Doesn't have smooth idle at light

Hi friends,
My sister car (94 Madzda protege) has the problem when stop at the light. The engine doesn't run smooth. It tumbles one every 5 seconds. I just recently replaced spark plug wire, spark plug, distributor cap and rotor. I recheck all these parts and they are ok. Please give me a help !!!. Thanks

[GioLanh]

I don't know anything about Protege.
But I can give U some advice about the problem in general.
1) Check timing
2) Might need to raise the idle up (by letting more air in or gas in)
3) It could be engine mount (does it shaking while in park?)

Hi Coldwind,

Yes, it doesn't happen when I park. I did raise the idle speed but the problem still occurs. I couldn't find the timing mark on this car to adjust the timing also. Any ideas are appreciated. Thanks

[GioLanh]

ok, U said it does NOT shake when in park and U did raise the idle up a little but still no change, right?
How many miles does the car have?
I suspect the problem is the engine mount. If the car runs fine in park and shakes a little in Drive at light, 90% is the engine mount.
Look for cracks or worn in the mount (front)!

I think your alternator is going to die. When you stop at a stop sign, the brake lights come on and consume a bit of energy; meanwhile, your alternator may not charge well to your battery. But the battery keeps drain down the power and not enought recharged. You may experience when you driving at night time.
It happened to my car... Hope this helps

[GioLanh]

Originally posted by congtu1
I think your alternator is going to die. When you stop at a stop sign, the brake lights come on and consume a bit of energy; meanwhile, your alternator may not charge well to your battery. But the battery keeps drain down the power and not enought recharged. You may experience when you driving at night time.
It happened to my car... Hope this helps

What u're talking about has nothing to do with his problem

[pLaYbOi]

for god sake...not every car has engine mount problems..

from my experience...u shouldnt adjust the idle<tighten throttle cable>...
most likely...ur engine is having an even mix of air/fuel..
u should clean injectors or have ur tb clean for better mixture..
if that doesnt help...go see a mechanic i guess..

[GioLanh]

Originally posted by pLaYbOi
for god sake...not every car has engine mount problems..

True !

but most of the old cars (100K+ miles) do have this problem.
Conditions:
1) Car shakes when stop at the traffic light
2) Car runs fine in park
3) Spark plugs + wires are new

Conclusions:
1) Engine mount worn (80+% accuracy)
2) Timing is off (20%)
3) ECU problem (10%)

[pLaYbOi]

in all the years<about 6 years now> ive been into cars...i have yet to see one car that needed engine mount to be replaced due to shaking...
probably it was ur car...but u cant apply that to most cars that have over 100k miles...
just so u know...most engine mounts are very solid...unless someone did a really bad swap b4...the mounts shoulnt come loose or worn at all..

Hi friends,
Thanks for all your help about my question. ColdWind, can you help me to understand how the engine tumbling problem is related to the front engine mount (shaking problem) before I made decision to fix this problem. Thanks alot.

[GioLanh]

apple,
I do not visually inspect ur car so I cannot guarantee that engine mount is the problem for ur shaking
Don't just blindly change the engine mount.
U have to make sure it's the problem.
How many miles does this car have?

To check the front engine mount:
1) U can run the car on RAM or jack it up about 12". Look for cracks or worn in the rubber.
2) while the car is on ground, have someone put it in drive. One leg puts on brake, the other push the gas pedal down (rpm goes from 1-4K). If the engine does not jump up too much, the mount is fine. Otherwise, the mount is worn out.

playboi,
I don't know if U read some thread I stated "I did not have much trouble with the cars I owned b/c I changed them so fast"
Anyway, the reason I suspected it was engine mount b/c I've seen quite a lot of those problems in old Honda cars (100+K miles)
If U do not think it's the engine mount, what do U think it's his shaking problem?

I did state in the previous thread that I do not know anything about Protege. It was just my suspicion and it could be wrong.

Hi friends,

Thanks you all for good input about the prolem of my car. I didn't have time to check on it in the past few days. But to answer Coldwind's question, the car only has 76,000 miles. I will let you all know what I find out. Thanks again.