When I bought the Mustang a few weeks ago, I knew there were lots of issues that needed attention. The seller told me that the "Check Engine Light" (CEL) was on all the time. The CEL is the dreaded light in the instrument panel of most modern cars. The usual advice is to take your car to the shop if it lights up because SOMETHING IS WRONG!
My Mustang's V8 engine was modified by some previous owner. What he did was an economy performance upgrade where he installed cylinder heads from a newer Ford product, possibly an Explorer. Yes, an Explorer! The cylinder heads are referred to as GT40P heads. These are later model, higher performance heads that were used on the Explorer and Mountaineer SUV's. Along with the associated GT40 upper and lower intake manifolds, it is reported that 20-40 more horsepower can be obtained at a low cost.
The problem with changing the manifold is that some sensors from the 1990 Mustang V8 do not have a location on the GT40 manifolds. I knew this and one of the first things I did was to purchase a sensor that measures the intake air temperature. The new intake manifold could have been drilled and tapped to accept the sensor. For the time being, it is just laying on the manifold until I can get it installed in the air intake tube(another acceptable location). This helped the engine run better(or so I thought), but the CEL stayed lit.
The next thing I tried had to do with the Exhaust Gas Recirc (EGR) valve. This is a system that recirculates exhaust gas back through the engine at some engine loads. This system had been removed. So after some research on the place called the Internet, I found that the removal of the EGR valve can cause some confusion with the Electronic Engine Control(EEC) and a company in Michigan makes a resistor that plugs into the EGR valve position transducer connector and "fake" the EEC into thinking the valve is still there. This was suppose to turn the CEL off. The resistor arrived Saturday and I plugged it in. The Mustang ran much better, but the light was still on.
So today, I ran diagnostics on the EEC to see what error codes the computer had. My friend Jim loaned me a reader that connects to a test connector in the Mustang. The test included both KeyOnEngineOff(KOEO) and KeyOnEngineRunning (KOER) tests. The KOER test was surprising because the tester actually reved the engine up to 2000 RPM's!
A few error codes showed up during the tests. Most were for removed equipment that was not critical. But one code jumped out: Coolant Temperature Sensor. It was not there! When all the mods were done to the engine, the location for the Coolant Temperature Sensor interfered with the distributor. The newer engines that the heads and intake manifolds came off of probably did not have a distributor, so the sensor could easily fit. So, of to the autoparts store and I bought a sensor. I plugged it into it's empty connector, started the engine and the LIGHT IS OUT! For now it is just laying on the manifold. But eventually, I will install it with a tee with the temperature gage sender on the other side of the manifold.
This was a big accomplishment in the Pony Car Project. I feel more assured that the Mustang will be reliable and hopefully it will run more efficiently and possibly get better gas mileage even though the gas mileage is pretty good already. I will not say that that I am really good at doing this kind of work, I am persistent and study the problem until I can come up with a solution. So I will just remain quiet and Smug.
Now before someone accuses me of defeating controls on the engine that have an effect on pollution, this car passed the smog test in Pierce County when the previous owner licensed it.
The tester for checking the computer's error codes. This was fun to use and took some of the mystique away from diagnosing a Electronic Engine Control system.
One of the first and very important purchases for the Mustang. A Electrical and Vacuum Troubleshooting Manual with the cars diagrams. When I bought the Bronco new in 1984 I bought a similar manual and it too was invaluable during the Great Bronco Engine Transplant.
Different laws in different states; from what you describe that Mustang wouldn't have even been allowed on the road here in Massachusetts. Here we have a required yearly inspection. Although it used to use a tailpipe emissions sniffer, it doesn't even do that any more. The inspecting shop just plugs directly into that computer bus socket, and if any code indicates anything about the computer having been tampered with, any sensor not working, or an unauthorized mod to the engine itself, the car fails inspection. You have 60 days to get the problem fixed and then pass re-inspection, after which it's illegal to put the car on the road. The inspection decals are color-coded by month as well as year, so it's hard to get away with anything for very long.
ReplyDeleteYou are right, "Differant Laws in Differant States". In Washington State, only in selected densely populated areas are smog tests done on motor vehicles. And then it is a tailpipe test only, the configuration is not evaluated. And after a car is 25 years old, it is no longer tested. Probably not many people keep cars that long anyway. In my area, testing is not required.
ReplyDeleteWay to troubleshoot, Dan! Congrats on figuring out the CEL issue. I didn't know you were so proficient on working on Mustangs too. Looks like you're getting tons of projects done on the "pony". :) Perfect timing. Nice cruising weather is just around the corner.
ReplyDeleteBrenda, I have learned a few things in my life. ☺
ReplyDeleteHmmm. A computer burp somehow changed "Chuck Kollars" into "Unknown'. Sorry.
ReplyDeleteI knew it was you, I tracked your visit from another site. Blogspot does some strange things since it is part of Google and they want everyone to be part of their empire! I think about changing to a differant blog site.
ReplyDelete