86 engine performance

[Denbob55]

Hi all. I own an 86 Merc convertible in decent shape, but was underwhelmed about the performance. So I put on an 87 HO upper manifold with 70mm throttle body before I discovered the speed density FI isn't able to compensate for the extra fuel/air mixture. Now of course I have irregular idling. Before I reverse everything is there a trick to getting the ECU to recognize the performance upgrade? thanks

[ChuckG]

It should be okay with a 65MM but there are several people who can burn a new EPROM for you. Pete Campbell in Michigan is certainly qualified to do it.

[Denbob55]

I found a mechanic who was raised on 80s Fords. It is as many of you say; check vacuum leaks, test sensors, check firing order. The last guy switched two cylinder wires, the TBS voltage was set too high, and the vacuum hose to the MAP sensor was disconnected. Now she runs fine as set up with the 70mm throttle body. Next we're going to check timing and go from there whether we need EPROM or not.

[Denbob55]

Hi Chuck, I can't find Pete Campbell on this site.

[ChuckG]

He's in the Facebook Coupe group. Livonia, Michigan

[ChuckG]

https://www.facebook.com/groups/316239573049979

[Denbob55]

Not to be a pain, but I was thrown off FB. I have no idea why, but if you find a minute maybe you can ask him for an email. if not then my loss

[ChuckG]

I sent his number via PM. I don't have an email.