Problem shutting puter down to check timing.

[Sitron]

I have a 97 5spd 3 cylinder geo metro and when I short out the puter per instructions nothing happens. What can I do?

[sas95]

With the engine fully warmed up, disconnect the MAP sensor electrical connector. The engine RPM should then drop to the range 650 rpm - 750 rpm. Now you can check and adjust the ignition timing.

The above info I received from other posts earlier this year on this forum when I was setting the timing on my '95 3-cyl Metro. On a number of Metros, grounding the prescribed line in the diagnostic connector simply does not work. You then have to work with the MAP sensor connector to drop the engine rpm down. Only then should you fiddle with the timing.

[Woodie83]

I think on a 97 the diagnostic connector is behind the glovebox. Doesn't really matter though as the factory setting is NOT what you want. Turn the distributor toward the firewall until you start to hear ping, sounds like there are marbles in your engine. Turn it back until the ping stops and that's the best setting for your engine in your climate with the way you drive and the gas you buy. It's usually around 10 degrees before and will give you better mileage, and more power than the factory setting while increasing exhaust valve life.

[Gene H]

Hey guys. I have the same problem with my 95 1.0 5 spd metro so I thought I would give your suggestion a try. I checked the timing with my light before doing anything. The mark was at 18 deg BTDC. I disconnected the MAP plug while the engine was running. It immediately shut off and check eng light came on. I restarted the eng and rechecked the timing at idle, It was still around 18 deg. So I tried Woodie83's suggestion to listen for the marbles. My distrib moved all the way to the end of the slot (top toward the firewall) and no marbles, but it did run much better. I checked the timing mark at that setting and it is off the pad (toward the firewall). I estimate 23 deg. I left it there and drove it to work today. Performance has improved with no discernible spark knock.
FYI, Last Jan I replaced the water pump and I didn't check the timing at that time. I was careful to get the timing marks lined up when removing and reinstalling the timing belt, but this result leads me to believe that I must have got it wrong. I'm thinking I must be off one tooth on the crank gear. I'm thinking I need to move the cam gear and belt CW until the belt moves one tooth on the crank gear. Before I tear into it this weekend, what do you guys think about this? Am I on the right track? Does this sound reasonable? I need to address the belt issue before I go any further with the computer issue.

[human ills]

I don't understand why you haven't run the jumper wire between the two connectors that is shown on the underhood label.

[Woodie83]

Could be that you've got the cam timing off. Also could be that your car doesn't have enough compression to get ping. Some engines won't ping no matter where you set the ignition timing. In this case, I'd say human ills is right. Jumper the connector and see what your base timing is. If it's in the 12 to 15 area with the distributor all the way at the end, your cam timing is probably right.

[Gene H]

OK guys, I followed your suggestions and here's the situation. In the past I had been using a piece of wire to jumper the connector and it didn't work. Today I used a #10 screw size, 18 ga wire, open end, electrical spade terminal as a jumper and it works great. I set timing at 8 deg with the jumper installed. The mark is is steady. Timing goes up to 12 deg when the jumper is removed so the jumper is working properly. The engine idles rough at this setting. I did a compression check and all cyls are 185 psi. I spliced in a vacuum gage, in-line prior to the MAP sensor, and it has 19-20 Hg and the needle is steady at idle. I sprayed propane around the intake manifold with no change in rpm. I took the car for a spin and it felt like it didn't have as much power. I moved the distributor back to the end of the slot and it runs smoother and seems to have more power. With the distributor at the end of the slot, the timing without jumper is at 23-24 degrees. With the jumper installed, it moves back to 19-20 degrees. Sounds to me like I need to check the timing belt. Do you agree?

[Woodie83]

Yes, sounds as if the cam is one tooth advanced. Nice job of covering all the bases, good troubleshooting technique.

[Gene H]

Well, I removed the belt cover and rotated crankshaft CW until I had compression on cyl 1. Stopped rotating the crankshaft when the arrow pointed directly at the marked tooth on the crank gear. Guess what. The mark on the cam gear lines up with the mark on the backing plate. The set up looks perfect per the picture in my manual. I have a cast cam gear and the mark that lines up is the one that is aligned with the "80C" web of the gear. Does anyone have any other suggestions? Should I move the cam gear one tooth anyway? Should I move the cam gear CW or CCW?

