[Mystic SVT]

The car sputters on low RPM (up to 3500-ish) when taking off, but especially when i give it gas and im already in gear at a low rpm (1000-2500) and feels as if its lost power all across the rpm band. Im thinking it might be the IMRC plates that might be getting stuck due to carbon build up. I dnt want to do all the work and have it be something else; if any of you with 96-98 cobras have experienced a similar problem let me know what your fix was. And also i know that the '96 cobras had cooling issues from the factory; What were the parts that needed replacing to fix this issue...thanx!!!

[Ryan_65Stallion]

sounds like it. have they ever been cleaned?

[Mystic SVT]

That I know of, no they haven't; but i've only owned the car for a little over a year...

[timpryor]

it sounds to me like the IMRC's

try this and if it works then you know its the IMRC's that need to be hand cleaned, from SVTP
Ok, you all wanna know about Seafoam. Seafoam is this stuff that is used to dissolve carbon deposits in your combustion chambers and will do the same on the IRMC's pretty well. I was sceptacle at first, but then I used it and WOW, what a difference on my 96 Cobra. It can be bought at most autoparts stores. People say to put it in the gas, but then it's just like injector cleaner and doesn't do shit barely. I was told to use the PCV valve to suck it into the motor, so that's what I did.

Step 1: with the motor off, simply pull the PCV hose out of the DRIVER-side valve cover, but leave it connected to the manifold.

Step 2: Open the bottle of Seafoam (the fluid, not the aerosol spray kind) and put the end of the PCV hose into the can, while keeping the can as upright as possible at first. You'll need 2 people, one to hold the can, one inside the car.

Step 3: Start the motor for about 12 seconds. This will suck all the contents out of the bottle into the motor. The can-holder should signal to the person in the car to turn-off the motor as soon as the can is empty. The faster you turn it off, the better. You'll notice that the motor will nearly die when it sucks in the Seafoam, this is normal. Seriously, it'll work fine after the process is done.

Step 4: Let the car sit for 30 minutes with the engine off.

Step 5: MAKE SURE YOU ARE IN A VEEERY WELL VENTILATED AREA. This will cause quite a smoke-show. Start the motor, let it idle for about 30 seconds. The engine will be sluggish and want to die, but will usually stay running. After 30 seconds or so, raise the RPM to about 2800 and hold it there until you feel the motor start to rev more freely (usually about 20-40 seconds). This step makes lots of smoke. That is all the dissolved carbon blowing out.

Step 6: Take the car out for a spin. Go WOT as soon as possible. This should clear the remaining contaminates.

Step 7: Drive the car around at different speeds and RPM's until it feels like the car is running like normal. After 10-15 of driving, you should notice a large increase in power, more smoothness in revs, and an all-round better running motor. After 74,000 miles I did this, and it felt like the engine had gained 20 horsepower, even though it was probably just underpowered with carbon before.


A can of Seafoam is about $4-5 and the can looks old-school. It has ornate style writing and kinda resembles an old shaving-cream can. Ask the store people, they'll know. It should be by the injector cleaners, etc.

Try it. You won't be dissapointed. PM me if you have questions/comments.

[Mystic SVT]

Thnx!! I'll try the seafoam today after work and hopefully that will wok. But even if it works I should still clean them by hand to get the remaining carbon build up right?

[timpryor]

yes the seafoam can't agitate itself therefore it can't remove all the carbon build up

[311-420]

seafoam is amazing. ive sucked it into my pcv on my mach just to do some preventative maintenance and also ran it through my gas. me and my friend did it in sonic parking lot. LOL

[96greengt]

Sounds like a plug cracked or a wire breaking down to me.

[Mystic SVT]

well I seafoamed it and it helped. It doesn't sputter as much anymore, just a bit sometimes. Im going to tear it apart this week to hand clean the IMRCs...and holy crap what a smoke show it was!!!!

[ANRmotorsports]

Just put IMRC deletes on it and be done!

[Mystic SVT]

I've heard that putting deletes kills bottom end torque on these motors bc of the intake port design; is this true?

[timpryor]

yes and no, it will but if you have gears it will compensate for that

[Mystic SVT]

well I'll be putting in a new rear end with with 31 splines and 3:55s. I'd go higher but I work just south of austin and live between san marcos and seguin and don't want to be fueling up every 3 days

[timpryor]

dude whats your gas mileage now? 21 maybe? My cobra with 4.10's gets 20.8 on the last tank running A/C all the time, 19 is the worst i have ever got with 4.10's and that was with 10+ track passes at WOT

[Mystic SVT]

I get about 22mpg on average. My buddy had 4:10s on his '98 cobra and hated them on the hwy but loved them in town, he switched to 3:55s and said his gas mileage went up tremendously so thats why I kind of don't want 4:10s...

[timpryor]

tremedously is what 1-2 mpg? unless he was ragging the shit out of his car he shouldn't have gotten less than 19 mpg with the 4.10's

[Mystic SVT]

He was averaging 17mpg and now gets 22mpg; to me thats a pretty good jump in mpg. Either way the rear end I have is built already, its just waiting to be put in and Im not really in a time to be spending a lot of money on my car right now since I've got school to pay for.