New Addiction with Issues

Hey guys and gals this is my first post on the forum. I am new to the mustang club as I just picked up my first Cobra-- 's'.
I had a friend who sold me his mint 98 coupe with 60k miles on it and the same week I noticed one on craigslist 98 conv. with 138k ( both BAB color ) and I could not resist ( 2 is 1 and 1 is none lol
So my issue is with this 138k mile car is from 2k to 4k it hesitates almost like its missing fuel or air. The owner could not figure out what was wrong with it and I have read everything that google has offered in the last 2 days.
Mods.
Cold Air Intake, BBK offroad H pipe, Flowmaster Exhaust - no cats, Steeda underdrive pulleys and new belt at 118k, New Clutch and adjustable quadrant 1/2018, Valve Cover and Intake Gasket 1/2018, Cleaned IMRC, New Alternator, Spark plugs and PCV valve at 118k, Fuel Filter 9/15, new auto craft TPS and MAF.
Also he had 3 shops run a compression test and drip down with all normal and no codes are thrown.
I called to verify at the shops for this and one of them said only thing left he could see would a valve being burnt.
Any help would be great and I am in Charlotte NC. Thanks

What's the issue? Or did I just miss it?

No I am a num nut and didnt put it. I edited the post. From 2k to 4k it hesitates almost like its missing fuel or air
Its sounds like this post but the issue he had that fixed it has been looked at with no luck.
https://www.svtperformance.com/forums/threads/97-cobra-low-rpm-stumble-hesitation.894290/page-2

I’m envious. A BRB Cobra is one car I’d love to have.
Have you done the normal checks on the intake system?


Pick your poison.

Thanks, I blew out the filter ( KN) when i replaced the MAF and TPS. Am I missing anything other?

Does the IMRC physically function?

The last owner had it cleaned and function tested. But if you got a way i can check it let me know I will do it.

You might clean the little wire, carefully, in the MAS that had collected oil from my K&N filter. This solved my 94 Cobra issues that were similar. I sprayed the wire with carb cleaner.

I replaced the whole Mass air flow sensor and body with a brand new one yesterday with the TPS.

I guess that didn't help then.

Stock wires and coil packs?

yes both ford stock. I checked the packs for spark and they all where good. I had a friend drive it tonight and said it might be that the car had no back pressure becasue of the cat delete and no o2 are hooked up?

Back pressure affecting engine performance is a myth. If I was you, I'd do a complete overhaul on the ignition system. Just do coils, wires, and plugs all at once. If it doesn't fix the issue, at least you've taken that out of the picture. As for the IMRCs, you can reach behind the intake and feel for the levers that actuate the IMRC butterflies. Also, welcome. I live just outside of Charlotte in Gaston County.

ok will try it. Any idea what the best spark plugs to get and gap?

JHeat said:

ok will try it. Any idea what the best spark plugs to get and gap?

Click to expand...

Autolite 764
.054 gap

As mentioned above, buy new OEM wires and coil packs. When swapping plugs, make sure there is no oil on the plug. You may have a bad donut gasket or 2 at the cam covers.

98 svt said:

Autolite 764
.054 gap

As mentioned above, buy new OEM wires and coil packs. When swapping plugs, make sure there is no oil on the plug. You may have a bad donut gasket or 2 at the cam covers.

Click to expand...

+1

As @98 svt said, Autolite 764s are great. As are regular NGK copper plugs.

Charlotte?

Take it to pro dyno or fastlane.

Sent from my SM-G892A using the svtperformance.com mobile app

pro dyno had it 3 times from the past owner and said it has to be a burn valve cause they could not find anything other wrong. I called them soon as i got the car and they where great in talking with me about all they had done and what they thought.

JHeat said:

said it might be that the car had no back pressure becasue of the cat delete and no o2 are hooked up?

Click to expand...

No O2 sensors are hooked up?

Wouldn't a burnt valve show during a leak-down test?

Maybe a vacuum leak somewhere. IMRC shafts maybe?

Do you know if the car had this problem before the aforementioned work was performed?