PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

Lean at low vacuum cruising

Old Jul 25, 2020 | 07:20 PM
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Default Lean at low vacuum cruising

Tired of fighting this issue so im wondering if you guys can help. Attached is a log with most driving conditions.
Problem is that when cruising at slower speeds and vacuum is low the car runs pretty lean. ive tried adding in fuel to the VE table but it doesnt matter. around 8.5 minutes in is a good example of the issue. Ive got the throttle cracker disabled because if its on the car dies when i clutch in with out pedaling the throttle. This is my first tune so go easy

36lb FIC injectors
220/220 cam
.600" lift
114LSA
Attached Files
File Type: hpl
7-25-20 log 1.hpl (3.47 MB, 77 views)
File Type: hpt
Stock 2 SD Tune Step 19.hpt (254.8 KB, 29 views)

Last edited by cpressl90; Jul 29, 2020 at 07:22 AM.
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Old Jul 29, 2020 | 07:23 AM
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Has anyone had this issue besides me?
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Old Jul 29, 2020 | 08:29 AM
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Need to smooth out your fuel table. Have you tried running CL and using the fuel trims for part throttle?
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Old Jul 29, 2020 | 08:18 PM
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Ill try CL with trims to see what happens this weekend. So far ive just done open loop and added fuel where its lean. that why at 30-35 kPa the VE is higher than 40-50 kPa. When the computer interpolates does it just use the values nearest or multiple values?
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Old Jul 30, 2020 | 08:54 AM
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I would install vacuum gauge to see what actual vacuum the motor is producing. Cruising with throttle barely open generally produces the highest engine vacuum. Low vacuum at cruise would only occur on a high load (steep incline) with throttle opened up. Any DTCs. Assuming speed density tune (not MAF)?
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Old Aug 1, 2020 | 10:49 AM
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Only DTC is EGR because its gone and MAF because it off. The rain finally cleared up so im going to put it back in CL and go for a drive
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Old Feb 13, 2022 | 12:40 PM
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it ended up being that the computer was looking at the secondary VE table because this is a P01 PCM And MAF was failed. i updated the OS where it only uses one VE table and turned the throttle cracker back on it it runs just fine now
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Old Feb 19, 2022 | 01:03 AM
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Originally Posted by cpressl90
it ended up being that the computer was looking at the secondary VE table because this is a P01 PCM And MAF was failed. i updated the OS where it only uses one VE table and turned the throttle cracker back on it it runs just fine now
Those little details can really run you in circles. At least you figured it out.
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