I have these three symtoms in my 88 gxl.

When I start the car and its cold it will start out at 3000rpms then the idle drops very rapidly and it pretty much surges and pops somtimes then it will idle at 750rpm range and then after the engine warms up the idle will drop to 200-250rpm range "but never stalls".

It backfires alot whenever I decelerate or shift. When I got the car "4months ago" I did the full tune up on it. Changed all fluids, sparkplugs, oil filter, oil etc... "oil every 3months or 3000miles".... Everything but the sparkplugs which two of them have small cracks on the connector caps "duno if thats to big of a deal but they are going to be replaced soon".
What Im wondering is could it be the TPS or somthing else?


Thanks in advance guys!

 

Meant to say the sparkplug wire caps have cracks. Not the sparkplugs.

 

Has the idle screw been tampered with? Why didn't you replace the sparkplug wires?

 

I tried adjusting the idle with the idle screw at one point but no matter what I did "adjustments in small incraments" and it did absolutely nothing to the idle speed. I didnt get around to changing the spark plug wires till today. Still have the same issues...

 

The 3000 rpm idle just after a cold start is normal. The ECU commands the BAC valve and bypass solenoid to that idle for the 1st 17 seconds. In the S5 cars it is called the 'accelerated warm up' system. You can stop it with a simple blip of the throttle if you dont want it to go on for the full 17 sec.

The rest of it sounds like your mixture is too rich during idle and decelleration.

Check trouble codes
Check for closed loop operation
Check for a lean mixture during decelleration: monitor lamp should be off, or the O2 voltage below .45 during decelleration. If not, check operation of the AAV (anti-afterburn valve)
Check fuel pressure: if the regulated pressure is too high, your car will run too rich

When you set the idle, did you put the required jumper in the initial set connector?

Have you set the idle mixture, with the FSM procedure?

Timing and advance?

TPS: check for dropouts, then set to 1k ohm at idle throttle.

Sensors that affect idle mixture:
Variable resistor (idle mixture adjust)
TPS
AFM
Boost
Air pressure
Water thermo
Intake air temp

 

Alright Ill see what I can do once I get off work. I also have another weird symtom... If I run the car hard when its not fully warmed up it blows quiet a bit of smoke but once the engine warms up if I run it hard it wont blow smoke. The car/engine/trans only have 60497 miles. Could the engine be due for a rebuild already? I did some research and people say its probably due to the fact that my oil seals inside the engine are bad?

 

If you think it might be the engine, check compression, and have the coolant checked for presence of exhaust gases (any radiator shop can do it).


The smoke might be a symptom of running too rich; or it might be a separate problem. Running rich will foul the plugs, and the smoke *might* be a symptom of incomplete combustion.

It also might be a symptom of worn out oil seals. Or, if the 'smoke' evaporates, it might actually be steam, which is a sign of blown water seals (common RX7 fault).

You may also have a fault with the oil injection system, which is supposed to inject oil in proportion to the throttle setting. There is a pushrod connected to the throttle linkage that goes down to the Metering Oil Pump, causing it to increase output at high thottle settings. If the cotter pin breaks and the pushrod comes off, the MOP will no longer pump the correct amount of oil for various power settings.

If you suspect the engine internals, I would start with the compression check, then the exhaust gases check, and then start down the list of things that might cause it to run too rich. If you can correct the low idle and rich mixture, you might find that the smoke goes away. If they are corrected and the smoke persists, then you may have to begin to suspect the seals.

The excess oil in the chambers might also be responsible for fouling the plugs, which could be affecting your drivability.

Pull a plug or two and see if they are wet and or fouled?

 

Another thing I notice is the exaust has a very strong smell to it. It's not a sweet smell more like a fresh gasoline smell.

 

Any ideas guys?

 

Also when I start it it no longer idles at 3000rpm for 20secs while in neutral and no longer idles at 1500rpm while in gear clutch disengaged for warm up. It will immediately go down to 750 rpm for a minute and then when it's warmed up it will drop to 250rpm. Sometimes when I steer now the car will stall. Any ideas guys...