March 1, 2005

A GT40 5.0?I recently bought an '88 Mustang GT and I'm having a problem understanding some parts of the VIN. The seller said the car was a "GT40" but I can't find any reference to that in any of my Mustang reference books. The VIN says it's a GT hatchback, but the engine code of "E" doesn't show in any of my reference books. I called a Ford information line and was told a 1988 E-code was, of course, the 5.0 EFI V-8. They also said all records at Ford are purged after 10 years and the 1988 records are gone. Do you have any information on a GT40 kit or engine set, or any information about a 1988 engine code of E?LeRoy Wilcox Via e-mail

Anyone is welcome to correct me if I'm wrong, but as far as I know there is no such thing as what you're talking about. It sounds as though the seller hyped something that doesn't exist. The '86-'93 EFI 5.0s were all the same 5.0 engine, as it was the one alternative over a four-cylinder Mustang. Other than running changes like converting to mass-air in 1989 from speed density (1988 for California cars), the change to better cylinder heads in 1987, and some allegedly minor cam-profile changes over the years, an '86-'93 Mustang 5.0 is a Mustang 5.0, period. There were no 5.0 "options" that would make one 5.0 more special than another, and I've never heard of a GT40 package offered by the factory.

The only exception is, of course, the '93 Cobra. It was the only Fox 5.0 Mustang that was a "step beyond" compared to all other EFI 5.0s. Maybe you're confused because its engine came with several upgraded parts, including a set of "GT-40" (cast iron) cylinder heads.

Since the '93 Cobra was made five years after the '88s, I'm fairly sure I'm correct about all other 5.0s. There is a GT-40 package offered by Ford Racing Performance Parts, but that's for aftermarket and not part of a factory offering. We did a story on the GT-40 package in our April 2003 issue.

According to the Mustang Red Book by Peter Sessler, the engine code for '86-'90 5.0s is "M," and the code for '91-'93 5.0s is "E." Assuming your car is indeed an '88, something might be amiss with your VIN if the Sessler book is correct. If it's wrong, the E-code is just that: a code for the 5.0L engine. This might shed some light, but could also raise more questions.

Based on two other sources of information (my '88 5.0 convertible and another book), there's a chance the code information in the Sessler book is a misprint. The VIN on my car clearly shows an "E" as the 8th character in the VIN (see photo), not an "M."

The Mustang 5.0 Technical Reference & Performance Handbook by Al Kirschenbaum has a V-8 engine codes chart, and it jibes with our cars by stating the code for '88-'93 5.0s is "E," and "M" for '85-'87 5.0s. Your car is simply like all the other legions of 5.0s out there with the code E, but there's nothing wrong with that. By the way, according to both books, the engine code for the '93 Cobra is "D," which, of course, indicates its unique engine.

Defroster TechI believe I may have a solution to the problem described by someone awhile back. The HVAC controls on his car were stuck in the defrost position. I have an '85 coupe, an '86 coupe, and an '86 convertible. Two of my cars have had the same problem. The HVAC control in these cars is vacuum-operated, and Ford designed the HVAC control to rest on "defrost" in the event of vacuum loss. So if there's a problem, you still have the most necessary function for inclement weather.

His problem is most likely a vacuum leak before the line reaches the control head. The worst case scenario is what was wrong with my '85: a crack in the back of the control head, requiring replacement.William McGinniMarietta, GA

Send your '79-'05 Mustang questions to: Late-Model Corral, 9036 Brittany Way, Tampa, FL 33619, or e-mail to with "Late-Model Corral" in the subject line. Include your name, city, and state in all letters and e-mails.