1986 c4 running lean and knocking slightly
Thread Starter
Instructor
Joined: Dec 2012
Posts: 120
Likes: 1
From: Canton Georgia
1986 c4 running lean and knocking slightly
Hey guys i finally started using tuner pro rt and as i was scanning i found that the car would start to knock around 3000 rpm like 2 to 3 counts as it went higher. But i also noticed that the blm's are staying around 150-160 which as far as i know is not good.
I have bosch III injectors that were stock replacements but could those be the cause of the lean running knock condition? Should i be worried about driving my car right now i have been taking it easy lately because of this. I am thinking of getting a tune from pcmforless if that could fix the problem. I am just at a loss of what to do and will appreciate all of the help.
One last thing i have the files im just not sure how to post them and i have a list of parts that i have replaced lately thanks guys.
I have bosch III injectors that were stock replacements but could those be the cause of the lean running knock condition? Should i be worried about driving my car right now i have been taking it easy lately because of this. I am thinking of getting a tune from pcmforless if that could fix the problem. I am just at a loss of what to do and will appreciate all of the help.
One last thing i have the files im just not sure how to post them and i have a list of parts that i have replaced lately thanks guys.
Drifting
Joined: Nov 2009
Posts: 1,341
Likes: 2
From: Perth Western Australia
St. Jude Donor '10
Hey guys i finally started using tuner pro rt and as i was scanning i found that the car would start to knock around 3000 rpm like 2 to 3 counts as it went higher. But i also noticed that the blm's are staying around 150-160 which as far as i know is not good.
I have bosch III injectors that were stock replacements but could those be the cause of the lean running knock condition? Should i be worried about driving my car right now i have been taking it easy lately because of this. I am thinking of getting a tune from pcmforless if that could fix the problem. I am just at a loss of what to do and will appreciate all of the help.
One last thing i have the files im just not sure how to post them and i have a list of parts that i have replaced lately thanks guys.
I have bosch III injectors that were stock replacements but could those be the cause of the lean running knock condition? Should i be worried about driving my car right now i have been taking it easy lately because of this. I am thinking of getting a tune from pcmforless if that could fix the problem. I am just at a loss of what to do and will appreciate all of the help.
One last thing i have the files im just not sure how to post them and i have a list of parts that i have replaced lately thanks guys.
Thread Starter
Instructor
Joined: Dec 2012
Posts: 120
Likes: 1
From: Canton Georgia
I checked the fuel pressure today. I had to use an oil pressure gauge because that is all i had. Anyway i hooked it up and primed it and the gauge went to 40 psi. While cruising at 1500rpm it was around 35psi
and when i went full throttle it went back up to 40psi. That sounds about right i guess but i am no sure. I was really hoping this would be the problem.
and when i went full throttle it went back up to 40psi. That sounds about right i guess but i am no sure. I was really hoping this would be the problem.
Thread Starter
Instructor
Joined: Dec 2012
Posts: 120
Likes: 1
From: Canton Georgia
Thread Starter
Instructor
Joined: Dec 2012
Posts: 120
Likes: 1
From: Canton Georgia
Hey i finally got around to putting that new o2 sensor in. The car seemed to run better on the low end but after scanning it i still found that the blm's were at 160 but they went down to about 140 some of the time. While cold the blm's are spot on perfect at 128 so maby something is causing the car to run lean in closed loop?
One thing i forget to mention is the car does not start very well when cold. Sometimes it will die on the first start and then has some hesitation for a while till warm. You can also hear the intake make some popping sounds i would say like intake backfire possibly? Not knock but some other kind of noise. Hopefully we can figure this thing out.
One thing i forget to mention is the car does not start very well when cold. Sometimes it will die on the first start and then has some hesitation for a while till warm. You can also hear the intake make some popping sounds i would say like intake backfire possibly? Not knock but some other kind of noise. Hopefully we can figure this thing out.
Drifting
Joined: Nov 2009
Posts: 1,341
Likes: 2
From: Perth Western Australia
St. Jude Donor '10
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Instructor
Joined: Dec 2012
Posts: 120
Likes: 1
From: Canton Georgia
Well unless i am doing something wrong i do not have a anything related to the MAF on my scanner but something called airflow which seems to move up with the engine rpm. Unless there is another definition file i can use for my car i do not know what those Maf raw or maf values would be.
Thread Starter
Instructor
Joined: Dec 2012
Posts: 120
Likes: 1
From: Canton Georgia
I found out what the problem was and it turned out to be the MAF sensor. After getting a reman bosch sensor the car runs perfect while cold and the blm's are no longer stuck at 160. Thanks for all the help 
Drifting
Joined: Nov 2009
Posts: 1,341
Likes: 2
From: Perth Western Australia
St. Jude Donor '10
Great news. Maybe if you had the 2 maf columns in your datalog the problem may have come to light.
Unfortunately my computer with tunerpro and the relevant def and ads files is out of order so I couldn't answer your question of last week.
However, the log file is an .ads file I believe. The .def file is for the tuning parameters.
Unfortunately my computer with tunerpro and the relevant def and ads files is out of order so I couldn't answer your question of last week.
However, the log file is an .ads file I believe. The .def file is for the tuning parameters.
Melting Slicks
Joined: Jun 2011
Posts: 2,383
Likes: 385
From: Leland , North Carolina