Hello,
I need help with my '86 mustang LX: The car was running fine at 1st(i am new owner): but now will only consistently start and idle pretty well; any amount of throttle results in the engine stumbling with no rpm increase beyond maybe 12 to 15 hundred and lots of black smoke, so its running too rich.
There are no obvious vacuum leaks, disconnected sensors, and the wiring seems intact.
I have run the diagnostic 'engine off' test and get only #31 (egr) error code. The motor does runs slightly better or different with EVP? electrics disconnected, and in the running engine test mode(seems to run fine at 1500 for examle, but the same stumbling occurs with any throttle application beyond that).
I would just like to get the car running correctly. This is a California emmisions car.
Running test codes are 44, 94, &31(air pump valve?)
The egr valve does move with the application of some vacuum. There is change measurable in the electrical resistance on the EVP with application of vacuum. I have shop manuals including the emissions diagnostic Volume H.
So my real question is what next?
The manual states that static test (engine diagnostic codes) #31 should be cleared 1st before 'chasing' the running test error codes. There seems to be plently of exhaust volume coming out of the tailpipe, but I cant excluded a partially clogged exhaust as black soot and smaller chunks of ? collect on the ground under the tailpipe.
The spark plugs were fouled black, but changed(resulting in no change in performance) and probably are fouled again at this point.
The engine would idle all day long if I let it and it starts easily either cold or hot with an appropriate transistion from cold engine to hot starting at 1500 rpm cold and going to about 650 when warm.
I want to remove the egr and try to clean it, thinking it maybe partially stuck open(ie wont close completely?) though the egr valve does apparently move if you put some vacuum on it, and moving the valve with some vacuum does make the engine run much worse.
This car did the same thing once before and I had to limp home at < 20 mph(cold idle on flat ground cold) which miracously did improved to 50mph(because of some throttle responsiveness) & over the course of 150 miles the car finally drove normally again by the time I got back home.
The car worked fine thereafter for some time (long enough for me to dare driving a longer distance on the highway again)unfortunately the same symptoms returned the next time I got about 50 miles outside of town. It did start to run hot before starting to sputter again, which could be controled by reducing speed to 50 mph, but eventually I had to limp back to town a second time(replaced radiator once back and have tried to 'drive it back to normal' again in town with no improvement over the course of two or three tanks of fuel; I kept thinking I had contaminated gas in my tank as symptoms were intermittant & seemed to be related to rain?; urrgh!!
I would like some guidance on what to try next ? I dont like buying parts to just test things, hoping to stumble on a 'cure'.
I have never needed to mess with an egr before and this one seems to bolt into a plate that lives underneath the CFI that is aluminum, so I am alittle concerned I may strip the threads on an attempted removal(bolts look very rusty and im not sure what i will find or even do, if i get the egr off, replace?.......I do think it is best to keep the CFI, so conversion to carb or something like that is not in the cards for me( I would rather sell the car before considering doing that); keeping it completely 'stock' however is not an issue I need care about here; I just would like a reliable good running car.......without too much more headache
Please help, thanks!
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