continued idle problems under load.

[cahman8]

I apologize for starting a new thread. I can't seem to find the original. I have a stock 91 Festiva that doesn't want idle very good under load, in gear or with ac on, both will kill it for sure. As it warms up it will begin to knock and ping under load. I've replaced wires, plugs, cap, and rotor. I've swapped out the ECM from a good running vehicle. I pick up 12 ohms on the ISC only a couple more than the called out amount. I've tried to put a timing light on it but ran into another issue with that. The timing light kills the motor. this is an old school timing light with the 3 alligator clamps, red and black for the battery and green on a spring between the plug and wire. the car also will not run when I ground the single wire STI terminal next to the brake booster as it calls out to do when checking the timing. So now I'm thinking there is an electrical issue causing problems. Can any one give me some advise? oh I also noticed what seems to be a lot of pressure when I remove the gas cap. Car runs out like a top on the highway.

[ryanprins13]

Sounds a bit strange. Do you have a can of ether or something that you can spray all around the intake tubing and intake manifold? I would check for vaccum leaks first like that. If the idle goes up when you spray somewhere thats where your leak is.

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[WmWatt]

A wavering needle on a tachometer or vacuum guage would indicate engine miss.
Sometimes a timing belt can skip and be off by a cog. A search here should bring up list of symptoms.

[cahman8]

I tried spraying alcohol as it was all I could find that I had. No results with that. I'll try to get some ether soon and try it.

[ryanprins13]

I tried spraying alcohol as it was all I could find that I had. No results with that. I'll try to get some ether soon and try it.

Like out of a squirt bottle? I think it needs to be aerosolized/atomized to work.

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[WmWatt]

Alcohol is good. So is plain water. Only difference is water in vaccum leak makes engine stumble while starter fluid, butane, and the like makes it accelerate. Ergo water in a household plant mister is good.

[ryanprins13]

Alcohol is good. So is plain water. Only difference is water in vaccum leak makes engine stumble while starter fluid, butane, and the like makes it accelerate. Ergo water in a household plant mister is good.

It actually gets sucked into smaller vaccum leaks?

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[FestYboy]

Crappy idle, but good mid/top range power... Check your cam timing.

[WmWatt]

"Crappy idle, but good mid/top range power... Check your cam timing." .. and that would be controlled by the timing belt?

[ricko1966]

Yes controlled by the timing belt. Retarding the cam hurts you down low but you pick it up in the upper RPM's Roll the engine over with a socket on the crank pulley until your engine is at TDC on your crank pulley, Pull the upper timing cover there should be a mark at the 12 oclock position of your cam pulley it should align with a pointer just above and behind the cam pulley.

[tooldude]

Timing light should not be able to kill the motor. Without listing lots of maybe's, check alternator case to output terminal for proper charging voltage, then case to battery (+) to see if it's getting there. Check for proper voltage on battery terminals before cranking.

[cahman8]

12.6 on the battery, 14.38 coming out of alternator, 14.18 going to battery. occasionally the voltage going to the battery would drop to about 6 volts for a second then bounce back up.

[cahman8]

yes with a spray bottle or with a sprayer on the bottle anyway. sprayers usually fit on the tall bottles of alcohol. use it for cleaning stuff. use it a lot at work.

[cahman8]

I got around to buying some ether and was unable to find any leaks. I'm gonna check the timing belt this weekend

[cahman8]

Any ideas why the STI connector is killing the engine when grounded. Supposedly it has to be grounded to check timing.