HELP 99 Metro 4cy Keeps Fuel Fouling Plugs

[azazel_18_2]

I have replaced coils because one was shorting out. I replaced the wires and the plugs with ngk plugs. I have replaced the ecu, crankshaft position sensor, and camshaft poition sensor. I have 180lbs of compression across the board. If i clean the plugs and put them in and crank it for a little bit then pull the plugs back out they are fouled with fuel. sometimes I can get lucky and after cleaning the plugs it will start but once you kill it and try to start it again the plugs get fuel fouled. Fuel pressure is right at 40psi and 35psi at running.
HEEEELLLLLPPPPP

[91Caprice9c1]

An oscilloscope reading of injector pulse width would be too nice. We could then determine if the ECM is commanding excessive pulse width (MAP sensor?) or if it is a mechanical malfunction (lazy injectors).

If you could get your hands on a scantool and have a look at "calculated load" and manifold pressure at idle this would give us some good insight as to what the ECM is being fed by the MAP to determine whether or not it is the culprit for fuel fouling.

-MechanicMatt

[Syndrome Zed]

Originally Posted by 91Caprice9c1

An oscilloscope reading of injector pulse width would be too nice. We could then determine if the ECM is commanding excessive pulse width (MAP sensor?) or if it is a mechanical malfunction (lazy injectors).

If you could get your hands on a scantool and have a look at "calculated load" and manifold pressure at idle this would give us some good insight as to what the ECM is being fed by the MAP to determine whether or not it is the culprit for fuel fouling.

-MechanicMatt

Would using a timing light to check the spray pattern help? I read a little trick where you can hook up the clamp on an inductive timing light to the fuel injector wiring harness, shine it into the throttle body, and thanks to the light strobing in sync with the injector pulses, you can see the actual spray pattern made by the injector. I havent' tried it yet (but you can bet I will just for the ness of trying it ) but maybe you'd be able to see if the spray pattern looked heavy?

[91Caprice9c1]

Andrew, I've done this with the throttle bodied metros. I attached my advance timing light as I would to check the timing, but pointed it down the TB and advanced it until I got a good view of the spray pattern. Works best at night =)

Unfortunately AZ's car is not throttle body injected, but multi-port.

-MechanicMatt

PS - Any progress with your poor car man?

*edit - Does the car foul the plugs after warming up? Does it foul them cold? My reasoning is that a bad O2 sensor (not to be confused with the catalyst monitor) can cause excess fuel to get dumped in once the car enters closed loop (~operating temperature). If you could attach a scan tool and look at the HO211 voltage, this could be meaningful information.

[azazel_18_2]

I have replaced the map and the ecu and still the same old crap. Most of the time the car will not start at all and the 2 or three times it has it doesn't throw a code. I just don't know what else could cause this pos not to start. I have replaced everything I can think of and the thing will not start. Somtimes it "gallops" like it wants to start but very rarely starts. I dropped the exhaust pipe and checked the cat and it wasn't clogged. I have spent a shit load of money trying to fix this. I have checked and sdouble checked my fuses. I took it to a GM dealer originally and they told me I had no compression in one cylindetr and it was trashed. Their exact words were,"The engine is trashed but we will buy it from you for $300." Well, I took it home mainly because it still ran just ran poorly. I replaced both coil packed, plugs, and wires and it ran great. Then one time I went out to start it and it just cranked and didn't start. It has 103k miles on it. Timing belt has been changed. I pulled the timing cover off and the timing belt is on perfect. I even bought the GM service manual and it didn't help. I did use NGK plugs also. I am getting a hot blue spark. I pulled the fuel rail and the injectors are spraying. I don't know what to do but cab fare is getting expensive and the dealer can't help me. Any ideas?

[azazel_18_2]

Another thing I can't test is the Coolant Temp Sensor. I would think that would make it run poorly but wouldn't start it from starting. I am going to check the condition of my fuel also.

[91Caprice9c1]

Coolant temp sensor. Thats could be very pertainent here. Again, it would be excellent if you could get a scan tool attached to your car to see what the ECM is seeing in terms of coolant temp. Keep us updated.

-MechanicMatt

[azazel_18_2]

I checked the fuel and it blew up in my face like it should. I will now be replacing the coolant temp sensor. That is the last thing I can think of that it could be.

[azazel_18_2]

I replaced the sensor and guess what? I got the same old crap. No start. Fuel fouling out plugs.

[Crvett69]

what does the coating on the plugs look like? if its a sooty black coating thats the carbon fuel fouling. if you get that on the plugs you need to replace them. with carbon fouling the spark will jump across the plug up inside the plug instead of across the gap under compression pressure. no way to really clean them right, just replace them. have you run a compression check to see what it is? pull all the plugs and floor the accelerator while cranking to check compression. you should have at least 175psi per cyl. any less and that may be causing your fouling problem. also pull fuel return line and make sure its not plugged going back to the tank

[azazel_18_2]

It is just fuel. I have checked compression and it is 185 which is above the 150min the gm book says it needs. Fuel return line is not plugged otherwise I would have high fuel pressure. I was thinking though. It ran before I did the timing belt AND oil pan gasket. It had just silicone but we went back with a gasket. I think this may be my problem BECAUSE the crankshaftn position sensor is bolted on top of the oil pan. This being the crankshaft position sensor is farther away from the thing that triggers the crankshaft position sensor. My guess is a weak signal or not signal. Could this be it? I was checking in my service manual and it says to just use silicone. Makes sense to me. Anybody else? I changed the coolant temp sensor and the same old crap. Any ideas? I really need to get her back on the road.

[brivers]

First thing I would do is put a timing light on it. Is it showing up where it should in the scale. If its off then you you may have the timing belt off a tooth. Then I would try to get crank sensor back to its original position. Maybe elongate holes or use shims, (I'm not familiar with how it bolts on) they are distance sensitive. Since these are the only things that are different from before chances are its one of them. Good luck.

[seadoon1]

On my 90 metro, the spring in the regulator got gummed up and stuck open, flooding the engine. Its under the cap in the top of throttle body. There is a diaphram in there to.

[azazel_18_2]

I GOT IT RUNNING AND IT RUNS WELL!!!! i REMOVED THE OIL PAN, PULLED THE GASKET OFF AND SILICONED THE PAN TO THE BLOCK SETTING THE AIRGAP IN THE CRANKSHAFT POSITION SENSOR BACK WHERE IT WAS. IT FIRED RIGHT UP AND RUNS GREAT. NO FUEL FLOODING!!!!! I DON'T UNDERSTAND WHY THEY WOULD MAKE A PAN GASKET IF IT WILL MAKE YOUR CAR NOT START!!!! I HAVE STARTED IT ABOUT A DOZEN TIMES AND IT RUNS GREAT!!!

[91Caprice9c1]

Congradulations. Maybe we wont omit information next time. It wasn't until post 11 in this thread, after an entirely different thread was exhausted, that you mentioned the pan gasket. In any case, I'm glad you go to the bottom of it, and thank you for keeping us abreast! A couple of lessons learned from your delima.

-MechanicMatt