sprayed meth and went leaner??
06-07-2010, 09:54 PM
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sprayed meth and went leaner?? I have a TT gto and today I finally got my meth kit all hooked up and ready to go. Currently I run 8.5 psi and mid 11s for AFR (nice and fat). Once I sprayed the meth I went to 10.0 psi and low 12s for AFR (no Knock). I run off the wastegates Im not sure how I gained any boost. I injected a 50/50 blend. Any Ideas as t whats going on?
mike
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06-07-2010, 11:09 PM
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Its because of teh fuel mass. Meth is causing more exhuast to be expelled per combustion cycle. Im guessing its primarily because your twins that are pretty small on the exhuast side?
It went leaner because the temp dropped causing more dense charge and more exhuast volume from the meth spinning the turbos faster raising boost. This is controllable usually, with the gates, but semi small twins could get over run and not be able to keep up.
Check the tune also, the afr change could be due to timing changes in the iat timing table. Its possible that the cooler iat is causing substantially more timing (4-6 degrees) causing a leaner condition, and quicker response from the turbos still causing slightly more boost.
It went leaner because the temp dropped causing more dense charge and more exhuast volume from the meth spinning the turbos faster raising boost. This is controllable usually, with the gates, but semi small twins could get over run and not be able to keep up.
Check the tune also, the afr change could be due to timing changes in the iat timing table. Its possible that the cooler iat is causing substantially more timing (4-6 degrees) causing a leaner condition, and quicker response from the turbos still causing slightly more boost.
06-08-2010, 07:48 AM
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hmm well it cant be the tune because the IAT sensor is in the maf so its not seeing the changes in air temp.
The air being more dense makes sense especially since I get my boost reading from the manifold. How exactly do I fix this? My turbos are 55mm on the hot side and I have 2.5 inch down pipes and exhaust.
The air being more dense makes sense especially since I get my boost reading from the manifold. How exactly do I fix this? My turbos are 55mm on the hot side and I have 2.5 inch down pipes and exhaust.
06-08-2010, 02:11 PM
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If you go extremely rich it can trick your O2 sensor into reporting lean. Trying lowering your meth injection in small increments and I'll bet you come back on to the scale on the very rich side.
Jim
Jim
06-08-2010, 09:16 PM
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If you FI computer does not see the reduction in intake temps it will think the air entering is hot - and put in the correct fuel to compensate for hot air, BUT the air is actually colder, so it has extra air and hence run leaner.
06-09-2010, 07:28 AM
#6
I can see you have MAF setup. My thoughts are that the MAF is maxed out and the PE table is still setup for 8.5 pounds. That is the problem with a MAF based tune. When the MAF is maxed and you add more air, you must adjust the PE table to get the same AF.
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06-09-2010, 09:20 AM
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a maf tune, with twins? Come on man......SD SD SD SD .....you need it. Well you dont really but on a pegged maf tune you cant change anything.....
06-12-2010, 09:31 AM
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the maf parameters are scaled and the car has run perfectly for 2 years at 570rwhp. I tired making some runs without the meth connected and its now over boosting from 10 to 12psi which shows me that its not methanol at all. The car on th stock motor shouldnt be running more than 8.5 psi without risk so im concerned. I checked all vac lines and they are good. Took wastegates off and checked them and they are good. The only thing I changed was installing the meth kit and removing my AC.. Since then it has made 10 psi or higher
06-12-2010, 11:28 PM
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when i disconnected the meth i saw it hit high 12s when it over boosted and I immediately got out if it.. the car usually sits in the mid 11s on 93 octane alone at 8.5psi..
im stumped i checked both wastegates... i checked all my vac lines... did boost leak tests.. im lost
im stumped i checked both wastegates... i checked all my vac lines... did boost leak tests.. im lost
