davidjoe007

Hi All,

Yesterday my Z started running funny. It started to bog out between 3000 to 3500 rmp. Especially when your petal to the metal. When you back off the throttle, about half way or more, it will then start to act normal. But when you really punch the trottle, it starts for bog. To me it sounds like either too much gas, or not enough.

I've changed the fuel filter, plugs, rotor, cap, and plug wires. I've never experienced this before, so I'm a bit miffed.

I'm thinking throttle positioning sensor... maybe a clogged muffler. But the truth is I really don't know.

Any ideas ya'll?

Thanks,

davidjoe007

ps the air filter was changed too.

NismoPick

What's the timing set to?
Have you checked all sensors and connections? (mainly the AFM and CHTS)
Yes, also check the tps.

All checks are in the free FSM: XenonS130 - S130 Reference

eXp0N3nT1aL

If your air flow meter is the same as mine( vane type that spins when you hit the gas and moves a vane in a circle.) the spring holding back the vane has to be at a certain tension in order for your air flow meter to read the right air/fuel ratio and tell the computer what amount of fuel to use according to the amount of air. the plastic ring holding the tension of that spring will eventually not want to hold the tension of the spring, causing the car to run richer and richer and richer.... I had to tighten mine every time I wanted to get passed 4000 RPMS lol it would start to sound like a rev limiter, then if you hit the gas harder, it would bog, and of course die if you hit it any harder than that.

davidjoe007

The cylinder head temp sensor looked really old... I changed it but it's still the same.

ANDREW280

Break out the fsm and test the afm sounds like the problem to me as i had the same issues.
-Andrew

kbowden

Not trying to steal the post. But I had basically the same thing happen to me just now. It was her first test drive after getting it running. When I hit around 3000 the AFM makes a popping sound and jumps a lil.

PredatorZ

A lot of Z problems are caused by bad, or lose or corroded connections, I know fricfrac has sourced and made a kit of some high quality connectors that clear up a lot of issues older Z's have, to quote Him " The connectors are the main issue being 30+ years old. I sell a kit that replaces the issue connectors including the hard to find AFM and TPS connector. That resolves a lot of electrical issues. Replacing the battery cables is fairly cheap and the ground can get rid of a lot of electrical problems. Run an extra ground from the negative battery terminal to the ECU then from the ECU to the intake plenum (where most of the sensors are or nearby)." unquote, you might talk to him if you need to more info on electrical , I think he has put extensive research and work into doing it right. Id say start there, eliminate the connectors as a possible issue and move forward with a much more reliable wiring system.

FricFrac

Thanks - you saved me repeating myself. I fell less like a robot today thanks to you It's all true though!

davidjoe007

So I put in a new TPS and no change.

The TPS looked very corroded so decided to replace it. I'll just call it preventative medicine. Anyways... the connector to the TPS looks corroded so I ordered one from O'reilly's. I was surprized they had one. It'll be here in a couple of days.

I also ordered the connector to the CHTS because that looks corroded too.

I really have a feeling that its the AFM. If I swap out the connectors to the TPS and CHTS and things dont change I'll take it to the guys at Dando's for a diagnostic. They're a bit pricey but they're good and I'm sure they can find the problem. Well, I'll keep you guys posted and thanks for all the words of wisdom.

davidjoe007

ps... I forgot to check the timing... she idles great so I really didn't suspect the timing but I gotta make sure. Thanks again for all the imput.

FricFrac

I made up a kit for the TPS, AFM, CHTS, injectors, etc. The TPS and AFM is tough to find.

ZZzzz

good kit too. i got one on mine!

FricFrac

Did you check the AFM with a meter as per the instructions in the FSM (www.xenons130.com)? Meter it out through the harness from the ECU. Rebuilding the AFM is a good idea as well. A lot of times the AFM connector will give you problems especially if the clip is missing.

PredatorZ

If I recall correctly, the connectors Fricfrac sourced are a major improvement over stock, with nice silicon seals. water penetrating into the connectors and Galvanic corrosion plus the harsh environment a car exists spells disaster for good conductivity, I might be wrong on the type of corrosion, of dissimilar metals, but it needs saying, an upgrade to a superior connector with modern engineering will pay for itself in the long run.
heres a link to his past post with some nice pics of the connectors
https://www.zdriver.com/forums/280zx...remlins-34055/

davidjoe007

So you're selling this on ebay right? SWEET!!

davidjoe007

So I installed the new TPS sensor connector and check the timing. Still the same. So it's not the CHTS nor the TPS, nor the connector to the TPS. The timing is good at 8.

I don't have a volt meter... I gotta get one to check the AFM.

FricFrac

Yup but it's cheaper through the forum.

FricFrac

AFM and CHTS are the main problems - TPS just changes the enrichment slightly.

cbaumy34

How much cheaper?

davidjoe007

changed the CHTS connector and still the same.

I have an appt at Dandos for a diagnostic in the morning.

I'll let ya'll know the results.

PS... i also changed the oxy sensor. UGGG...

davidjoe007

So it was the AFM guys... no it's running great.

cbaumy34

Did you just clean the afm or the connectors?

davidjoe007

I had the work done at Dandos... they specialize in Z's... they did a fantastic job. She's running great!

cpark_12

What exactly did they do? Clean it? Replace it?