Grand7

iTrader: (1)

Picked up my 89 FC about 6 months ago and ever since have been dealing with some idle issues along with some other things that could be related.

Back story: I bought the car already with the idle issues thinking it was the TPS as the idle was never consistent ( would idle at 1000rpm, 1200rpm, 1500rpm whenever.) I got the TPS professionally replaced here in the bay area where I'm currently located, it idles at 750rpm just fine while being driven and warmed up.

Now I'm having some flooding issues at start up ( hot or cold ), I am experiencing idle surge when cold at start up for a few seconds, really low rpm ( below 750 ) on a hot start almost and sometimes the car will shut off, and last but not least whenever I let go of the gas ( clutch in or not ) my rpm will also drop extremely low almost and sometimes to a stall.

The original mechanic I took the car to who works on RX-7's all day long told me that these problems are most likely due to the fact the car was converted from automatic to manual which I hadn't done. What I find strange is that he said he has done these conversions plenty of times but didn't say these are problems he's experienced.

Since then I've taken the car to another mechanic who has helped me try to diagnose the problem and we have come to the conclusion of leaky injectors as fuel pressure falls below spec which I believe is 18psi as the minimum when the car is off and the car runs extremely rich all the time literally.

I'm no expert with the rotaries as it's my first one. I've just done a bit of reading on here.

Any help is extremely appreciated. I will post a video soon enough.

Grand7

iTrader: (1)

Sorry wasn't specific enough, my FC is a 1989 N/A no mods.

Grand7

iTrader: (1)

Appreciate the help folks.

Mps_hell

Have you replaced the injectors yet? If not, its a good place to start. Also the fuel pulse damper is more then likely dead. Could also have a bad fuel line or bad vac lines the pump might be tost there is a lot of things that could be doing this

satch

iTrader: (1)

Check for error codes.

Grand7

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I will find out today if the injectors are the culprit or not.

I plan on upgrading the fuel pump to a Walbro 255, any thoughts about this particular fuel pump? The reason for this one is I can get it for a really good price.

Forgive me if this is a dumb question, would I still get an error code if the check engine light isn't even on?

Mps_hell

In an FC I would trust that the check engine light isn't ever going to come on

misterstyx69

iTrader: (142)

Not sure why you would get it when the car runs rich as hell all the time.
a 255 is a waste on an N/A anyways.You are just fine on a stock replacement( plus they'd be cheap in the Parts section..ahem!.plug for club!)
I'd service the injectors,Not run crappy Bottled juice through the tank,I mean take them out and get them cleaned.
..replace the fuel pump,sock and the fuel filter( driver's side frame,under your feet).
You got something else going on there too,but I can't stick a finger on it.
Tps adjustment wouldn't hurt.
Sorry,Not up on the S5 code storage,so you'd just have to find out if you go to pull codes if indeed there is any there to read.

Aaron Cake

iTrader: (1)

There's almost no reason to ever replace injectors unless they are actually bad. They can be serviced at a local injection shop for about $25 per injector and the shop will inform you if you have a bad one.

S5s don't have the same fuel damper issues as S4.

There's no point. Your stock pump already flows more than enough fuel. A Walbro would just overwhelm the stock regulator and cause the car to run rich.

For your problem, make absolutely sure there aren't any vacuum leaks and adjust the TPS (not just replace it).

Grand7

iTrader: (1)

So no fuel pump, got it.

The reason I order injectors over just getting my current ones serviced is because I still have to use the car to get to class and to work, I dearly pay for it when it comes to fueling up. Otherwise I would just done that.

their were no obvious vacuum leaks but after doing some homework, I haven't checked the rats nest yet. I will definitely also check the TPS, I am hoping it was adjusted correctly considering it wasn't cheap.

Appreciate the help so far guys.

Grand7

iTrader: (1)

I'll check the parts section out. From what I've read maybe grounds can be an issue.Since I haven't gotten my injectors in just yet I haven't really been able to check but when I do I'll do a check of all of those points.

I also find out how to pull up the codes, though I do know for a fact the check engine light works but I'll check anyway.

I just figured out how to post videos on here but here is my hot start issue.

DREAM SPEED

In most cases of this problem could be a vacuum issue.

fredward

Yeah I agree. Sounds like vacuum

savicious

I just did a vacuum hose replacement on my 93. Take your time. Take pictures and study the hose diagrams. There are some great sites with info. Be super careful with solenoids. The nipples break easily. I used a razor blade and sliced the hoses off. Most of them chipped off and took considerable time to free from old hoses.

Ebay has kits available for rx7 and they're good quality. They have been mentioned here before and I was very happy with quality and fitment.

Grand7

iTrader: (1)

Hoping to get all of my vacuum hoses replaced soon, now that I know ebay has some good ones I can take a look.

I just got some footage of my cold start that I will upload and hopefully post in the next hour.

Again I appreciate all the help and suggestions from you guys. I want to get this car to finally run healthy.

Grand7

iTrader: (1)

Idle surge starts around the 2 minute mark. The surge always starts right above 1500rpm like clockwork and the engine doesn't rev up to 3k like it should for a few seconds.

Still have yet to go to the shop yet to try and fix this problem. Hopefully tomorrow.

satch

iTrader: (1)

3K rev upon a cold start only occures if the coolant is above a certain temp. There is a temp sensor to tell the engine if it is okay to rev the car upon start up. If the temp of the coolant is too cold the engine protects itself from reving up so it only works when the coolant is above 62 degrees or so as stated in the service manual.

It appears your TPS is in need of being set properly. After 20 minutes of driving the Green/Red wire of the TPS sensor should read 1 volt w/key to the on position. It is imperative the engine is as warm as possible before the reading is to be made. The engine looks to be cutting fuel at 1500 rpm or so and the fuel is then reintroduced which prevents the idle from dropping too low and the process repeats itself over and over.