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1825 Views 17 Replies 6 Participants Last post by  Trevor
I replaced my EGR valve today after getting it back from the shop...they said the tech working on my truck couldnt do anything about the rough idle/lean miss...he said all the stuff i already have done they would have done...they just said run 93 octane through once as the gas is really oily...

the EGR didnt change anything really...i have got to be getting close to finding the problem if its even curable...

compression good
fuel pressure good
timing on
EGR system good
cap/rotor/plugs/wires good
IAC good
O2 sensor good
No vacuum leaks

it seems worse as it gets to operating temp and on from there

any ideas?

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SES light on? I think that year has a crank sensor? That does not tell the computer...
no SES light...i dont think it has a Crank Sensor...i could be wrong though
Injectors, Fuel Filter? Check out the injector cone spray pattern. If it's not smooth, you may have dirty injectors. If not, sounds ECM related. The truck is almost 20 years old, solid state electronics aren't designed to last forever. :(
yea fuel system checks starting to think it might be ECM gonna add a few new sensors before i have the ECM checked though
WTF? "The gas is really oily?" Did someone put diesel in your tank? I've never heard of "oily gas".

Older Chevies had a mechanical fuel pump that sometimes leaked at the diaphram. That didn't cause oily gas though it did cause gas in the oil.
yea thats what i said when the mechanic told me that
any other ideas im stumped!
any other ideas im stumped!
any other ideas im stumped!
The most common problem is reversing the No 5 and No 7 plug wires when changing the plug wires. The other most common problem is the "gizmo" on top of the distributor shaft developing hair line cracks below the rotor. It doesn't connect to anything but triggers the ignition coil. To this day, I still can't tell what the cracks are caused by or what they even look like, but someone told me that was my problem and, by God, they were right. IIRC, it acts like a bad fuel pump and may even run perfect some times. I bought one (whole distributor) from NAPA, problem solved. I tried just the shaft, but I ended up breaking the distributor gear.
What does IIRC stand for?

I didnt even think about the plug wires being switched. Didnt even think that could happen.Ill look into that. Thanks

Im gonna replace my cap and rotor tomarrow and put dielectric grease on all the ignition parts and see what that does...thnks

any other ideas will be greatly appreciated.
I got an idea, but I'm probably just over-complicating it like I always do. When you say fuel system checked, what do you mean? I know you can check the's throttle body injection right, in 89? Anyway, you can hook up a timing light to #1 cylinder and just add degrees on the gun until it syncs with the injectors and you should be able to see the pattern. That or current ramp them, if you've got a high end scope, probably don't (I don't). Sorry, I know rambling doesn't help, but maybe the timing light and injectors might help. Worked for an old Dakota I worked on, one injector was shooting a cone and the other was just barely dripping...caused lean running condition and failed a smog test. Hope any of this helps...
ive never thought of that...but my inj. are good...and the rest of fuel system checks out as does fuel pressure...

How hard is it to take the Dist. out and take a look at that?
ive never thought of that...but my inj. are good...and the rest of fuel system checks out as does fuel pressure...

How hard is it to take the Dist. out and take a look at that?
The part I was trying to describe is called the reluctor, and on your truck, it is permanently attached to the distributor shaft and is the 8pointed star shaped part that the rotor mounts to. You can inspect it by removing only the cap and rotor. I did a search on the WWW and I wasn't particularly thrilled with the responses on reluctor cracks that I found. My chevy dealer used to stock the reluctor and shaft, so I trust that they do go bad. I chased the problem for over a year, changing plugs, wires, cap, rotor, egr, fuel pump, intake gaskets, etc.
alright ill give that a look and take some pics of the reluctor and get back to you

any other ideas i could look at?
Is the timing correct? To set correctly, disconnect the tan w/ black wire.

Is the ECT (engine coolant sensor) any good? It's the pin sensor at the gooseneck. Cheap IIRC. It tells the computer the engine temp and is not the same as the temperature sender for the gauge.
had fuel press. and timing checked and there both on

was gonna replace the engine CTS because it is cheap (under 20$ i think) ill probably do that this weekend hopefully...was gonna get my ign module tested while im at it

any other ideas that i could add to the list?

1 - 18 of 18 Posts
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