UKPOC forums

1996 2.0ltr 16v Ford Probe.
Owned by my mother for nearly 20 years. She stopped using it 3 years ago as it was running badly and it was stored - but at age 79, she now wants it fixed!
I've kept it running for many years but am struggling with its current problem.
It starts great and revs cleanly without load up to 4000rpm, but it won't rev any higher. On the road it is seriously down on power but it doesn't pop or bang.

My first thought was that it was another distributor problem and I decided that the HEI ignitor modification would make sense, but no improvement at all. New leads and plugs - no change. The distributor is the Mitsubishi type with the coil built in - so I fitted a new coil - no better. Clogged exhaust or cat perhaps? I disconnected the exhaust in front of the cat - still no better. Bad fuel or failing fuel pump maybe? I got a fuel pressure tester and pressure is good. It increases a little when the vacuum to the fuel pressure regulator is disconnected and also when revved. Fuel is pumping out before the filter at 2 litres per minute. I then used an external type fuel pump to supply fresh fuel to the fuel filter directly. Pressure was good and I saw an improvement - it revved to 5000rpm with no load. But no higher. I'd expect it to rev to the red line and beyond....

So the fresh fuel increased the revs. My thought therefore is that it can't be ignition related. If the ignition was holding it back, it would hold it back whatever the fuel.
I've ordered an adapter to fit the schrader valve on the fuel rail so I can look at that, but I'm struggling for good ideas now . . . .
The spark plugs are sooty . . .
I checked the voltage output from the throttle position sensor and that is ok.
Could the front flexi pipe in the exhaust somehow collapse internally?
The air filter is clean and open.
It just feels like something is restricting it - it wants to go.
I'm tempted to try another engine ECU, but I don't know if I'll run into immobiliser problems . . .
Any thoughts appreciated.

I wold say the vaf or dissy

Thanks for the reply. Dizzy or VAF?
VAF? Is that what I call MAF (Mass Airflow sensor)? Or is it something to do with fuel pressure?
I tested the old fuel and new fuel side by side out of two separate fuel cans and using an external pump and found this time that the results were identical. The car revved to 4750 rpm with no load on both old and new fuel. The old fuel does look more yellow than new but the results were the same.
I read that a faulty MAF could give similar symptons to a bad fuel pump and so put a new MAF on. There were no engine fault codes, but I thought I'd try it ..... no change.
My schrader adapter arrived and screws to the fuel rail, but doesn't seem to depress the valve pin, so doesn't work so I haven't progressed on that.
I did a compression test on all 4 cylinders and all are good.
VAF? What is VAF?

VAF = Vane Air Flow, which is fitted to the Probe. MAF is Mass Air Flow. They do the same job measuring the Air flow to the engine.
They can get dirty and not work properly, take it out and clean.

When I first started reading I was thinking fuel filter, especially after being laid up so long.
Id be inclined to change the fuel, the fuel filter and air filter as a matter of course and Id give the fuel some injector cleaner too. When I bought the FM it had been running on supermarket fuel (false economy in my humble opinion) E5 fuel and injector cleaner fixed low power at tickover and irratic tickover in very short order.

Im also happy to blame all Probe faults on the dizzy and when its starting to fail it does underperform, but your problem sounds like shortage of air or fuel to me.
Too little air, black smoke, too little fuel, white smoke.

So I'd changed the VAF (MAF) without any change - still wouldn't rev properly.
But a new £10 part arrived from China - a Mitsubishi M67580 transistor. This matched the one in an old (previously faulty, possibly original) distributor which I'd kept for spares. I removed the original transistor / ignitor and soldered the new one in place. Removed the HEI module I'd previously fitted and returned the wiring connections back to standard. Fitted the "refurbished" distributor and hey presto the problem was fixed. Lively revving to the red line without hesitation. So either the HEI ignition module or the wiring to it was causing the problem at high revs.
I breathed a sigh of relief and left it parked up for a few days. . . . .
. . . . and then, as seems typical for this car, when I went to road test it, it starts misfiring. It seems like a different fault but was maybe just being masked by the previous fault. I've rechecked the ignition timing - ok. However, it now won't idle when I carry out the checking procedure of linking the GND and TEN connectors in the diagnostic socket. Previously, it would.
The spark plugs are sooting up really quickly so its obviously running rich. I've changed back to the original VAF - no change.
So it will now rev up without load but has a misfire under load.
I'm tempted to get a complete distributor - there are some new ones on Ebay for under £100 but they look different . . . my 4 cyl distributor cap looks like those described as S3 with the plug lead connectors coming straight out of the cap . . . the distributors I've seen advertised have the leads coming out at an angle, more like the 6 cyl ones . . . do we know if they're interchangeable?
Am I back to fuel issues again? Arrrgh!

As your car is a 1996, it is very likely it is a S3 distributor ( dizzy)
It should say on the side of the dizzy and if the caps match even better.

IF the HE1 system used to work well, I think a replacement module for that would be a simple move.
Then look for an original distributor.