Mark Houlahan
Tech Editor, Mustang Monthly
January 1, 2001

A Whole Lot Of Shakin' Goin' OnRecently, I purchased a '96 Mustang GT convertible-VIN 1FALP45XOTF116733. My car has 17,000 miles with 17-inch rims and the original tires. It is in perfect condition and has never been damaged. I wonder if you could help me solve or improve a situation that I am experiencing with my car.

The car-especially the windshield frame, the rear deck, and the rear quarters-shakes when going over certain jarring bumps. I know that the body on a convertible is not as rigid as that on a coupe, but this shaking is annoying. When I testdrove other used GT convertibles, I noticed the same problem. However, the one that I purchased seemed to be the tightest of them all-probably because of the low miles.

I put KYB shocks and struts on the car, and this improved the ride and handling. I also had a shop install Kenny Brown subframe connectors, but they didn't seem to make much difference. Can you give me some advice as to what I can do to help improve this situation?

I was thinking of changing to polygraphite bushings and/or different coil springs. I don't want to alter the ride height or make the car ride terribly stiff. Can you comment and make suggestions?Paul OndrusClarendon Hills, IL

We're surprised that the subframe connectors didn't make much of a difference to you, especially after Ford added them to convertibles as a TSB (Technical Service Bulletin) upgrade (not Kenny Brown's, mind you). Your two suggestions-bushings and springs-will not help your problem. Bushings will make the car and the suspension more like "one unit" and will transfer harsh road conditions right to the body. The same goes for the springs. Lowering the car and putting stiffer springs in will make for even more shake, rattle, and roll.

Stiffening the body structure is your best solution for body and cowl shake. Adding a stiffening brace under the hood and/or under the engine cradle will help, as will an interior support bar-if you are willing to live with a bar inside the passenger compartment. A rear shock tower brace will help too and is almost invisible in the trunk. Have a reputable body shop check out the Unibody for any cracked spot welds too. Sometimes just welding up the framerails and other areas that receive only cursory spot welds will help in stiffening the chassis also.

Where's That Manual Choke?My '89 5.0 began to experience some rough running about five months ago. It is what I would best describe as stumbling. It is most obvious on the 1-2 upshift. Occasionally, it will backfire through the induction if I push it at all while I go up an incline. If it were a carbureted car, I would know that there was a problem with the choke.

It appears as though I need to pull the choke out a little bit. I've also noticed that upon starting the car, the engine frequently does not run at an rpm higher than the normal idle for a short period of time as it used to do. This condition lasts for only three to four minutes, then it runs as strong as ever. The car has 175,000 miles on it, but you would never know it. The engine is bone stock, except for a K&N air filter.

I do all of my own mechanical work, but I've taken the car to Ford dealers four times in its life. Each time, it came back with more problems than it had when I took it in. I've kept up a steady maintenance schedule throughout the car's life. I changed the plugs, but with very little effect. It appears to be a fuel management problem.

I ran the EEC IV self-diagnostic, and both the KOEO and KOER tests result in a service code 11-system passes. I performed both tests with the car warmed up, as specified in the manual that came with the tester. Since this problem exists only after a cold start, I tried running the diagnostics with a cold start. The KOEO yielded a code 24 and the KOER had a code 21, both indicating that the engine coolant temperature was not up to normal parameters, as I would expect.