Lean
Thread Starter
Instructor
Joined: Sep 2002
Posts: 116
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From: Boise ID
Lean
I have an 88 35th anniversary that is stock with 150,000 miles on the clock. I have suspected for sometime now that is running extremely lean and today reaffirmed these suspicions. I pulled two spark plugs that have been in the motor about 6 months now and they are white as they can get. I have noticed a definite lack of power but there are no trouble codes. I do not have a scanner at my disposal yet so I have been trying to check everything the hard way, with a volt meter at the computer. Everything I have checked so far comes out good.
1. Fuel pressure (while driving)
2. MAF (voltage increase with RPM)
3. TPS (voltage increase smoothly)
4. Coolant and Air Temp. (resistance vs. temp good)
Any help on what would cause the engine to run lean would be greatly appreciated It seems to be worse in open loop, it is my guess that the O2 and knock sensors help curb the lean condition in closed loop. One more thing, not that I should be complaining but the average gas mileage indicator shows what I think is very high, 18.7 (this is in town driving).
Thanks for any advice,
Ethan
1. Fuel pressure (while driving)
2. MAF (voltage increase with RPM)
3. TPS (voltage increase smoothly)
4. Coolant and Air Temp. (resistance vs. temp good)
Any help on what would cause the engine to run lean would be greatly appreciated It seems to be worse in open loop, it is my guess that the O2 and knock sensors help curb the lean condition in closed loop. One more thing, not that I should be complaining but the average gas mileage indicator shows what I think is very high, 18.7 (this is in town driving).
Thanks for any advice,
Ethan
Thread Starter
Instructor
Joined: Sep 2002
Posts: 116
Likes: 0
From: Boise ID
Re: Lean (oldace84)
I'm at a loss, I was hoping someone would have some advice that has experienced this problem before. Tonight I double checked the manifold temp and coolant temp sensors, both seemed to be right on. I'm leaning towards injectors, they don't seem to be going into an asymmetrical firing mode under acceleration. Is it possible for old injectors to wear to the point they will not keep up with the opening frequency requested by the computer?
Ethan :confused:
Ethan :confused:
Melting Slicks
Joined: Oct 2002
Posts: 3,193
Likes: 1
From: Cincinnati Oh
Re: Lean (ethan1321)
Are all 8 injectors showing lean? The O2 sensor might be a good bet, and it's a cheap fix at $20.
Otherwise, fuel filter might be partially clogged? Not really sure though.
Otherwise, fuel filter might be partially clogged? Not really sure though.
