Riflemanpro

Hello all,

I have a 2002 Mustang GT with 174,xxx miles on it. I know it's a lot but i'm rebuilding soon! Anyway, currently I am having trouble with the motor. To preface I have a CAI, new plugs, msd coils, a off-road x-pipe, SLP exhaust, and few other that don't pertain. It is untuned and ever since the install of the SLP exhaust when we have a massive downpour or an impending downpour when the air pressure starts to drop and the air starts to chill the car will hunt for idle or just die entirely. Today, after two whole days of downpours I go to drive, start it up and it idle like crap. huge misfires that rocked the whole car, finely after a few seconds of keeping it alive it settles. I head to the road and tip in to the gas and can feel the whole car shake and bog with misfires and it feels dead but I press on hoping it will iron out when it warms up and dries out but when I get up on the highway the check engine light starts blinking. I immediately limped it home and it has sat since. What do you guys think I should do to stop this? any and all responses would be appreciated.

dhavi4226

Have you checked all connectors, vacuum hoses and intake duct connections for cracks and/or leaks . Also make sure no moisture exists in the plug well or the coil pack. Dielectric grease is recommended at the bottom of the boot and the connection. Any checkengine light.

dawson1112

Have the codes pulled via OBD2 , I know that the flashing indicates a miss, but there may be other codes set.

Before I replaced the exhaust on my 2000 gt the PO had it all hacked up and the up stream o2 sensors were cut/and or disconnected. The engine did the same kind of back firing and had a miss at idle. Sometimes it was good at wot and other times it would spit and sputter like crazy. New upsteam o2s and a sealed exhaust with no leaks solved all the problems with it.



Also the MSD coils are not as dependable as the OEM coils. Pulling codes will tell you where that misfire is located if its 1 or 2 cylinders that are missing... If it reads random multiple misfire then that means its randomly missing on all of the cylinders and it could be a fuel delivery problem.

Riflemanpro

I have in the past went through what connections I could see and once I even tried hitting areas of the engine with water till it started actin up but it did not work. I pulled the codes about 4 months ago and I got two code neither I nor my step-father (who works for a body shop) recognized and one code that showed it was reading rich AFR which we attributed to not having the cats.

dawson1112

Removing cats will not affect the air/fuel mix on these cars....

The downstream o2s will simply set a code for inefficient catalyst, the upstream o2 sensors are what the computer uses to read the air/fuel mix.

You have 2 sets of o2 sensors,,, Upstream , and Downstream. The Upstream sensors read the air/fuel mix so the computer can adjust for it, , , the down stream sensors gather data for the computer to compare with the upstream sensors..... This way the computer can monitor the efficiency of the cats..

Riflemanpro

Hmm....I'm gonna get a tuner and start with telling the computer what's going on and go from there.

ShiftinGT

Was the car out in the rain during those two days? Maybe water seeped through the hood scoop and got your coils wet.

Riflemanpro

Yes it was

Eduardo

I have the exact same problem that you're experiencing. When I would start my car in the mornings it would act as if it had an aggressive cam in it then when the motor would warm up the idle would smooth out and it became drivable. Now its happening almost every time I start my car and unfortunately for me, its a blown head gasket. My coolant looks dark colored which is an indicator of head gasket failure. I would check to see if your coolant is has discolored or have a leak down test performed on your car.

Riflemanpro

Yea, there is some white smoke now coming from the exhaust but no antifreeze in the oil or vise versa. So we are thinking the gasket has had a small hole that would seal up when it warmed and now that winter has beaten it, it's finally about to go. We are going to try and replace that and see if it helps.