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.

Additionally, three times during this period, one plug fouled upon a warm start-up. I was able to clear it with about 15 seconds of higher rpm (2,500) running. This may or may not be related. Where do I go from here?Chuck CromIndependence, ORThough your EEC test didn't come up with anything conclusive, you still have a problem somewhere. Let's take a look at some supporting systems. Have you checked the available fuel pressure? Fuel pressure should be in the 38-42-psi range for the car to run smoothly-anything lower and you can have a hesitation or stumble on acceleration. As for your low idle on a cold start-up, the culprit could be a sludged throttle body and/or the idle-air bypass controller. When the throttle body wall and throttle blade get coated in sludge from crankcase-vapor recirculation, it can drastically affect idle speed. Often times, the inside walls and bypass opening of the idle-air bypass controller will be so conta-minated, hardly any air flows through at idle. While this usually throws a code 12 or 13, sometimes the PCM isn't sensitive enough to detect this problem. Inspect the throttle body for buildup, and clean it with a rag soaked in carburetor cleaner. If the idle-air bypass is full of sludge deposits, you can unbolt it from the side of the throttle body and clean it separately as well. Good luck with your repairs.

The V-6 DoctorIn the Oct. 2000 issue, you responded to a letter ("V-6 History Lesson," p. 84) without really responding to it. It seems that the 3.8L V-6 from the '83-'86 is the black sheep of the Blue Oval family. Nobody really responds to questions about it. Sure, it will never make the power of a 5.0, but performance and economy can be improved.

Cars with this engine can potentially handle better than the nose-heavy GT, thanks to aluminum heads, intake, and front cover. Responding to a question from a reader helps that reader and other readers in the same boat. Furthermore, the 2.9 was never, never used in a Mustang. The solid lifter 2.8 was used from the '74 to the '82-171ci, German-built. The 2.9 was used in the Ranger/Bronco II. Less popular engine sizes are a good, cheap way into the hobby. I am in the process of restoring an '84 Mercury Capri with a 3.8, a C5, and a 2.73:1 axle. I have found that there is virtually no information on these cars. They are much more rare than a Mustang, in that only 14,117 were built for the '84 model year (and less and less after that). I would like to know about how to obtain information on the '79-'86 Mustang and Capri that would help in the restoration.E. GrimmeEast Hampton, CT

Sorry, Mr. Grimme. We stand by our answer and believe that we gave the reader good information to help him on his way. As for the 2.9/2.8 snafu, yes, you are correct there. We got our ".8" and our ".9" mixed up when we were writing the reply. If you read this column regularly, we do not answer only 5.0 questions (just read the letter below yours). Quite often, there are turbo four, inline-four, V-6, modular V-8, and other letters printed on these pages. Why even a Mustang II, a Fox-body Thunderbird, a Mark VII, or a Capri can show up here from time to time. We definitely don't discriminate. If we are guilty of anything, it is not getting answers to our readers fast enough, due to our volume of mail. If we had the budget, we could hire someone just to fire back e-mail replies (please hold the resumes).

To answer your question, contact the Mustang Club of America for judging rules and judging sheets for '79-'86 Mustangs. You will find plenty of detailing information there. Also, check out major shows, such as MCA Nationals-where the best cars are brought out. Take some notes and plenty of pictures as to where things go: colors, orientation, and more. Good luck with your restoration.

3.8 Power HungryI have been a Mustang fan for quite some time now. I own a '97 3.8 V-6 Mustang. I have already added a dual exhaust system using Flowmaster mufflers, a K&N filter, an underdrive pulley system, and a Hypertech chip. Besides the supercharger system from Vortech, what else could I add to get a little more horsepower out of my Pony?Trey SmithWaynesboro, MS

One word, Trey-nitrous. A nice little 75hp, fogger-style system will really wake up your V-6 for when you need it. The system is reasonably priced and quite simple to install, if you keep the horsepower numbers down. Other options you can look into include a steeper set of rear gears and a cold air/ram air conversion. Of course, if you want to make more naturally aspirated horsepower, there are companies such as Super Six Motorsports [(912) 926-4489] that offer ported heads, intakes, custom cams, and more. One of Super Six's cars has all of its own engine upgrades and a Vortech supercharger putting out nearly 400 hp at the rear wheels. Yes, look again-that read "400 hp." Give Super Six a call, and tell them Mustang Monthly sent you.

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