Got BLM to IAC is 0


Jun 19, 2005
Ok was chasing a High BLM (150) got it down to 128 by installing EGR blockoff plate and replacing vacuum hoses, installing a TT chip and LS1 MAF w/ Translator...but now when the car starts cold the IAC is 175 then once it warms up it quickly drops to 0...any ideas? The car seems to be idling decently, RPM's 850-900 once warm..around 750RPM when cold -- should I mess with it? TPS is .45
Going to take IAC off and clean and do the reset procedure ; do I need new gasket for IAC?

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Going to take IAC off and clean and do the reset procedure ; do I need new gasket for IAC?

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TPS is too high,the IAC affects the tps and vise-versa...make sense ? You can reuse the gasket if it looks good...
Set the tps at 42 key on at idle it will stay at 42 and change to 44 ..
Did cleaning your iac valve work? My iac was stuck at 30 no matter how much I turned the screw. So I took out the iac and it was black with carbon. Cleaned it and reinstalled it. Also sprayed out the throttle body. The iac went to 0 and turning the screw didn't help. Went for a drive, turned the screw out when I got home and adjusted it to 27. TPS is .42. So all is well for now at least.
Haven't had a chance to clean out IAC but did notice driver side header is cracked; would that cause this?

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That could be one of your problems I would check all your hose for leaks dry rot . That crack header will give high blms for sure .
Remove the header and have it welded.
That is the cheapest solution. Very common issue with these cars.
Jack the car up make sure you use jack stands and put the emergency on go under the carve safe . take the 2 bolts off that go to the flange then you have 4 more bolts for the header and the alternator bracket .take stuff out of the way like dip stick and maybe plug wires .not hard at all .but take pics before doing anything in case .
any tips on removing the 29 year old header? is there any how-to's regarding it? thanks
....and hit the fasteners with PB Blaster or your favorite penetrant prior to attempting removal. Taking off the tire will give better access to the fasteners.

Take the manifold to a good welder. Anybody can bugger it up and weld it shut but if you want to give it the best shot of lasting a while before you have to do it again, find a good welder and put a gusset between the #3 and #5 tubes. IIRC the manifold material is 409 stainless and should be tigged to keep the heat down (I believe we used 309 wire on mine but can't remember now). The metal is very thin and could be challenging to work with especially if it's already had one or more repair attempts. Putting the manifold on a spare head before tigging will minimize flange warpage. If no spare head I would clamp the daylights out of it. Check the flange for trueness before reinstalling, usually with no gasket. That's how they came from the factory.