[Gene H]

Moving the cam gear one tooth doesn't,t work. I could have these mixed up but when I moved the cam one tooth CW the timing was way advanced to a point that I couldn't get it back to 5 deg when I retarded the distributor. When I moved the cam gear one tooth CCW from home position it was the opposite effect. Full advance on the distributor would barely get me to the 5 deg mark. In these setups, the timing mark on the cam gear and backplate were very noticeably misaligned. I put everything back to normal. The pin on the timing gear is not broken. Since I was running the car at full advance for a while (23 deg), when I pulled the plugs, I checked gap and color. The gap was correct and the color was a nice tan. I guess I'll pull the crank gear today to check the key. If that turns out to be good, then I'm stumped.

[91Caprice9c1]

Okay guys... I'm going to reveal some density here. Gene, what's the problem you're having?

-MechanicMatt

[Gene H]

When I set my timing at factory setting of 5 deg w/jumper the motor stumbles and shakes. Since Jan I have used a setting of about 10 degrees. The motor ran smooth at the 10 deg setting but when driving I felt that the car was a little sluggish. I tried Woodies83 method of adjusting the timing and it turns out that the engine runs best when the distributor is set at the end of the slot. I ran the car to work 2 days this past week at that extreme setting and found the car to have improved performance and there was no pinging when going up a hill. I was expecting the engine to stumble and miss at that setting. Since it didn’t, I became suspicious of my timing belt setup. As you can see indicated above, my belt setup turned out to be correct. I checked the crankshaft gear key and it is fine. My EGR valve will stall the motor when I depress the diaphragm so that system is working. . I do not have a “check engine” indication so there are no other problems that I know of. I have good vacuum readings at idle. By the way, my motor is a JDM if that matters.
My concern/problem is that I don’t understand why my motor is giving these results. Everyone else says to use 5-8 degrees setting, but that doesn’t work for my motor. I want to run as much advance as I can to improve mileage and performance but I don’t want to hurt my motor. I’ve always believed that too much advance will burn valves. At this extreme end of slot setting the motor should stumble or ping when idling? Mine doesn’t. What could be causing these results and should I be concerned about them? Or should I just crank it up, relax and enjoy the ride.

[91Caprice9c1]

Gene, this is a stumper. I don't have any real good advice despite the thinking I've done over this the passed couple of days.

First, how are your ignition components? Coil, cap, rotor, wires, plugs (you observed the plugs, but only gave info on them after bumping up the timing). A weak/incomplete spark may be slowing down the flame front in the combustion chamber, requiring the spark to occur unusually soon to achieve proper performance.

We can't say that low compression/vacuum is to blame, and seeings how your vacuum at idle is healthy it seems unlikely that you have any exhaust blockage. We can also rule out valvetrain and rotating assembly.

Another thing that can be slowing your flame front, is a rich condition (lean conditions also slow the flame front, but you aren't pinging). And like I said, I'm going out on a limb here and I don't have anything really good to suggest... But if I had to, I'd inspect for a rich condition. Check your fuel pressure, KOEO and at idle, look for a leaky injector, and have a look at your ignition components.


Say guys, how does elevation effect timing? I remember a member once making a remark about timing with regard to altitude... Gene, Marathon WI, you're above 1k ft. ?


-MechanicMatt

[Gene H]

Thanks MechanicMatt:
The distributor, dist cap, wires and coil are the parts that were in the car when I bought it last summer. I didn't replace them at that time since they looked good and the car ran with them. I'll check these parts and also check fuel pressure as soon as I can get to it and I'll report back. I know my MPG has improved since my gas gage is sitting in a better position at 200 miles as it did when I had 150 miles on the tank.
I'll be busy Sat picking up a 92 metro that I bought today for the transmission, $175 for the car, busted A-frame section. 100,000 miles, motor runs really good, transmission is said to be good. We'll see

[Arnoldtheskier]

Timing mark errors:

A factory changed crank gear. Took me the best part of 500 years to figure this out on some 73-4 454 Chev's

Wrong pulleys,dampners, covers with the mark reference wrong..right from the factory.

2 piece dampners where the ring has slipped.

Worn keyways,keys. My favourites are always the ones where it has come loose and gotten sloppy and then they have been really tightened up! Wherever. Then to figure that one out you have to loosen the pulley.

Faults in some timing lights

The advance/retard mechanism in some lights with that feature.

Worn, stuck, advance/retard mechanisms incl vac, cent. including the plate,weights,springs,pins,bushings etc

Worn distributor that allows the driven gear on the distributor to ride up on the drive gear.

Worn timing gears,belts/chains

Sometimes you end up with a piston stop or a clock to find actual tdc. Then you have to reference it on the dampner/pulley. Then to get really accurate you end up having to degree it with a wheel. Then try 2 timing lights.