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Stutters and won't rev past 2400


wingnutthehutt

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I have a 76 280Z. All stock to the BOMK. I started it today after sitting for four or five months. Started on first crank. Let it idle for a while, let it get close to temp, and revved it a little. Sounded fine. Or as fine as normal. Shut it down and gave it a bath. Started it up, let it get to temp, and then went to take it around the block. The car started to sputter as soon as it hit 2400. I almost got rear ended cuz the thing pretty much shook me to a pulp. It was like the rev limiter had engaged, but not quite the same.

 

I pulled it over and it still idled fine. Popped the hood and listened. The MAF gets really loud when it cuts out. I think that's just becuase of the lack of engine noise relative to the TP. I started it up later when it had cooled down to change spots in the driveway and it seemed fine.

 

I'm going to check again in the morning and let it get up to temp and see what happens then.

 

I've searched and no one had anything quite like this. Clues? Suggestions?

 

Thanks,

Carl

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There is a accel switch on the drivers side of the engine - about midway down the engine - you got it wet. Disconnect it , dry it out, put some dielectric grease in it and put it back together. Engine should run fine until you get it wet again. This is a VERY typical problem with the L28.

Or - if you wait until tomorrow the problem will probably magically go away.

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Gave IT a bath, the car, not me. I rinsed out the engine compartment with a hose. I've done if before with no ill effects, but maybe four months of sitting added up to a further decayed connector was my first thought. Went out this morning. Pulled the cap, everything's clean and dry. Checked the TPS connection, it's good. Started it up, sputters even worse.

 

Now it's running on less than 6 cylinders, sounds more like 4. Blows lots of blue fuel soaked smoke. Unfortunately, it won't stay running long enough for me to check the plug cables or to pull them and check which cylinder it is. I know that 5 has low compression.

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When you checked the TPS connector did you carefully blow it out or just look at it? Trust me - it takes literally just a microscopic amount of moisture to cause the problem you're having with the 2400 RPM stuttering. The other symptoms you're describing are another problem. If you can get your engine to run by itself I'd let it idle for about 30 minutes after coming to tmeperature and then shut it down and try it 6-8 hours later after it's had time to thoroughly dry itself out.

Hve you checked the SECRET aluminum bullet connectors about 18" into your wiring harness from the engine temp and thermotine sensors on your thermostat housing? Those can also cause a very rich running conditon as they are wrapped in the wiring insulation and corrode over time.

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I pulled if off and blew it out, slid it on and off five or six times to remove anything else that may have been in there and blew it out again.

 

Phantom, I've never heard of these SECRET connectors. I'll go search for them and see what I can do right now. When I ran it on a smog machine it came up way rich already, so that may help no matter what.

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I cleaned those connectors. Still no improvement. Also tried pulling the air filter in attempt to lien it out a little bit. No dice.

 

I have a theory, tell me if I'm totally off base here.

 

Since I know it has a blown headgasket- is it possible that when the engine got to a certain point it increased suction on exhuast stroke pulled the gasket enough to lose compression on one or two more cylinders? And at a certain point it became bad enough that now it's completely blown, or am I still facing an electrical issue?

 

 

I can't get it to run at all without my hand on the throttle linkage now, so I have a feeling I'm not going to get much further with the tools at hand. If I could get it home to Sacramento, I could pull out a compression tester and a voltmeter. But here, at my mom's house in Concord, CA, I'm pretty much limited to a couple of screwdrivers.

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I cleaned those connectors. Still no improvement. Also tried pulling the air filter in attempt to lien it out a little bit. No dice.

 

So you found the "lumps" in the insulation, peeled it away, and cleaned the connectors? THat's great. NOw you need to pull the plugs and clean them.

 

I have a theory' date=' tell me if I'm totally off base here.

 

Since I know it has a blown headgasket- is it possible that when the engine got to a certain point it increased suction on exhuast stroke pulled the gasket enough to lose compression on one or two more cylinders? And at a certain point it became bad enough that now it's completely blown, or am I still facing an electrical issue?[/quote']

 

You're kidding. You're asking about how to get an engine running that you know has a blown head gasket?!?! Fix that first and then come back.

 

 

I can't get it to run at all without my hand on the throttle linkage now, so I have a feeling I'm not going to get much further with the tools at hand. If I could get it home to Sacramento, I could pull out a compression tester and a voltmeter. But here, at my mom's house in Concord, CA, I'm pretty much limited to a couple of screwdrivers.
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Ok, since I'm starting to catch some flack now, to clarify. It was running and reliable when I parked it a few months ago. I used it as a commuter all the time until it came up due for smog and failed a pre-test. It was gradually putting out less power, but not burning oil. It started going through water so I stopped driving it.

 

Basically, I'm now going to write off this entire car. I have little interest in rebuilding an L28 for this car. I'm pretty fed up with it. It's been a money pit since the day I registered it.

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Dr Hunt, that has always been my viewpoint. Why spend money on a pacemaker when you can drop in the heart of a lion!

 

Pulled the plugs, they were filthy, swapped in some new ones. Started, ran good for about four seconds and started sputtering again. Pulled a plug and it was fuel fouled already and felt like some oil too.

 

Stick a fork in it. It's done.

 

It's an N42 head, block casting reads L28 074228. What block does that make it?

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  • 2 months later...

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