SurgeNJ

I SeaFoamed my 83 280ZX N/A last night by putting 1/3 can each in vaccuum line, crank case & gas tank. I did what needs to be done but now I have the car idling at 1200 RPMs then after a few seconds it ramps up to 1700-1800 RPM and then starts the 1800 to 1200 & back to 1800 and so forth till I shut off the motor. What could be the problem? TPS? Do I just adjust it down to 700 RPM? The 1800 to 1200 & back to 1800 and so forth happened every once in a while before the sea foam when I would let off the accelerator so it is an exsisting condition. Any suggestions? Thanks in advance.

FricFrac

XenonS130 and download the FSM - that's a better cure than a can of Seafoam...

zxguy1986

Thanks for your post. I gotta go read the instructions on a can of Seafoam now... Other than your weird idle thing, can you tell us what you wanted/expected it to do for your 280z when you added it? Maybe it wasn't the answer.

SurgeNJ

I wanted to make car run better which it now does. It is a bit more responsive & has more pick up. Other than idling higher than normal it is now running good.

zxguy1986

Thanks for the info. I checked out the bunch of sites with Seafoam instructions and found these:

Sea Foam Motor Treatment - Sea Foam Sales Company
How to use SeaFoam to clean your Engine - The RIGHT way!
How to use Seafoam to clean up your engine | eHow
SeaFoam Instructions | eHow

Please take a look at them, esp the top one (Seafoam mfr's) and let us know if you did anything way different from what they say to do.

Nobody is citing any potential damage if you use Seafoam correctly. So my guess at this point is that the Seafoam worked for you and it degunked something that wasn't working right before and now it is. The 280z guys here will have a better idea of exactly what that could be. Are all your vacuum hoses newer and well-connected at both ends?

Otherwise, it sounds to me like you have a simple sensor-to-ECU signal problem. Fix that (replace sensor)and you are set for a complete FSM tune-up, including setting your idle where it should be.

Let's give the 280 pros here a shot at this. Good job on keeping her in such good running shape.

Lazlo

Those sypmtoms are similar to what you would have with a vacuum leak. It could be a sensor, or you may just be pulling air from somewhere.

SO basically, I am agreeing with ZX guy

FricFrac

If you go through the FSM it will walk you through pretty much all of the issues you'll run up against. That includes issues with the AFM, CHTS, Vaccum leaks, etc...

SurgeNJ

To update the situation. The car runs great. Sea Foam did it job. Response time is great. I let my mechanic look at it & he confirmed that the issues I have are from a faulty throttle position sensor. Not to do with the Sea Foam. He told me to order it & He will install it correctly! FYI, I followed the Sea Foam manufacurers instructions exactly.

PredatorZ

Great that she is running good, always a good day when another Z is back on the road, well done ! If your electrical connections on the TPS, EFI and MAF are old and not like new anymore, Fricfrac has made up a kit of next gen connectors, I did my 280zx, was about 50$ for the kit, I did a bit of a write up on them in my 81zx post, page 2 I get into the EFI wiring.

https://www.zdriver.com/forums/280zx...y-39110/page2/

Just knowing all the connections are solid makes me feel good, and she has been running like a champ since I worked on her, only 358K on the odometer !

Old Codger

Tisk, Tisk, Tisk....PredatorZ... You told me you were going to spell out the abbreviations



Old Codger