Protege - no spark in #1 and #4

[GazzBC]

Hi folks - longtime lurker, first time poster.

Looking for some suggestions on my problem. My wife's 1990 Protege (1.8 SOHC) had been running rough. I did my usual tune up (plugs, wires, new cap & rotor) after which it only ran on 2 cylinders for a day. I'm getting no spark (or extremely weak spark) on #1 & #4. Now I can't get it to start at all.

What I have done so far:

- switched back to the old plugs/wires/cap in case I had a couple of bad plugs or wires, no difference.

- tested for spark using both an inductive light and an inductive timing light - both say no spark on 1 and 4, or at least not enough to register.

- pulled the wires at cap - I get at least some yellow spark.

- tested coil for battery voltage & resistance. All looks good.

- inspected inside of distributer for any obvious damage to the pickup coil - looks okay.

- sprayed carb cleaner around (when it was still running) to see if there were any obvious vacuum leaks - none that I could find.

What I haven't done yet:

- read the codes to see if there is a bad sensor;

- checked to see if the timing belt has slippped (could this possibly result in no spark in 2 cylinders?);

- checked for fuel (although I can smell it flooding and the plugs are wet);

- checked the pickup coil resistance (not sure what it should be).

Any ideas of what I should be looking at next, or what might cause this that I haven't thought of?

[GazzBC]

Oh, and a little more info.

Before it died completely, it had pretty bad lag. After blipping the throttle, it would stumble a bit; I could also hear a small backfire now and then as I let off. Sounds like timing, but with no spark in #1 I can't use a timing light...

[Flash75]

Is your distributor shaft rotating when the engine is cranked? I'm not familiar with your car, but I assume the distributor is driven by the cam. If the timing belt slips it could throw the timing off enough to keep the engine from running. That wouldn't explain why you have no spark #1 & 4 and a good spark on #2 & #3, I assume you did check #2 & #3 for spark? Have you checked compression? If compression is off I would check the valve timing.
A quick way to get a rough idea is to turn the engine so that #1 cylinder is at TDC of the compression stroke. Check that the intake and exhaust valves for #4 cylinder are open at approximately the same opening. Rocking the crankshaft over and under TDC should will help you estimate how much the #4 valves are open. If they are opened approximately equal your valve timing should be close enough for the engine to run.

Clifton

[GazzBC]

Originally Posted by Flash75

Is your distributor shaft rotating when the engine is cranked? I'm not familiar with your car, but I assume the distributor is driven by the cam. If the timing belt slips it could throw the timing off enough to keep the engine from running. That wouldn't explain why you have no spark #1 & 4 and a good spark on #2 & #3, I assume you did check #2 & #3 for spark? Have you checked compression? If compression is off I would check the valve timing.
A quick way to get a rough idea is to turn the engine so that #1 cylinder is at TDC of the compression stroke. Check that the intake and exhaust valves for #4 cylinder are open at approximately the same opening. Rocking the crankshaft over and under TDC should will help you estimate how much the #4 valves are open. If they are opened approximately equal your valve timing should be close enough for the engine to run.

Clifton

Thanks Clifton -

The distributor is turning and I do have spark at #2 and #3. I haven't checked compression yet, but I will. In the meantime, I will be changing the timing belt anyhow as the water pump has been making some horrible noises for a while, so I'll ensure that it hasn't slipped. Beyond that, unless the codes turn up a bad sensor (like maybe the camshaft position sensor or pickup coil), I'm at a loss.

[Flash75]

Now that I know your distributor is turning, you have spark on 2 & 4 and you are going to replace the timing belt, forget my suggestion to check compression. It has nothing to do with cylinders 1 & 4 not firing. I don't have a wiring diagram for your car so I cannot help on the electrical data. Hope you find the problem soon.

Clifton