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78 280z won't rev


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I am working on my cooling system and had a mishap which has caused an unusual problem. The car got hot and after adding water was run breifly without the radiator cap. (I know... dumb) The radiator is not stock and the cap is located on the left side. Hot water and steam dosed the left side of the engine and the car began to stumble badly. When I stopped, the car would idle, but would not rev. I managed to limp home but the car would not get above 30 mph. After sitting eight hours, it ran much better but still something is wrong. It will almost run normal at small throttle openings but if you punch the throttle it feels like some cylinders are cutting out. I assumed something got wet and tried displacing the water with WD40. The air flow meter was directly in the path of the water so I removed it and cleaned it and it's connector. Didn't help. The injectors and their connectors are new and so is the water temp sensor. I also removed the distributor cap and inspected using electronics cleaner spray to clean everything. Still no joy. Everything on the engine is on this side (ignition, fuel injection, coil, wiring ect) and it could be anything. I suppose the engine could have been hurt from getting hot as well, but it really didn't get that hot and no water from the exhaust or any outward signs of this. The fact that it improved after sitting for 8 hours makes this (engine damage) less possible in my mind. Any help with suggestions or similar experiences would help. thanks Andy

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Almost sounds like the TPS is wet

You know, that occured to me and I forgot to check it last night. It is right in the vicinity of where the water went and the cover is... well... 28 years old. And it almost seems like an electronic cutting out of something, like how the tps works with the two contact points. Thanks man, I'll check it

or possibly the fuse links (seen that happen also)
That seems less likely as the fusible links (that is what you meant right?) have brand new covers and are on the other side of the engine compartment. Thanks Cruez!
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  • 1 month later...
Guest MHarpham

I am Having the Same EXACT problem as you! I worked on the car all day yesterday and did not get it fixed. Several people at shops and on the computer have mentioned the TPS. Anyway, I will continue to attempt repairs tomorrow after work. I would be very interested in exchanging information with you to solve this problem. My water problem came from the thermostat housing leaking from a bad gasket and blowing water all over the engine. I cant get my car over 50. my whole fuel system for the most part is new. I have a new coil, cap rotor, plugs wires.

Matt

'78 280z 2+2

mattharpham@hotmail.com

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Just pull the connection off the TPS, blow it out good - both pieces - with compressed air. Put some dielectric grease on it and reassemble. YOu should be good to go. I can't count the number of times I came out of a car wash when I had the L28 and had to do that but using my lungs to blow it out. Got a wee bit light-headed each time.

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I don't check this forum much, but anyhow my tps was the problem. I cleaned the tps with electrical contact cleaner that night and never had another problem with it. The 28 year old stock fuel injection has proven a lot of fun and I'm still learning.

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If the car sat for a while with a warm motor it probably evaporated the moisture out of the contact area. Cleaning the contacts with contact cleaner probably did little to actually correct your problem. If, in fact, the contacts were corroded you need to go back and mechanically clean them with a small file or sand paper and then coat them thoroughly with a dielectric grease that will reduce their propensity to corrode and also help keep water away from them if that area gets wet again..

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  • 2 weeks later...
Guest MHarpham

Ok I finally Fixed my 78 so it runs fairly well. The big problem that was causing mine not to rev was the AFM. the two little contacts in it were not touching the circuit board at all. once i bent them back down to touch the board it started running a lot better but still not great. Also found the screw that holds the spring tension to be completely loose. I was not sure how to set that so i lined up the mark on the gear wheel to the glue spot.. That was better but still not good enough so I turned it another complete turn and lined it up the same way. I then Adjusted my timing a bit and had to calm my idle some. The starting running pretty darn good and I was able to drive it almost 200 miles and finally bring it home with no problem. Next thing was that it does not idle all that smoothly. I pulled off my tps sensor and opened it. Compared it to the books picture and found that the idle contact somehow is bent and not making contact at all. I have not been able to tweak that back to work right yet I m affraid to break it. So, I plan to order a new one. Found one at Napa for $45. I hope that any of this helps you with your problem.

MHarpham

'78 280Z

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