atomic_fungus (atomic_fungus) wrote,
atomic_fungus
atomic_fungus

#1982: Jalopy hit the road today.

Got it insured and took it for a drive.

...it drives. It moves under its own power. It is not perfect, but it goes.

The engine stumbles when the throttle is opened quickly, and under load. If, for example, I'm going uphill in 4th gear at around 40 MPH and try to accelerate, it stumbles.

As long as it's not stumbling it has plenty of power.

Well, it's the first time I ever:

1) removed and installed an engine in the same car
2) tore a multi-cylinder engine down to the bare block and rebuilt it
3) diagnosed and corrected the inevitable problems with starting and running

...leaving me only with the drivability issue, the stumbling problem I'm talking about now. I'd say I did pretty damn good, getting it back to 99% usability. And it is 99%--I can drive the car--so I am already 'way, 'way ahead of most people.

All I can do at this point is throw parts at it. Here's a list of things I'm pretty sure are not causing the drivability problem:
* spark plugs
* ignition coil
* throttle position sensor
* vacuum lines (leaking)
* clogged fuel filter
Obviously there are a lot of things it could be, but those IU am pretty sure I've eliminated.

Tomorrow I'll be taking it to Pete, the guy I worked for in 2005 as a "part-time as-needed" mechanic, and we'll see if there's anything he can help with. He's got tools and a wealth of experience I don't have, so we'll see how he does with it.

Here are the possibilities I've come up with:
* bad spark plug wires
* clogged O2 sensor
* dirty MAF sensor
* fuel pressure issue
That last one--fuel pressure--might be it. The likelihood of the fuel pump having a problem seems low, but I know how this crap works, believe me.

One time, when I was a computer tech, I had to go to an asphalt company near here to replace the AC power supply on an HP Laserjet III. They had put one of our refilled toner carts into the thing and it had popped, giving the infamous "51 service error". I think it was the 51 error. It might have been the 50 code, but IIRC the 50 code required shorting a capacitor on the formatter to reset if you didn't want to wait an hour for it to clear on its own, and I didn't take the bottom cover off the thing; just the top cover.

Anyway: the customer was convinced that the toner cartridge had blown up his printer, and I tried to explain to him that the fuser switched on when you closed the toner cartridge hatch on the thing and that it was coincidental. His reply: "Yeah, I know you have to say that." *sigh*

The procedure for priming the fuel rail on the Escort is to switch the ignition to "run" and then back to off, over and over and over and over again. Interesting thing about fuel pumps in cars: the motors inside them are cooled by the fuel running through the pump. With some pumps, the motor is immersed in gasoline. (No air can get to the place where the motor brushes are happily creating all kinds of sparks, which is why the whole damn thing doesn't blow up.)

If you're trying to prime the system, though, for a little while that motor is running without any gasoline present to cool it--and if the motor is already 14 years old, this might cause a failure, and then it might cause the thing to lose just enough power that it doesn't create enough pressure in the fuel rail any longer....

I know the potential fuel pressure issue is not due to the fuel filter, which I replaced--unless, of course, the filter I got was bad. That would be more than a little annoying. The filter I installed, however, was exactly the same size and shape as the one it replaced, so I'm pretty sure I don't have the wrong filter.

The O2 sensor: apparently it's possible for an O2 sensor to respond correctly and appear (to the computer) to be perfectly in spec, yet not actually function correctly. I'm not sure how likely this is to cause the problem I'm seeing, but in my searches for vacuum diagrams for the car I came across some mentions of O2 sensors causing this kind of trouble.

I have spares of just about everything, thanks to having an entire spare engine. Everything worked when the engines were pulled; why would they go bad after just sitting? So tomorrow I expect to take the following parts with me:
* Throttle body
* O2 sensor
* coil assembly w/wires
* MAF sensor
* whatever else I think of between now and then
Well, heck, what else can I do?
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