Rich running after rebuild - LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums
 
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post #1 of 8 (permalink) Old 08-07-2014, 09:44 PM Thread Starter
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Rich running after rebuild

Just finished my 94 TA engine overhaul and cam install. Lunati 219/227 and all req valve train installed. 1.6 Roller rockers. Has a base tune but the LT BLM's are rich. I just replaced a leaking evap purge valve so it is better but the RH bank at idle is still pulling fuel. But at cruise both banks seem to run rich. Fuel pressure at idle is 39 & 47 with vac disconnected. Vac at idle is 16.5-17" Hg. Spark plug gap is .050". Could someone look at my DataMaster logs and maybe see what I'm not. the normal driving uni is before evap fix and the Cold Start uni is mainly at idle/ fast idle from OL to CL. Thanks, Jeff.
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post #2 of 8 (permalink) Old 08-07-2014, 10:03 PM Thread Starter
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Sorry couldn't attach the logs too big. I can email them if any could help? Please!!!!
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post #3 of 8 (permalink) Old 08-07-2014, 10:07 PM
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I have no datalog experience... but how rich is rich?

Is your bumper covered with black specs?

Is your idle rough?

descreened maf?

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post #4 of 8 (permalink) Old 08-07-2014, 10:11 PM Thread Starter
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idle is good, has base tune and the guy that is doing it says the BLM's at cruise are 108-115. But after the evap repair at idle it looks like th RH bank is still pulling fuel. The MAF is OEM. Tail pipes are black but its not spewing out.
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post #5 of 8 (permalink) Old 08-07-2014, 10:14 PM Thread Starter
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New plugs, GM O2's as well
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post #6 of 8 (permalink) Old 08-08-2014, 07:07 AM
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Things that cause split blm's; intake leaks, other vacuum leaks, exhaust leaks, toasted plug wires,fouled plugs, dirty and clogged injectors, o2's bad, bad wiring to o2's.

If you have long tube headers, check the stretched wiring you installed for the o2's.

There are also those who believe getting extra air through the iac system can help.

Last edited by cocobolo95; 08-08-2014 at 07:12 AM.
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post #7 of 8 (permalink) Old 09-02-2014, 07:50 PM Thread Starter
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Actually went SD tune and that fixed the LT trim issue. Now have a no start/ cut out problem. Just died driving and had to get it towed. Looked at it with DataMaster-no codes until I did KOEO and I got 36,41 & 42. Ugh!!!!
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post #8 of 8 (permalink) Old 09-02-2014, 08:00 PM
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you can easily get a maf tune working too, but with that cam speed density will do well if you take the time to perfect it.

what happens with a maf and a larger cam is a range of corrupt airflow that's hard to measure. instead of being sucked straight in, wobbles around and pulses back and forth a bit, screwing with maf readings.

you can just scale the maf tables back a bit and it'll stop

there are other things you can change to truly stabilize closed loop and get it behaving more like a stock engine, namely CORRCL. if you don't, it'll tend to fight itself (overcorrect the afr based on o2 fluctuations), the integrator will be all over the place, and so will your AFR and long term trims.

as far as the split BLMs go, are you running longtubes? first thing is to try jacking up the integrator delay times quite a bit.
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