1999 Mx5 won't start

[jet244]

Would the next step be to check timing? If so whats the best way? Also is there any way to test the cam angle sensor or should i just try out a mates?

[hks_kansei]

Easiest way to check ignition timing is with a light.

Being an nb also check the crank sensor is clean etc.

For valve timing take the rocker cover off and turn the engine to top dead on #1
Check where the cam lobes are, and then check the marks on the cam pulleys line up where they should.


So it has fuel, it has spark, it has air.
I'd be checking compression if you have the gear.

I'd also be making sure the cyls are clear of fuel before putting the plugs in (give it a few cranks without the plugs, should clear it out)

[Okibi]

Have you checked that you're getting spark from both coils and that everything is plugged in around the right way? NB8A coil packs are known to fail.

[jet244]

Easiest way to check ignition timing is with a light.

Being an nb also check the crank sensor is clean etc.

For valve timing take the rocker cover off and turn the engine to top dead on #1
Check where the cam lobes are, and then check the marks on the cam pulleys line up where they should.


So it has fuel, it has spark, it has air.
I'd be checking compression if you have the gear.

I'd also be making sure the cyls are clear of fuel before putting the plugs in (give it a few cranks without the plugs, should clear it out)

The crank sensor is clean. I did a compression test and got around 150 in 3 cylinders and low 140s in the other. I dont have a timing light yet so havent been able to check that and haven't got around to checking the valve timing but i assume the compression test does that?

Also tried starting with the tps and maf unplugged with no result.

Not sure what to try next other than timing light.

[jet244]

Have you checked that you're getting spark from both coils and that everything is plugged in around the right way? NB8A coil packs are known to fail.

yeah checked all that and both coilpacks are new

[bigdog]

If you have spark, fuel and compression then it can only be the timing of the spark or the valve timing stopping it. Given all the sensors are new the logical culprit is the timing belt.

[StanTheMan]

Your car has been off the road for weeks. Its not going to take a huge amount of time to che3ck the easy way described in a post on the previous page.

Get it to TDC guided by a screwdriver. You can also check the timing mark which should also be on TDC on the crank pulley. you don't need a timing light. If your cam sprockets are still lined up correctly it means your mechanical timing is correct.

If the timing belt has skipped a few teeth on the crank sprocket. when both indicators (screwdriver &^ Timing mark on the crank pulley) are lined up. Your cam gears will be out of alignment. 15 minutes work max.on an NA. NB8A couled be 20 minutes rather than pulling it down completely.

If mechanical timing proves to be out . I found it easier to pull it down properly & set the cam timing. Rather than using screwdriver & TDC mark on Flywheel mark. You alsoi need to expose the timing belt pulley to reset it.

But to check & confirm. You don't need to pull it down completely.

*leghorn-foghorn voice*

“Stop, I say stop it boy, you’re doin’ alot of choppin’ but no chips are flyin"

[93_Clubman]

^+1 - if cam timing checks out ok then, given car won't start, check ignition timing as per manga_blue's post here:
viewtopic.php?style=3&f=29&t=60547&start=15
Or gslander's first post here:
viewtopic.php?f=81&t=57581&start=15

[Mr Morlock]

Experts in abundance- not me though- however compression is merely the pressure in the cylinder on the up stroke with valves closed, so timing can be out nominally say a tooth or two and not start but show compression. I would definitely be checking the visuals for cam timing- and what to remove e.g. is it best to remove the cam cover or just observe through the oil filler cap? . Also be careful about putting screw drivers down plug holes and bear in mind that this should not be done other than when the engine is being turned over with control.In the old days a cork could be used or even thumb to feel for compression on the right stroke - it was easier seeing where the rotor button was pointing. That begs the question how to turn the engine over under careful control i.e. not using a starter motor. A question for those that know- how do you check say ignition timing with a timing light if the engine is not running- I don't know and maybe the poster does not either.

[hks_kansei]

Turning an engine over without the starter is as simple as placing a socket or spanner over the large nut on the crank pulley and turning it.

Checking cam timing needs to be done with the rocker cover removed. The oil cap is simply too small of a hole to see the cam position clearly, and also means you can only see one cam.


Using a screwdriver to check for top dead is safe with basic common sense, use one with a handle big enough it won't fall down inside, or even better, one with a long tang so it's always sticking out the top (mx5 stroke is 85mm, so most screwdrivers are more than long enough)

Ignition timing can be checked as long as the car has spark. You can test it with the car simply cranking and not starting (of course, you'll only be able to check base timing, not advance etc, which isn't an issue since you can't change the advance curves on an mx5 anyway)

[StanTheMan]

Gawd never really thought about a screwdriver falling in. OMG LOL imagine if that happened. ahhhh sheeeeeet.

Lucky for me Ive always used a big screw driver.

[StanTheMan]

on that note it is perhaps also a good idea to remove spark plugs in all Cylinders. juts makes it for easier manual turning as per HKS's post without compression resistance.

[jet244]

haven't had time to take the rocker cover off yet but i'll do that tomorrow to check the cam timing. In the meantime there is a buzzing sound coming from in the intake. It sounds kind of like an electrical hum and gets louder if you open the throttle. This only happens when the ignition is in the ON position.

[93_Clubman]

there is a buzzing sound coming from in the intake

ICV if an aftermarket ECU is fitted: viewtopic.php?t=65171
Or ICV, when using factory ECU, if a pod air filter is fitted:
viewtopic.php?style=3&f=29&t=45889

[jet244]

Your car has been off the road for weeks. Its not going to take a huge amount of time to che3ck the easy way described in a post on the previous page.

Get it to TDC guided by a screwdriver. You can also check the timing mark which should also be on TDC on the crank pulley. you don't need a timing light. If your cam sprockets are still lined up correctly it means your mechanical timing is correct.

If the timing belt has skipped a few teeth on the crank sprocket. when both indicators (screwdriver &^ Timing mark on the crank pulley) are lined up. Your cam gears will be out of alignment. 15 minutes work max.on an NA. NB8A couled be 20 minutes rather than pulling it down completely.

If mechanical timing proves to be out . I found it easier to pull it down properly & set the cam timing. Rather than using screwdriver & TDC mark on Flywheel mark. You alsoi need to expose the timing belt pulley to reset it.

But to check & confirm. You don't need to pull it down completely.

*leghorn-foghorn voice*

“Stop, I say stop it boy, you’re doin’ alot of choppin’ but no chips are flyin"

Great news, I suppose, the timing belt seems to be way off. I got the front piston to tdc using a screwdriver and I think that's how the timing marks are supposed to line up on the crank pulley. The cams seem to be pointing off in funny directions. Just wanted to check if the timing is out with you guys before i go putting a new belt in. The old one seems to have some damage. Also does it matter which rotation tdc is for the cam timing or do i have to rotate it 360 to check?