toricred

96 CE LT-1, 120K miles

I'm having problems with the car running rough at idle and sometimes difficult to start without giving it some gas. I'm used to cars that require the foot on the brake to start so needing to give it gas seems odd to me. I've replaced the fuel injectors and it got a little better, plus more power, plugs and wires, fuel filter and cleaned out the air filter (K&N).

I don't know that much about working on engines, but I'm beginning to learn. Would those symptoms match a problem with the Optispark? I believe it is the original 20 year old equipment. Since there are so many horror stories on replacing the Opti and finding a good one seems to be difficult, I want to be sure before I start the hunt to find a good one.

PatternDayTrader

You could be right about the opti but at the minimum I would check fuel pressure before you go through the hassle of replacing the distributor. Obviously, if you open the hood and the water pump is leaking coolant all over it then yeah you might as well replace it, but barring that, I would perform some basic checks first. Since you said a k&n air filter then you might as well add inspecting the mass air flow sensor to the list.

toricred

OK, so a really dumb question. How do I check the fuel pressure? I'm assuming there's a valve somewhere to connect the fuel pressure gauge, but I'm not certain where.

PatternDayTrader

Correct.

There is a test port on the fuel rail. Here is a link to a picture. It is labeled "Schrader valve".

https://www.bing.com/images/search?q...7o0&ajaxhist=0

toricred

Found it. I need to pick up a gauge tomorrow at AutoZone after I help a friend move. Thank you so much for helping me locate the right port.

toricred

OK, so the fuel pressure is only 39 (according to FSM it should be between 41 and 47. The pressure stays consistent after the fuel pump is turned off, so I'm guessing it might be the regulator. Interesting since I replaced that just last year shortly after replacing the entire fuel sending unit and the fuel pump. I did also just realize that I bought the fuel filter, but apparently I didn't get it installed yet as it's sitting on my passenger seat still in the package.

Wait a minute, I did the pressure test with the gas cap off. Should it have been on and if so shouldn't it raise the pressure slightly?

PatternDayTrader

Well install the filter but the 39psi is within what I would call a gage calibration margin of error. So leave that for now. An egr valve stuck open will do exactly what your saying. Oil on the mass air sensor screen and wire (from the k&n filter) can cause all kinds of trouble. Plugs and wires can cause trouble but usually it will be present at all times, and of course the opti-distributor. It's been my experience the distributor will act up much worse when hot, until one day it won't start cold. Ever again.

toricred

What's the easiest way to test for a stuck egr valve. I'll look at the MAF sensor screen later today, but I need to know if I'll need any more parts or tools before AutoZone closes.

toricred

I put in the new EGR valve today. It was a pain to get the old one out and the new one in because of the tight space back there, but it seems to have fixed the starting and idling problems. It's too soon to tell on the gas mileage.