Ok, so I dropped in my rebuilt engine and it started right up, but it idled with a very bouncy idle. Once I tried to rev it up some it just bounces a little more and gets a lot louder. Timing is set, so thats not a problem. I assume I have a vac leak, but could that really make it run like this? I looked all around and sprayed propane around (didn't have anything else handy) and didn't get any idle change that I could detect.

So, is there anything else that could make it do this? Something unplugged, maybe? I'd really like to get it running soon, and I would appreciate any help you can offer.

Thank You.

 

It's not a vac leak, I'm 90% sure.

Have you tested your afm? Do you still have your emissions?

SPec.

 

I have not tested the afm, and I have no emissions. I have gotten rid of the rats nest completely. I have also verified that both primary injectors are working and it has spark on all plugs. I used all new gaskets and ran all new vac lines. I need to get new lines for the 2 that go to the brake booster, but for the moment I just took them out and capped them off since its obviously not running right now (in addition, I have misplaced my shifter lever, so its REALLY not going anywhere.)

Now that the timing is set, it fires up immediately, but it just won't rev up at all. Its actually a pretty stable idle, other than the small bounce. I'll see if I can't get a video of it in the next few days, as time permits.

Also, is it normal for so much of the sound to come from the intake? When I partially open the throttle (or even open the idle adjust screw all the way) I can start to hear a bit of sucking sound coming from the air filter, and it turns to a roar at open throttle. It does have a decent sized streetport.


Edit: I do have a Bonez filter, and the way it mounts causes the AFM to be sideways. Could that be the problem? Its never caused a problem in the past.

 

is this a s4? NA?

 

Its an 87 NA (see sig). It has an s5 UIM on it.

 

did you make sure all ur electrical connections are connected and have all your engine to chassis grounds(ecu grounds etc)?
are spark plugs nice and clean?(not fouled)

video would be big help.

 

sometimes if the battery voltage is low it can cause bouncing idle but first try just dissconnecting it and reconnecting. then if that dosent work throw it on the charger for a bit. i have the bouncing idle issue in my S4 NA from time to time.

 

Define *won't rev up at all*.

I've seen this on my cars twice. It was a stuck TPS issue (starting to hate that word *issue*). I unplugged the TPS and could then drive the car again. Stuck TPS in my case.

Just suggesting to unplug the TPS and see if it will rev.

When mine *would not rev*, I mean it would idle fine, but step fully on the pedal and it'd not go above 1000rpm give or take. I'm talking about a car that was running fine for years and this problem just happened at the store. Stuck tps plunger.

 

First, I am almost 100% sure that everything is connected. I can't find anything thats not connected.

Second, the battery is fine. It has a full charge (I just took it to O'Reilly's and had it checked there) plus the volt meter reads about 14 volts.

I'll check the TPS when I get home, that sounds like a definite possibility.. And what I mean by it won't rev up at all, is just that. It idles around 1200 and bounces a little. When I floor it, it gets a lot louder, and bounces a little more.
I'll update when I get home.

 

AFM or TPS, most likely stuck.

 

Ok, sounds good. I'll check out both of those when I get back. I am already planning on taking off the AFM to mount it properly. At the moment its rotated 90 degrees since that is how the Bonez filter kit mounts the AFM. It was like that when I bought it and I never got around to fixing it, but now seems like a good time.
Thanks for the suggestions.

 

Ok, so the car drives fine with the TPS unplugged? I thought unplugging the TPS would cause it to run badly.

 

on an s5, it will. on most s4's it usually improves driveability because the stock TPS is so jacked up. I have run across a few s4's that refused to run without the TPS, though. I ran an 87 t2 of mine for a couple years with no TPS, seemed to run best that way.

 

That seems really odd. What is the purpose of even having the tps then if you can unplug it and run the same/better?

 

O.O you can unplug it ? WoW these cars surprise me every time I read these forums LOL

 

Yeah, that doesn't seem too logical, but nothing surprises me anymore with this car....

 

The TPS does things like cut the fuel when you let off the pedal and control the emissions related solenods and a couple of other things. It does NOT control fuel delivery as such. That's a afm related jpb. Talking series four narrow band and series five narrow range TPS.

Like most of the sensors, it has a Fail Safe mode it fails to. See FSM.

If you go to the RELATIONSHIP CHART in the Fuel and Emissions section of the series FIVE FSM, you can see the things the TPS narrow range effects. Timing Lead and Trail, BAC, FPR solenoid, Relief and Switching solenods, fuel pump resistor relay and fuel injection amount. Now as to how MUCH it effects these items is another story. And HOW it effects the above is another story. When it says Fuel Injection Amount, it does NOT mean the TPS decides how much fuel to deliver. Plus, remember the Fail Safe Mode or Default Mode if you will.

 

Awesome, thanks for the info Hailers, you never cease to amaze. Now it makes much more sense.

 

you said that the AFM is tilted?..then Straighten it out..if the Flapper on the AFM can't move then the Car is going to BOG under acceleration...Put the AFM to "level"..and see what happens...and to do this,Just Remove your Air Filter(tempoarily,since you Mentioned that the BONEZ filter was hindering you from putting the AFM level).

 

Its fixed!!! I just unplugged the TPS, and it works just fine. Thanks a bunch to everyone that helped, I don't know what I'd do without you!

Now I could drive it if I could just find my damn shifter. Hopefully I can find one at the junkyard tomorrow.

As for the filter, its not that the filter is causing the problem, its just the way the mounting bracket that comes with it is designed. Aaron Cake has a writeup on how to do it right: http://aaroncake.net/RX-7/intake.htm That isn't really causing much of a problem, though, since its been that way for at least 5 years since before I bought the car. I'll fix it this weekend.

 

Get a short shifter I want one to!!!!!

 

I would, but getting the car running completely exhausted my savings account. I literally have 7 dollars left, and that was with twice the amount of money I initially thought I would need. I was also planning on waiting for Aaroncake's short shifter, if thats ever going to happen.
So let this be a lesson to everyone doing this on a budget: plan for AT LEAST 50% more money than you think you need.

 

^ and 50% more time at least. sometimes 100. In my case an anticipated 4 month project took 8 months--that is, to get the car assembled AND actually driveable.

 

Well, if it gives any indication of the time spent, I first pulled the motor in November of 2005. A lot of time was spent accumulating money, but there were COUNTLESS hours spent working on various things; from taking apart/rebuilding parts, cleaning, inventorying, doing odd jobs to get extra money.

I'm going to do a full writeup chronicling the progress of this project. Partly, I want to write it down for my sake, and partly I want other people attempting this to know what all goes into a project like this.

 

damn why didnt i think of that. my plunger got stuck too once, then i banged on it a few times with my hammer and it popped out.lol
we need some more hailers in here. help threads wouldnt have to be so long.