Rev limiter????? 95 metro

Does the 95 metro have a rev limiter? If so is it internal to the ecm or a seperate component that can be replaced?

Does the 95 metro have a rev limiter? If so is it internal to the ecm or a seperate component that can be replaced?

I am not an expert, but I am a mechanic that works on most every car for 40 years. I just bought a 93 GEO it feels like a rev limiter on mine also. It could be the hydraulic lifters floating out; but I doubt it. Or it could be just the gas saver cams that are in them, that falls on its face when you try to wind it up above it’s air flowing limits. If I were to guess I would say it is a rev limiter controlled by the ECM, by restricting gas flow to the injectors. I would also add that I am convinced there is nothing else on my car or in my engine that can limit the RPM’S. But you may want to change your gas filter or check fuel pressure and flow rate. Mine was clogged and left me broke down. I forgot to re test the rev limit after the filter change. I never associated the low RPM’S to the clogged gas filter until now! Hmmm? maybe that is what it was. I hope this helps.

I wind the piss out of my Metros. 25mph in first, 40-45 in second, 60 in 3rd, 80 in 4th. I'm not sure how high up that equates to, ~6-6250rpms, but the 3cyls really start to lose their breath around that engine speed because of valve springs, lifter charging and cam profile.

I don't shift that high too often for the sake of longevity but it does seem to drop them into the torque curve in the next gear this way.

My point is: These things should rev well beyond what can be thought of as reasonable. If you feel that your revs are being somehow limited, it is probably a driveability problem and not an ECM enforced ceiling.

-MechanicMatt

O.K., here's what I know for sure.
Fuel pressure and compression is great. Plugs, wires and cap are new. Swapped out almost every sensor except for cam and crank position sensor.
No codes
Car runs pefect and smooth up to about 1500-2000rmps then the injector begins to fire erraticaly. Pouring fuel in while trying to rev makes no difference at all.

Could the timimg belt have slipped? ( Would it still run smooth at low idle?)

Or could either the crank or cam sensor be failing at higher rmps?

Those two sensors are pretty expensive so I dont want to just buy them for test reasons.

I would strongly suggest unbolting the exhaust from the exhaust manifold via the two sprung 14mm hex bolts then running the car. Use penetrating lube if necessary. What you are describing may be indicative of a clogged catalytic converter.


Could the timimg belt have slipped? ( Would it still run smooth at low idle?)

Unlikely.

Or could either the crank or cam sensor be failing at higher rmps?

Yes. Is it really a 95 w/ a crank sensor? I know some cars phased in OBDII in 95 but I haven't seen a 95 metro with a crank sensor.

The camshaft position sensor has a direct effect on coil and fuel injector firing. If you have a manual you can check resistence with a DVOM and air gap with a feeler gauge, I dont have specs handy. Too large an air gap can cause poor signal resolution at higher rpms, make sure the two screws holding the cam sensor in place beneath the rotor are secure.

Look for cracks and/or carbon tracks on the coil itself and measure resistence between the primary and secondary windings with a DVOM if possible.

In addition to the fuel pressure test it would behoove you to perform a fuel volume test. Pressure might be within spec but pressure is relatively static. It's volume that sustains greater engine speeds. You mentioned that adding fuel didn't help but so this may be less of an issue, but it never hurts to be sure. Again I don't have specs for you. How does the key-on engine off pressure compare to the idle pressure, and how does the pressure fluctuate while reving?

And if you have specs, a DVOM and a vacuum pump you can test the MAP sensor for proper range. OBDII would detect a map sensor out of range, I wouldn't expect OBDI to.


-MechanicMatt

O.K., here's what I know for sure.
Fuel pressure and compression is great. Plugs, wires and cap are new. Swapped out almost every sensor except for cam and crank position sensor.
No codes
Car runs pefect and smooth up to about 1500-2000rmps then the injector begins to fire erraticaly. Pouring fuel in while trying to rev makes no difference at all.

Could the timimg belt have slipped? ( Would it still run smooth at low idle?)

Or could either the crank or cam sensor be failing at higher rmps?

Those two sensors are pretty expensive so I dont want to just buy them for test reasons.

The problem sounds like what that other guy said, a clogged cat. To test for this you could do a simple vacuum test. I don’t know what the specs are for the vacuum, if I were to guess, I would say 17 lb. or above would be good, but check the book. If the vacuum is low, most likely it is clogged. Then open up the exhaust and see if it runs great. If this was the problem and it is clogged. Then you must find out what caused it. And fix it to get the good gas mileage.