ccmcelroy
08-20-2015, 08:54 PM
I have a strange issue with my svo. I have been trying to work all of the bugs out and have successfully done so except for this problem. If I run the car with the boost switch set on non premium fuel(10 psi) it will run fine ( even at wot in every gear) but when you change to the premium setting on the switch it will boost fine in 1st and 2nd gear then when you go to third or higher it will start to miss/stutter when boost goes above 10 psi. I have replaced the plugs with autolite copper plugs. I replaced the plug wires(Motorcraft), distributor cap and rotor button(Motorcraft), replaced the tfi/ignition module(Motorcraft) as well. The timing is set at 10 degrees spout out. TPS sensor has been checked and in normal range. The car has a few mods so here they are. It has a spearco front mount intercooler, evergreen t3/t4 turbo with ported e6 manifold, 3 inch down pipe to a full 2 1/2 inch magnaflo exhaust, a big valve head with a a234 slider camshaft, kirban afpr, a walbro 255 in tank fuel pump, new fuel filter, new pulse dampener. I have checked the fuel pressure while idling and it is in range. So with that said I am leaning toward a few things. I have a turbosmart bypass valve that is placed right before the throttle body and I am thinking it could have a vacuum issue. I haven't checked it yet but after reading the instructions again tonight it states that it should have its own vacuum supply and not share with another which is the way it is installed at this time. If it isn't that I am thinking it is a fuel issue. I am just not sure. I have been working on this issue for weeks now. I have read countless threads on this site and several addressed similar issues with stuttering/missing under wot but all of the others seem to have had the issue during any wot. Mine only does it when above 10 psi wot and only in higher gears and when the fuel switch is set on premium. I haven't ran any codes yet going to try and work on it some more next week when I am off. Any help would be appreciated.