My dd FC just started running rough for no reason. Like, it's always been reliable as ****, and just NOW decided to be a bitchass.

It sounds, looks, and feels like a vacuum leak, but I(/we/Jesse/microdrifter001) can't find ****.

Here's a video:


http://vimeo.com/10239348


It's running rough as ****, and won't idle.

It's just a stock S4 NA with emissions removed and an intake. All the vacuum nipple caps are accounted for, and there aren't any rips or tears in any vacuum lines.

So far, I've checked:

- AFM, cleaned it and tried another one
- cleaned and replaced plugs
- switched spark plug wires, they're fine
- coilpacks, both are working
- switched fuel pump, ****'s fine
- Put fresh gas in it


Right now, I'm regasketing the upper and lower intake manifolds to see if that helps...I'm ******* running out of ideas though...


Broken TPS?

Stuck seal?





halp.

 

Steam clean it the motor.

IF it's a stuck seal, that might help.

If that solves the problem, use 1oz of pre-mix per gallon of gas & go out and beat on it a little bit.

Check your oil, does it smell like gas?

Have you done anything to it lately?

You can also pull you fuel pump relay, pull a plug and listen to the pulses to see if your seals are intact or working properly.

If you can't distinguish the sounds, hold a paper towel next to the hole and watch for it to be pushed away 3 times per turn of the crank.

If it pushes away a few times, then gets sucked back twards the hole, the you have a stuck seal.

 

Sea Foam it.. maybe injectors are cloggin up?

 

Did you check for codes? That is a simple way to see if a specific component recently failed.

Did you pressurize the intake, spray soapy water all over the engine, and check for bubbles? (spray the brake booster, and its line)

Voltage at fuel pump?

When you rev over ~4k rpm does it sound/feel better? (sorry if that was in the video I am at work cant look at it) Might be a stuck / clogged primary injector. I hate injectors.

Compression tested? At low RPM does it shake the stick and car violently? When you start it can you hear clanking from your AFM flapper slamming shut?

Might have chipped or cracked an apex seal/corner/side seal, or the seal/spring is stuck/jammed.

Good luck.

 

Still running like ****, but I managed to get it up to normal operating temp.

Then, it started smoking a little bit.

Then, I noticed my fuel line to my secondary fuel rail is bulging like a ************.




WTF?

 

...aaand there's very little/no pressure in the return line.

What does this mean?

Dead primary injector(s)?

 

Fuel filter clogged
Regulator **** up

 

well take that hose off and figure out why its bulging. if its bulging that much it needs replacting.
do you actuallu have pressure? like from the pump?

 

damn that fuel lines about to go critical!

 

opps.

 

The return line should never have a lot of pressure. Pressure is only created when there is something restricting or blocking flow. (Such as a fuel pressure regulator stopping flow causing pressure in the line TO the injectors.) There shouldn't be anything blocking flow in your return line to your fuel tank. If you had a lot of pressure I would be concerned.

It looks like that line has semi failed. The first layer of the fuel line got a hole or cut in it, and the heat and slight fuel pressure is causing the line to balloon.

I'm not quite sure how you linked low pressure in the return line to a dead primary injector. Maybe I am missing something? Care to explain a little more?


(When you say return line, are you talking about post FRP to fuel tank, or the line between the primary to secondary injectors?)

 

Replaced fuel hoses with high-pressure fuel-injection hoses and bought a new fuel filter.

Still runs rough.

I give up.

****'s for sale.

https://www.rx7club.com/nw-sale-wanted-classifieds-209/1988-mazda-rx7-gtu-%241000-obo-893292/


lol

 

un plug the TPS. If it does the same thing and doesn't get worse it's the TPS. also make sure all your ground straps are still in good shape. FC's are notorious for both these things causing huge issues.

 

You get everything running smoothly again?