice/tips would be appreciated.
Well it sounds like the IAC (Idle Air Control Valve) might be getting stuck
(http://www.lmctruck.com/icatalog/cd/0112.html #4 on
bottom of page).
It has 4 wires that come out of the back, and is on the left corner of the
throttle body. With 200,000 + miles on it, I would bet
that the throttle body
(and it components) need a good cleaning. I would remove the throttle body,
unscrew the IAC, and really clean out everything, and
replace all the
gaskets with a kit you can buy from LMC, or your favorite parts store. There are
little veins on the bottom side of the throttle
body that can get
gummed up pretty easy. Also, if you have an EGR valve, I would replace that as
well. Clean out all the vac lines that feed into the
throttle body also.
If you end up changing the IAC valve, you'll have to get the truck warmed up,
and on the road over 30 MPH for a few miles. The
computer will "learn"
the new valve, and your idle problems should go away. This kind of job is really
easy to do. There are only three bolts that hold
the throttle body onto
the intake manifold. You'll need a set of star/hex screw driver/bits to take the
throttle body apart for the gasket replacement. You
might want to go
ahead and replace the fuel pressure regulator parts as well (its part of the
throttle body), and have the two fuel injectors
The low oil pressure in your case is just slow engine idle. With the auto trans,
it should idle 750 to 900 rpms, and dip slightly
when you turn the wheel hard, or
the AC comes on, etc... but shouldn't drop below 700. In fact, you should hear
the truck speed up the idle speed when these things
That makes a lot of sense to me. I think in the beginning someone told me
it may be a fuel problem and I ran just about every fuel conditioner/cleaner
with fill-ups. I think it may have helped a little but not too much.
That's a problem I'll get to in a couple of weeks or so, unless it gets
worse. I just don't have the time right now. When you say to get the
injectors pressure cleaned, does that involve taking them out and to a shop
or can that be done at home (I have an air compressor) I've seen the
injectors in work and they look like they put out a pretty good pattern, a
decent spray. I do want to do it all at once as far as the TBI is concerned
so when I get a free weekend I'll take care of it. Can I get to the IAC
valve without taking the throttle body apart, and use a carb cleaner for now
until I can tear it apart, or would that be a waste of time?
Hi Frank... Yea, you can take the IAC out without taking the throttle body off.
screws in. You can clean out allot with the old carb spray. There is a large vac
pipe on the
back that you can pull off and get to more of the "inners". It's such a simple
Almost no moving parts to speak of. GM realized their mistake, and no longer
220 throttle body (IFAIK that is). It's a great little gem. The IAC controls the
if your having idle problems, that's where its at.
Pressure cleaning is something the shop has to do. They will hook them up to a
do-dad and run cleaner through em under pressure. Jiffy lube can do it with em
installed in the truck. Not sure of the price though. But check with a couple
stores, they may offer the service... and you'll have to take them out. With
miles, I can guarantee they need it bad. It'll be like a new truck after you do.
Try removing the #1 plug turn over engine till you feel air comming out of
hole then with a scockt wrench turn over engine till piston is all the way
to the top[stick a pencel in the hole] then it should read Top dead center
or 0 at crankshaft then check where the rotor is pointing if it not at # 1
the timing chain has jumped
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