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Ford Mustang Forums Tech Related Engine & Performance 5.0 Pushrod Guys

studdering/jumping when cold outside

BAD5.0 27.02.2014, 23:08
Been having some stiffer jumping issues as well as 100 other people, seems to only do it when its cold out. New motor with about 15k replaced in 2012, 24lb injectors, full bolt ons, too much to type. I'm running a 93 cobra FPR, 190lph pump, c&l MAF 75mm. 76mm tb. And set at 15*btdc. Since the issue has occured, I've changed plugs wires oil change fueel filter, fpr, and found no vacuum leaks(that I can tell) and changed my tps. Tps is at .98dcv. Not sure what else to check and I'm going insane. I wonder about my ATS, my new lower intake did not have a port for it, I know it needs to be close to the manifold but it was relocated on the cold air intake close to my tb. My set up has been the same since motor build with no issues until recently. I don't know if I have a dirty/clogged fuel injector, or what, but it happens more frequent on cold start. I do have a b303 cam with 1.6 pedestal roller rockers. I don't have a fp guage and my fox is my daily driver. I have cleaned my ATS and my IAC. Could be a faulty IAC, I don't know the voltage range for those to check it or else I would. Also replaced cap and rotor since the issues... running out of ideas. Any help would be appreciated. Let me know if more details are needed. Thanks everyone
BAD5.0 27.02.2014, 23:08
Studder* not stiffer lol
BAD5.0 27.02.2014, 23:15
Also a9p computer and has not been dynotuned. Been needing to run it to kurtis at archangel but haven't got around to it.
broke again 28.02.2014, 00:02
you need to know what your fuel pressure is, but that cam will be a little grumpy till the car warms up. tune would likely help but i just live with it and tune with fuel pressure and timing instead of paying.
BAD5.0 28.02.2014, 00:12
Yeah I will be buying a fp guage this weekend. Online it shows the 93 cobra fpr to be set at 45psi wwhich shouldn't be right. Maybe up to 45. But I should be around 40-42, correct? Also going to try trimming my IAC gasket to match the ports. Noticed the gasket is smaller than the ports on both the iac and the tb. Going to clean salt and peppers and probably check some voltages from my CPU this weekend. Also need to check all grounds.
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