new ignition module and more problems

[djbess]

When I bought my 280zx, it had a problem, that it would cut off randomly while driving, the tach just shot to zero but you can still hear the engine running. So I thought it was the Ignition module, also note, that the plug that is on the side of the IM if it was unplugged it made no difference to the cars running, it just ran fine until it cut off and it took a while to start up.

Today, I got my IM in the mail, I go install it and right away it has a lumpy Idle, I take it out make sure everything was connected properly and still lumpy, I install the old one it takes a while to start but it runs smoother. I put the new one back in and then it still idles lumpy but it starts faster, Also the little plug on the bottom has an affect on idle if I unplug it. After taking off the valve cover I discovered that according to the Chilton my timing chain is stretched. I decided it was to much work to do tonight, so I put everything back together and start it up for kicks and it runs great, I drive up the street and back and it has power and is very smooth. I go back into the driveway put away my tools take down my lights, recheck my engine bay for tools forgot that I had to tighten the bolt on the dist, that I had loosed to set the timing, which was already at 8d BTDC. And the car runs like crap again, full throttle and only 20mph up the street and then won’t rev past 3000rpms. After the car cooled down, I check the TVS to make sure it worked, and it seem to be good. I decide to go for a test drive and then the car sputters until 2200rpms, then it revs to 4k makes power until 6k while on the colder side, after it warmed up wont rev past 3k then wouldn’t rev past 2k and the exhaust manifold was glowing orange, for only a 10min drive. What do I do next?

[First Gen Z]

I'd try a different ECU.

[sideshowbob]

Possible leaky fuel injectors or CS valve. Glowing headers can be a symptom of seriously rich mixture and/or bad valve timing. The chain may have jumped a tooth. Is it smoking? Funny smell? Plug wires connected correctly? Coil check out? Replacing the ECU is expensive and probably a last resort.

[djbess]

well now the car runs fine untill it starts to warm up then it decideds to slowly loose power under 2500 untill it reaches the poin where it will only rev to 2k, and backfire out the intake and rarly the exhaust

[TomoHawk]

Sounds like the thre ignition module is getting weak, or something is messing with the signal. I didn't think the Ignotion Module would wear out?

[my_mad_z]

Have you tried to changed the coil? Coils tend to play up when they get warm.... Also, check your leads as they may be failing as the car warms up as well.

I had a similar problem; when the engine was approaching operating temperature, it would have a lumpy idle and lose power..... I tried everything but had no luck..... I changed the coil and noticed an improvement but the problem was still there..... ended up changing the leads and she was as good as new; I should have done that in the first place but the resistance in the leads was within spec..... problem turned out to be the leads were failing as the engine bay temperature increased.

Check your valve clearances and make sure they are all to speck as well.

Hope you sort the problem out.

Marc.

[TomoHawk]

..... ended up changing the leads and she was as good as new; I should have done that in the first place but the resistance in the leads was within spec..... problem turned out to be the leads were failing as the engine bay temperature increased.

which leads are those?

Is there something other than an OEM replacement forthe ignition module? I'd like to get some information on a 'performance' one.

thx

[my_mad_z]

The ignition leads that run from the distributor to the spark plugs. Cold readings with a multimeter can show that the resistance is within specification, however, a faulty/warn lead can breakdown/fail as its temperature increases.

Not sure if there is a performance ignition module replacement, I've only seen OEM.

[djbess]

well I put the old IM back in and everything is good, maybe the new IM is defective? And with the old IM it takes longer to heat up than the new IM. Also when up unplug the electronic advance on the old one nothing happens but on the new one it makes the idle drop.