A mechanic changed my spark plugs and wires 7 years ago in my car with 3800 v6 don't know if it is platinum or iridium but it is Autolite plugs and wires. I only put 15k miles since then. It is running okay but I am only getting 16 mpg. I changed my upstream oxygen sensor, it looked ash color, I suspect the fuel injector cleaners caused my oxygen sensor to turn into ash color. Do you guys think my spark plugs would go bad by the use of fuel injector cleaners and with the age? .
Do my spark plugs go bad due to age and excessive use of fuel injector cleaners?
- Thread starter easym
- Start date
I don’t think so. I changed the OE spark plugs on the Firebird in my signature in 1997 at ~29000 miles and I have 47000 miles currently. I have no issues.
Did you get better mpg after the new oxygen sensor? Do you happen to still have the old one and be able to take pics? 
How many total miles on the car now? How often did you use the cleaners, and what kind did you use?
If you do replace the spark plugs again, use ACDelco or NGK iridium plugs, along with ACDelco GM OE wires
How many total miles on the car now? How often did you use the cleaners, and what kind did you use?
If you do replace the spark plugs again, use ACDelco or NGK iridium plugs, along with ACDelco GM OE wires
Dump those Autolites.
I don't think it's due to cleaners.
Isn't the 3800 a waste spark ignition? While the wasted spark isn't igniting fuel, I've always felt that the odometer shows plugs as x-miles in service is actually more like 2x-miles. :
:
What mpg do you normally get? Typically, these V'6s get really crap city mpg like ~16mpg. Highway is usually much better at ~27mpg.
Isn't the 3800 a waste spark ignition? While the wasted spark isn't igniting fuel, I've always felt that the odometer shows plugs as x-miles in service is actually more like 2x-miles. :
:What mpg do you normally get? Typically, these V'6s get really crap city mpg like ~16mpg. Highway is usually much better at ~27mpg.
I get close to 16 mpg in mixed driving. I changed the oxygen sensor it looked ash in color, some told me it was called silicone poisoning due to additives. I will take a picture of my oxygen sensor tomorrow.I don't think it's due to cleaners.
Isn't the 3800 a waste spark ignition? While the wasted spark isn't igniting fuel, I've always felt that the odometer shows plugs as x-miles in service is actually more like 2x-miles. :
What mpg do you normally get? Typically, these V'6s get really crap city mpg like ~16mpg. Highway is usually much better at ~27mpg.
Again, more info needed on year & engine/miles,,,,etc...
It is a 2001 Pontiac grand prix 3800 V6 117k miles.
You are just shooting in the dark and guessing by changing items which were not bad.. Look at your fuel trims to actually see how your 3800 is running and go from there. Did you check for any stored codes?? You probably will not improve much in mileage no matter what you do.
- Joined
- Dec 28, 2011
- Messages
- 5,058
Your right! I just wonder is there even more than a dozen codes possible on the 3800? THis one has to be the Series II 3800 right? It's been a while since I worked on my momz 3800 in her Buick LeSabere.
There are no codes, just reduced mileage at 16 mpg.
Both my Series ll and lll would get 15/16 around town so you have something going on. The Series ll was a bit better on the highway but not much.
This is the pic of my old oxygen sensor.Did you get better mpg after the new oxygen sensor? Do you happen to still have the old one and be able to take pics?
How many total miles on the car now? How often did you use the cleaners, and what kind did you use?
If you do replace the spark plugs again, use ACDelco or NGK iridium plugs, along with ACDelco GM OE wires
Attachments
.
Last edited:
- Joined
- Dec 28, 2011
- Messages
- 5,058
Old school engine so I'd say old school troubleshooting. Replace plugs, change oil, etc... Any idea if the fuel filter has been replaced? I think this was still an external filter back then?? Not sure. I would do those 3 cheap and easy tasks first and walk it from there.
Edit: Draft a checklist from cheapest to $$ and go down the list. Eliminate as many gremlins as you can to narrow down the issue.
As others have said, get rid of the Autolite plugs. It's amazing you made it 7 years on them.
I can't explain it, but GM engines run best on AC plugs. Get a set of AC Iridium plugs in that car. You will immediately tell the difference.
I can't explain it, but GM engines run best on AC plugs. Get a set of AC Iridium plugs in that car. You will immediately tell the difference.
Have you checked engine operating temperature?
The thermostat could be sticking.
Yes, it reaches the operating temperature fine. I put in a OEM thermostat last year.
Similar threads
- Locked