Just bought 94 FD, Weird Symptoms? HELP!
 

Just bought a 94 FD (DP, MID PIPE, HKS AIR INTAKE only) Heres the symptoms:

- Rough idle with bogging and it will occasionally stall at a light, AC or no.
- Idle exhaust smells rich
- When driving, as I shift the RPMs stay high for about 2 seconds after I depress the clutch to shift, then the RPMs come down to normal... This happens with about 50% of shifting...

And heres the weird one:

When driving/accelerating all is fine until I hit a bump/crack and the acceleration blips hard, to the point that it feels like the car stalled then 1 second later it gets right back in to accelerating.

So, any help is appreciated. I am new to RX-7s and I love the car so far, I just want it to work right! Thanks

Hi miami...

(DP, MID PIPE, HKS AIR INTAKE only) ...

Are you sure these are the only mods??

stalling at idle most time after cold start can be a symptom of larger injectors and the ecu is not exactely tuned with new lag-time.
rich smelling is normal when you run completely decat as it sounds when you have a car with replaced DP and Mid Pipe.


All in all it sounds that your ecu doesen´t really know what to do when idle or other RPM controlling by the ecu isn´t correct.
Maybe caused by the mods.

Do you still have the original ecu?

greetings marc

It sounds funny but, check to see if the electrical connector is plugged in and seated snug on the throttle body.

right!
most times the easiest and most stupid sounding failures cause such behaviours!

Problems
 

As far as I know the ECU has not been changed, like I said I just bought the car 2 days ago and I am going on what I was told. I'll check the electrical connector on the Throttle Body today, that would be absolutely great if that was the problem. Would that explain the weird RPM sticking high when I shift?

Can you take a picture of the engine bay? If the car is running the stock ECU and has had the airpump removed (for the midpipe), then it will idle like crap at the stock idle rpms. There are some work-arounds for this if it is the case with the car.

Engine Bay
 

Here is the engine bay - I know it is dirty, I promise I'll work on that.

BTW the hose that goes nowhere resting on the Y pipe was like that along with the hose coming out of the air pump that goes into a little black plastic piece with HKS written on it, also going nowhere...? I'm not familiar with that...? Any input :scratch:

It appears the airpump is still there, however I cannot tell if the electrical connector is hooked up.

That hose is the ACV relief line. It basically just goes no where. You can do something like in this thread to clean things up and not have a hose just laying there:

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/eliminate-air-pump-moo-%241-1-minute-486061/

(Dale's site is down, but there is more information and pictures in the thread)

Please help diagnose!
 

Thx Mahjik, I plugged it up and the MOO is gone forever, thx.

I checked the connections on the air pump and throttle body, both are secure.
I asked about the ECU and injectors, both stock.

Here is the problems I am still trying to diagnose:

- Erradic idle causing the car to stall, sometimes even with AC off.:icon_no2:

- Weird loss of power when I hit a bump that caused HARD hesitation in acceleration.

THX for any help -

Make sure there is still some way for it to vent. You'll notice my old picture in that thread showed some holes drilled in the cap I used.

There could be many causes for this, but start checking the various systems which control the idle. Start with verifying your clutch switch is good. Next, check/clean the ISC. Make sure the dashpot is working and the TPS is adjusted.

This could be related to your problem above or it could be something different. I would suggest fixing one problem at a time. Fix the idle issue then tackle this one (if it still exist).

I would update/change engine ground wires. Classic symptoms of bad engine ground.

Dion

Thanks for the suggestions, I'll work on them this week and keep you posted...