94redGTConv

Hey guys, I just bought a 94 Mustang GT Convertible 5 Speed. The guy I had bought it from told me it had been rebuilt in 08 when it hit 200k and now its at 245. When I had bought it I immediately changed oil to full synthetic gapped my new plugs to 54 and (k&n filter) recleaned (wasn't my buy) and of course oil filter and royale purple synchromax tranny fluid. recently I had a warming up issue and it'd lug hard I'd get up to 50 and on the way there everyone would pass me til I warmed up, noits not carbed its efi. I've had an 01 auto gt as my first car and so I know how a stang should feel well this feels pretty hesitant in throttle response, any ideas guys?


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dawson1112

The ect may be bad or the maf may be dirty. First thing I would do is see if it has any codes stored in the ecm. One of the sensors is giving false data to the computer. The ecm probly is seeing a higher temp than what the engine actually is. This will cause the computer to run the air/fuel mix leaner than it should for a cold engine.

mattdel

I'm thinking restriction. Still got stock cats?

dawson1112

would it clear up once it warmed up if it was a restriction?

mattdel

Could.

Venomantidote95

I havent heard of an over temp causing a leanout condition! usually adding fuel is a compensation for an over heating condition, that is the main point of a 160* thermostat with a aftermarket computer chip although if you have an erratic over temp signal it could cut the injector finring and if it was a restriction when it gets hot it`ll get worse since everything grows in size once at running temp or higher!

What exactly is it doing, just sluggish until warm or does it pop or backfire etc? Get the codes and go from there post them here once you have them any parts store can put a scanner on it or loan you one write them down and let us know!

dawson1112

actually if the engine coolant temp sensor is giving a false reading to the ecm that the engine is up to temp allready the ecm will lean the mix or be in a closed loop . If the engine is actually cold it requires a richer mix of fuel to air to run properly. And when I think about it the restricted cats when cold could cause it to run poorly untill they heat up and the holes in the catalyst expand allowing more hot exaust gas to pass through.

dawson1112

and I should also add that if the air intake temp sensor is giving a false reading telling the ecm the air is hotter than it actually is this will also lean the fuel mix out . And if the air intake sensor is giving a false reading of the air being colder than it is it will cause the ecm to leangthen the injector pulse making the air fuel mix richer .
These 2 sensors work in tandom with one another feeding the computer data that it uses to keep an optimal air fuel mix . I actually relocated my air intake sensor to just behind the filter to get a slightly cooler air reading this allows me to have a slightly richer mix and at the same time lets me add a degree of timing btc without detonating.

94redGTConv

well I got my friend to try and diagnose it and he told me to get a new sensor and I did and its running wayyyy better, but I forgot to reset the computer and its still bringing the ect sensor is bad code, but do you guys think I should cut my cats off? I live in Tennessee so I don't have to have them. thanks guys


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dawson1112

I would cut the cats of if i was you . and eliminate the smog crap. They sound way better with out the cats if you have the right mufflers on it and not the stock ones.
I cut all that crap off of mine and went to a set of super 44s. You will be suprised how well the engine likes being let free to breath.