MclarenF1

iTrader: (1)

A bit of a background regarding my situation can be found in this thread.

https://www.rx7club.com/power-fc-forum-47/idle-issues-888760/

So to sum it up, I was waiting for my car to warm up last about a week and a half ago. After idling for a little bit, it started to idle really crappy with lots of sputtering. under part throttle it sputters alot, and under WOT, when I get to about 4000rpms, it starts to buck violently. Last time I started it it took forever to get it started. And if I don't give it gas, the car with eventually idle lower and lower until it just dies out. It sounds like a go-kart kinda.

So I did a compression check, and I'm at over 90psi on both rotors, the injectors are showing their proper resistances, and I don't think the plugs are bad considering that they have only a few thousand miles on them, same with the plug wires. The MAP sensor and TPS are both showing normal readings.

Any ideas on what could be the problem? Cause I'm pretty much out of ideas.

oyy0

Sounds like a faulty CTS.

TpCpLaYa

iTrader: (10)

I would try new plugs and maybe swap in some known good wires. I'd also check the coils out. From there I would move on to testing the injectors. All this can be done in a few hours and will eliminate A LOT of the possibilities of your problem.

DaleClark

iTrader: (55)

Sounds like you could have a fuel problem. I've got an FD in my driveway now that I've been helping a buddy (Juan) with. Start it up, it idles OK, start driving and it starts off OK. Get one block down the road and it starts missing, 2 blocks and it's basically running on one rotor, cutting in and out.

The problem in his case is a car that sat for YEARS with a quarter tank of gas. The whole inside of the tank is rusted out and the gas is filled with rust, silt, and dirt. Fuel pump pre-filter was CAKED with thick dirt.

If you haven't done the fuel filter in recent memory, could be a good place to start. Pull the fuel pump and check the in-tank filter and see how the tank looks.

Dale

oppa637

iTrader: (6)

Is your car still idle hunting?

Railgun

Looking at the other thread, I noticed that you had the MAP sensor disconnected. Given the current symptoms, is your TPS plugged in? How are you getting the readings from it? Make sure it's got a good connection. What are you basing your readings from the MAP sensor on?

But to Dale's point, it could be that too, though I would almost expect it to have similar symptoms whether cold or hot it it was an injector problem.

What are your AFRs or are you not able to check them? Once warm, your DC changes and I'm wondering if it's leaning out or enriching too much.

As far as drive-ability, in keeping with the injector theme, it could be a problem with your secondaries if it gets really bad under heavy load or it could just be a fuel delivery issue as well in that your maps are off.

Can you toss up your maps?

MclarenF1

iTrader: (1)

I'm kind of thinking it's a fuel problem, cause the engine is one of those "JDM low mileage engines," so it probably sat for a while.

I did the fuel filter probably about 3k miles ago. I'll pull the fuel pump out and take a look around. I have a Supra pump waiting to be installed anyway.

I'm unable to check my AFRs right now.

I'm still on the Power FC base map. The only things I have changed are the idle recovery settings.

The car doesn't hunt anymore, but I'm pretty sure it would if I lowered the idle recovery settings. Before this current problem it idled at about 1k rpms when cold, and work its way up to around 1500-1600rpms when fully warmed up. Now it idles at about 675-750 when cold and about 1300 when fully warmed.

The TPS readouts are within range, and even swapped in another throttle body I had with a differeny TPS and that didn't do anything.

I'm thinking it might be an injector issue, just because the engine sat. I have a set of injectors on the other engine I have, I'll swap them out with the current ones to see if that does anything.

I think the high idle and hunting may be the LIM manifold gasket, as that was the only place I couln't really get to when spraying around for vacuum leaks. Hopefully I can get this bad boy running before break is over. I've only driven it about 700 miles since the swap.

oppa637

iTrader: (6)

did you cut the remove the 4 wires when installing the pfc

MclarenF1

iTrader: (1)

Didn't need to, my pins were removed.

Speed of light

iTrader: (8)

I had a very similar problem a couple of years ago. Checked everything to no avail.. Turned out to be a bad trailing plug.

MclarenF1

iTrader: (1)

Tonight I decided to swap the rails between my two engines. Upon inspection of the Pulsation Damper for the primaries, I discovered a small hole in the center of the top of it. Problem solved?

And also, would it be a good idea to replace the rubber rings in the injector rail holes on the engine?

dabigesii

iTrader: (4)

I've been having this same problem, I was breaking in my motor built by a very reputable guy...200 miles no boost, fill the tank then starts running like crap. Still haven't figured out the problem, I have to start checking this out then. My fuel pressure guage shows the same psi no matter where I set my regulator at too...this has to be the problem, my vacuum is stable at idle when it does start...no bouncing needle syndrom.

RotaryEvolution

iTrader: (30)

pull the codes and reset them.

MclarenF1

iTrader: (1)

So I replaced the plugs and the fuel rail assembly and it worked!

Now I am back to the hunting idle, but I may onto something. When I first fired it up I had some residual smoke in the engine (had to REALLY deflood it), and some of it was coming out around the exhaust manifold areas. Maybe my lower intake gasket is toast, which is causing a vacuum leak, which is causing my idle hunt?

oyy0

a vacuum leak would cause the idle to change, get it fixed?

MclarenF1

iTrader: (1)

I haven't had a chance to switch the LIM gasket yet. It starts hunting when it reaches 49*C. And throttle off to on is fairly jerky, but that may just be because I have all my thottle plate screws backed all the way out.