I have a 1994 with manual transmission with a very weird ignition problem. Or I should say, what I believe to be an ignition problem. I have had her to 2 shops and neither could find the solution.

The car starts, runs and drives perfectly whether cold or when up to operating temp. Other than my problem, there isn’t a single electrical abnormality at all.

Here’s the problem. When driving him on my favorite road, if I’m going 60-70mph and apply relatively hard braking say, 50% the engine immediately dies and the ignition light comes on. It’s as if someone literally turned off the ignition key. I’m usually downshifting (but not always when this happens) and since the ignition is still “on” once I let up the clutch, the engine starts right up and all is fine. This issue popped up out of the blue and now I can repeat it over and over again with I’d say 90% accuracy. So it doesn’t happen 100% of the time. Since I take this road on the way home, I have not tried to reproduce the problem when the engine is cold.

The only time I have ever had this kind of a problem was years ago on a car that had a carb and the floats were totally messed up. But even then it would almost die and not sie completely like this.

For what it’s worth, the entire Optispark was replaced a year ago and I have had no issues at all. Like I said, other than this, the car runs just fine. No codes were thrown when hooked up to an OBD computer. The alternator checked out and the battery is 4 months old and I always connect it to a smart tender when it’s not driven for 2 or 3 days. I checked and it's held in place rock solid.

Any ideas? I have no clue.

Thanks,

Ron B.

 

Sounds like the base idle is set to low + the IAC (idle air control) valve may be lazy.

 

..... ..... Your IAC valve is probably coked up and due for a good cleaning .........

 

I know you said this occurs downshifting or not, but do you always have the clutch in when 50% braking?

 

first problem is determining whether its a him or a her. then ,it may be a case of fuel shortage due to problem in the fuel tank. I would hook up a fuel pressure gage and tape it to the windshield where you can watch it while braking.

 

I don't always have the clutch depressed when braking. I've tried leaving the car in gear and tried different gears and the engine almost always cuts out. Then I tried downshifting while braking doing my best heel-toe and it still almost always stalls. It doesn't seem to matter whether the clutch is depressed or not. I've even tried shifting to neutral and braking hard and it almost always stalls then too.

I will try cleaning the Idle air control valve and see if that helps. Now to FIND the IAC! My idle is set if anything a bit high so I'm hoping the IAC is the answer.

Until I find the culprit, all opinions are welcomed!

 

Have you tried testing on a full fuel tank compared to a near empty tank of fuel?

 

I agree. Sounds like its fuel starving. You might try after it shuts down again, cranking it back up and stomping it. This will slosh the fuel the other way and may reveal low fuel in the tank issue common to the C4. Solution is to keep it above a half or install a sump at the fuel pump. Search this solution here for a how to.