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92 Lumina high speed miss


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04-19-03, 11:00 PM   #1  
Gomer-techimo
92 Lumina high speed miss

92 Lumina 3.1 (T) 105K

Wires, plugs, filters etc. (tune up parts) last within the last 15K.

The problem is a miss above 65MPH or so. It is really pronounced above 75MPH. No check engine light or codes stored.

I am wondering how to go about narrowing down the source of the problem. Could it be weak coils or an ignition module? Or possibly a fuel injector? Where to start?

I am partially leaning towards a weak coil. I had a problem for about a month last year where I had a dead miss under load. It turned out to be a plug wire that was not securely snapped over the plug. My understanding is this is the sort of thing that can damage a coil. Is that correct? Problem is I don't remember what cylinder the wire was loose so I'd probably have to replace all three coils ($20 apiece, and not too hard to get at).

I know I can pull the coils and check the resistance... but is it possible for the coil to pass that check and still be weak?

As always, any advice is welcome... and thanks ahead of time!
Gomer

 
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04-20-03, 05:48 AM   #2  
Joe_F
Start with autolibrary.org and see what you find. If you willy nilly change parts, you'll easily spend more than this thing could ever be worth. Could be a fuel problem too.

Why on God's green earth do you need to drive over 75 mph? LOL.

(That's a scary thought in a Chevy Lumina ).

 
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04-20-03, 07:15 AM   #3  
Gomer-techimo
Start with autolibrary.org and see what you find
What exactly am I looking for here? I spend a fair bit of time poking around that site and as of now, I haven't found the information I need. It is great for testing and replacement of components but does little in the way of troubleshooting a driveability issue.

I was just looking for some insite to my problem is all.

As for the 75 MPH comment =) The Luminator sees the interstate quite a bit (500 miles/week is not uncommon)... and everyone knows the de facto speed limit is 80.

I bought the thing for $1,500 with 55K on it and just want to keep it running smoothly as long as possible. I don't mind feeding it a little $$ every now and then and I enjoy getting my hands dirty =)

 
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04-20-03, 07:35 AM   #4  
Joe_F
If you want true diagnostic charts, time for a GM service manual. That is the only true repair/diagnostic book. That is why it costs 2 times more than most other repair manuals. Think of this as another tool in your toolbox, that is exactly what it is.

As for Autolibrary.org, you have to dig into it. Lots of good information there.

The Lumina platform is rough and crude to me but gets the job done. I'd much prefer a rear drive GM. Far superior in every way and much more comfortable .

 
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04-20-03, 09:54 AM   #5  
darrell McCoy
As suggested, trial and error can sometimes outcost the price of a manual or good diagnostic test. However my opinion is it is fuel related. Possibley and injector. I am not a fix in a can person but GM has a detergent they use in the tank with good results for injectors if there is one that is not performing right/partial clog. Caution: "Not for repeated use". Last I saw was 18 bucks for a bottle and MUST be used in full gas tank.

 
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04-20-03, 08:56 PM   #6  
Gomer-techimo
GM #12345104 detergent.

I will run a can of that through the system and see what happens. I tend to view most of that stuff you get at the local parts store as snake-oil. Maybe since this is from the dealer it will be different eh?

As for my miss... I was just seeking a "yeah.. that is typical", or a "could be anything." Looks like I got the latter.

I'd wouldn't mind taking it somewhere and having it thrown on an diagnostic machine... but I don't really know of any garages in the area that I trust. There are as many great places out there as there are places that will just want to throw parts at it like I could.

Thanks again for the info.

 
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04-21-03, 05:56 AM   #7  
Joe_F
Without seeing the vehicle and knowing its maintenance history, "it could be anything" .

Tell us what has been done and verified and we'll go from there.

 
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04-21-03, 07:04 AM   #8  
Gomer-techimo
Plugs, wires, fuel filter 15K ago
Air filter 5K ago
PCV valve... not replaced. There exists such a part, but it is not located on the forward valve cover. There is a breather tube running from the valve cover to the intake, but no place for a valve. I believe the PCV valve is located in the rear valve cover, but I will have to rotate the engine to get at it.
Knock Sensor and pigtail, 10K ago

 
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04-21-03, 07:17 AM   #9  
Joe_F
Fuel filter is overdue, start there. What brand of ignition wires, etc, were used?

How's the fuel pressure? Compression?

 
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04-21-03, 08:54 AM   #10  
Can you replicate the problem by running the engine at the same RPM as when the car is missing? As in if you run the car in 2nd gear at that RMP, will the problem show up also?

 
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04-22-03, 03:45 PM   #11  
Gomer-techimo
trinitro: This miss only occurs at cruising speed. the car has plenty of power and accelerates just fine.

Joe:
How often are you replacing your fuel filters? The maintenance schedule I have calls for a change every 30,000 miles.

Wires were Bosch, plugs were AC Delco.

Regarding the fuel pressure test. I haven't done that. Do you suspect the regulator or pump is malfunctioning and causing this problem? I can check it easy enough I guess... just need to run across town to borrow a gauge. I imagine I could test it in the parking lot, that schrader valve is easy enough to get to. Save myself the return trip.

Regarding the compression check... That is going to have to wait another 15K miles. Changing the plugs on this beast is not a pleasant task. Pulling the plugs on this beast when it is hot is very unpleasant. I worry more about damaging threads pulling plugs from a hot engine than I do this engine suffering from low compression.

Is that a common problem for the 3.1? This vehicle was my grandfathers before I got it. Oil changes and air filters were always done right on schedule. Unless the 3.1 suffers from some defect that causes abnormal internal failure, I think we can rule that out.

Gomer

 
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04-22-03, 04:13 PM   #12  
Joe_F
30k=WAY too long on a gas filter change. Every 10k for me. Avoids problems. With today's fuel, you never know what you get .

Yes, check the fuel pressure--it's part of the basics. Use Delco wires as well.

 
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04-23-03, 06:54 PM   #13  
Gomer-techimo
10K eh? Have you actually seen them clog at 15K or done a post-mortem of one of them at 10 to see what they are like on the inside? How about we split the difference and call it 20K =) Anyone else feel that the maintenance interval should be that conservative?

Meanwhile, when I get a chance here in the next couple weeks (long hours at work = no time for wrenching) I'll pull a pressure test on the fuel system and let you know what I find. Then p'raps we can proceed to step 2.

 
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04-24-03, 07:06 AM   #14  
Joe_F
I have seen horrors due to bad fuel, so in turn it is best to spend a few bucks on a new gas filter than cause damage .

 
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